The JMP_NOSPEC macro branches to __x86_retpoline_*() rather than the
__x86_indirect_thunk_*() wrappers used by C code. Detect jumps to
__x86_retpoline_*() as retpoline dynamic jumps.
Presumably this doesn't trigger a user-visible bug. I only found it
when testing vmlinux.o validation.
Fixes: 39b735332c ("objtool: Detect jumps to retpoline thunks")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/31f5833e2e4f01e3d755889ac77e3661e906c09f.1611263461.git.jpoimboe@redhat.com
This is basically a revert of commit 644592d328 ("objtool: Fail the
kernel build on fatal errors").
That change turned out to be more trouble than it's worth. Failing the
build is an extreme measure which sometimes gets too much attention and
blocks CI build testing.
These fatal-type warnings aren't yet as rare as we'd hope, due to the
ever-increasing matrix of supported toolchains/plugins and their
fast-changing nature as of late.
Also, there are more people (and bots) looking for objtool warnings than
ever before, so even non-fatal warnings aren't likely to be ignored for
long.
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
The ORC unwinder showed a warning [1] which revealed the stack layout
didn't match what was expected. The problem was that paravirt patching
had replaced "CALL *pv_ops.irq.save_fl" with "PUSHF;POP". That changed
the stack layout between the PUSHF and the POP, so unwinding from an
interrupt which occurred between those two instructions would fail.
Part of the agreed upon solution was to rework the custom paravirt
patching code to use alternatives instead, since objtool already knows
how to read alternatives (and converging runtime patching infrastructure
is always a good thing anyway). But the main problem still remains,
which is that runtime patching can change the stack layout.
Making stack layout changes in alternatives was disallowed with commit
7117f16bf4 ("objtool: Fix ORC vs alternatives"), but now that paravirt
is going to be doing it, it needs to be supported.
One way to do so would be to modify the ORC table when the code gets
patched. But ORC is simple -- a good thing! -- and it's best to leave
it alone.
Instead, support stack layout changes by "flattening" all possible stack
states (CFI) from parallel alternative code streams into a single set of
linear states. The only necessary limitation is that CFI conflicts are
disallowed at all possible instruction boundaries.
For example, this scenario is allowed:
Alt1 Alt2 Alt3
0x00 CALL *pv_ops.save_fl CALL xen_save_fl PUSHF
0x01 POP %RAX
0x02 NOP
...
0x05 NOP
...
0x07 <insn>
The unwind information for offset-0x00 is identical for all 3
alternatives. Similarly offset-0x05 and higher also are identical (and
the same as 0x00). However offset-0x01 has deviating CFI, but that is
only relevant for Alt3, neither of the other alternative instruction
streams will ever hit that offset.
This scenario is NOT allowed:
Alt1 Alt2
0x00 CALL *pv_ops.save_fl PUSHF
0x01 NOP6
...
0x07 NOP POP %RAX
The problem here is that offset-0x7, which is an instruction boundary in
both possible instruction patch streams, has two conflicting stack
layouts.
[ The above examples were stolen from Peter Zijlstra. ]
The new flattened CFI array is used both for the detection of conflicts
(like the second example above) and the generation of linear ORC
entries.
BTW, another benefit of these changes is that, thanks to some related
cleanups (new fake nops and alt_group struct) objtool can finally be rid
of fake jumps, which were a constant source of headaches.
[1] https://lkml.kernel.org/r/20201111170536.arx2zbn4ngvjoov7@treble
Cc: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Create a new struct associated with each group of alternatives
instructions. This will help with the removal of fake jumps, and more
importantly with adding support for stack layout changes in
alternatives.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:
#include "warn.h"
#include "arch_elf.h"
it does not make it apparent from which directory the file comes from.
To make it slightly better, and actually to avoid name clashes some arch
specific files have "arch_" suffix. And files from an arch folder have
to revert to including via ../ e.g:
#include "../../elf.h"
With additional architectures support and the code base growth there is
a need for clearer headers naming scheme for multiple reasons:
1. to make it instantly obvious where these files come from (objtool
itself / objtool arch|generic folders / some other external files),
2. to avoid name clashes of objtool arch specific headers, potential
obtool arch generic headers and the system header files (there is
/usr/include/elf.h already),
3. to avoid ../ includes and improve code readability.
4. to give a warm fuzzy feeling to developers who are mostly kernel
developers and are accustomed to linux kernel headers arranging
scheme.
Doesn't this make it instantly obvious where are these files come from?
#include <objtool/warn.h>
#include <arch/elf.h>
And doesn't it look nicer to avoid ugly ../ includes? Which also
guarantees this is elf.h from the objtool and not /usr/include/elf.h.
#include <objtool/elf.h>
This patch defines and implements new objtool headers arranging
scheme. Which is:
- all generic headers go to include/objtool (similar to include/linux)
- all arch headers go to arch/$(SRCARCH)/include/arch (to get arch
prefix). This is similar to linux arch specific "asm/*" headers but we
are not abusing "asm" name and calling it what it is. This also helps
to prevent name clashes (arch is not used in system headers or kernel
exports).
To bring objtool to this state the following things are done:
1. current top level tools/objtool/ headers are moved into
include/objtool/ subdirectory,
2. arch specific headers, currently only arch/x86/include/ are moved into
arch/x86/include/arch/ and were stripped of "arch_" suffix,
3. new -I$(srctree)/tools/objtool/include include path to make
includes like <objtool/warn.h> possible,
4. rewriting file includes,
5. make git not to ignore include/objtool/ subdirectory.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Correct objtool orc generation endianness problems to enable fully
functional x86 cross-compiles on big endian hardware.
Introduce bswap_if_needed() macro, which does a byte swap if target
endianness doesn't match the host, i.e. cross-compilation for little
endian on big endian and vice versa. The macro is used for conversion
of multi-byte values which are read from / about to be written to a
target native endianness ELF file.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Architectures without PUSH/POP instructions will always access the stack
though memory operations (SRC/DEST_INDIRECT). Make those operations have
the same effect on the CFA as PUSH/POP, with no stack pointer
modification.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
On arm64, the compiler can set the frame pointer either
with a move operation or with and add operation like:
add (SP + constant), BP
For a simple move operation, the CFA base is changed from SP to BP.
Handle also changing the CFA base when the frame pointer is set with
an addition instruction.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
A valid stack frame should contain both the return address and the
previous frame pointer value.
On x86, the return value is placed on the stack by the calling
instructions. On other architectures, the callee needs to explicitly
save the return address on the stack.
Add the necessary checks to verify a function properly sets up all the
elements of the stack frame.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
The Clang assembler likes to strip section symbols, which means objtool
can't reference some text code by its section. This confuses objtool
greatly, causing it to seg fault.
The fix is similar to what was done before, for ORC reloc generation:
e81e072443 ("objtool: Support Clang non-section symbols in ORC generation")
Factor out that code into a common helper and use it for static call
reloc generation as well.
Reported-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://github.com/ClangBuiltLinux/linux/issues/1207
Link: https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoimboe@redhat.com
- Most of the changes are cleanups and reorganization to make the objtool code
more arch-agnostic. This is in preparation for non-x86 support.
Fixes:
- KASAN fixes.
- Handle unreachable trap after call to noreturn functions better.
- Ignore unreachable fake jumps.
- Misc smaller fixes & cleanups.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2020-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
"Most of the changes are cleanups and reorganization to make the
objtool code more arch-agnostic. This is in preparation for non-x86
support.
Other changes:
- KASAN fixes
- Handle unreachable trap after call to noreturn functions better
- Ignore unreachable fake jumps
- Misc smaller fixes & cleanups"
* tag 'objtool-core-2020-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
perf build: Allow nested externs to enable BUILD_BUG() usage
objtool: Allow nested externs to enable BUILD_BUG()
objtool: Permit __kasan_check_{read,write} under UACCESS
objtool: Ignore unreachable trap after call to noreturn functions
objtool: Handle calling non-function symbols in other sections
objtool: Ignore unreachable fake jumps
objtool: Remove useless tests before save_reg()
objtool: Decode unwind hint register depending on architecture
objtool: Make unwind hint definitions available to other architectures
objtool: Only include valid definitions depending on source file type
objtool: Rename frame.h -> objtool.h
objtool: Refactor jump table code to support other architectures
objtool: Make relocation in alternative handling arch dependent
objtool: Abstract alternative special case handling
objtool: Move macros describing structures to arch-dependent code
objtool: Make sync-check consider the target architecture
objtool: Group headers to check in a single list
objtool: Define 'struct orc_entry' only when needed
objtool: Skip ORC entry creation for non-text sections
objtool: Move ORC logic out of check()
...
applied to indirect function calls. Remove a data load (indirection) by
modifying the text.
They give the flexibility of function pointers, but with better
performance. (This is especially important for cases where
retpolines would otherwise be used, as retpolines can be pretty
slow.)
API overview:
DECLARE_STATIC_CALL(name, func);
DEFINE_STATIC_CALL(name, func);
DEFINE_STATIC_CALL_NULL(name, typename);
static_call(name)(args...);
static_call_cond(name)(args...);
static_call_update(name, func);
x86 is supported via text patching, otherwise basic indirect calls are used,
with function pointers.
There's a second variant using inline code patching, inspired by jump-labels,
implemented on x86 as well.
The new APIs are utilized in the x86 perf code, a heavy user of function pointers,
where static calls speed up the PMU handler by 4.2% (!).
The generic implementation is not really excercised on other architectures,
outside of the trivial test_static_call_init() self-test.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull static call support from Ingo Molnar:
"This introduces static_call(), which is the idea of static_branch()
applied to indirect function calls. Remove a data load (indirection)
by modifying the text.
They give the flexibility of function pointers, but with better
performance. (This is especially important for cases where retpolines
would otherwise be used, as retpolines can be pretty slow.)
API overview:
DECLARE_STATIC_CALL(name, func);
DEFINE_STATIC_CALL(name, func);
DEFINE_STATIC_CALL_NULL(name, typename);
static_call(name)(args...);
static_call_cond(name)(args...);
static_call_update(name, func);
x86 is supported via text patching, otherwise basic indirect calls are
used, with function pointers.
There's a second variant using inline code patching, inspired by
jump-labels, implemented on x86 as well.
The new APIs are utilized in the x86 perf code, a heavy user of
function pointers, where static calls speed up the PMU handler by
4.2% (!).
The generic implementation is not really excercised on other
architectures, outside of the trivial test_static_call_init()
self-test"
* tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
static_call: Fix return type of static_call_init
tracepoint: Fix out of sync data passing by static caller
tracepoint: Fix overly long tracepoint names
x86/perf, static_call: Optimize x86_pmu methods
tracepoint: Optimize using static_call()
static_call: Allow early init
static_call: Add some validation
static_call: Handle tail-calls
static_call: Add static_call_cond()
x86/alternatives: Teach text_poke_bp() to emulate RET
static_call: Add simple self-test for static calls
x86/static_call: Add inline static call implementation for x86-64
x86/static_call: Add out-of-line static call implementation
static_call: Avoid kprobes on inline static_call()s
static_call: Add inline static call infrastructure
static_call: Add basic static call infrastructure
compiler.h: Make __ADDRESSABLE() symbol truly unique
jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved()
module: Properly propagate MODULE_STATE_COMING failure
module: Fix up module_notifier return values
...
- Add deadlock detection for recursive read-locks. The rationale is outlined
in:
224ec489d3: ("lockdep/Documention: Recursive read lock detection reasoning")
The main deadlock pattern we want to detect is:
TASK A: TASK B:
read_lock(X);
write_lock(X);
read_lock_2(X);
- Add "latch sequence counters" (seqcount_latch_t):
A sequence counter variant where the counter even/odd value is used to
switch between two copies of protected data. This allows the read path,
typically NMIs, to safely interrupt the write side critical section.
We utilize this new variant for sched-clock, and to make x86 TSC handling safer.
- Other seqlock cleanups, fixes and enhancements
- KCSAN updates
- LKMM updates
- Misc updates, cleanups and fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"These are the locking updates for v5.10:
- Add deadlock detection for recursive read-locks.
The rationale is outlined in commit 224ec489d3 ("lockdep/
Documention: Recursive read lock detection reasoning")
The main deadlock pattern we want to detect is:
TASK A: TASK B:
read_lock(X);
write_lock(X);
read_lock_2(X);
- Add "latch sequence counters" (seqcount_latch_t):
A sequence counter variant where the counter even/odd value is used
to switch between two copies of protected data. This allows the
read path, typically NMIs, to safely interrupt the write side
critical section.
We utilize this new variant for sched-clock, and to make x86 TSC
handling safer.
- Other seqlock cleanups, fixes and enhancements
- KCSAN updates
- LKMM updates
- Misc updates, cleanups and fixes"
* tag 'locking-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
lockdep: Revert "lockdep: Use raw_cpu_*() for per-cpu variables"
lockdep: Fix lockdep recursion
lockdep: Fix usage_traceoverflow
locking/atomics: Check atomic-arch-fallback.h too
locking/seqlock: Tweak DEFINE_SEQLOCK() kernel doc
lockdep: Optimize the memory usage of circular queue
seqlock: Unbreak lockdep
seqlock: PREEMPT_RT: Do not starve seqlock_t writers
seqlock: seqcount_LOCKNAME_t: Introduce PREEMPT_RT support
seqlock: seqcount_t: Implement all read APIs as statement expressions
seqlock: Use unique prefix for seqcount_t property accessors
seqlock: seqcount_LOCKNAME_t: Standardize naming convention
seqlock: seqcount latch APIs: Only allow seqcount_latch_t
rbtree_latch: Use seqcount_latch_t
x86/tsc: Use seqcount_latch_t
timekeeping: Use seqcount_latch_t
time/sched_clock: Use seqcount_latch_t
seqlock: Introduce seqcount_latch_t
mm/swap: Do not abuse the seqcount_t latching API
time/sched_clock: Use raw_read_seqcount_latch() during suspend
...
encounter an MCE in kernel space but while copying from user memory by
sending them a SIGBUS on return to user space and umapping the faulty
memory, by Tony Luck and Youquan Song.
* memcpy_mcsafe() rework by splitting the functionality into
copy_mc_to_user() and copy_mc_to_kernel(). This, as a result, enables
support for new hardware which can recover from a machine check
encountered during a fast string copy and makes that the default and
lets the older hardware which does not support that advance recovery,
opt in to use the old, fragile, slow variant, by Dan Williams.
* New AMD hw enablement, by Yazen Ghannam and Akshay Gupta.
* Do not use MSR-tracing accessors in #MC context and flag any fault
while accessing MCA architectural MSRs as an architectural violation
with the hope that such hw/fw misdesigns are caught early during the hw
eval phase and they don't make it into production.
* Misc fixes, improvements and cleanups, as always.
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Merge tag 'ras_updates_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RAS updates from Borislav Petkov:
- Extend the recovery from MCE in kernel space also to processes which
encounter an MCE in kernel space but while copying from user memory
by sending them a SIGBUS on return to user space and umapping the
faulty memory, by Tony Luck and Youquan Song.
- memcpy_mcsafe() rework by splitting the functionality into
copy_mc_to_user() and copy_mc_to_kernel(). This, as a result, enables
support for new hardware which can recover from a machine check
encountered during a fast string copy and makes that the default and
lets the older hardware which does not support that advance recovery,
opt in to use the old, fragile, slow variant, by Dan Williams.
- New AMD hw enablement, by Yazen Ghannam and Akshay Gupta.
- Do not use MSR-tracing accessors in #MC context and flag any fault
while accessing MCA architectural MSRs as an architectural violation
with the hope that such hw/fw misdesigns are caught early during the
hw eval phase and they don't make it into production.
- Misc fixes, improvements and cleanups, as always.
* tag 'ras_updates_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mce: Allow for copy_mc_fragile symbol checksum to be generated
x86/mce: Decode a kernel instruction to determine if it is copying from user
x86/mce: Recover from poison found while copying from user space
x86/mce: Avoid tail copy when machine check terminated a copy from user
x86/mce: Add _ASM_EXTABLE_CPY for copy user access
x86/mce: Provide method to find out the type of an exception handler
x86/mce: Pass pointer to saved pt_regs to severity calculation routines
x86/copy_mc: Introduce copy_mc_enhanced_fast_string()
x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()
x86/mce: Drop AMD-specific "DEFERRED" case from Intel severity rule list
x86/mce: Add Skylake quirk for patrol scrub reported errors
RAS/CEC: Convert to DEFINE_SHOW_ATTRIBUTE()
x86/mce: Annotate mce_rd/wrmsrl() with noinstr
x86/mce/dev-mcelog: Do not update kflags on AMD systems
x86/mce: Stop mce_reign() from re-computing severity for every CPU
x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR
x86/mce: Increase maximum number of banks to 64
x86/mce: Delay clearing IA32_MCG_STATUS to the end of do_machine_check()
x86/MCE/AMD, EDAC/mce_amd: Remove struct smca_hwid.xec_bitmap
RAS/CEC: Fix cec_init() prototype
Pull KCSAN updates for v5.10 from Paul E. McKenney:
- Improve kernel messages.
- Be more permissive with bitops races under KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=y.
- Optimize debugfs stat counters.
- Introduce the instrument_*read_write() annotations, to provide a
finer description of certain ops - using KCSAN's compound instrumentation.
Use them for atomic RNW and bitops, where appropriate.
Doing this might find new races.
(Depends on the compiler having tsan-compound-read-before-write=1 support.)
- Support atomic built-ins, which will help certain architectures, such as s390.
- Misc enhancements and smaller fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The motivations to go rework memcpy_mcsafe() are that the benefit of
doing slow and careful copies is obviated on newer CPUs, and that the
current opt-in list of CPUs to instrument recovery is broken relative to
those CPUs. There is no need to keep an opt-in list up to date on an
ongoing basis if pmem/dax operations are instrumented for recovery by
default. With recovery enabled by default the old "mcsafe_key" opt-in to
careful copying can be made a "fragile" opt-out. Where the "fragile"
list takes steps to not consume poison across cachelines.
The discussion with Linus made clear that the current "_mcsafe" suffix
was imprecise to a fault. The operations that are needed by pmem/dax are
to copy from a source address that might throw #MC to a destination that
may write-fault, if it is a user page.
So copy_to_user_mcsafe() becomes copy_mc_to_user() to indicate
the separate precautions taken on source and destination.
copy_mc_to_kernel() is introduced as a non-SMAP version that does not
expect write-faults on the destination, but is still prepared to abort
with an error code upon taking #MC.
The original copy_mc_fragile() implementation had negative performance
implications since it did not use the fast-string instruction sequence
to perform copies. For this reason copy_mc_to_kernel() fell back to
plain memcpy() to preserve performance on platforms that did not indicate
the capability to recover from machine check exceptions. However, that
capability detection was not architectural and now that some platforms
can recover from fast-string consumption of memory errors the memcpy()
fallback now causes these more capable platforms to fail.
Introduce copy_mc_enhanced_fast_string() as the fast default
implementation of copy_mc_to_kernel() and finalize the transition of
copy_mc_fragile() to be a platform quirk to indicate 'copy-carefully'.
With this in place, copy_mc_to_kernel() is fast and recovery-ready by
default regardless of hardware capability.
Thanks to Vivek for identifying that copy_user_generic() is not suitable
as the copy_mc_to_user() backend since the #MC handler explicitly checks
ex_has_fault_handler(). Thanks to the 0day robot for catching a
performance bug in the x86/copy_mc_to_user implementation.
[ bp: Add the "why" for this change from the 0/2th message, massage. ]
Fixes: 92b0729c34 ("x86/mm, x86/mce: Add memcpy_mcsafe()")
Reported-by: Erwin Tsaur <erwin.tsaur@intel.com>
Reported-by: 0day robot <lkp@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Erwin Tsaur <erwin.tsaur@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/160195562556.2163339.18063423034951948973.stgit@dwillia2-desk3.amr.corp.intel.com
In reaction to a proposal to introduce a memcpy_mcsafe_fast()
implementation Linus points out that memcpy_mcsafe() is poorly named
relative to communicating the scope of the interface. Specifically what
addresses are valid to pass as source, destination, and what faults /
exceptions are handled.
Of particular concern is that even though x86 might be able to handle
the semantics of copy_mc_to_user() with its common copy_user_generic()
implementation other archs likely need / want an explicit path for this
case:
On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote:
> >
> > However now I see that copy_user_generic() works for the wrong reason.
> > It works because the exception on the source address due to poison
> > looks no different than a write fault on the user address to the
> > caller, it's still just a short copy. So it makes copy_to_user() work
> > for the wrong reason relative to the name.
>
> Right.
>
> And it won't work that way on other architectures. On x86, we have a
> generic function that can take faults on either side, and we use it
> for both cases (and for the "in_user" case too), but that's an
> artifact of the architecture oddity.
>
> In fact, it's probably wrong even on x86 - because it can hide bugs -
> but writing those things is painful enough that everybody prefers
> having just one function.
Replace a single top-level memcpy_mcsafe() with either
copy_mc_to_user(), or copy_mc_to_kernel().
Introduce an x86 copy_mc_fragile() name as the rename for the
low-level x86 implementation formerly named memcpy_mcsafe(). It is used
as the slow / careful backend that is supplanted by a fast
copy_mc_generic() in a follow-on patch.
One side-effect of this reorganization is that separating copy_mc_64.S
to its own file means that perf no longer needs to track dependencies
for its memcpy_64.S benchmarks.
[ bp: Massage a bit. ]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com
Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
With CONFIG_UBSAN_TRAP enabled, the compiler may insert a trap
instruction after a call to a noreturn function. In this case, objtool
warns that the UD2 instruction is unreachable.
This is a behavior seen with Clang, from the oldest version capable of
building the mainline x64_64 kernel (9.0), to the latest experimental
version (12.0).
Objtool silences similar warnings (trap after dead end instructions), so
so expand that check to include dead end functions.
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Rong Chen <rong.a.chen@intel.com>
Cc: Marco Elver <elver@google.com>
Cc: Philip Li <philip.li@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: kasan-dev@googlegroups.com
Cc: x86@kernel.org
Cc: clang-built-linux@googlegroups.com
BugLink: https://github.com/ClangBuiltLinux/linux/issues/1148
Link: https://lore.kernel.org/lkml/CAKwvOdmptEpi8fiOyWUo=AiZJiX+Z+VHJOM2buLPrWsMTwLnyw@mail.gmail.com
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Relocation for a call destination could point to a symbol that has
type STT_NOTYPE.
Lookup such a symbol when no function is available.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
When a function is annotated with STACK_FRAME_NON_STANDARD, objtool
doesn't validate its code paths. It also skips sibling call detection
within the function.
But sibling call detection is actually needed for the case where the
ignored function doesn't have any return instructions. Otherwise
objtool naively marks the function as implicit static noreturn, which
affects the reachability of its callers, resulting in "unreachable
instruction" warnings.
Fix it by just enabling sibling call detection for ignored functions.
The 'insn->ignore' check in add_jump_destinations() is no longer needed
after
e6da956795 ("objtool: Don't use ignore flag for fake jumps").
Fixes the following warning:
arch/x86/kvm/vmx/vmx.o: warning: objtool: vmx_handle_exit_irqoff()+0x142: unreachable instruction
which triggers on an allmodconfig with CONFIG_GCOV_KERNEL unset.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/5b1e2536cdbaa5246b60d7791b76130a74082c62.1599751464.git.jpoimboe@redhat.com
It is possible for alternative code to unconditionally jump out of the
alternative region. In such a case, if a fake jump is added at the end
of the alternative instructions, the fake jump will never be reached.
Since the fake jump is just a mean to make sure code validation does not
go beyond the set of alternatives, reaching it is not a requirement.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
save_reg already checks that the register being saved does not already
have a saved state.
Remove redundant checks before processing a register storing operation.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
The set of registers that can be included in an unwind hint and their
encoding will depend on the architecture. Have arch specific code to
decode that register.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Unwind hints are useful to provide objtool with information about stack
states in non-standard functions/code.
While the type of information being provided might be very arch
specific, the mechanism to provide the information can be useful for
other architectures.
Move the relevant unwint hint definitions for all architectures to
see.
[ jpoimboe: REGS_IRET -> REGS_PARTIAL ]
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
The way to identify jump tables and retrieve all the data necessary to
handle the different execution branches is not the same on all
architectures. In order to be able to add other architecture support,
define an arch-dependent function to process jump-tables.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Raphael Gault <raphael.gault@arm.com>
[J.T.: Move arm64 bits out of this patch,
Have only one function to find the start of the jump table,
for now assume that the jump table format will be the same as
x86]
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
As pointed out by the comment in handle_group_alt(), support of
relocation for instructions in an alternative group depends on whether
arch specific kernel code handles it.
So, let objtool arch specific code decide whether a relocation for
the alternative section should be accepted.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Now that the objtool_file can be obtained outside of the check function,
orc generation builtin no longer requires check to explicitly call its
orc related functions.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Structure objtool_file can be used by different subcommands. In fact
it already is, by check and orc.
Provide a function that allows to initialize objtool_file, that builtin
can call, without relying on check to do the correct setup for them and
explicitly hand the objtool_file to them.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
GCC can turn our static_call(name)(args...) into a tail call, in which
case we get a JMP.d32 into the trampoline (which then does a further
tail-call).
Teach objtool to recognise and mark these in .static_call_sites and
adjust the code patching to deal with this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135805.101186767@infradead.org
Add the inline static call implementation for x86-64. The generated code
is identical to the out-of-line case, except we move the trampoline into
it's own section.
Objtool uses the trampoline naming convention to detect all the call
sites. It then annotates those call sites in the .static_call_sites
section.
During boot (and module init), the call sites are patched to call
directly into the destination function. The temporary trampoline is
then no longer used.
[peterz: merged trampolines, put trampoline in section]
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135804.864271425@infradead.org
Adds the new __tsan_read_write compound instrumentation to objtool's
uaccess whitelist.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Adds the new TSAN functions that may be emitted for atomic builtins to
objtool's uaccess whitelist.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
- Add support for non-rela relocations, in preparation to merge 'recordmcount'
functionality into objtool.
- Fix assumption that broke under --ffunction-sections (LTO) builds.
- Misc cleanups.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
- Add support for non-rela relocations, in preparation to merge
'recordmcount' functionality into objtool
- Fix assumption that broke under --ffunction-sections (LTO) builds
- Misc cleanups
* tag 'objtool-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Add support for relocations without addends
objtool: Rename rela to reloc
objtool: Use sh_info to find the base for .rela sections
objtool: Do not assume order of parent/child functions
Address KCOV vs noinstr. There is no function attribute to selectively
suppress KCOV instrumentation, instead teach objtool to NOP out the
calls in noinstr functions.
This cures a bunch of KCOV crashes (as used by syzcaller).
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Merge tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Borislav Petkov:
"Three fixes from Peter Zijlstra suppressing KCOV instrumentation in
noinstr sections.
Peter Zijlstra says:
"Address KCOV vs noinstr. There is no function attribute to
selectively suppress KCOV instrumentation, instead teach objtool
to NOP out the calls in noinstr functions"
This cures a bunch of KCOV crashes (as used by syzcaller)"
* tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix noinstr vs KCOV
objtool: Provide elf_write_{insn,reloc}()
objtool: Clean up elf_write() condition
Since many compilers cannot disable KCOV with a function attribute,
help it to NOP out any __sanitizer_cov_*() calls injected in noinstr
code.
This turns:
12: e8 00 00 00 00 callq 17 <lockdep_hardirqs_on+0x17>
13: R_X86_64_PLT32 __sanitizer_cov_trace_pc-0x4
into:
12: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
13: R_X86_64_NONE __sanitizer_cov_trace_pc-0x4
Just like recordmcount does.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
With there being multiple ways to change the ELF data, let's more
concisely track modification.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
The UBSAN instrumentation only inserts external CALLs when things go
'BAD', much like WARN(). So treat them similar to WARN()s for noinstr,
that is: allow them, at the risk of taking the machine down, to get
their message out.
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Merge the state of the locking kcsan branch before the read/write_once()
and the atomics modifications got merged.
Squash the fallout of the rebase on top of the read/write once and atomic
fallback work into the merge. The history of the original branch is
preserved in tag locking-kcsan-2020-06-02.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Before supporting additional relocation types rename the relevant
types and functions from "rela" to "reloc". This work be done with
the following regex:
sed -e 's/struct rela/struct reloc/g' \
-e 's/\([_\*]\)rela\(s\{0,1\}\)/\1reloc\2/g' \
-e 's/tmprela\(s\{0,1\}\)/tmpreloc\1/g' \
-e 's/relasec/relocsec/g' \
-e 's/rela_list/reloc_list/g' \
-e 's/rela_hash/reloc_hash/g' \
-e 's/add_rela/add_reloc/g' \
-e 's/rela->/reloc->/g' \
-e '/rela[,\.]/{ s/\([^\.>]\)rela\([\.,]\)/\1reloc\2/g ; }' \
-e 's/rela =/reloc =/g' \
-e 's/relas =/relocs =/g' \
-e 's/relas\[/relocs[/g' \
-e 's/relaname =/relocname =/g' \
-e 's/= rela\;/= reloc\;/g' \
-e 's/= relas\;/= relocs\;/g' \
-e 's/= relaname\;/= relocname\;/g' \
-e 's/, rela)/, reloc)/g' \
-e 's/\([ @]\)rela\([ "]\)/\1reloc\2/g' \
-e 's/ rela$/ reloc/g' \
-e 's/, relaname/, relocname/g' \
-e 's/sec->rela/sec->reloc/g' \
-e 's/(\(!\{0,1\}\)rela/(\1reloc/g' \
-i \
arch.h \
arch/x86/decode.c \
check.c \
check.h \
elf.c \
elf.h \
orc_gen.c \
special.c
Notable exceptions which complicate the regex include gelf_*
library calls and standard/expected section names which still use
"rela" because they encode the type of relocation expected. Also, keep
"rela" in the struct because it encodes a specific type of relocation
we currently expect.
It will eventually turn into a member of an anonymous union when a
susequent patch adds implicit addend, or "rel", relocation support.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Objtool currently only compiles for x86 architectures. This is
fine as it presently does not support tooling for other
architectures. However, we would like to be able to convert other
kernel tools to run as objtool sub commands because they too
process ELF object files. This will allow us to convert tools
such as recordmcount to use objtool's ELF code.
Since much of recordmcount's ELF code is copy-paste code to/from
a variety of other kernel tools (look at modpost for example) this
means that if we can convert recordmcount we can convert more.
We define weak definitions for subcommand entry functions and other weak
definitions for shared functions critical to building existing
subcommands. These return 127 when the command is missing which signify
tools that do not exist on all architectures. In this case the "check"
and "orc" tools do not exist on all architectures so we only add them
for x86. Future changes adding support for "check", to arm64 for
example, can then modify the SUBCMD_CHECK variable when building for
arm64.
Objtool is not currently wired in to KConfig to be built for other
architectures because it's not needed for those architectures and
there are no commands it supports other than those for x86. As more
command support is enabled on various architectures the necessary
KConfig changes can be made (e.g. adding "STACK_VALIDATION") to
trigger building objtool.
[ jpoimboe: remove aliases, add __weak macro, add error messages ]
Cc: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
check_kcov_mode() is called by write_comp_data() and
__sanitizer_cov_trace_pc(), which are already on the uaccess safe list.
It's notrace and doesn't call out to anything else, so add it to the
list too.
This fixes the following warnings:
kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc()+0x15: call to check_kcov_mode() with UACCESS enabled
kernel/kcov.o: warning: objtool: write_comp_data()+0x1b: call to check_kcov_mode() with UACCESS enabled
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Merge tag 'v5.7-rc6' into objtool/core, to pick up fixes and resolve semantic conflict
Resolve structural conflict between:
59566b0b62: ("x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up")
which introduced a new reference to 'ftrace_epilogue', and:
0298739b79: ("x86,ftrace: Fix ftrace_regs_caller() unwind")
Which renamed it to 'ftrace_caller_end'. Rename the new usage site in the merge commit.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of iterating through all instructions to find the last
instruction each time .rela.discard.(un)reachable points beyond the
section, use find_insn to locate the last instruction by looking at
the last bytes of the section instead.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200421220843.188260-3-samitolvanen@google.com
Randy reported a false-positive:
arch/x86/hyperv/hv_apic.o: warning: objtool: hv_apic_write()+0x25: alternative modifies stack
What happens is that:
alternative_io("movl %0, %P1", "xchgl %0, %P1", X86_BUG_11AP,
13d: 89 9d 00 d0 7f ff mov %ebx,-0x803000(%rbp)
decodes to an instruction with CFI-ops because it modifies RBP.
However, due to this being a !frame-pointer build, that should not in
fact change the CFI state.
So instead of dis-allowing any CFI-op, verify the op would've actually
changed the CFI state.
Fixes: 7117f16bf4 ("objtool: Fix ORC vs alternatives")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
- Ensure that direct mapping alias is always flushed when changing page
attributes. The optimization for small ranges failed to do so when
the virtual address was in the vmalloc or module space.
- Unbreak the trace event registration for syscalls without arguments
caused by the refactoring of the SYSCALL_DEFINE0() macro.
- Move the printk in the TSC deadline timer code to a place where it is
guaranteed to only be called once during boot and cannot be rearmed by
clearing warn_once after boot. If it's invoked post boot then lockdep
rightfully complains about a potential deadlock as the calling context
is different.
- A series of fixes for objtool and the ORC unwinder addressing variety
of small issues:
Stack offset tracking for indirect CFAs in objtool ignored subsequent
pushs and pops
Repair the unwind hints in the register clearing entry ASM code
Make the unwinding in the low level exit to usermode code stop after
switching to the trampoline stack. The unwind hint is not longer valid
and the ORC unwinder emits a warning as it can't find the registers
anymore.
Fix the unwind hints in switch_to_asm() and rewind_stack_do_exit()
which caused objtool to generate bogus ORC data.
Prevent unwinder warnings when dumping the stack of a non-current
task as there is no way to be sure about the validity because the
dumped stack can be a moving target.
Make the ORC unwinder behave the same way as the frame pointer
unwinder when dumping an inactive tasks stack and do not skip the
first frame.
Prevent ORC unwinding before ORC data has been initialized
Immediately terminate unwinding when a unknown ORC entry type is
found.
Prevent premature stop of the unwinder caused by IRET frames.
Fix another infinite loop in objtool caused by a negative offset which
was not catched.
Address a few build warnings in the ORC unwinder and add missing
static/ro_after_init annotations
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Merge tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
"A set of fixes for x86:
- Ensure that direct mapping alias is always flushed when changing
page attributes. The optimization for small ranges failed to do so
when the virtual address was in the vmalloc or module space.
- Unbreak the trace event registration for syscalls without arguments
caused by the refactoring of the SYSCALL_DEFINE0() macro.
- Move the printk in the TSC deadline timer code to a place where it
is guaranteed to only be called once during boot and cannot be
rearmed by clearing warn_once after boot. If it's invoked post boot
then lockdep rightfully complains about a potential deadlock as the
calling context is different.
- A series of fixes for objtool and the ORC unwinder addressing
variety of small issues:
- Stack offset tracking for indirect CFAs in objtool ignored
subsequent pushs and pops
- Repair the unwind hints in the register clearing entry ASM code
- Make the unwinding in the low level exit to usermode code stop
after switching to the trampoline stack. The unwind hint is no
longer valid and the ORC unwinder emits a warning as it can't
find the registers anymore.
- Fix unwind hints in switch_to_asm() and rewind_stack_do_exit()
which caused objtool to generate bogus ORC data.
- Prevent unwinder warnings when dumping the stack of a
non-current task as there is no way to be sure about the
validity because the dumped stack can be a moving target.
- Make the ORC unwinder behave the same way as the frame pointer
unwinder when dumping an inactive tasks stack and do not skip
the first frame.
- Prevent ORC unwinding before ORC data has been initialized
- Immediately terminate unwinding when a unknown ORC entry type
is found.
- Prevent premature stop of the unwinder caused by IRET frames.
- Fix another infinite loop in objtool caused by a negative
offset which was not catched.
- Address a few build warnings in the ORC unwinder and add
missing static/ro_after_init annotations"
* tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/unwind/orc: Move ORC sorting variables under !CONFIG_MODULES
x86/apic: Move TSC deadline timer debug printk
ftrace/x86: Fix trace event registration for syscalls without arguments
x86/mm/cpa: Flush direct map alias during cpa
objtool: Fix infinite loop in for_offset_range()
x86/unwind/orc: Fix premature unwind stoppage due to IRET frames
x86/unwind/orc: Fix error path for bad ORC entry type
x86/unwind/orc: Prevent unwinding before ORC initialization
x86/unwind/orc: Don't skip the first frame for inactive tasks
x86/unwind: Prevent false warnings for non-current tasks
x86/unwind/orc: Convert global variables to static
x86/entry/64: Fix unwind hints in rewind_stack_do_exit()
x86/entry/64: Fix unwind hints in __switch_to_asm()
x86/entry/64: Fix unwind hints in kernel exit path
x86/entry/64: Fix unwind hints in register clearing code
objtool: Fix stack offset tracking for indirect CFAs
Kristen found a hang in objtool when building with -ffunction-sections.
It was caused by evergreen_pcie_gen2_enable.cold() being laid out
immediately before evergreen_pcie_gen2_enable(). Since their "pfunc" is
always the same, find_jump_table() got into an infinite loop because it
didn't recognize the boundary between the two functions.
Fix that with a new prev_insn_same_sym() helper, which doesn't cross
subfunction boundaries.
Reported-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/378b51c9d9c894dc3294bc460b4b0869e950b7c5.1588110291.git.jpoimboe@redhat.com
Change objtool to support intra-function calls. On x86, an intra-function
call is represented in objtool as a push onto the stack (of the return
address), and a jump to the destination address. That way the stack
information is correctly updated and the call flow is still accurate.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200414103618.12657-4-alexandre.chartre@oracle.com
Quoting Julien:
"And the other suggestion is my other email was that you don't even
need to add INSN_EXCEPTION_RETURN. You can keep IRET as
INSN_CONTEXT_SWITCH by default and x86 decoder lookups the symbol
conaining an iret. If it's a function symbol, it can just set the type
to INSN_OTHER so that it caries on to the next instruction after
having handled the stack_op."
Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.913283807@infradead.org
With the unconditional use of handle_insn_ops(), INSN_STACK has lost
its purpose. Remove it.
Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.854203028@infradead.org
Now that every instruction has a list of stack_ops; we can trivially
distinquish those instructions that do not have stack_ops, their list
is empty.
This means we can now call handle_insn_ops() unconditionally.
Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.795115188@infradead.org
UNWIND_HINT_RET_OFFSET will adjust a modified stack. However if a
callee-saved register was pushed on the stack then the stack frame
will still appear modified. So stop checking registers when
UNWIND_HINT_RET_OFFSET is used.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200407073142.20659-3-alexandre.chartre@oracle.com
Fix is_fentry_call() so that it works if a call has no destination
set (call_dest). This needs to be done in order to support intra-
function calls.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200414103618.12657-2-alexandre.chartre@oracle.com
Jann reported that (for instance) entry_64.o:general_protection has
very odd ORC data:
0000000000000f40 <general_protection>:
#######sp:sp+8 bp:(und) type:iret end:0
f40: 90 nop
#######sp:(und) bp:(und) type:call end:0
f41: 90 nop
f42: 90 nop
#######sp:sp+8 bp:(und) type:iret end:0
f43: e8 a8 01 00 00 callq 10f0 <error_entry>
#######sp:sp+0 bp:(und) type:regs end:0
f48: f6 84 24 88 00 00 00 testb $0x3,0x88(%rsp)
f4f: 03
f50: 74 00 je f52 <general_protection+0x12>
f52: 48 89 e7 mov %rsp,%rdi
f55: 48 8b 74 24 78 mov 0x78(%rsp),%rsi
f5a: 48 c7 44 24 78 ff ff movq $0xffffffffffffffff,0x78(%rsp)
f61: ff ff
f63: e8 00 00 00 00 callq f68 <general_protection+0x28>
f68: e9 73 02 00 00 jmpq 11e0 <error_exit>
#######sp:(und) bp:(und) type:call end:0
f6d: 0f 1f 00 nopl (%rax)
Note the entry at 0xf41. Josh found this was the result of commit:
764eef4b10 ("objtool: Rewrite alt->skip_orig")
Due to the early return in validate_branch() we no longer set
insn->cfi of the original instruction stream (the NOPs at 0xf41 and
0xf42) and we'll end up with the above weirdness.
In other discussions we realized alternatives should be ORC invariant;
that is, due to there being only a single ORC table, it must be valid
for all alternatives. The easiest way to ensure this is to not allow
any stack modifications in alternatives.
When we enforce this latter observation, we get the property that the
whole alternative must have the same CFI, which we can employ to fix
the former report.
Fixes: 764eef4b10 ("objtool: Rewrite alt->skip_orig")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.499074346@infradead.org
Assign a unique identifier to every alternative instruction group in
order to be able to tell which instructions belong to what
alternative.
[peterz: extracted from a larger patch]
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
While jumping from outside an alternative region to the middle of an
alternative region is very likely wrong, jumping from an alternative
region into the same region is valid. It is a common pattern on arm64.
The first pattern is unlikely to happen in practice and checking only
for this adds a lot of complexity.
Just remove the current check.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20200327152847.15294-6-jthierry@redhat.com
When the current frame address (CFA) is stored on the stack (i.e.,
cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack
offset when there are subsequent pushes or pops. This results in bad
ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the
previous stack pointer on the stack and does a subsequent push.
This fixes the following unwinder warning:
WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0
Fixes: 627fce1480 ("objtool: Add ORC unwind table generation")
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Reported-by: Dave Jones <dsj@fb.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Reported-by: Joe Mario <jmario@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com
Consider all of .entry.text as noinstr. This gets us coverage across
the PTI boundary. While we could add everything .noinstr.text into
.entry.text that would bloat the amount of code in the user mapping.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.525037514@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation of further changes, once again break out the loop body.
No functional changes intended.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.405863817@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
validate_functions() iterates all sections their symbols; this is
pointless to do for !text sections as they won't have instructions
anyway.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.346582716@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for find_insn_containing(), change insn_hash to use
sec_offset_hash().
This actually reduces runtime; probably because mixing in the section
index reduces the collisions due to text sections all starting their
instructions at offset 0.
Runtime on vmlinux.o from 3.1 to 2.5 seconds.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.227240432@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Validate that any call out of .noinstr.text is in between
instr_begin() and instr_end() annotations.
This annotation is useful to ensure correct behaviour wrt tracing
sensitive code like entry/exit and idle code. When we run code in a
sensitive context we want a guarantee no unknown code is ran.
Since this validation relies on knowing the section of call
destination symbols, we must run it on vmlinux.o instead of on
individual object files.
Add two options:
-d/--duplicate "duplicate validation for vmlinux"
-l/--vmlinux "vmlinux.o validation"
Where the latter auto-detects when objname ends with "vmlinux.o" and
the former will force all validations, also those already done on
!vmlinux object files.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.106268040@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Objtool keeps per instruction CFI state in struct insn_state and will
save/restore this where required. However, insn_state has grown some
!CFI state, and this must not be saved/restored (that would
loose/destroy state).
Fix this by moving the CFI specific parts of insn_state into struct
cfi_state.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.045821071@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There's going to be a new struct cfi_state, rename this one to make
place.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.986441913@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Normally objtool ensures a function keeps the stack layout invariant.
But there is a useful exception, it is possible to stuff the return
stack in order to 'inject' a 'call':
push $fun
ret
In this case the invariant mentioned above is violated.
Add an objtool HINT to annotate this and allow a function exit with a
modified stack frame.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.690601403@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Teach objtool a little more about IRET so that we can avoid using the
SAVE/RESTORE annotation. In particular, make the weird corner case in
insn->restore go away.
The purpose of that corner case is to deal with the fact that
UNWIND_HINT_RESTORE lands on the instruction after IRET, but that
instruction can end up being outside the basic block, consider:
if (cond)
sync_core()
foo();
Then the hint will land on foo(), and we'll encounter the restore
hint without ever having seen the save hint.
By teaching objtool about the arch specific exception frame size, and
assuming that any IRET in an STT_FUNC symbol is an exception frame
sized POP, we can remove the use of save/restore hints for this code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.631224674@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instruction sets can include more or less complex operations which might
not fit the currently defined set of stack_ops.
Combining more than one stack_op provides more flexibility to describe
the behaviour of an instruction. This also reduces the need to define
new stack_ops specific to a single instruction set.
Allow instruction decoders to generate multiple stack_op per
instruction.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200327152847.15294-11-jthierry@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the prefix of section name is not '.rodata', the following
function call can never return 0.
strcmp(sec->name, C_JUMP_TABLE_SECTION)
So the name comparison is pointless, just remove it.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The initial register state is set up by arch specific code. Use the
value the arch code has set when restoring registers from the stack.
Suggested-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The .alternatives section can contain entries with no original
instructions. Objtool will currently crash when handling such an entry.
Just skip that entry, but still give a warning to discourage useless
entries.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a function fails its validation, it might leave a stale state
that will be used for the validation of other functions. That would
cause false warnings on potentially valid functions.
Reset the instruction state before the validation of each individual
function.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
POP operations are already in the code path where the destination
operand is OP_DEST_REG. There is no need to check the operand type
again.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If func is NULL, a seg fault can result.
This is a theoretical issue which was found by Coverity, ID: 1492002
("Dereference after null check").
Fixes: c705cecc84 ("objtool: Track original function across branches")
Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@redhat.com
If a switch jump table's indirect branch is in a ".cold" subfunction in
.text.unlikely, objtool doesn't detect it, and instead prints a false
warning:
drivers/media/v4l2-core/v4l2-ioctl.o: warning: objtool: v4l_print_format.cold()+0xd6: sibling call from callable instruction with modified stack frame
drivers/hwmon/max6650.o: warning: objtool: max6650_probe.cold()+0xa5: sibling call from callable instruction with modified stack frame
drivers/media/dvb-frontends/drxk_hard.o: warning: objtool: init_drxk.cold()+0x16f: sibling call from callable instruction with modified stack frame
Fix it by comparing the function, instead of the section and offset.
Fixes: 13810435b9 ("objtool: Support GCC 8's cold subfunctions")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/157c35d42ca9b6354bbb1604fe9ad7d1153ccb21.1585761021.git.jpoimboe@redhat.com
CONFIG_UBSAN_TRAP causes GCC to emit a UD2 whenever it encounters an
unreachable code path. This includes __builtin_unreachable(). Because
the BUG() macro uses __builtin_unreachable() after it emits its own UD2,
this results in a double UD2. In this case objtool rightfully detects
that the second UD2 is unreachable:
init/main.o: warning: objtool: repair_env_string()+0x1c8: unreachable instruction
We weren't able to figure out a way to get rid of the double UD2s, so
just silence the warning.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/6653ad73c6b59c049211bd7c11ed3809c20ee9f5.1585761021.git.jpoimboe@redhat.com
Add explicitly invoked KCSAN check functions to objtool's uaccess
whitelist. This is needed in order to permit calling into
kcsan_check_scoped_accesses() from the fast-path, which in turn calls
__kcsan_check_access(). __kcsan_check_access() is the generic variant
of the already whitelisted specializations __tsan_{read,write}N.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refresh
Resolve these conflicts:
arch/x86/Kconfig
arch/x86/kernel/Makefile
Do a minor "evil merge" to move the KCSAN entry up a bit by a few lines
in the Kconfig to reduce the probability of future conflicts.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull locking updates from Ingo Molnar:
"The main changes in this cycle were:
- Continued user-access cleanups in the futex code.
- percpu-rwsem rewrite that uses its own waitqueue and atomic_t
instead of an embedded rwsem. This addresses a couple of
weaknesses, but the primary motivation was complications on the -rt
kernel.
- Introduce raw lock nesting detection on lockdep
(CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal
lock differences. This too originates from -rt.
- Reuse lockdep zapped chain_hlocks entries, to conserve RAM
footprint on distro-ish kernels running into the "BUG:
MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep
chain-entries pool.
- Misc cleanups, smaller fixes and enhancements - see the changelog
for details"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
Documentation/locking/locktypes: Minor copy editor fixes
Documentation/locking/locktypes: Further clarifications and wordsmithing
m68knommu: Remove mm.h include from uaccess_no.h
x86: get rid of user_atomic_cmpxchg_inatomic()
generic arch_futex_atomic_op_inuser() doesn't need access_ok()
x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()
objtool: whitelist __sanitizer_cov_trace_switch()
[parisc, s390, sparc64] no need for access_ok() in futex handling
sh: no need of access_ok() in arch_futex_atomic_op_inuser()
futex: arch_futex_atomic_op_inuser() calling conventions change
completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()
lockdep: Add posixtimer context tracing bits
lockdep: Annotate irq_work
lockdep: Add hrtimer context tracing bits
lockdep: Introduce wait-type checks
completion: Use simple wait queues
sched/swait: Prepare usage in completions
...
it's not really different from e.g. __sanitizer_cov_trace_cmp4();
as it is, the switches that generate an array of labels get
rejected by objtool, while slightly different set of cases
that gets compiled into a series of comparisons is accepted.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In preparation to adding a vmlinux.o specific pass, rearrange some
code. No functional changes intended.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.924304616@infradead.org
Perf shows we spend a measurable amount of time spend cleaning up
right before we exit anyway. Avoid the needsless work and just
terminate.
This reduces objtool on vmlinux.o runtime from 5.4s to 4.8s
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.800720170@infradead.org
Perf showed that __hash_init() is a significant portion of
read_sections(), so instead of doing a per section rela_hash, use an
elf-wide rela_hash.
Statistics show us there are about 1.1 million relas, so size it
accordingly.
This reduces the objtool on vmlinux.o runtime to a third, from 15 to 5
seconds.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.739153726@infradead.org
Have it print a few numbers which can be used to size the hashtables.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.321381240@infradead.org
Now that func_for_each_insn() is available, rename
func_for_each_insn_all(). This gets us:
sym_for_each_insn() - iterate on symbol offset/len
func_for_each_insn() - iterate on insn->func
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.083720147@infradead.org
There is func_for_each_insn() and func_for_each_insn_all(), the both
iterate the instructions, but the first uses symbol offset/length
while the second uses insn->func.
Rename func_for_each_insn() to sym_for_eac_insn() because it iterates
on symbol information.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.024341229@infradead.org
Trivial 'cleanup' to save one indentation level and match
validate_call().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160923.963996225@infradead.org
A recent clang change, combined with a binutils bug, can trigger a
situation where a ".Lprintk$local" STT_NOTYPE symbol gets created at the
same offset as the "printk" STT_FUNC symbol. This confuses objtool:
kernel/printk/printk.o: warning: objtool: ignore_loglevel_setup()+0x10: can't find call dest symbol at .text+0xc67
Improve the call destination detection by looking specifically for an
STT_FUNC symbol.
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/872
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25551
Link: https://lkml.kernel.org/r/0a7ee320bc0ea4469bd3dc450a7b4725669e0ea9.1581997059.git.jpoimboe@redhat.com
Clang has the ability to create a switch table which is not a jump
table, but is rather a table of string pointers. This confuses objtool,
because it sees the relocations for the string pointers and assumes
they're part of a jump table:
drivers/ata/sata_dwc_460ex.o: warning: objtool: sata_dwc_bmdma_start_by_tag()+0x3a2: can't find switch jump table
net/ceph/messenger.o: warning: objtool: ceph_con_workfn()+0x47c: can't find switch jump table
Make objtool's find_jump_table() smart enough to distinguish between a
switch jump table (which has relocations to text addresses in the same
function as the original instruction) and other anonymous rodata (which
may have relocations to elsewhere).
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/485
Link: https://lkml.kernel.org/r/263f6aae46d33da0b86d7030ced878cb5cab1788.1581997059.git.jpoimboe@redhat.com
Relocations in alternative code can be dangerous, because the code is
copy/pasted to the text section after relocations have been resolved,
which can corrupt PC-relative addresses.
However, relocations might be acceptable in some cases, depending on the
architecture. For example, the x86 alternatives code manually fixes up
the target addresses for PC-relative jumps and calls.
So disallow relocations in alternative code, except where the x86 arch
code allows it.
This code may need to be tweaked for other arches when objtool gets
support for them.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Link: https://lkml.kernel.org/r/7b90b68d093311e4e8f6b504a9e1c758fd7e0002.1581359535.git.jpoimboe@redhat.com
When objtool encounters a fatal error, it usually means the binary is
corrupt or otherwise broken in some way. Up until now, such errors were
just treated as warnings which didn't fail the kernel build.
However, objtool is now stable enough that if a fatal error is
discovered, it most likely means something is seriously wrong and it
should fail the kernel build.
Note that this doesn't apply to "normal" objtool warnings; only fatal
ones.
Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Link: https://lkml.kernel.org/r/f18c3743de0fef673d49dd35760f26bdef7f6fc3.1581359535.git.jpoimboe@redhat.com
Pull x86 asm updates from Ingo Molnar:
"The main changes in this cycle were:
- Cross-arch changes to move the linker sections for NOTES and
EXCEPTION_TABLE into the RO_DATA area, where they belong on most
architectures. (Kees Cook)
- Switch the x86 linker fill byte from x90 (NOP) to 0xcc (INT3), to
trap jumps into the middle of those padding areas instead of
sliding execution. (Kees Cook)
- A thorough cleanup of symbol definitions within x86 assembler code.
The rather randomly named macros got streamlined around a
(hopefully) straightforward naming scheme:
SYM_START(name, linkage, align...)
SYM_END(name, sym_type)
SYM_FUNC_START(name)
SYM_FUNC_END(name)
SYM_CODE_START(name)
SYM_CODE_END(name)
SYM_DATA_START(name)
SYM_DATA_END(name)
etc - with about three times of these basic primitives with some
label, local symbol or attribute variant, expressed via postfixes.
No change in functionality intended. (Jiri Slaby)
- Misc other changes, cleanups and smaller fixes"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
x86/entry/64: Remove pointless jump in paranoid_exit
x86/entry/32: Remove unused resume_userspace label
x86/build/vdso: Remove meaningless CFLAGS_REMOVE_*.o
m68k: Convert missed RODATA to RO_DATA
x86/vmlinux: Use INT3 instead of NOP for linker fill bytes
x86/mm: Report actual image regions in /proc/iomem
x86/mm: Report which part of kernel image is freed
x86/mm: Remove redundant address-of operators on addresses
xtensa: Move EXCEPTION_TABLE to RO_DATA segment
powerpc: Move EXCEPTION_TABLE to RO_DATA segment
parisc: Move EXCEPTION_TABLE to RO_DATA segment
microblaze: Move EXCEPTION_TABLE to RO_DATA segment
ia64: Move EXCEPTION_TABLE to RO_DATA segment
h8300: Move EXCEPTION_TABLE to RO_DATA segment
c6x: Move EXCEPTION_TABLE to RO_DATA segment
arm64: Move EXCEPTION_TABLE to RO_DATA segment
alpha: Move EXCEPTION_TABLE to RO_DATA segment
x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment
x86/vmlinux: Actually use _etext for the end of the text segment
vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA
...
This patch adds KCSAN runtime functions to the objtool whitelist.
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The new check_zeroed_user() function uses variable shifts inside of a
user_access_begin()/user_access_end() section and that results in GCC
emitting __ubsan_handle_shift_out_of_bounds() calls, even though
through value range analysis it would be able to see that the UB in
question is impossible.
Annotate and whitelist this UBSAN function; continued use of
user_access_begin()/user_access_end() will undoubtedly result in
further uses of function.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cyphar@cyphar.com
Cc: keescook@chromium.org
Cc: linux@rasmusvillemoes.dk
Fixes: f5a1a536fa ("lib: introduce copy_struct_from_user() helper")
Link: https://lkml.kernel.org/r/20191021131149.GA19358@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix the following warning seen on GCC 7.3:
kunit/test-test.o: warning: objtool: kunit_test_unsuccessful_try() falls through to next function kunit_test_catch()
kunit_try_catch_throw is a function added in the following patch in this
series; it allows KUnit, a unit testing framework for the kernel, to
bail out of a broken test. As a consequence, it is a new __noreturn
function that objtool thinks is broken (as seen above). So fix this
warning by adding kunit_try_catch_throw to objtool's noreturn list.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://www.spinics.net/lists/linux-kbuild/msg21708.html
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Explicitly check kvm_rebooting in kvm_spurious_fault() prior to invoking
BUG(), as opposed to assuming the caller has already done so. Letting
kvm_spurious_fault() be called "directly" will allow VMX to better
optimize its low level assembly flows.
As a happy side effect, kvm_spurious_fault() no longer needs to be
marked as a dead end since it doesn't unconditionally BUG().
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A clang build reported an (obvious) double CLAC while a GCC build did not;
it turns out that objtool only re-visits instructions if the first visit
was with AC=0. If OTOH the first visit was with AC=1, it completely ignores
any subsequent visit, even when it has AC=0.
Fix this by using a visited mask instead of a boolean, and (explicitly)
mark the AC state.
$ ./objtool check -b --no-fp --retpoline --uaccess drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xea: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xd9: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xb2: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x39: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x0: <=== (func)
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/617
Link: https://lkml.kernel.org/r/5359166aad2d53f3145cd442d83d0e5115e0cd17.1564007838.git.jpoimboe@redhat.com
A Clang-built kernel is showing the following warning:
arch/x86/kernel/platform-quirks.o: warning: objtool: x86_early_init_platform_quirks()+0x84: unreachable instruction
That corresponds to this code:
7e: 0f 85 00 00 00 00 jne 84 <x86_early_init_platform_quirks+0x84>
80: R_X86_64_PC32 __x86_indirect_thunk_r11-0x4
84: c3 retq
This is a conditional retpoline sibling call, which is now possible
thanks to retpolines. Objtool hasn't seen that before. It's
incorrectly interpreting the conditional jump as an unconditional
dynamic jump.
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/30d4c758b267ef487fb97e6ecb2f148ad007b554.1563413318.git.jpoimboe@redhat.com
This makes it easier to add new instruction types. Also it's hopefully
more robust since the compiler should warn about out-of-range enums.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/0740e96af0d40e54cfd6a07bf09db0fbd10793cd.1563413318.git.jpoimboe@redhat.com
This fixes objtool for both a GCC issue and a Clang issue:
1) GCC issue:
kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0x8d5: sibling call from callable instruction with modified stack frame
With CONFIG_RETPOLINE=n, GCC is doing the following optimization in
___bpf_prog_run().
Before:
select_insn:
jmp *jumptable(,%rax,8)
...
ALU64_ADD_X:
...
jmp select_insn
ALU_ADD_X:
...
jmp select_insn
After:
select_insn:
jmp *jumptable(, %rax, 8)
...
ALU64_ADD_X:
...
jmp *jumptable(, %rax, 8)
ALU_ADD_X:
...
jmp *jumptable(, %rax, 8)
This confuses objtool. It has never seen multiple indirect jump
sites which use the same jump table.
For GCC switch tables, the only way of detecting the size of a table
is by continuing to scan for more tables. The size of the previous
table can only be determined after another switch table is found, or
when the scan reaches the end of the function.
That logic was reused for C jump tables, and was based on the
assumption that each jump table only has a single jump site. The
above optimization breaks that assumption.
2) Clang issue:
drivers/usb/misc/sisusbvga/sisusb.o: warning: objtool: sisusb_write_mem_bulk()+0x588: can't find switch jump table
With clang 9, code can be generated where a function contains two
indirect jump instructions which use the same switch table.
The fix is the same for both issues: split the jump table parsing into
two passes.
In the first pass, locate the heads of all switch tables for the
function and mark their locations.
In the second pass, parse the switch tables and add them.
Fixes: e55a73251d ("bpf: Fix ORC unwinding in non-JIT BPF code")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/e995befaada9d4d8b2cf788ff3f566ba900d2b4d.1563413318.git.jpoimboe@redhat.com
Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Now that C jump tables are supported, call them "jump tables" instead of
"switch tables". Also rename some other variables, add comments, and
simplify the code flow a bit.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/cf951b0c0641628e0b9b81f7ceccd9bcabcb4bd8.1563413318.git.jpoimboe@redhat.com
Even calls to __noreturn functions need the frame pointer setup first.
Such functions often dump the stack.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/aed62fbd60e239280218be623f751a433658e896.1563413318.git.jpoimboe@redhat.com
dead_end_function() can no longer return an error. Simplify its
interface by making it return boolean.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9e6679610768fb6e6c51dca23f7d4d0c03b0c910.1563413318.git.jpoimboe@redhat.com
- Add an alias check in validate_functions(). With this change, aliases
no longer need uaccess_safe set.
- Add an alias check in decode_instructions(). With this change, the
"if (!insn->func)" check is no longer needed.
- Don't create aliases for zero-length functions, as it can have
unexpected results. The next patch will spit out a warning for
zero-length functions anyway.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/26a99c31426540f19c9a58b9e10727c385a147bc.1563413318.git.jpoimboe@redhat.com
If 'insn->func' is NULL, objtool skips some important checks, including
sibling call validation. So if some .fixup code does an invalid sibling
call, objtool ignores it.
Treat all code branches (including alts) as part of the original
function by keeping track of the original func value from
validate_functions().
This improves the usefulness of some clang function fallthrough
warnings, and exposes some additional kernel bugs in the process.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/505df630f33c9717e1ccde6e4b64c5303135c25f.1563413318.git.jpoimboe@redhat.com
After an objtool improvement, it's reporting that __memcpy_mcsafe() is
calling mcsafe_handle_tail() with AC=1:
arch/x86/lib/memcpy_64.o: warning: objtool: .fixup+0x13: call to mcsafe_handle_tail() with UACCESS enabled
arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0x34: (alt)
arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0xb: (branch)
arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0x0: <=== (func)
mcsafe_handle_tail() is basically an extension of __memcpy_mcsafe(), so
AC=1 is supposed to be set. Add mcsafe_handle_tail() to the uaccess
safe list.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/035c38f7eac845281d3c3d36749144982e06e58c.1563413318.git.jpoimboe@redhat.com
The elftoolchain version of libelf has a function named elf_open().
The function name isn't quite accurate anyway, since it also reads all
the ELF data. Rename it to elf_read(), which is more accurate.
[ jpoimboe: rename to elf_read(); write commit description ]
Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/7ce2d1b35665edf19fd0eb6fbc0b17b81a48e62f.1562793604.git.jpoimboe@redhat.com
Objtool doesn't know how to read C jump tables, so it has to whitelist
functions which use them, causing missing ORC unwinder data for such
functions, e.g. ___bpf_prog_run().
C jump tables are very similar to GCC switch jump tables, which objtool
already knows how to read. So adding support for C jump tables is easy.
It just needs to be able to find the tables and distinguish them from
other data.
To allow the jump tables to be found, create an __annotate_jump_table
macro which can be used to annotate them.
The annotation is done by placing the jump table in an
.rodata..c_jump_table section. The '.rodata' prefix ensures that the data
will be placed in the rodata section by the vmlinux linker script. The
double periods are part of an existing convention which distinguishes
kernel sections from GCC sections.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Kairui Song <kasong@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lkml.kernel.org/r/0ba2ca30442b16b97165992381ce643dc27b3d1a.1561685471.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not see http www gnu org licenses
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details [based]
[from] [clk] [highbank] [c] you should have received a copy of the
gnu general public license along with this program if not see http
www gnu org licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 355 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When a function falls through to the next function due to a compiler
bug, objtool prints some obscure warnings. For example:
drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame
drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8
Instead it should be printing:
drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages()
This used to work, but was broken by the following commit:
13810435b9 ("objtool: Support GCC 8's cold subfunctions")
The padding nops at the end of a function aren't actually part of the
function, as defined by the symbol table. So the 'func' variable in
validate_branch() is getting cleared to NULL when a padding nop is
encountered, breaking the fallthrough detection.
If the current instruction doesn't have a function associated with it,
just consider it to be part of the previously detected function by not
overwriting the previous value of 'func'.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Fixes: 13810435b9 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The ignore flag is set on fake jumps in order to keep
add_jump_destinations() from setting their jump_dest, since it already
got set when the fake jump was created.
But using the ignore flag is a bit of a hack. It's normally used to
skip validation of an instruction, which doesn't really make sense for
fake jumps.
Also, after the next patch, using the ignore flag for fake jumps can
trigger a false "why am I validating an ignored function?" warning.
Instead just add an explicit check in add_jump_destinations() to skip
fake jumps.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/71abc072ff48b2feccc197723a9c52859476c068.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull objtool updates from Ingo Molnar:
"This is a series from Peter Zijlstra that adds x86 build-time uaccess
validation of SMAP to objtool, which will detect and warn about the
following uaccess API usage bugs and weirdnesses:
- call to %s() with UACCESS enabled
- return with UACCESS enabled
- return with UACCESS disabled from a UACCESS-safe function
- recursive UACCESS enable
- redundant UACCESS disable
- UACCESS-safe disables UACCESS
As it turns out not leaking uaccess permissions outside the intended
uaccess functionality is hard when the interfaces are complex and when
such bugs are mostly dormant.
As a bonus we now also check the DF flag. We had at least one
high-profile bug in that area in the early days of Linux, and the
checking is fairly simple. The checks performed and warnings emitted
are:
- call to %s() with DF set
- return with DF set
- return with modified stack frame
- recursive STD
- redundant CLD
It's all x86-only for now, but later on this can also be used for PAN
on ARM and objtool is fairly cross-platform in principle.
While all warnings emitted by this new checking facility that got
reported to us were fixed, there might be GCC version dependent
warnings that were not reported yet - which we'll address, should they
trigger.
The warnings are non-fatal build warnings"
* 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions
x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
sched/x86_64: Don't save flags on context switch
objtool: Add Direction Flag validation
objtool: Add UACCESS validation
objtool: Fix sibling call detection
objtool: Rewrite alt->skip_orig
objtool: Add --backtrace support
objtool: Rewrite add_ignores()
objtool: Handle function aliases
objtool: Set insn->func for alternatives
x86/uaccess, kcov: Disable stack protector
x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP
x86/uaccess, ubsan: Fix UBSAN vs. SMAP
x86/uaccess, kasan: Fix KASAN vs SMAP
x86/smap: Ditch __stringify()
x86/uaccess: Introduce user_access_{save,restore}()
x86/uaccess, signal: Fix AC=1 bloat
x86/uaccess: Always inline user_access_begin()
x86/uaccess, xen: Suppress SMAP warnings
...
This fixes the following warning seen on GCC 7.3:
arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_regs()
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/3418ebf5a5a9f6ed7e80954c741c0b904b67b5dc.1554398240.git.jpoimboe@redhat.com
Having DF escape is BAD(tm).
Linus; you suggested this one, but since DF really is only used from
ASM and the failure case is fairly obvious, do we really need this?
OTOH the patch is fairly small and simple, so let's just do this
to demonstrate objtool's superior awesomeness.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is important that UACCESS regions are as small as possible;
furthermore the UACCESS state is not scheduled, so doing anything that
might directly call into the scheduler will cause random code to be
ran with UACCESS enabled.
Teach objtool too track UACCESS state and warn about any CALL made
while UACCESS is enabled. This very much includes the __fentry__()
and __preempt_schedule() calls.
Note that exceptions _do_ save/restore the UACCESS state, and therefore
they can drive preemption. This also means that all exception handlers
must have an otherwise redundant UACCESS disable instruction;
therefore ignore this warning for !STT_FUNC code (exception handlers
are not normal functions).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It turned out that we failed to detect some sibling calls;
specifically those without relocation records; like:
$ ./objdump-func.sh defconfig-build/mm/kasan/generic.o __asan_loadN
0000 0000000000000840 <__asan_loadN>:
0000 840: 48 8b 0c 24 mov (%rsp),%rcx
0004 844: 31 d2 xor %edx,%edx
0006 846: e9 45 fe ff ff jmpq 690 <check_memory_region>
So extend the cross-function jump to also consider those that are not
between known (or newly detected) parent/child functions, as
sibling-cals when they jump to the start of the function.
The second part of that condition is to deal with random jumps to the
middle of other function, as can be found in
arch/x86/lib/copy_user_64.S for example.
This then (with later patches applied) makes the above recognise the
sibling call:
mm/kasan/generic.o: warning: objtool: __asan_loadN()+0x6: call to check_memory_region() with UACCESS enabled
Also make sure to set insn->call_dest for sibling calls so we can know
who we're calling. This is useful information when printing validation
warnings later.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Really skip the original instruction flow, instead of letting it
continue with NOPs.
Since the alternative code flow already continues after the original
instructions, only the alt-original is skipped.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation of function attributes, we need each instruction to
have a valid link back to its function.
Therefore make sure we set the function association for alternative
instruction sequences; they are, after all, still part of the function.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Objtool uses over 512k of stack, thanks to the hash table embedded in
the objtool_file struct. This causes an unnecessarily large stack
allocation and breaks users with low stack limits.
Move the struct off the stack.
Fixes: 042ba73fe7 ("objtool: Add several performance improvements")
Reported-by: Vassili Karpov <moosotc@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/df92dcbc4b84b02ffa252f46876df125fb56e2d7.1552954176.git.jpoimboe@redhat.com
Add support for processing switch jump tables in objects with multiple
.rodata sections, such as those created by '-ffunction-sections' and
'-fdata-sections'. Currently, objtool always looks in .rodata for jump
table information, which results in many "sibling call from callable
instruction with modified stack frame" warnings with objects compiled
using those flags.
The fix is comprised of three parts:
1. Flagging all .rodata sections when importing ELF information for
easier checking later.
2. Keeping a reference to the section each relocation is from in order
to get the list_head for the other relocations in that section.
3. Finding jump tables by following relocations to .rodata sections,
rather than always referencing a single global .rodata section.
The patch has been tested without data sections enabled and no
differences in the resulting orc unwind information were seen.
Note that as objtool adds terminators to end of each .text section the
unwind information generated between a function+data sections build and
a normal build aren't directly comparable. Manual inspection suggests
that objtool is now generating the correct information, or at least
making more of an effort to do so than it did previously.
Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
Pull x86 asm updates from Thomas Gleixner:
"The lowlevel and ASM code updates for x86:
- Make stack trace unwinding more reliable
- ASM instruction updates for better code generation
- Various cleanups"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/entry/64: Add two more instruction suffixes
x86/asm/64: Use 32-bit XOR to zero registers
x86/build/vdso: Simplify 'cmd_vdso2c'
x86/build/vdso: Remove unused vdso-syms.lds
x86/stacktrace: Enable HAVE_RELIABLE_STACKTRACE for the ORC unwinder
x86/unwind/orc: Detect the end of the stack
x86/stacktrace: Do not fail for ORC with regs on stack
x86/stacktrace: Clarify the reliable success paths
x86/stacktrace: Remove STACKTRACE_DUMP_ONCE
x86/stacktrace: Do not unwind after user regs
x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg8b_double() to micro-optimize code generation
The existing UNWIND_HINT_EMPTY annotations happen to be good indicators
of where entry code calls into C code for the first time. So also use
them to mark the end of the stack for the ORC unwinder.
Use that information to set unwind->error if the ORC unwinder doesn't
unwind all the way to the end. This will be needed for enabling
HAVE_RELIABLE_STACKTRACE for the ORC unwinder so we can use it with the
livepatch consistency model.
Thanks to Jiri Slaby for teaching the ORCs about the unwind hints.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/lkml/20180518064713.26440-5-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
machine_real_restart() is annotated as '__noreturn", so add it to the
objtool noreturn list. This fixes the following warning with clang and
CONFIG_CC_OPTIMIZE_FOR_SIZE=y:
arch/x86/kernel/reboot.o: warning: objtool: native_machine_emergency_restart() falls through to next function machine_power_off()
Reported-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lkml.kernel.org/r/791712792aa4431bdd55bf1beb33a169ddf3b4a2.1529423255.git.jpoimboe@redhat.com
The kbuild test robot reported the following issue:
kernel/time/posix-stubs.o: warning: objtool: sys_ni_posix_timers.cold.1()+0x0: unreachable instruction
This file creates symbol aliases for the sys_ni_posix_timers() function.
So there are multiple ELF function symbols for the same function:
23: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_create
24: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 sys_ni_posix_timers
25: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __ia32_sys_timer_create
26: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_gettime
Here's the corresponding cold subfunction:
11: 0000000000000000 45 FUNC LOCAL DEFAULT 6 sys_ni_posix_timers.cold.1
When analyzing overlapping functions, objtool only looks at the first
one in the symbol list. The rest of the functions are basically ignored
because they point to instructions which have already been analyzed.
So in this case it analyzes the __x64_sys_timer_create() function, but
then it fails to recognize that its cold subfunction is
sys_ni_posix_timers.cold.1(), because the names are different.
Make the subfunction detection a little smarter by associating each
subfunction with the first function which jumps to it, since that's the
one which will be analyzed.
Unfortunately we still have to leave the original subfunction detection
code in place, thanks to GCC switch tables. (See the comment for more
details.)
Fixes: 13810435b9 ("objtool: Support GCC 8's cold subfunctions")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/d3ba52662cbc8e3a64a3b64d44b4efc5674fd9ab.1527855808.git.jpoimboe@redhat.com
With the following commit:
fd35c88b74 ("objtool: Support GCC 8 switch tables")
I added a "can't find switch jump table" warning, to stop covering up
silent failures if add_switch_table() can't find anything.
That warning found yet another bug in the objtool switch table detection
logic. For cases 1 and 2 (as described in the comments of
find_switch_table()), the find_symbol_containing() check doesn't adjust
the offset for RIP-relative switch jumps.
Incidentally, this bug was already fixed for case 3 with:
6f5ec2993b ("objtool: Detect RIP-relative switch table references")
However, that commit missed the fix for cases 1 and 2.
The different cases are now starting to look more and more alike. So
fix the bug by consolidating them into a single case, by checking the
original dynamic jump instruction in the case 3 loop.
This also simplifies the code and makes it more robust against future
switch table detection issues -- of which I'm sure there will be many...
Switch table detection has been the most fragile area of objtool, by
far. I long for the day when we'll have a GCC plugin for annotating
switch tables. Linus asked me to delay such a plugin due to the
flakiness of the plugin infrastructure in older versions of GCC, so this
rickety code is what we're stuck with for now. At least the code is now
a little simpler than it was.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f400541613d45689086329432f3095119ffbc328.1526674218.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Typically a switch table can be found by detecting a .rodata access
followed an indirect jump:
1969: 4a 8b 0c e5 00 00 00 mov 0x0(,%r12,8),%rcx
1970: 00
196d: R_X86_64_32S .rodata+0x438
1971: e9 00 00 00 00 jmpq 1976 <dispc_runtime_suspend+0xb6a>
1972: R_X86_64_PC32 __x86_indirect_thunk_rcx-0x4
Randy Dunlap reported a case (seen with GCC 4.8) where the .rodata
access uses RIP-relative addressing:
19bd: 48 8b 3d 00 00 00 00 mov 0x0(%rip),%rdi # 19c4 <dispc_runtime_suspend+0xbb8>
19c0: R_X86_64_PC32 .rodata+0x45c
19c4: e9 00 00 00 00 jmpq 19c9 <dispc_runtime_suspend+0xbbd>
19c5: R_X86_64_PC32 __x86_indirect_thunk_rdi-0x4
In this case the relocation addend needs to be adjusted accordingly in
order to find the location of the switch table.
The fix is for case 3 (as described in the comments), but also make the
existing case 1 & 2 checks more precise by only adjusting the addend for
R_X86_64_PC32 relocations.
This fixes the following warnings:
drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame
drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b6098294fd67afb69af8c47c9883d7a68bf0f8ea.1526305958.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With GCC 8, some issues were found with the objtool switch table
detection.
1) In the .rodata section, immediately after the switch table, there can
be another object which contains a pointer to the function which had
the switch statement. In this case objtool wrongly considers the
function pointer to be part of the switch table. Fix it by:
a) making sure there are no pointers to the beginning of the
function; and
b) making sure there are no gaps in the switch table.
Only the former was needed, the latter adds additional protection for
future optimizations.
2) In find_switch_table(), case 1 and case 2 are missing the check to
ensure that the .rodata switch table data is anonymous, i.e. that it
isn't already associated with an ELF symbol. Fix it by adding the
same find_symbol_containing() check which is used for case 3.
This fixes the following warnings with GCC 8:
drivers/block/virtio_blk.o: warning: objtool: virtio_queue_rq()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+72
net/ipv6/icmp.o: warning: objtool: icmpv6_rcv()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64
drivers/usb/core/quirks.o: warning: objtool: quirks_param_set()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+48
drivers/mtd/nand/raw/nand_hynix.o: warning: objtool: hynix_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+24
drivers/mtd/nand/raw/nand_samsung.o: warning: objtool: samsung_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+32
drivers/gpu/drm/nouveau/nvkm/subdev/top/gk104.o: warning: objtool: gk104_top_oneinit()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: damian <damian.tometzki@icloud.com>
Link: http://lkml.kernel.org/r/20180510224849.xwi34d6tzheb5wgw@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
GCC 8 moves a lot of unlikely code out of line to "cold" subfunctions in
.text.unlikely. Properly detect the new subfunctions and treat them as
extensions of the original functions.
This fixes a bunch of warnings like:
kernel/cgroup/cgroup.o: warning: objtool: parse_cgroup_root_flags()+0x33: sibling call from callable instruction with modified stack frame
kernel/cgroup/cgroup.o: warning: objtool: cgroup_addrm_files()+0x290: sibling call from callable instruction with modified stack frame
kernel/cgroup/cgroup.o: warning: objtool: cgroup_apply_control_enable()+0x25b: sibling call from callable instruction with modified stack frame
kernel/cgroup/cgroup.o: warning: objtool: rebind_subsystems()+0x325: sibling call from callable instruction with modified stack frame
Reported-and-tested-by: damian <damian.tometzki@icloud.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/0965e7fcfc5f31a276f0c7f298ff770c19b68706.1525923412.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Objtool has some crude logic for detecting static "noreturn" functions
(aka "dead ends"). This is necessary for being able to correctly follow
GCC code flow when such functions are called.
It's remotely possible for two functions to call each other via sibling
calls. If they don't have RET instructions, objtool's noreturn
detection logic goes into a recursive loop:
drivers/char/ipmi/ipmi_ssif.o: warning: objtool: return_hosed_msg()+0x0: infinite recursion (objtool bug!)
drivers/char/ipmi/ipmi_ssif.o: warning: objtool: deliver_recv_msg()+0x0: infinite recursion (objtool bug!)
Instead of reporting an error in this case, consider the functions to be
non-dead-ends.
Reported-and-tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: damian <damian.tometzki@icloud.com>
Link: http://lkml.kernel.org/r/7cc156408c5781a1f62085d352ced1fe39fe2f91.1525923412.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the ORC unwinder was made the default on x86_64, Clang-built
defconfig kernels have triggered some new objtool warnings:
drivers/gpu/drm/i915/i915_gpu_error.o: warning: objtool: i915_error_printf()+0x6c: return with modified stack frame
drivers/gpu/drm/i915/intel_display.o: warning: objtool: pipe_config_err()+0xa6: return with modified stack frame
The problem is that objtool has never seen clang-built binaries before.
Shockingly enough, objtool is apparently able to follow the code flow
mostly fine, except for one instruction sequence. Instead of a LEAVE
instruction, clang restores RSP and RBP the long way:
67c: 48 89 ec mov %rbp,%rsp
67f: 5d pop %rbp
Teach objtool about this new code sequence.
Reported-and-test-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/fce88ce81c356eedcae7f00ed349cfaddb3363cc.1521741586.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix the objtool build when cross-compiling a 64-bit kernel on a 32-bit
host. This also simplifies read_retpoline_hints() a bit and makes its
implementation similar to most of the other annotation reading
functions.
Reported-by: Sven Joachim <svenjoac@gmx.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: b5bc2231b8 ("objtool: Add retpoline validation")
Link: http://lkml.kernel.org/r/2ca46c636c23aa9c9d57d53c75de4ee3ddf7a7df.1520380691.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Continue the switch table detection whack-a-mole. Add a check to
distinguish KASAN data reads from switch data reads. The switch jump
tables in .rodata have relocations associated with them.
This fixes the following warning:
crypto/asymmetric_keys/x509_cert_parser.o: warning: objtool: x509_note_pkey_algo()+0xa4: sibling call from callable instruction with modified stack frame
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/d7c8853022ad47d158cb81e953a40469fc08a95e.1519784382.git.jpoimboe@redhat.com
