Commit graph

441 commits

Author SHA1 Message Date
Linus Torvalds
35ce8ae9ae Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull signal/exit/ptrace updates from Eric Biederman:
 "This set of changes deletes some dead code, makes a lot of cleanups
  which hopefully make the code easier to follow, and fixes bugs found
  along the way.

  The end-game which I have not yet reached yet is for fatal signals
  that generate coredumps to be short-circuit deliverable from
  complete_signal, for force_siginfo_to_task not to require changing
  userspace configured signal delivery state, and for the ptrace stops
  to always happen in locations where we can guarantee on all
  architectures that the all of the registers are saved and available on
  the stack.

  Removal of profile_task_ext, profile_munmap, and profile_handoff_task
  are the big successes for dead code removal this round.

  A bunch of small bug fixes are included, as most of the issues
  reported were small enough that they would not affect bisection so I
  simply added the fixes and did not fold the fixes into the changes
  they were fixing.

  There was a bug that broke coredumps piped to systemd-coredump. I
  dropped the change that caused that bug and replaced it entirely with
  something much more restrained. Unfortunately that required some
  rebasing.

  Some successes after this set of changes: There are few enough calls
  to do_exit to audit in a reasonable amount of time. The lifetime of
  struct kthread now matches the lifetime of struct task, and the
  pointer to struct kthread is no longer stored in set_child_tid. The
  flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is
  removed. Issues where task->exit_code was examined with
  signal->group_exit_code should been examined were fixed.

  There are several loosely related changes included because I am
  cleaning up and if I don't include them they will probably get lost.

  The original postings of these changes can be found at:
     https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org
     https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org
     https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org

  I trimmed back the last set of changes to only the obviously correct
  once. Simply because there was less time for review than I had hoped"

* 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits)
  ptrace/m68k: Stop open coding ptrace_report_syscall
  ptrace: Remove unused regs argument from ptrace_report_syscall
  ptrace: Remove second setting of PT_SEIZED in ptrace_attach
  taskstats: Cleanup the use of task->exit_code
  exit: Use the correct exit_code in /proc/<pid>/stat
  exit: Fix the exit_code for wait_task_zombie
  exit: Coredumps reach do_group_exit
  exit: Remove profile_handoff_task
  exit: Remove profile_task_exit & profile_munmap
  signal: clean up kernel-doc comments
  signal: Remove the helper signal_group_exit
  signal: Rename group_exit_task group_exec_task
  coredump: Stop setting signal->group_exit_task
  signal: Remove SIGNAL_GROUP_COREDUMP
  signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process
  signal: Make coredump handling explicit in complete_signal
  signal: Have prepare_signal detect coredumps using signal->core_state
  signal: Have the oom killer detect coredumps using signal->core_state
  exit: Move force_uaccess back into do_exit
  exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit
  ...
2022-01-17 05:49:30 +02:00
Linus Torvalds
64ad946152 - Get rid of all the .fixup sections because this generates
misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and
 LIVEPATCH as the backtrace misses the function which is being fixed up.
 
 - Add Straight Light Speculation mitigation support which uses a new
 compiler switch -mharden-sls= which sticks an INT3 after a RET or an
 indirect branch in order to block speculation after them. Reportedly,
 CPUs do speculate behind such insns.
 
 - The usual set of cleanups and improvements
 -----BEGIN PGP SIGNATURE-----
 
 iQIyBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmHfKA0ACgkQEsHwGGHe
 VUqLJg/2I2X2xXr5filJVaK+sQgmvDzk67DKnbxRBW2xcPF+B5sSW5yhe3G5UPW7
 SJVdhQ3gHcTiliGGlBf/VE7KXbqxFN0vO4/VFHZm78r43g7OrXTxz6WXXQRJ1n67
 U3YwRH3b6cqXZNFMs+X4bJt6qsGJM1kdTTZ2as4aERnaFr5AOAfQvfKbyhxLe/XA
 3SakfYISVKCBQ2RkTfpMpwmqlsatGFhTC5IrvuDQ83dDsM7O+Dx1J6Gu3fwjKmie
 iVzPOjCh+xTpZQp/SIZmt7MzoduZvpSym4YVyHvEnMiexQT4AmyaRthWqrhnEXY/
 qOvj8/XIqxmix8EaooGqRIK0Y2ZegxkPckNFzaeC3lsWohwMIGIhNXwHNEeuhNyH
 yvNGAW9Cq6NeDRgz5MRUXcimYw4P4oQKYLObS1WqFZhNMqm4sNtoEAYpai/lPYfs
 zUDckgXF2AoPOsSqy3hFAVaGovAgzfDaJVzkt0Lk4kzzjX2WQiNLhmiior460w+K
 0l2Iej58IajSp3MkWmFH368Jo8YfUVmkjbbpsmjsBppA08e1xamJB7RmswI/Ezj6
 s5re6UioCD+UYdjWx41kgbvYdvIkkZ2RLrktoZd/hqHrOLWEIiwEbyFO2nRFJIAh
 YjvPkB1p7iNuAeYcP1x9Ft9GNYVIsUlJ+hK86wtFCqy+abV+zQ==
 =R52z
 -----END PGP SIGNATURE-----

Merge tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 core updates from Borislav Petkov:

 - Get rid of all the .fixup sections because this generates
   misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and
   LIVEPATCH as the backtrace misses the function which is being fixed
   up.

 - Add Straight Line Speculation mitigation support which uses a new
   compiler switch -mharden-sls= which sticks an INT3 after a RET or an
   indirect branch in order to block speculation after them. Reportedly,
   CPUs do speculate behind such insns.

 - The usual set of cleanups and improvements

* tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
  x86/entry_32: Fix segment exceptions
  objtool: Remove .fixup handling
  x86: Remove .fixup section
  x86/word-at-a-time: Remove .fixup usage
  x86/usercopy: Remove .fixup usage
  x86/usercopy_32: Simplify __copy_user_intel_nocache()
  x86/sgx: Remove .fixup usage
  x86/checksum_32: Remove .fixup usage
  x86/vmx: Remove .fixup usage
  x86/kvm: Remove .fixup usage
  x86/segment: Remove .fixup usage
  x86/fpu: Remove .fixup usage
  x86/xen: Remove .fixup usage
  x86/uaccess: Remove .fixup usage
  x86/futex: Remove .fixup usage
  x86/msr: Remove .fixup usage
  x86/extable: Extend extable functionality
  x86/entry_32: Remove .fixup usage
  x86/entry_64: Remove .fixup usage
  x86/copy_mc_64: Remove .fixup usage
  ...
2022-01-12 16:31:19 -08:00
Linus Torvalds
1be5bdf8cd KCSAN updates for v5.17
This series provides KCSAN fixes and also the ability to take memory
 barriers into account for weakly-ordered systems.  This last can increase
 the probability of detecting certain types of data races.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEbK7UrM+RBIrCoViJnr8S83LZ+4wFAmHbuRwTHHBhdWxtY2tA
 a2VybmVsLm9yZwAKCRCevxLzctn7jKDPEACWuzYnd/u/02AHyRd3PIF3Px9uFKlK
 TFwaXX95oYSFCXcrmO42YtDUlZm4QcbwNb85KMCu1DvckRtIsNw0rkBU7BGyqv3Z
 ZoJEfMNpmC0x9+IFBOeseBHySPVT0x7GmYus05MSh0OLfkbCfyImmxRzgoKJGL+A
 ADF9EQb4z2feWjmVEoN8uRaarCAD4f77rSXiX6oTCNDuKrHarqMld/TmoXFrJbu2
 QtfwHeyvraKBnZdUoYfVbGVenyKb1vMv4bUlvrOcuJEgIi/J/th4FupR3XCGYulI
 aWJTl2TQTGnMoE8VnFHgI27I841w3k5PVL+Y1hr/S4uN1/rIoQQuBzCtlnFeCksa
 BiBXsHIchN8N0Dwh8zD8NMd2uxV4t3fmpxXTDAwaOm7vs5hA8AJ0XNu6Sz94Lyjv
 wk2CxX41WWUNJVo3gh6SrS4mL6lC8+VvHF1hbIap++jrevj58gj1jAR1fdx4ANlT
 e2qA00EeoMngEogDNZH42/Fxs3H9zxrBta2ZbkPkwzIqTHH+4pIQDCy2xO3T3oxc
 twdGPYpjYdkf79EGsG4I4R/VA/IfcS09VIWTce8xSDeSnqkgFhcG37r1orJe8hTB
 tH+ODkNOsz5HaEoa8OoAL4ko2l0fL99p2AtMPpuQfHjRj7aorF+dJIrqCizASxwx
 37PjQgOmHeDHgQ==
 =Q5fg
 -----END PGP SIGNATURE-----

Merge tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:
 "This provides KCSAN fixes and also the ability to take memory barriers
  into account for weakly-ordered systems. This last can increase the
  probability of detecting certain types of data races"

* tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits)
  kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it
  kcsan: Avoid nested contexts reading inconsistent reorder_access
  kcsan: Turn barrier instrumentation into macros
  kcsan: Make barrier tests compatible with lockdep
  kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
  compiler_attributes.h: Add __disable_sanitizer_instrumentation
  objtool, kcsan: Remove memory barrier instrumentation from noinstr
  objtool, kcsan: Add memory barrier instrumentation to whitelist
  sched, kcsan: Enable memory barrier instrumentation
  mm, kcsan: Enable barrier instrumentation
  x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock()
  x86/barriers, kcsan: Use generic instrumentation for non-smp barriers
  asm-generic/bitops, kcsan: Add instrumentation for barriers
  locking/atomics, kcsan: Add instrumentation for barriers
  locking/barriers, kcsan: Support generic instrumentation
  locking/barriers, kcsan: Add instrumentation for barriers
  kcsan: selftest: Add test case to check memory barrier instrumentation
  kcsan: Ignore GCC 11+ warnings about TSan runtime support
  kcsan: test: Add test cases for memory barrier instrumentation
  kcsan: test: Match reordered or normal accesses
  ...
2022-01-11 09:51:26 -08:00
Eric W. Biederman
1fb466dff9 objtool: Add a missing comma to avoid string concatenation
Recently the kbuild robot reported two new errors:

>> lib/kunit/kunit-example-test.o: warning: objtool: .text.unlikely: unexpected end of section
>> arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_opcodes()

I don't know why they did not occur in my test setup but after digging
it I realized I had accidentally dropped a comma in
tools/objtool/check.c when I renamed rewind_stack_do_exit to
rewind_stack_and_make_dead.

Add that comma back to fix objtool errors.

Link: https://lkml.kernel.org/r/202112140949.Uq5sFKR1-lkp@intel.com
Fixes: 0e25498f8c ("exit: Add and use make_task_dead.")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-15 11:33:22 -06:00
Eric W. Biederman
cead185526 exit: Rename complete_and_exit to kthread_complete_and_exit
Update complete_and_exit to call kthread_exit instead of do_exit.

Change the name to reflect this change in functionality.  All of the
users of complete_and_exit are causing the current kthread to exit so
this change makes it clear what is happening.

Move the implementation of kthread_complete_and_exit from
kernel/exit.c to to kernel/kthread.c.  As this function is kthread
specific it makes most sense to live with the kthread functions.

There are no functional change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Eric W. Biederman
ca3574bd65 exit: Rename module_put_and_exit to module_put_and_kthread_exit
Update module_put_and_exit to call kthread_exit instead of do_exit.

Change the name to reflect this change in functionality.  All of the
users of module_put_and_exit are causing the current kthread to exit
so this change makes it clear what is happening.  There is no
functional change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Eric W. Biederman
bbda86e988 exit: Implement kthread_exit
The way the per task_struct exit_code is used by kernel threads is not
quite compatible how it is used by userspace applications.  The low
byte of the userspace exit_code value encodes the exit signal.  While
kthreads just use the value as an int holding ordinary kernel function
exit status like -EPERM.

Add kthread_exit to clearly separate the two kinds of uses.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Eric W. Biederman
0e25498f8c exit: Add and use make_task_dead.
There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Peter Zijlstra
82a8954acd objtool: Remove .fixup handling
The .fixup has gone the way of the Dodo, that test will always be
false.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101326.261496792@infradead.org
2021-12-11 09:09:51 +01:00
Marco Elver
0509811952 objtool, kcsan: Remove memory barrier instrumentation from noinstr
Teach objtool to turn instrumentation required for memory barrier
modeling into nops in noinstr text.

The __tsan_func_entry/exit calls are still emitted by compilers even
with the __no_sanitize_thread attribute. The memory barrier
instrumentation will be inserted explicitly (without compiler help), and
thus needs to also explicitly be removed.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:28 -08:00
Marco Elver
0525bd82f6 objtool, kcsan: Add memory barrier instrumentation to whitelist
Adds KCSAN's memory barrier instrumentation to objtool's uaccess
whitelist.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:28 -08:00
Peter Zijlstra
1cc1e4c8aa objtool: Add straight-line-speculation validation
Teach objtool to validate the straight-line-speculation constraints:

 - speculation trap after indirect calls
 - speculation trap after RET

Notable: when an instruction is annotated RETPOLINE_SAFE, indicating
  speculation isn't a problem, also don't care about sls for that
  instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
2021-12-08 19:26:50 +01:00
Peter Zijlstra
988f01683c objtool: Fix pv_ops noinstr validation
Boris reported that in one of his randconfig builds, objtool got
infinitely stuck. Turns out there's trivial list corruption in the
pv_ops tracking when a function is both in a static table and in a code
assignment.

Avoid re-adding function to the pv_ops[] lists when they're already on
it.

Fixes: db2b0c5d7b ("objtool: Support pv_opsindirect calls for noinstr")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20211202204534.GA16608@worktop.programming.kicks-ass.net
2021-12-03 09:11:42 +01:00
Peter Zijlstra
2105a92748 static_call,x86: Robustify trampoline patching
Add a few signature bytes after the static call trampoline and verify
those bytes match before patching the trampoline. This avoids patching
random other JMPs (such as CFI jump-table entries) instead.

These bytes decode as:

   d:   53                      push   %rbx
   e:   43 54                   rex.XB push %r12

And happen to spell "SCT".

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211030074758.GT174703@worktop.programming.kicks-ass.net
2021-11-11 13:09:31 +01:00
Linus Torvalds
79ef0c0014 Tracing updates for 5.16:
- kprobes: Restructured stack unwinder to show properly on x86 when a stack
   dump happens from a kretprobe callback.
 
 - Fix to bootconfig parsing
 
 - Have tracefs allow owner and group permissions by default (only denying
   others). There's been pressure to allow non root to tracefs in a
   controlled fashion, and using groups is probably the safest.
 
 - Bootconfig memory managament updates.
 
 - Bootconfig clean up to have the tools directory be less dependent on
   changes in the kernel tree.
 
 - Allow perf to be traced by function tracer.
 
 - Rewrite of function graph tracer to be a callback from the function tracer
   instead of having its own trampoline (this change will happen on an arch
   by arch basis, and currently only x86_64 implements it).
 
 - Allow multiple direct trampolines (bpf hooks to functions) be batched
   together in one synchronization.
 
 - Allow histogram triggers to add variables that can perform calculations
   against the event's fields.
 
 - Use the linker to determine architecture callbacks from the ftrace
   trampoline to allow for proper parameter prototypes and prevent warnings
   from the compiler.
 
 - Extend histogram triggers to key off of variables.
 
 - Have trace recursion use bit magic to determine preempt context over if
   branches.
 
 - Have trace recursion disable preemption as all use cases do anyway.
 
 - Added testing for verification of tracing utilities.
 
 - Various small clean ups and fixes.
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCYYBdxhQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6qp1sAQD2oYFwaG3sx872gj/myBcHIBSKdiki
 Hry5csd8zYDBpgD+Poylopt5JIbeDuoYw/BedgEXmscZ8Qr7VzjAXdnv/Q4=
 =Loz8
 -----END PGP SIGNATURE-----

Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - kprobes: Restructured stack unwinder to show properly on x86 when a
   stack dump happens from a kretprobe callback.

 - Fix to bootconfig parsing

 - Have tracefs allow owner and group permissions by default (only
   denying others). There's been pressure to allow non root to tracefs
   in a controlled fashion, and using groups is probably the safest.

 - Bootconfig memory managament updates.

 - Bootconfig clean up to have the tools directory be less dependent on
   changes in the kernel tree.

 - Allow perf to be traced by function tracer.

 - Rewrite of function graph tracer to be a callback from the function
   tracer instead of having its own trampoline (this change will happen
   on an arch by arch basis, and currently only x86_64 implements it).

 - Allow multiple direct trampolines (bpf hooks to functions) be batched
   together in one synchronization.

 - Allow histogram triggers to add variables that can perform
   calculations against the event's fields.

 - Use the linker to determine architecture callbacks from the ftrace
   trampoline to allow for proper parameter prototypes and prevent
   warnings from the compiler.

 - Extend histogram triggers to key off of variables.

 - Have trace recursion use bit magic to determine preempt context over
   if branches.

 - Have trace recursion disable preemption as all use cases do anyway.

 - Added testing for verification of tracing utilities.

 - Various small clean ups and fixes.

* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
  tracing/histogram: Fix semicolon.cocci warnings
  tracing/histogram: Fix documentation inline emphasis warning
  tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
  tracing: Show size of requested perf buffer
  bootconfig: Initialize ret in xbc_parse_tree()
  ftrace: do CPU checking after preemption disabled
  ftrace: disable preemption when recursion locked
  tracing/histogram: Document expression arithmetic and constants
  tracing/histogram: Optimize division by a power of 2
  tracing/histogram: Covert expr to const if both operands are constants
  tracing/histogram: Simplify handling of .sym-offset in expressions
  tracing: Fix operator precedence for hist triggers expression
  tracing: Add division and multiplication support for hist triggers
  tracing: Add support for creating hist trigger variables from literal
  selftests/ftrace: Stop tracing while reading the trace file by default
  MAINTAINERS: Update KPROBES and TRACING entries
  test_kprobes: Move it from kernel/ to lib/
  docs, kprobes: Remove invalid URL and add new reference
  samples/kretprobes: Fix return value if register_kretprobe() failed
  lib/bootconfig: Fix the xbc_get_info kerneldoc
  ...
2021-11-01 20:05:19 -07:00
Linus Torvalds
43aa0a195f objtool updates:
- Improve retpoline code patching by separating it from alternatives which
    reduces memory footprint and allows to do better optimizations in the
    actual runtime patching.
 
  - Add proper retpoline support for x86/BPF
 
  - Address noinstr warnings in x86/kvm, lockdep and paravirtualization code
 
  - Add support to handle pv_opsindirect calls in the noinstr analysis
 
  - Classify symbols upfront and cache the result to avoid redundant
    str*cmp() invocations.
 
  - Add a CFI hash to reduce memory consumption which also reduces runtime
    on a allyesconfig by ~50%
 
  - Adjust XEN code to make objtool handling more robust and as a side
    effect to prevent text fragmentation due to placement of the hypercall
    page.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmF/GFgTHHRnbHhAbGlu
 dXRyb25peC5kZQAKCRCmGPVMDXSYoc1JD/0Sz6seP2OUMxbMT3gCcFo9sMvYTdsM
 7WuGFbBbnCIo7g8JH7k0zRRBigptMp2eUtQXKkgaaIbWN4JbuVKf8KxN5/qXxLi4
 fJ12QnNTGH9N2jtzl5wKmpjaKJnnJMD9D10XwoR+T6gn6NHd+AgLEs7GxxuQUlgo
 eC9oEXhNHC8uNhiZc38EwfwmItI1bRgaLrnZWIL4rYGSMxfCK1/cEOpWrFfX9wmj
 /diB6oqMyPXZXMCtgpX7TniUr5XOTCcUkeO9mQv5bmyq/YM/8hrTbcVSJlsVYLvP
 EsBnUSHAcfLFiHXwa1RNiIGdbiPjbN+UYeXGAvqF58f3e5dTIHtN/UmWo7OH93If
 9rLMVNcMpsfPx7QRk2IxEPumLCkyfwjzfKrVDM6P6TKEIUzD1og4IK9gTlfykVsh
 56G5XiCOC/X2x8IMxKTLGuBiAVLFHXK/rSwoqhvNEWBFKDbP13QWs0LurBcW09Sa
 /kQI9pIBT1xFA/R+OY5Xy1cqNVVK1Gxmk8/bllCijA9pCFSCFM4hLZE5CevdrBCV
 h5SdqEK5hIlzFyypXfsCik/4p/+rfvlGfUKtFsPctxx29SPe+T0orx+l61jiWQok
 rZOflwMawK5lDuASHrvNHGJcWaTwoo3VcXMQDnQY0Wulc43J5IFBaPxkZzgyd+S1
 4lktHxatrCMUgw==
 =pfZi
 -----END PGP SIGNATURE-----

Merge tag 'objtool-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Thomas Gleixner:

 - Improve retpoline code patching by separating it from alternatives
   which reduces memory footprint and allows to do better optimizations
   in the actual runtime patching.

 - Add proper retpoline support for x86/BPF

 - Address noinstr warnings in x86/kvm, lockdep and paravirtualization
   code

 - Add support to handle pv_opsindirect calls in the noinstr analysis

 - Classify symbols upfront and cache the result to avoid redundant
   str*cmp() invocations.

 - Add a CFI hash to reduce memory consumption which also reduces
   runtime on a allyesconfig by ~50%

 - Adjust XEN code to make objtool handling more robust and as a side
   effect to prevent text fragmentation due to placement of the
   hypercall page.

* tag 'objtool-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
  bpf,x86: Respect X86_FEATURE_RETPOLINE*
  bpf,x86: Simplify computing label offsets
  x86,bugs: Unconditionally allow spectre_v2=retpoline,amd
  x86/alternative: Add debug prints to apply_retpolines()
  x86/alternative: Try inline spectre_v2=retpoline,amd
  x86/alternative: Handle Jcc __x86_indirect_thunk_\reg
  x86/alternative: Implement .retpoline_sites support
  x86/retpoline: Create a retpoline thunk array
  x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h
  x86/asm: Fixup odd GEN-for-each-reg.h usage
  x86/asm: Fix register order
  x86/retpoline: Remove unused replacement symbols
  objtool,x86: Replace alternatives with .retpoline_sites
  objtool: Shrink struct instruction
  objtool: Explicitly avoid self modifying code in .altinstr_replacement
  objtool: Classify symbols
  objtool: Support pv_opsindirect calls for noinstr
  x86/xen: Rework the xen_{cpu,irq,mmu}_opsarrays
  x86/xen: Mark xen_force_evtchn_callback() noinstr
  x86/xen: Make irq_disable() noinstr
  ...
2021-11-01 13:24:43 -07:00
Peter Zijlstra
134ab5bd18 objtool,x86: Replace alternatives with .retpoline_sites
Instead of writing complete alternatives, simply provide a list of all
the retpoline thunk calls. Then the kernel is free to do with them as
it pleases. Simpler code all-round.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.850007165@infradead.org
2021-10-28 23:25:25 +02:00
Peter Zijlstra
c509331b41 objtool: Shrink struct instruction
Any one instruction can only ever call a single function, therefore
insn->mcount_loc_node is superfluous and can use insn->call_node.

This shrinks struct instruction, which is by far the most numerous
structure objtool creates.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.785456706@infradead.org
2021-10-28 23:25:25 +02:00
Peter Zijlstra
dd003edeff objtool: Explicitly avoid self modifying code in .altinstr_replacement
Assume ALTERNATIVE()s know what they're doing and do not change, or
cause to change, instructions in .altinstr_replacement sections.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.722511775@infradead.org
2021-10-28 23:25:25 +02:00
Peter Zijlstra
1739c66eb7 objtool: Classify symbols
In order to avoid calling str*cmp() on symbol names, over and over, do
them all once upfront and store the result.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.658539311@infradead.org
2021-10-28 23:25:24 +02:00
Michael Forney
86e1e054e0 objtool: Update section header before relocations
The libelf implementation from elftoolchain has a safety check in
gelf_update_rel[a] to check that the data corresponds to a section
that has type SHT_REL[A] [0]. If the relocation is updated before
the section header is updated with the proper type, this check
fails.

To fix this, update the section header first, before the relocations.
Previously, the section size was calculated in elf_rebuild_reloc_section
by counting the number of entries in the reloc_list. However, we
now need the size during elf_write so instead keep a running total
and add to it for every new relocation.

[0] https://sourceforge.net/p/elftoolchain/mailman/elftoolchain-developers/thread/CAGw6cBtkZro-8wZMD2ULkwJ39J+tHtTtAWXufMjnd3cQ7XG54g@mail.gmail.com/

Signed-off-by: Michael Forney <mforney@mforney.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20210509000103.11008-2-mforney@mforney.org
2021-10-06 20:11:57 -07:00
Michael Forney
b46179d6bb objtool: Check for gelf_update_rel[a] failures
Otherwise, if these fail we end up with garbage data in the
.rela.orc_unwind_ip section, leading to errors like

  ld: fs/squashfs/namei.o: bad reloc symbol index (0x7f16 >= 0x12) for offset 0x7f16d5c82cc8 in section `.orc_unwind_ip'

Signed-off-by: Michael Forney <mforney@mforney.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20210509000103.11008-1-mforney@mforney.org
2021-10-06 20:11:53 -07:00
Peter Zijlstra
b08cadbd3b Merge branch 'objtool/urgent'
Fixup conflicts.

# Conflicts:
#	tools/objtool/check.c
2021-10-07 00:40:17 +02:00
Joe Lawrence
fe255fe6ad objtool: Remove redundant 'len' field from struct section
The section structure already contains sh_size, so just remove the extra
'len' member that requires extra mirroring and potential confusion.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20210822225037.54620-3-joe.lawrence@redhat.com
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
2021-10-05 12:03:21 -07:00
Joe Lawrence
dc02368164 objtool: Make .altinstructions section entry size consistent
Commit e31694e0a7 ("objtool: Don't make .altinstructions writable")
aligned objtool-created and kernel-created .altinstructions section
flags, but there remains a minor discrepency in their use of a section
entry size: objtool sets one while the kernel build does not.

While sh_entsize of sizeof(struct alt_instr) seems intuitive, this small
deviation can cause failures with external tooling (kpatch-build).

Fix this by creating new .altinstructions sections with sh_entsize of 0
and then later updating sec->sh_size as alternatives are added to the
section.  An added benefit is avoiding the data descriptor and buffer
created by elf_create_section(), but previously unused by
elf_add_alternative().

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20210822225037.54620-2-joe.lawrence@redhat.com
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
2021-10-05 12:03:20 -07:00
Josh Poimboeuf
4d8b35968b objtool: Remove reloc symbol type checks in get_alt_entry()
Converting a special section's relocation reference to a symbol is
straightforward.  No need for objtool to complain that it doesn't know
how to handle it.  Just handle it.

This fixes the following warning:

  arch/x86/kvm/emulate.o: warning: objtool: __ex_table+0x4: don't know how to handle reloc symbol type: kvm_fastop_exception

Fixes: 24ff652573 ("objtool: Teach get_alt_entry() about more relocation types")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/feadbc3dfb3440d973580fad8d3db873cbfe1694.1633367242.git.jpoimboe@redhat.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-kernel@vger.kernel.org
2021-10-05 12:03:20 -07:00
Linus Torvalds
7fab1c12bd objtool: print out the symbol type when complaining about it
The objtool warning that the kvm instruction emulation code triggered
wasn't very useful:

    arch/x86/kvm/emulate.o: warning: objtool: __ex_table+0x4: don't know how to handle reloc symbol type: kvm_fastop_exception

in that it helpfully tells you which symbol name it had trouble figuring
out the relocation for, but it doesn't actually say what the unknown
symbol type was that triggered it all.

In this case it was because of missing type information (type 0, aka
STT_NOTYPE), but on the whole it really should just have printed that
out as part of the message.

Because if this warning triggers, that's very much the first thing you
want to know - why did reloc2sec_off() return failure for that symbol?

So rather than just saying you can't handle some type of symbol without
saying what the type _was_, just print out the type number too.

Fixes: 24ff652573 ("objtool: Teach get_alt_entry() about more relocation types")
Link: https://lore.kernel.org/lkml/CAHk-=wiZwq-0LknKhXN4M+T8jbxn_2i9mcKpO+OaBSSq_Eh7tg@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-10-03 13:45:48 -07:00
Peter Zijlstra
24ff652573 objtool: Teach get_alt_entry() about more relocation types
Occasionally objtool encounters symbol (as opposed to section)
relocations in .altinstructions. Typically they are the alternatives
written by elf_add_alternative() as encountered on a noinstr
validation run on vmlinux after having already ran objtool on the
individual .o files.

Basically this is the counterpart of commit 44f6a7c075 ("objtool:
Fix seg fault with Clang non-section symbols"), because when these new
assemblers (binutils now also does this) strip the section symbols,
elf_add_reloc_to_insn() is forced to emit symbol based relocations.

As such, teach get_alt_entry() about different relocation types.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/YVWUvknIEVNkPvnP@hirez.programming.kicks-ass.net
2021-10-01 13:57:47 +02:00
Josh Poimboeuf
5b284b1933 objtool: Ignore unwind hints for ignored functions
If a function is ignored, also ignore its hints.  This is useful for the
case where the function ignore is conditional on frame pointers, e.g.
STACK_FRAME_NON_STANDARD_FP().

Link: https://lkml.kernel.org/r/163163048317.489837.10988954983369863209.stgit@devnote2

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-09-30 21:24:07 -04:00
Peter Zijlstra
db2b0c5d7b objtool: Support pv_opsindirect calls for noinstr
Normally objtool will now follow indirect calls; there is no need.

However, this becomes a problem with noinstr validation; if there's an
indirect call from noinstr code, we very much need to know it is to
another noinstr function. Luckily there aren't many indirect calls in
entry code with the obvious exception of paravirt. As such, noinstr
validation didn't work with paravirt kernels.

In order to track pv_ops[] call targets, objtool reads the static
pv_ops[] tables as well as direct assignments to the pv_ops[] array,
provided the compiler makes them a single instruction like:

  bf87:       48 c7 05 00 00 00 00 00 00 00 00        movq   $0x0,0x0(%rip)
    bf92 <xen_init_spinlocks+0x5f>
    bf8a: R_X86_64_PC32     pv_ops+0x268

There are, as of yet, no warnings for when this goes wrong :/

Using the functions found with the above means, all pv_ops[] calls are
now subject to noinstr validation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210624095149.118815755@infradead.org
2021-09-17 13:20:26 +02:00
Peter Zijlstra
f56dae88a8 objtool: Handle __sanitize_cov*() tail calls
Turns out the compilers also generate tail calls to __sanitize_cov*(),
make sure to also patch those out in noinstr code.

Fixes: 0f1441b44e ("objtool: Fix noinstr vs KCOV")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org
2021-09-15 15:51:45 +02:00
Peter Zijlstra
8b946cc38e objtool: Introduce CFI hash
Andi reported that objtool on vmlinux.o consumes more memory than his
system has, leading to horrific performance.

This is in part because we keep a struct instruction for every
instruction in the file in-memory. Shrink struct instruction by
removing the CFI state (which includes full register state) from it
and demand allocating it.

Given most instructions don't actually change CFI state, there's lots
of repetition there, so add a hash table to find previous CFI
instances.

Reduces memory consumption (and runtime) for processing an
x86_64-allyesconfig:

  pre:  4:40.84 real,   143.99 user,    44.18 sys,      30624988 mem
  post: 2:14.61 real,   108.58 user,    25.04 sys,      16396184 mem

Suggested-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210624095147.756759107@infradead.org
2021-09-15 15:51:45 +02:00
Peter Zijlstra
9af9dcf11b x86/xen: Mark cpu_bringup_and_idle() as dead_end_function
The asm_cpu_bringup_and_idle() function is required to push the return
value on the stack in order to make ORC happy, but the only reason
objtool doesn't complain is because of a happy accident.

The thing is that asm_cpu_bringup_and_idle() doesn't return, so
validate_branch() never terminates and falls through to the next
function, which in the normal case is the hypercall_page. And that, as
it happens, is 4095 NOPs and a RET.

Make asm_cpu_bringup_and_idle() terminate on it's own, by making the
function it calls as a dead-end. This way we no longer rely on what
code happens to come after.

Fixes: c3881eb58d ("x86/xen: Make the secondary CPU idle tasks reliable")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org
2021-09-15 15:51:44 +02:00
Linus Torvalds
b89c07dea1 A single ELF format fix for a section flags mismatch bug that breaks
kernel tooling such as kpatch-build.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmDZYv4RHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1ipeBAAhJPS/kCQ17Y5zGyMB0/6yfCWIifODoS7
 9J+6/mqKHPDdV07yzPtOXuTTmpKV4OHPi8Yj8kaXs5L5fOmQ1uAwITwZNF5hU0a5
 CiFIsubUCJmglf9b6L9EH5pBEQ72Cq4u8zIhJ9LmZ4t625AHJAm2ikZgascc4U67
 RvVoGr5sYTo0YEsc1IDM1wUtnUhXBNjS1VwkXNnCFFTXYHju47MeY1sPHq2hvkzO
 iJGC9A+hxfM1eQt9/qC/2L/6F/XECN61gcR9Get8TkWeEGHmPG+FthmPLd4oO9Ho
 03J4JfMbmXumWosAeilYBNUkfii/M5Em78Wpv/cB94iSt67rq7Eb+8gm4D5svmfN
 l+utsPY/HYB+uWV0hy2cV/ORRiwcJnon54dEWL6912YkKz+OIb3DK/7l9ex5lW+D
 r3o8NP0s6S+RgUkOFxz5VaYK1giu6fiaFysWdKeflvwlvY/64owMepQ1QfPBbeB7
 3DTzvuYZ4Cb1x/vR6WBbFqGcuJKZ1CsZIBLCblveUs+G0wlu147K5E1qlXg/Wvq7
 5Vzznc4fmRng8np5hxAw8ieLkatWg7szyryUV/4H2Ubs/jWGcH628ZYbapaCb7EM
 Eson65xzbVfhnz16z8sN13XIF1lGe8sb0+qiFSclEfyDUnZDuhwMn6d9Ubqxrg5J
 uTULEzmY/rI=
 =MvPd
 -----END PGP SIGNATURE-----
mergetag object d33b9035e1
 type commit
 tag objtool-core-2021-06-28
 tagger Ingo Molnar <mingo@kernel.org> 1624859477 +0200
 
 The biggest change in this cycle is the new code to handle
 and rewrite variable sized jump labels - which results in
 slightly tighter code generation in hot paths, through the
 use of short(er) NOPs.
 
 Also a number of cleanups and fixes, and a change to the
 generic include/linux/compiler.h to handle a s390 GCC quirk.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmDZZGcRHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1goYg/7BxUIJXP0F5wbrMbAvJIDRgR/j3TA+ztk
 uNU1yabBGluMxCqJ87HadJ+A5d010G+GRUn/birVr7w1UuwWv8HOda78dnyG7tme
 xm78/1FlOnstuOTQxhK6rjbb2cp+QOmdsAQkq1TF4SOxArBQiwtjiOvytHjb5yNx
 7LrlbtuZ7Dtc0qd2evkG4ma4QkGoDhBS1dRogrItc27ZLuFIQoNnEd2K2QNMgczw
 a/Jx8fgNmdoJSq+vkBn9TnS/cJYUW/PAlPNtO3ac8yE857aDIVnjXFRzveAP/nTh
 rwFD6aCGnJAqyqP7A8ElNjySos5O+ebYApxe7rEx0TNLbrc55qSP9lpdIO+vgytV
 Xzy4O7z6o+lailQ4EoF8Qf+rlPeue0kLF23SsNbZY1uT0vjX1Uv70xgKbkuyPygp
 GNXAy6dOXK0AfaZYL/Wa50yVnJnkYDjes/hHr+HEam5Oad566pqIyQNP8yWSPqaf
 KHkL//1pb5C2RKwot4IYv/ftHfZB5QftoFq6bhGBc1GXUd/FiqivvGHPW/6g7rxi
 ZIrXs+Fqm/5KP9mssNONfyz5XEvbcUTD1CbeqX9eyVbiYZbLp1oWSgtogiRW9ya+
 HR7t0Dt/UFzFWbilb6EZff/Hdr1NZBZLdrfpvVDoMf5tR9J0BIOyjddTu89g/FIO
 KcfJ5yyjJBU=
 =+HAB
 -----END PGP SIGNATURE-----

Merge tags 'objtool-urgent-2021-06-28' and 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fix and updates from Ingo Molnar:
 "An ELF format fix for a section flags mismatch bug that breaks kernel
  tooling such as kpatch-build.

  The biggest change in this cycle is the new code to handle and rewrite
  variable sized jump labels - which results in slightly tighter code
  generation in hot paths, through the use of short(er) NOPs.

  Also a number of cleanups and fixes, and a change to the generic
  include/linux/compiler.h to handle a s390 GCC quirk"

* tag 'objtool-urgent-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Don't make .altinstructions writable

* tag 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Improve reloc hash size guestimate
  instrumentation.h: Avoid using inline asm operand modifiers
  compiler.h: Avoid using inline asm operand modifiers
  kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> := n'
  objtool: Reflow handle_jump_alt()
  jump_label/x86: Remove unused JUMP_LABEL_NOP_SIZE
  jump_label, x86: Allow short NOPs
  objtool: Provide stats for jump_labels
  objtool: Rewrite jump_label instructions
  objtool: Decode jump_entry::key addend
  jump_label, x86: Emit short JMP
  jump_label: Free jump_entry::key bit1 for build use
  jump_label, x86: Add variable length patching support
  jump_label, x86: Introduce jump_entry_size()
  jump_label, x86: Improve error when we fail expected text
  jump_label, x86: Factor out the __jump_table generation
  jump_label, x86: Strip ASM jump_label support
  x86, objtool: Dont exclude arch/x86/realmode/
  objtool: Rewrite hashtable sizing
2021-06-28 11:35:55 -07:00
Josh Poimboeuf
e31694e0a7 objtool: Don't make .altinstructions writable
When objtool creates the .altinstructions section, it sets the SHF_WRITE
flag to make the section writable -- unless the section had already been
previously created by the kernel.  The mismatch between kernel-created
and objtool-created section flags can cause failures with external
tooling (kpatch-build).  And the section doesn't need to be writable
anyway.

Make the section flags consistent with the kernel's.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/6c284ae89717889ea136f9f0064d914cd8329d31.1624462939.git.jpoimboe@redhat.com
2021-06-24 08:55:20 +02:00
Peter Zijlstra
d33b9035e1 objtool: Improve reloc hash size guestimate
Nathan reported that LLVM ThinLTO builds have a performance regression
with commit 25cf0d8aa2 ("objtool: Rewrite hashtable sizing"). Sami
was quick to note that this is due to their use of -ffunction-sections.

As a result the .text section is small and basing the number of relocs
off of that no longer works. Instead have read_sections() compute the
sum of all SHF_EXECINSTR sections and use that.

Fixes: 25cf0d8aa2 ("objtool: Rewrite hashtable sizing")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Debugged-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lkml.kernel.org/r/YMJpGLuGNsGtA5JJ@hirez.programming.kicks-ass.net
2021-06-14 14:05:36 +02:00
Peter Zijlstra
2d49b721dc objtool: Only rewrite unconditional retpoline thunk calls
It turns out that the compilers generate conditional branches to the
retpoline thunks like:

  5d5:   0f 85 00 00 00 00       jne    5db <cpuidle_reflect+0x22>
	5d7: R_X86_64_PLT32     __x86_indirect_thunk_r11-0x4

while the rewrite can only handle JMP/CALL to the thunks. The result
is the alternative wrecking the code. Make sure to skip writing the
alternatives for conditional branches.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Lukasz Majczak <lma@semihalf.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
2021-06-11 08:53:06 +02:00
Peter Zijlstra
584fd3b318 objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()
When an ELF object uses extended symbol section indexes (IOW it has a
.symtab_shndx section), these must be kept in sync with the regular
symbol table (.symtab).

So for every new symbol we emit, make sure to also emit a
.symtab_shndx value to keep the arrays of equal size.

Note: since we're writing an UNDEF symbol, most GElf_Sym fields will
be 0 and we can repurpose one (st_size) to host the 0 for the xshndx
value.

Fixes: 2f2f7e47f0 ("objtool: Add elf_create_undef_symbol()")
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/YL3q1qFO9QIRL/BA@hirez.programming.kicks-ass.net
2021-06-10 10:08:24 +02:00
Peter Zijlstra
48001d26c1 objtool: Reflow handle_jump_alt()
Miroslav figured the code flow in handle_jump_alt() was sub-optimal
with that goto. Reflow the code to make it clearer.

Reported-by: Miroslav Benes <mbenes@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YJ00lgslY+IpA/rL@hirez.programming.kicks-ass.net
2021-05-14 09:00:10 +02:00
Vasily Gorbik
f66c05d6ba objtool/x86: Fix elf_add_alternative() endianness
Currently x86 kernel cross-compiled on big endian system fails at boot with:

  kernel BUG at arch/x86/kernel/alternative.c:258!

Corresponding bug condition look like the following:

  BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32);

Fix that by converting alternative feature/cpuid to target endianness.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-2.thread-6c9df9.git-6c9df9a8098d.your-ad-here.call-01620841104-ext-2554@work.hours
2021-05-12 21:17:01 +02:00
Vasily Gorbik
46c7405df7 objtool: Fix elf_create_undef_symbol() endianness
Currently x86 cross-compilation fails on big endian system with:

  x86_64-cross-ld: init/main.o: invalid string offset 488112128 >= 6229 for section `.strtab'

Mark new ELF data in elf_create_undef_symbol() as symbol, so that libelf
does endianness handling correctly.

Fixes: 2f2f7e47f0 ("objtool: Add elf_create_undef_symbol()")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-1.thread-6c9df9.git-d39264656387.your-ad-here.call-01620841104-ext-2554@work.hours
2021-05-12 21:16:53 +02:00
Peter Zijlstra
e2d9494bef objtool: Provide stats for jump_labels
Add objtool --stats to count the jump_label sites it encounters.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.153101906@infradead.org
2021-05-12 14:54:56 +02:00
Peter Zijlstra
6d37b83c5d objtool: Rewrite jump_label instructions
When a jump_entry::key has bit1 set, rewrite the instruction to be a
NOP. This allows the compiler/assembler to emit JMP (and thus decide
on which encoding to use).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.091028792@infradead.org
2021-05-12 14:54:56 +02:00
Peter Zijlstra
cbf82a3dc2 objtool: Decode jump_entry::key addend
Teach objtool about the the low bits in the struct static_key pointer.

That is, the low two bits of @key in:

  struct jump_entry {
	s32 code;
	s32 target;
	long key;
  }

as found in the __jump_table section. Since @key has a relocation to
the variable (to be resolved by the linker), the low two bits will be
reflected in the relocation's addend.

As such, find the reloc and store the addend, such that we can access
these bits.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.028024143@infradead.org
2021-05-12 14:54:55 +02:00
Peter Zijlstra
25cf0d8aa2 objtool: Rewrite hashtable sizing
Currently objtool has 5 hashtables and sizes them 16 or 20 bits
depending on the --vmlinux argument.

However, a single side doesn't really work well for the 5 tables,
which among them, cover 3 different uses. Also, while vmlinux is
larger, there is still a very wide difference between a defconfig and
allyesconfig build, which again isn't optimally covered by a single
size.

Another aspect is the cost of elf_hash_init(), which for large tables
dominates the runtime for small input files. It turns out that all it
does it assign NULL, something that is required when using malloc().
However, when we allocate memory using mmap(), we're guaranteed to get
zero filled pages.

Therefore, rewrite the whole thing to:

 1) use more dynamic sized tables, depending on the input file,
 2) avoid the need for elf_hash_init() entirely by using mmap().

This speeds up a regular kernel build (100s to 98s for
x86_64-defconfig), and potentially dramatically speeds up vmlinux
processing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.452881700@infradead.org
2021-05-12 14:54:50 +02:00
Linus Torvalds
03b2cd72aa Objtool updates in this cycle were:
- Standardize the crypto asm code so that it looks like compiler-generated
    code to objtool - so that it can understand it. This enables unwinding
    from crypto asm code - and also fixes the last known remaining objtool
    warnings for LTO and more.
 
  - x86 decoder fixes: clean up and fix the decoder, and also extend it a bit
 
  - Misc fixes and cleanups
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmCJEOQRHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1jN0A//dZIR9GPW1cHkPD3Na+lxb+RWgCVnFUgw
 meLEOum389zWr7S8YmcFpKWLy94f3l24i/e7ufKn6/RMdaQuT6pZUa6teiNPqDKN
 Qq1v6EX/LT49Q1zh/zCCnKdlmF1t7wDyA1/+HBLnB4YfYEtteEt+p2Apyv4xIHOl
 xWqaTMFcVR/El9FXSyqRWRR4zuqY0Uatz0fmfo5jmi2xq460k53fQlTLA/0w5Jw0
 V3omyA3AYMUW6YlW5TGUINOhyDeAJm4PWl3siSUnSd6t8A/TVs5zpZX15BtseCle
 0FRp2SbxOoVkiyo3N3XmkfYYns9+4wK7cr9qja9U9MsSBZJZwaBm2LO/t2WFrAhq
 5dkOsoPmpIsjutsQnIhQgtVT9I/A4/u5m5Zi3trlXsBS0XAt/q+2GPfEngFmgb3q
 nae4rhGUsQ3NTGBiqNuMHQF4yeEvQZ8DCf3ytTz7DjBeiQ9nAtwzbUUGQjYl2mj1
 ZPOnl7Xmq/Nyw+AmdpffFPiEUJxqEg9HWjDo7DQATXb3Hw2VJ3cU8jwPRqDDlO10
 OB81vysXNGTmhOngHXexxncpmU9gDOIC1imZZpw5lNx4W9Qn20AlGaGAIbqzlfx0
 p5VuhkIWCySe1bOZx03xuk7Gq7GBIPPy/a2m204Ftipetlo1HBYwT3KB/wVpHmh7
 CSjWgdiW3+k=
 =poAZ
 -----END PGP SIGNATURE-----

Merge tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - Standardize the crypto asm code so that it looks like compiler-
   generated code to objtool - so that it can understand it. This
   enables unwinding from crypto asm code - and also fixes the last
   known remaining objtool warnings for LTO and more.

 - x86 decoder fixes: clean up and fix the decoder, and also extend it a
   bit

 - Misc fixes and cleanups

* tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/crypto: Enable objtool in crypto code
  x86/crypto/sha512-ssse3: Standardize stack alignment prologue
  x86/crypto/sha512-avx2: Standardize stack alignment prologue
  x86/crypto/sha512-avx: Standardize stack alignment prologue
  x86/crypto/sha256-avx2: Standardize stack alignment prologue
  x86/crypto/sha1_avx2: Standardize stack alignment prologue
  x86/crypto/sha_ni: Standardize stack alignment prologue
  x86/crypto/crc32c-pcl-intel: Standardize jump table
  x86/crypto/camellia-aesni-avx2: Unconditionally allocate stack buffer
  x86/crypto/aesni-intel_avx: Standardize stack alignment prologue
  x86/crypto/aesni-intel_avx: Fix register usage comments
  x86/crypto/aesni-intel_avx: Remove unused macros
  objtool: Support asm jump tables
  objtool: Parse options from OBJTOOL_ARGS
  objtool: Collate parse_options() users
  objtool: Add --backup
  objtool,x86: More ModRM sugar
  objtool,x86: Rewrite ADD/SUB/AND
  objtool,x86: Support %riz encodings
  objtool,x86: Simplify register decode
  ...
2021-04-28 12:53:24 -07:00
Josh Poimboeuf
99033461e6 objtool: Support asm jump tables
Objtool detection of asm jump tables would normally just work, except
for the fact that asm retpolines use alternatives.  Objtool thinks the
alternative code path (a jump to the retpoline) is a sibling call.

Don't treat alternative indirect branches as sibling calls when the
original instruction has a jump table.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/460cf4dc675d64e1124146562cabd2c05aa322e8.1614182415.git.jpoimboe@redhat.com
2021-04-19 12:36:32 -05:00
Peter Zijlstra
9bc0bb5072 objtool/x86: Rewrite retpoline thunk calls
When the compiler emits: "CALL __x86_indirect_thunk_\reg" for an
indirect call, have objtool rewrite it to:

	ALTERNATIVE "call __x86_indirect_thunk_\reg",
		    "call *%reg", ALT_NOT(X86_FEATURE_RETPOLINE)

Additionally, in order to not emit endless identical
.altinst_replacement chunks, use a global symbol for them, see
__x86_indirect_alt_*.

This also avoids objtool from having to do code generation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.320177914@infradead.org
2021-04-02 12:47:28 +02:00
Peter Zijlstra
50e7b4a1a1 objtool: Skip magical retpoline .altinstr_replacement
When the .altinstr_replacement is a retpoline, skip the alternative.
We already special case retpolines anyway.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.259429287@infradead.org
2021-04-02 12:46:57 +02:00
Peter Zijlstra
7bd2a600f3 objtool: Cache instruction relocs
Track the reloc of instructions in the new instruction->reloc field
to avoid having to look them up again later.

( Technically x86 instructions can have two relocations, but not jumps
  and calls, for which we're using this. )

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.195441549@infradead.org
2021-04-02 12:46:15 +02:00