Commit graph

915829 commits

Author SHA1 Message Date
Julien Thierry
9e98d62aa7 objtool: Remove check preventing branches within alternative
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
2020-04-30 20:14:31 +02:00
Ingo Molnar
0c98be8118 objtool: Constify arch_decode_instruction()
Mostly straightforward constification, except that WARN_FUNC()
needs a writable pointer while we have read-only pointers,
so deflect this to WARN().

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200422103205.61900-4-mingo@kernel.org
2020-04-23 08:34:18 +02:00
Ingo Molnar
bc359ff2f6 objtool: Rename elf_read() to elf_open_read()
'struct elf *' handling is an open/close paradigm, make sure the naming
matches that:

   elf_open_read()
   elf_write()
   elf_close()

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200422103205.61900-3-mingo@kernel.org
2020-04-23 08:34:18 +02:00
Ingo Molnar
894e48cada objtool: Constify 'struct elf *' parameters
In preparation to parallelize certain parts of objtool, map out which uses
of various data structures are read-only vs. read-write.

As a first step constify 'struct elf' pointer passing, most of the secondary
uses of it in find_symbol_*() methods are read-only.

Also, while at it, better group the 'struct elf' handling methods in elf.h.

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200422103205.61900-2-mingo@kernel.org
2020-04-23 08:34:18 +02:00
Thomas Gleixner
0cc9ac8db0 objtool: Also consider .entry.text as noinstr
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>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
932f8e987b objtool: Add STT_NOTYPE noinstr validation
Make sure to also check STT_NOTYPE symbols for noinstr violations.

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/20200416115119.465335884@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
4b5e2e7ffe objtool: Rearrange validate_section()
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>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
da837bd6f1 objtool: Avoid iterating !text section symbols
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>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
6804c1afd7 kbuild/objtool: Add objtool-vmlinux.o pass
Now that objtool is capable of processing vmlinux.o and actually has
something useful to do there, (conditionally) add it to the final link
pass.

This will increase build time by a few 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/20200416115119.287494491@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
87ecb582f0 objtool: Use sec_offset_hash() for insn_hash
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>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
34f7c96d96 objtool: Optimize !vmlinux.o again
When doing kbuild tests to see if the objtool changes affected those I
found that there was a measurable regression:

          pre		  post

  real    1m13.594        1m16.488s
  user    34m58.246s      35m23.947s
  sys     4m0.393s        4m27.312s

Perf showed that for small files the increased hash-table sizes were a
measurable difference. Since we already have -l "vmlinux" to
distinguish between the modes, make it also use a smaller portion of
the hash-tables.

This flips it into a small win:

  real    1m14.143s
  user    34m49.292s
  sys     3m44.746s

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/20200416115119.167588731@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
c4a33939a7 objtool: Implement noinstr validation
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>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
e7c0219b32 objtool: Fix !CFI insn_state propagation
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>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
a3608f5954 objtool: Rename struct cfi_state
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>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
c536ed2fff objtool: Remove SAVE/RESTORE hints
The SAVE/RESTORE hints are now unused; remove them.

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/20200416115118.926738768@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
9f2dfd61dd x86,ftrace: Shrink ftrace_regs_caller() by one byte
'Optimize' ftrace_regs_caller. Instead of comparing against an
immediate, the more natural way to test for zero on x86 is: 'test
%r,%r'.

  48 83 f8 00             cmp    $0x0,%rax
  74 49                   je     226 <ftrace_regs_call+0xa3>

  48 85 c0                test   %rax,%rax
  74 49                   je     225 <ftrace_regs_call+0xa2>

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/20200416115118.867411350@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
dc2745b619 x86,ftrace: Use SIZEOF_PTREGS
There's a convenient macro for 'SS+8' called FRAME_SIZE. Use it to
clarify things.

(entry/calling.h calls this SIZEOF_PTREGS but we're using
asm/ptrace-abi.h)

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/20200416115118.808485515@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
0298739b79 x86,ftrace: Fix ftrace_regs_caller() unwind
The ftrace_regs_caller() trampoline does something 'funny' when there
is a direct-caller present. In that case it stuffs the 'direct-caller'
address on the return stack and then exits the function. This then
results in 'returning' to the direct-caller with the exact registers
we came in with -- an indirect tail-call without using a register.

This however (rightfully) confuses objtool because the function shares
a few instruction in order to have a single exit path, but the stack
layout is different for them, depending through which path we came
there.

This is currently cludged by forcing the stack state to the non-direct
case, but this generates actively wrong (ORC) unwind information for
the direct case, leading to potential broken unwinds.

Fix this issue by fully separating the exit paths. This results in
having to poke a second RET into the trampoline copy, see
ftrace_regs_caller_ret.

This brings us to a second objtool problem, in order for it to
perceive the 'jmp ftrace_epilogue' as a function exit, it needs to be
recognised as a tail call. In order to make that happen,
ftrace_epilogue needs to be the start of an STT_FUNC, so re-arrange
code to make this so.

Finally, a third issue is that objtool requires functions to exit with
the same stack layout they started with, which is obviously violated
in the direct case, employ the new HINT_RET_OFFSET to tell objtool
this is an expected exception.

Together, this results in generating correct ORC unwind information
for the ftrace_regs_caller() function and it's trampoline copies.

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/20200416115118.749606694@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
e25eea89bb objtool: Introduce HINT_RET_OFFSET
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>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
b746046238 objtool: Better handle IRET
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>
2020-04-22 10:53:50 +02:00
Julien Thierry
65ea47dcf4 objtool: Support multiple stack_op per instruction
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>
2020-04-22 10:53:50 +02:00
Muchun Song
1ee444700e objtool: Remove redundant .rodata section name comparison
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>
2020-04-22 10:53:50 +02:00
Nick Desaulniers
e378fa17d3 objtool: Documentation: document UACCESS warnings
Compiling with Clang and CONFIG_KASAN=y was exposing a few warnings:

  call to memset() with UACCESS enabled

Document how to fix these for future travelers.

Link: https://github.com/ClangBuiltLinux/linux/issues/876
Suggested-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Suggested-by: Matt Helsley <mhelsley@vmware.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
6f8ca67683 objtool: Split out arch-specific CFI definitions
Some CFI definitions used by generic objtool code have no reason to vary
from one architecture to another.  Keep those definitions in generic
code and move the arch-specific ones to a new arch-specific header.

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>
2020-04-22 10:53:49 +02:00
Raphael Gault
bfb08f2203 objtool: Add abstraction for destination offsets
The jump and call destination relocation offsets are x86-specific.
Abstract them by calling arch-specific implementations.

[ jthierry: Remove superfluous comment; replace other addend offsets
      	    with arch_dest_rela_offset() ]

Signed-off-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>
2020-04-22 10:53:49 +02:00
Julien Thierry
aff5e16918 objtool: Use arch specific values in restore_reg()
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>
2020-04-22 10:53:49 +02:00
Julien Thierry
7170cf47d1 objtool: Ignore empty alternatives
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>
2020-04-22 10:53:49 +02:00
Julien Thierry
0699e551af objtool: Clean instruction state before each function validation
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>
2020-04-22 10:53:49 +02:00
Julien Thierry
a70266b5b2 objtool: Remove redundant checks on operand type
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>
2020-04-22 10:53:49 +02:00
Julien Thierry
aa5847270a objtool: Always do header sync check
Currently, the check of tools files against kernel equivalent is only
done after every object file has been built. This means one might fix
build issues against outdated headers without seeing a warning about
this.

Check headers before any object is built. Also, make it part of a
FORCE'd recipe so every attempt to build objtool will report the
outdated headers (if any).

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>
2020-04-22 10:53:49 +02:00
Julien Thierry
5377cae94a objtool: Fix off-by-one in symbol_by_offset()
Sometimes, WARN_FUNC() and other users of symbol_by_offset() will
associate the first instruction of a symbol with the symbol preceding
it.  This is because symbol->offset + symbol->len is already outside of
the symbol's range.

Fixes: 2a362ecc3e ("objtool: Optimize find_symbol_*() and read_symbols()")
Signed-off-by: Julien Thierry <jthierry@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>
2020-04-22 10:53:49 +02:00
Peter Zijlstra
963d566917 objtool: Fix 32bit cross builds
Apparently there's people doing 64bit builds on 32bit machines.

Fixes: 74b873e49d ("objtool: Optimize find_rela_by_dest_range()")
Reported-by: youling257@gmail.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Linus Torvalds
18bf34080c Merge branch 'akpm' (patches from Andrew)
Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  tools/vm: fix cross-compile build
  coredump: fix null pointer dereference on coredump
  mm: shmem: disable interrupt when acquiring info->lock in userfaultfd_copy path
  shmem: fix possible deadlocks on shmlock_user_lock
  vmalloc: fix remap_vmalloc_range() bounds checks
  mm/shmem: fix build without THP
  mm/ksm: fix NULL pointer dereference when KSM zero page is enabled
  tools/build: tweak unused value workaround
  checkpatch: fix a typo in the regex for $allocFunctions
  mm, gup: return EINTR when gup is interrupted by fatal signals
  mm/hugetlb: fix a addressing exception caused by huge_pte_offset
  MAINTAINERS: add an entry for kfifo
  mm/userfaultfd: disable userfaultfd-wp on x86_32
  slub: avoid redzone when choosing freepointer location
  sh: fix build error in mm/init.c
2020-04-21 13:26:54 -07:00
Linus Torvalds
8160a563cf Bugfixes, and a few cleanups to the newly-introduced assembly language
vmentry code for AMD.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Bugfixes, and a few cleanups to the newly-introduced assembly language
  vmentry code for AMD"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: PPC: Book3S HV: Handle non-present PTEs in page fault functions
  kvm: Disable objtool frame pointer checking for vmenter.S
  MAINTAINERS: add a reviewer for KVM/s390
  KVM: s390: Fix PV check in deliverable_irqs()
  kvm: Handle reads of SandyBridge RAPL PMU MSRs rather than injecting #GP
  KVM: Remove CREATE_IRQCHIP/SET_PIT2 race
  KVM: SVM: Fix __svm_vcpu_run declaration.
  KVM: SVM: Do not setup frame pointer in __svm_vcpu_run
  KVM: SVM: Fix build error due to missing release_pages() include
  KVM: SVM: Do not mark svm_vcpu_run with STACK_FRAME_NON_STANDARD
  kvm: nVMX: match comment with return type for nested_vmx_exit_reflected
  kvm: nVMX: reflect MTF VM-exits if injected by L1
  KVM: s390: Return last valid slot if approx index is out-of-bounds
  KVM: Check validity of resolved slot when searching memslots
  KVM: VMX: Enable machine check support for 32bit targets
  KVM: SVM: move more vmentry code to assembly
  KVM: SVM: fix compilation with modular PSP and non-modular KVM
2020-04-21 12:59:10 -07:00
Linus Torvalds
189522da8b virtio: fixes, cleanups
Some bug fixes.
 Cleanup a couple of issues that surfaced meanwhile.
 Disable vhost on ARM with OABI for now - to be fixed
 fully later in the cycle or in the next release.
 
 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio fixes and cleanups from Michael Tsirkin:

 - Some bug fixes

 - Cleanup a couple of issues that surfaced meanwhile

 - Disable vhost on ARM with OABI for now - to be fixed fully later in
   the cycle or in the next release.

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (24 commits)
  vhost: disable for OABI
  virtio: drop vringh.h dependency
  virtio_blk: add a missing include
  virtio-balloon: Avoid using the word 'report' when referring to free page hinting
  virtio-balloon: make virtballoon_free_page_report() static
  vdpa: fix comment of vdpa_register_device()
  vdpa: make vhost, virtio depend on menu
  vdpa: allow a 32 bit vq alignment
  drm/virtio: fix up for include file changes
  remoteproc: pull in slab.h
  rpmsg: pull in slab.h
  virtio_input: pull in slab.h
  remoteproc: pull in slab.h
  virtio-rng: pull in slab.h
  virtgpu: pull in uaccess.h
  tools/virtio: make asm/barrier.h self contained
  tools/virtio: define aligned attribute
  virtio/test: fix up after IOTLB changes
  vhost: Create accessors for virtqueues private_data
  vdpasim: Return status in vdpasim_get_status
  ...
2020-04-21 12:27:18 -07:00
Linus Torvalds
b61f7ff0f6 tpmdd updates for Linux v5.6-rc3
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Merge tag 'tpmdd-next-20200421' of git://git.infradead.org/users/jjs/linux-tpmdd

Pull tpm fixes from Jarkko Sakkinen:
 "A few bug fixes"

* tag 'tpmdd-next-20200421' of git://git.infradead.org/users/jjs/linux-tpmdd:
  tpm/tpm_tis: Free IRQ if probing fails
  tpm: fix wrong return value in tpm_pcr_extend
  tpm: ibmvtpm: retry on H_CLOSED in tpm_ibmvtpm_send()
  tpm: Export tpm2_get_cc_attrs_tbl for ibmvtpm driver as module
2020-04-21 12:24:33 -07:00
Linus Torvalds
20f1648909 Two trivial clang-format changes:
- Don't indent C++ namespaces (Ian Rogers)
 
  - The usual clang-format macro list update (Miguel Ojeda)
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Merge tag 'clang-format-for-linus-v5.7-rc3' of git://github.com/ojeda/linux

Pull clang-format fixlets from Miguel Ojeda:
 "Two trivial clang-format changes:

   - Don't indent C++ namespaces (Ian Rogers)

   - The usual clang-format macro list update (Miguel Ojeda)"

* tag 'clang-format-for-linus-v5.7-rc3' of git://github.com/ojeda/linux:
  clang-format: Update with the latest for_each macro list
  clang-format: don't indent namespaces
2020-04-21 12:07:42 -07:00
Lucas Stach
cf01699ee2 tools/vm: fix cross-compile build
Commit 7ed1c1901f ("tools: fix cross-compile var clobbering") moved
the setup of the CC variable to tools/scripts/Makefile.include to make
the behavior consistent across all the tools Makefiles.

As the vm tools missed the include we end up with the wrong CC in a
cross-compiling evironment.

Fixes: 7ed1c1901f (tools: fix cross-compile var clobbering)
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Kelly <martin@martingkelly.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200416104748.25243-1-l.stach@pengutronix.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:56 -07:00
Sudip Mukherjee
db973a7289 coredump: fix null pointer dereference on coredump
If the core_pattern is set to "|" and any process segfaults then we get
a null pointer derefernce while trying to coredump. The call stack shows:

    RIP: do_coredump+0x628/0x11c0

When the core_pattern has only "|" there is no use of trying the
coredump and we can check that while formating the corename and exit
with an error.

After this change I get:

    format_corename failed
    Aborting core

Fixes: 315c69261d ("coredump: split pipe command whitespace before expanding template")
Reported-by: Matthew Ruffell <matthew.ruffell@canonical.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Wise <pabs3@bonedaddy.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200416194612.21418-1-sudipm.mukherjee@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:56 -07:00
Yang Shi
94b7cc01da mm: shmem: disable interrupt when acquiring info->lock in userfaultfd_copy path
Syzbot reported the below lockdep splat:

    WARNING: possible irq lock inversion dependency detected
    5.6.0-rc7-syzkaller #0 Not tainted
    --------------------------------------------------------
    syz-executor.0/10317 just changed the state of lock:
    ffff888021d16568 (&(&info->lock)->rlock){+.+.}, at: spin_lock include/linux/spinlock.h:338 [inline]
    ffff888021d16568 (&(&info->lock)->rlock){+.+.}, at: shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
    but this lock was taken by another, SOFTIRQ-safe lock in the past:
     (&(&xa->xa_lock)->rlock#5){..-.}

    and interrupts could create inverse lock ordering between them.

    other info that might help us debug this:
     Possible interrupt unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(&(&info->lock)->rlock);
                                   local_irq_disable();
                                   lock(&(&xa->xa_lock)->rlock#5);
                                   lock(&(&info->lock)->rlock);
      <Interrupt>
        lock(&(&xa->xa_lock)->rlock#5);

     *** DEADLOCK ***

The full report is quite lengthy, please see:

  https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2004152007370.13597@eggly.anvils/T/#m813b412c5f78e25ca8c6c7734886ed4de43f241d

It is because CPU 0 held info->lock with IRQ enabled in userfaultfd_copy
path, then CPU 1 is splitting a THP which held xa_lock and info->lock in
IRQ disabled context at the same time.  If softirq comes in to acquire
xa_lock, the deadlock would be triggered.

The fix is to acquire/release info->lock with *_irq version instead of
plain spin_{lock,unlock} to make it softirq safe.

Fixes: 4c27fe4c4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Reported-by: syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/r/1587061357-122619-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:56 -07:00
Hugh Dickins
ea0dfeb420 shmem: fix possible deadlocks on shmlock_user_lock
Recent commit 71725ed10c ("mm: huge tmpfs: try to split_huge_page()
when punching hole") has allowed syzkaller to probe deeper, uncovering a
long-standing lockdep issue between the irq-unsafe shmlock_user_lock,
the irq-safe xa_lock on mapping->i_pages, and shmem inode's info->lock
which nests inside xa_lock (or tree_lock) since 4.8's shmem_uncharge().

user_shm_lock(), servicing SysV shmctl(SHM_LOCK), wants
shmlock_user_lock while its caller shmem_lock() holds info->lock with
interrupts disabled; but hugetlbfs_file_setup() calls user_shm_lock()
with interrupts enabled, and might be interrupted by a writeback endio
wanting xa_lock on i_pages.

This may not risk an actual deadlock, since shmem inodes do not take
part in writeback accounting, but there are several easy ways to avoid
it.

Requiring interrupts disabled for shmlock_user_lock would be easy, but
it's a high-level global lock for which that seems inappropriate.
Instead, recall that the use of info->lock to guard info->flags in
shmem_lock() dates from pre-3.1 days, when races with SHMEM_PAGEIN and
SHMEM_TRUNCATE could occur: nowadays it serves no purpose, the only flag
added or removed is VM_LOCKED itself, and calls to shmem_lock() an inode
are already serialized by the caller.

Take info->lock out of the chain and the possibility of deadlock or
lockdep warning goes away.

Fixes: 4595ef88d1 ("shmem: make shmem_inode_info::lock irq-safe")
Reported-by: syzbot+c8a8197c8852f566b9d9@syzkaller.appspotmail.com
Reported-by: syzbot+40b71e145e73f78f81ad@syzkaller.appspotmail.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2004161707410.16322@eggly.anvils
Link: https://lore.kernel.org/lkml/000000000000e5838c05a3152f53@google.com/
Link: https://lore.kernel.org/lkml/0000000000003712b305a331d3b1@google.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:56 -07:00
Jann Horn
bdebd6a283 vmalloc: fix remap_vmalloc_range() bounds checks
remap_vmalloc_range() has had various issues with the bounds checks it
promises to perform ("This function checks that addr is a valid
vmalloc'ed area, and that it is big enough to cover the vma") over time,
e.g.:

 - not detecting pgoff<<PAGE_SHIFT overflow

 - not detecting (pgoff<<PAGE_SHIFT)+usize overflow

 - not checking whether addr and addr+(pgoff<<PAGE_SHIFT) are the same
   vmalloc allocation

 - comparing a potentially wildly out-of-bounds pointer with the end of
   the vmalloc region

In particular, since commit fc9702273e ("bpf: Add mmap() support for
BPF_MAP_TYPE_ARRAY"), unprivileged users can cause kernel null pointer
dereferences by calling mmap() on a BPF map with a size that is bigger
than the distance from the start of the BPF map to the end of the
address space.

This could theoretically be used as a kernel ASLR bypass, by using
whether mmap() with a given offset oopses or returns an error code to
perform a binary search over the possible address range.

To allow remap_vmalloc_range_partial() to verify that addr and
addr+(pgoff<<PAGE_SHIFT) are in the same vmalloc region, pass the offset
to remap_vmalloc_range_partial() instead of adding it to the pointer in
remap_vmalloc_range().

In remap_vmalloc_range_partial(), fix the check against
get_vm_area_size() by using size comparisons instead of pointer
comparisons, and add checks for pgoff.

Fixes: 833423143c ("[PATCH] mm: introduce remap_vmalloc_range()")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Link: http://lkml.kernel.org/r/20200415222312.236431-1-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:56 -07:00
Hugh Dickins
0783ac95b4 mm/shmem: fix build without THP
Some optimizers don't notice that shmem_punch_compound() is always true
(PageTransCompound() being false) without CONFIG_TRANSPARENT_HUGEPAGE==y.

Use IS_ENABLED to help them to avoid the BUILD_BUG inside HPAGE_PMD_NR.

Fixes: 71725ed10c ("mm: huge tmpfs: try to split_huge_page() when punching hole")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2004142339170.10035@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
Muchun Song
56df70a63e mm/ksm: fix NULL pointer dereference when KSM zero page is enabled
find_mergeable_vma() can return NULL.  In this case, it leads to a crash
when we access vm_mm(its offset is 0x40) later in write_protect_page.
And this case did happen on our server.  The following call trace is
captured in kernel 4.19 with the following patch applied and KSM zero
page enabled on our server.

  commit e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring")

So add a vma check to fix it.

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
  Oops: 0000 [#1] SMP NOPTI
  CPU: 9 PID: 510 Comm: ksmd Kdump: loaded Tainted: G OE 4.19.36.bsk.9-amd64 #4.19.36.bsk.9
  RIP: try_to_merge_one_page+0xc7/0x760
  Code: 24 58 65 48 33 34 25 28 00 00 00 89 e8 0f 85 a3 06 00 00 48 83 c4
        60 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 8b 46 08 a8 01 75 b8 <49>
        8b 44 24 40 4c 8d 7c 24 20 b9 07 00 00 00 4c 89 e6 4c 89 ff 48
  RSP: 0018:ffffadbdd9fffdb0 EFLAGS: 00010246
  RAX: ffffda83ffd4be08 RBX: ffffda83ffd4be40 RCX: 0000002c6e800000
  RDX: 0000000000000000 RSI: ffffda83ffd4be40 RDI: 0000000000000000
  RBP: ffffa11939f02ec0 R08: 0000000094e1a447 R09: 00000000abe76577
  R10: 0000000000000962 R11: 0000000000004e6a R12: 0000000000000000
  R13: ffffda83b1e06380 R14: ffffa18f31f072c0 R15: ffffda83ffd4be40
  FS: 0000000000000000(0000) GS:ffffa0da43b80000(0000) knlGS:0000000000000000
  CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000040 CR3: 0000002c77c0a003 CR4: 00000000007626e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
    ksm_scan_thread+0x115e/0x1960
    kthread+0xf5/0x130
    ret_from_fork+0x1f/0x30

[songmuchun@bytedance.com: if the vma is out of date, just exit]
  Link: http://lkml.kernel.org/r/20200416025034.29780-1-songmuchun@bytedance.com
[akpm@linux-foundation.org: add the conventional braces, replace /** with /*]
Fixes: e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring")
Co-developed-by: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Cc: Markus Elfring <Markus.Elfring@web.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200416025034.29780-1-songmuchun@bytedance.com
Link: http://lkml.kernel.org/r/20200414132905.83819-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
George Burgess IV
a21151b9d8 tools/build: tweak unused value workaround
Clang has -Wself-assign enabled by default under -Wall, which always
gets -Werror'ed on this file, causing sync-compare-and-swap to be
disabled by default.

The generally-accepted way to spell "this value is intentionally
unused," is casting it to `void`.  This is accepted by both GCC and
Clang with -Wall enabled: https://godbolt.org/z/qqZ9r3

Signed-off-by: George Burgess IV <gbiv@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Link: http://lkml.kernel.org/r/20200414195638.156123-1-gbiv@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
Christophe JAILLET
461e156536 checkpatch: fix a typo in the regex for $allocFunctions
Here, we look for function such as 'netdev_alloc_skb_ip_align', so a '_'
is missing in the regex.

To make sure:
   grep -r --include=*.c skbip_a * | wc   ==>   0 results
   grep -r --include=*.c skb_ip_a * | wc  ==> 112 results

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200407190029.892-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
Michal Hocko
d180870d83 mm, gup: return EINTR when gup is interrupted by fatal signals
EINTR is the usual error code which other killable interfaces return.
This is the case for the other fatal_signal_pending break out from the
same function.  Make the code consistent.

ERESTARTSYS is also quite confusing because the signal is fatal and so
no restart will happen before returning to the userspace.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Link: http://lkml.kernel.org/r/20200409071133.31734-1-mhocko@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
Longpeng
3c1d7e6ccb mm/hugetlb: fix a addressing exception caused by huge_pte_offset
Our machine encountered a panic(addressing exception) after run for a
long time and the calltrace is:

    RIP: hugetlb_fault+0x307/0xbe0
    RSP: 0018:ffff9567fc27f808  EFLAGS: 00010286
    RAX: e800c03ff1258d48 RBX: ffffd3bb003b69c0 RCX: e800c03ff1258d48
    RDX: 17ff3fc00eda72b7 RSI: 00003ffffffff000 RDI: e800c03ff1258d48
    RBP: ffff9567fc27f8c8 R08: e800c03ff1258d48 R09: 0000000000000080
    R10: ffffaba0704c22a8 R11: 0000000000000001 R12: ffff95c87b4b60d8
    R13: 00005fff00000000 R14: 0000000000000000 R15: ffff9567face8074
    FS:  00007fe2d9ffb700(0000) GS:ffff956900e40000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffffd3bb003b69c0 CR3: 000000be67374000 CR4: 00000000003627e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
      follow_hugetlb_page+0x175/0x540
      __get_user_pages+0x2a0/0x7e0
      __get_user_pages_unlocked+0x15d/0x210
      __gfn_to_pfn_memslot+0x3c5/0x460 [kvm]
      try_async_pf+0x6e/0x2a0 [kvm]
      tdp_page_fault+0x151/0x2d0 [kvm]
     ...
      kvm_arch_vcpu_ioctl_run+0x330/0x490 [kvm]
      kvm_vcpu_ioctl+0x309/0x6d0 [kvm]
      do_vfs_ioctl+0x3f0/0x540
      SyS_ioctl+0xa1/0xc0
      system_call_fastpath+0x22/0x27

For 1G hugepages, huge_pte_offset() wants to return NULL or pudp, but it
may return a wrong 'pmdp' if there is a race.  Please look at the
following code snippet:

    ...
    pud = pud_offset(p4d, addr);
    if (sz != PUD_SIZE && pud_none(*pud))
        return NULL;
    /* hugepage or swap? */
    if (pud_huge(*pud) || !pud_present(*pud))
        return (pte_t *)pud;

    pmd = pmd_offset(pud, addr);
    if (sz != PMD_SIZE && pmd_none(*pmd))
        return NULL;
    /* hugepage or swap? */
    if (pmd_huge(*pmd) || !pmd_present(*pmd))
        return (pte_t *)pmd;
    ...

The following sequence would trigger this bug:

 - CPU0: sz = PUD_SIZE and *pud = 0 , continue
 - CPU0: "pud_huge(*pud)" is false
 - CPU1: calling hugetlb_no_page and set *pud to xxxx8e7(PRESENT)
 - CPU0: "!pud_present(*pud)" is false, continue
 - CPU0: pmd = pmd_offset(pud, addr) and maybe return a wrong pmdp

However, we want CPU0 to return NULL or pudp in this case.

We must make sure there is exactly one dereference of pud and pmd.

Signed-off-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200413010342.771-1-longpeng2@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
Bartosz Golaszewski
5701feb0a9 MAINTAINERS: add an entry for kfifo
Kfifo has been written by Stefani Seibold and she's implicitly expected
to Ack any changes to it.  She's not however officially listed as kfifo
maintainer which leads to delays in patch review.  This patch proposes
to add an explitic entry for kfifo to MAINTAINERS file.

[akpm@linux-foundation.org: alphasort F: entries, per Joe]
[akpm@linux-foundation.org: remove colon, per Bartosz]
Link: http://lkml.kernel.org/r/20200124174533.21815-1-brgl@bgdev.pl
Link: http://lkml.kernel.org/r/20200413104250.26683-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00
Peter Xu
b64d8d1e1b mm/userfaultfd: disable userfaultfd-wp on x86_32
Userfaultfd-wp is not yet working on 32bit hosts, but it's accidentally
enabled previously.  Disable it.

Fixes: 5a281062af ("userfaultfd: wp: add WP pagetable tracking to x86")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Link: http://lkml.kernel.org/r/20200413141608.109211-1-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21 11:11:55 -07:00