diff options
| author | Will Deacon <will@kernel.org> | 2020-05-19 14:56:05 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-05-21 14:59:26 +0300 |
| commit | a4eb355a3fdad85d16e4b098e8d56bb28b812ce0 (patch) | |
| tree | 6926231c6775a41e08ff85376027ef2d7e65cfdd /arch/arm64/kernel/vdso32 | |
| parent | 9a964285572b5a3ea268bd744bb6837aecf09640 (diff) | |
| download | linux-a4eb355a3fdad85d16e4b098e8d56bb28b812ce0.tar.xz | |
arm64: vdso: Fix CFI directives in sigreturn trampoline
Daniel reports that the .cfi_startproc is misplaced for the sigreturn
trampoline, which causes LLVM's unwinder to misbehave:
| I run into this with LLVM’s unwinder.
| This combination was always broken.
This prompted Dave to question our use of CFI directives more generally,
and I ended up going down a rabbit hole trying to figure out how this
very poorly documented stuff gets used.
Move the CFI directives so that the "mysterious NOP" is included in
the .cfi_{start,end}proc block and add a bunch of comments so that I
can save myself another headache in future.
Cc: Tamas Zsoldos <tamas.zsoldos@arm.com>
Reported-by: Dave Martin <dave.martin@arm.com>
Reported-by: Daniel Kiss <daniel.kiss@arm.com>
Tested-by: Daniel Kiss <daniel.kiss@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/vdso32')
| -rw-r--r-- | arch/arm64/kernel/vdso32/sigreturn.S | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/kernel/vdso32/sigreturn.S b/arch/arm64/kernel/vdso32/sigreturn.S index b36d4e2267a3..b0091064c3d6 100644 --- a/arch/arm64/kernel/vdso32/sigreturn.S +++ b/arch/arm64/kernel/vdso32/sigreturn.S @@ -3,6 +3,9 @@ * This file provides both A32 and T32 versions, in accordance with the * arm sigreturn code. * + * Please read the comments in arch/arm64/kernel/vdso/sigreturn.S to + * understand some of the craziness in here. + * * Copyright (C) 2018 ARM Limited */ |