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| author | Dan Scales <danscales@google.com> | 2019-12-18 17:27:27 -0800 |
|---|---|---|
| committer | Dan Scales <danscales@google.com> | 2019-12-20 19:01:41 +0000 |
| commit | 21713f41d17514a432a881655332fbcde4814b45 (patch) | |
| tree | 91c0e3d2abcc0589402a8b17aeaa9300ec34f239 /src/runtime/sys_linux_amd64.s | |
| parent | 3f51350c706c8ff663f12867bcfec98aa9fc46bf (diff) | |
| download | go-21713f41d17514a432a881655332fbcde4814b45.tar.gz go-21713f41d17514a432a881655332fbcde4814b45.zip | |
runtime: make sure BP is saved in nanotime1/walltime1, else frame pointer may not be preserved
nanotime1 and walltime1 do not preserve BP on linux amd64. Previously, this
did not cause a problem, because nanotime/walltime do preserve the BP. But now
with mid-stack inlining, nanotime/walltime are usually inlined, so BP is not
preserved. So, the BP is now wrong in any function after a call to
nanotime()/walltime() on amd64. That means the frame pointer on the stack can
be wrong for any further function call made after the nanotime() call (notably
runtime.main and various GC functions). [386 doesn't use framepointer.]
Fix is to set a frame size of 8 for nanotime1 and walltime1, which means the
standard prolog/epilog that saves/restore BP in the stack frame is added.
I noticed this while investigating issue 16638 (use frame pointers for
runtime.Callers). This change would needed for progress on that issue (which
doesn't have a high priority). Verified that this fix works/is useful for issue
16638.
Change-Id: I19e19ef2c1a517d737a34928baae034f2eb0b2c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/212079
Run-TryBot: Dan Scales <danscales@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src/runtime/sys_linux_amd64.s')
| -rw-r--r-- | src/runtime/sys_linux_amd64.s | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s index 174120f887..9493101460 100644 --- a/src/runtime/sys_linux_amd64.s +++ b/src/runtime/sys_linux_amd64.s @@ -205,7 +205,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-28 RET // func walltime1() (sec int64, nsec int32) -TEXT runtime·walltime1(SB),NOSPLIT,$0-12 +// non-zero frame-size means bp is saved and restored +TEXT runtime·walltime1(SB),NOSPLIT,$8-12 // We don't know how much stack space the VDSO code will need, // so switch to g0. // In particular, a kernel configured with CONFIG_OPTIMIZE_INLINING=n @@ -262,7 +263,9 @@ fallback: MOVL DX, nsec+8(FP) RET -TEXT runtime·nanotime1(SB),NOSPLIT,$0-8 +// func nanotime1() int64 +// non-zero frame-size means bp is saved and restored +TEXT runtime·nanotime1(SB),NOSPLIT,$8-8 // Switch to g0 stack. See comment above in runtime·walltime. MOVQ SP, BP // Save old SP; BP unchanged by C code. |