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runtime: use 2*regSize for saved frame pointer check

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Previously, we checked for a saved frame pointer by looking for a
2*ptrSize gap between the argument pointer and the locals pointer.
The intent of this check was to look for a two stack slot gap (caller
IP and saved frame pointer), but stack slots are regSize, not ptrSize.

Correct this by checking instead for a 2*regSize gap.

On most platforms, this made no difference because ptrSize==regSize.
However, on amd64p32 (nacl), the saved frame pointer check incorrectly
fired when there was no saved frame pointer because the one stack slot
for the caller IP left an 8 byte gap, which is 2*ptrSize (but not
2*regSize) on amd64p32.

Fixes #9760.

Change-Id: I6eedcf681fe5bf2bf924dde8a8f2d9860a4d758e
Reviewed-on: https://go-review.googlesource.com/3781
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Austin Clements 2015-02-03 09:09:56 -05:00
parent c901bd01c1
commit 67a03fd6a2
2 changed files with 3 additions and 2 deletions
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3
src/runtime/stack1.go
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@ -466,9 +466,10 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
}
// Adjust saved base pointer if there is one.
if thechar == '6' && frame.argp-frame.varp == 2*ptrSize {
if thechar == '6' && frame.argp-frame.varp == 2*regSize {
if !framepointer_enabled {
print("runtime: found space for saved base pointer, but no framepointer experiment\n")
print("argp=", hex(frame.argp), " varp=", hex(frame.varp), "\n")
throw("bad frame layout")
}
if stackDebug >= 3 {