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runtime: call cgocallbackg indirectly

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cgocallback calls cgocallbackg after switching the stack. Call it
indirectly to bypass the linker's nosplit check.

Apparently (at least on Windows) cgocallbackg can use quite a bit
stack space in a nosplit chain. We have been running over the
nosplit limit, or very close to the limit. Since it switches
stack in cgocallback, it is not meaningful to count frames above
cgocallback and below cgocallbackg together. Bypass the check.

For #45658.

Change-Id: Ie22017e3f82d2c1fcc37336696f2d02757856399
Reviewed-on: https://go-review.googlesource.com/c/go/+/312669
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
This commit is contained in:
Cherry Zhang 2021-04-22 11:12:21 -04:00
parent d5b2d809b0
commit d3853fb4e6
1 changed files with 2 additions and 1 deletions
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3
src/runtime/asm_amd64.s
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@ -911,7 +911,8 @@ havem:
MOVQ BX, 0(SP) MOVQ BX, 0(SP)
MOVQ CX, 8(SP) MOVQ CX, 8(SP)
MOVQ DX, 16(SP) MOVQ DX, 16(SP)
CALL runtime·cgocallbackg(SB) MOVQ $runtime·cgocallbackg(SB), AX
CALL AX // indirect call to bypass nosplit check. We're on a different stack now.
// Compute the size of the frame again. FP and SP have // Compute the size of the frame again. FP and SP have
// completely different values here than they did above, // completely different values here than they did above,