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runtime: fix stack alignment for Windows amd64 lib entry 

Windows amd64 calling convention requires 16-bytes aligned
stack pointer. Before this patch, the real frame size is
0x48 (frame size) + 0x10 (frame pointer & return address),
which does not satisfy the alignment requirement.

_cgo_sys_thread_create eventually calls NtCreateThread,
which receives a pointer to a ThreadContext structure
allocated from (mis-aligned) stack, and may fail with
STATUS_DATATYPE_MISALIGNMENT on some implementations.

BP is saved/restored by prolog/epilog.
AX, CX, DX are volatile, no need to save and restore.

Fixes #41075
This commit is contained in:
Youfu Zhang 2021-02-23 11:25:47 +08:00
parent 5f3dabbb79
commit 15d2bd740e
1 changed files with 1 additions and 13 deletions
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14
src/runtime/rt0_windows_amd64.s
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@ -16,24 +16,12 @@ TEXT _rt0_amd64_windows(SB),NOSPLIT,$-8
// phase.
// Leave space for four pointers on the stack as required
// by the Windows amd64 calling convention.
TEXT _rt0_amd64_windows_lib(SB),NOSPLIT,$0x48
MOVQ BP, 0x20(SP)
MOVQ BX, 0x28(SP)
MOVQ AX, 0x30(SP)
MOVQ CX, 0x38(SP)
MOVQ DX, 0x40(SP)
TEXT _rt0_amd64_windows_lib(SB),NOSPLIT,$0x20
// Create a new thread to do the runtime initialization and return.
MOVQ _cgo_sys_thread_create(SB), AX
MOVQ $_rt0_amd64_windows_lib_go(SB), CX
MOVQ $0, DX
CALL AX
MOVQ 0x20(SP), BP
MOVQ 0x28(SP), BX
MOVQ 0x30(SP), AX
MOVQ 0x38(SP), CX
MOVQ 0x40(SP), DX
RET
TEXT _rt0_amd64_windows_lib_go(SB),NOSPLIT,$0