runtime: make stack 16-byte aligned for external code in _rt0_amd64_linux_lib

Fixes #16618.

Change-Id: Iffada12e8672bbdbcf2e787782c497e2c45701b1
Reviewed-on: https://go-review.googlesource.com/25550
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/runtime/rt0_linux_amd64.s b/src/runtime/rt0_linux_amd64.s
index 564b51c0b3ccc811301da183d53c84015fad5688..ced471f5cb435afda22892d7f3f9d77492e45e56 100644 (file)
--- a/src/runtime/rt0_linux_amd64.s
+++ b/src/runtime/rt0_linux_amd64.s
@@ -12,13 +12,18 @@ TEXT _rt0_amd64_linux(SB),NOSPLIT,$-8
 
 // When building with -buildmode=c-shared, this symbol is called when the shared
 // library is loaded.
-TEXT _rt0_amd64_linux_lib(SB),NOSPLIT,$0x48
+// Note: This function calls external C code, which might required 16-byte stack
+// alignment after cmd/internal/obj applies its transformations.
+TEXT _rt0_amd64_linux_lib(SB),NOSPLIT,$0x50
+       MOVQ    SP, AX
+       ANDQ    $-16, SP
        MOVQ    BX, 0x10(SP)
        MOVQ    BP, 0x18(SP)
        MOVQ    R12, 0x20(SP)
        MOVQ    R13, 0x28(SP)
        MOVQ    R14, 0x30(SP)
        MOVQ    R15, 0x38(SP)
+       MOVQ    AX, 0x40(SP)
 
        MOVQ    DI, _rt0_amd64_linux_lib_argc<>(SB)
        MOVQ    SI, _rt0_amd64_linux_lib_argv<>(SB)
@@ -50,6 +55,7 @@ restore:
        MOVQ    0x28(SP), R13
        MOVQ    0x30(SP), R14
        MOVQ    0x38(SP), R15
+       MOVQ    0x40(SP), SP
        RET
 
 TEXT _rt0_amd64_linux_lib_go(SB),NOSPLIT,$0