runtime: correct syscall10/syscall10X on openbsd/amd64

The syscall10/syscall10X implementation uses an incorrect stack offset for
arguments a7 to a10. Correct this so that the syscall arguments work as
intended.

Updates #36435
Fixes #43927

Change-Id: Ia7ae6cc8c89f50acfd951c0f271f3b3309934499
Reviewed-on: https://go-review.googlesource.com/c/go/+/287252
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/runtime/sys_openbsd_amd64.s b/src/runtime/sys_openbsd_amd64.s
index 534645eec4144f396f54754437a32206c530dbc6..b3a76b57a3afd4a5a33cbdca7f684f3dabbd1408 100644 (file)
--- a/src/runtime/sys_openbsd_amd64.s
+++ b/src/runtime/sys_openbsd_amd64.s
@@ -676,27 +676,31 @@ TEXT runtime·syscall10(SB),NOSPLIT,$0
        PUSHQ   BP
        MOVQ    SP, BP
        SUBQ    $48, SP
+
+       // Arguments a1 to a6 get passed in registers, with a7 onwards being
+       // passed via the stack per the x86-64 System V ABI
+       // (https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf).
        MOVQ    (7*8)(DI), R10  // a7
        MOVQ    (8*8)(DI), R11  // a8
        MOVQ    (9*8)(DI), R12  // a9
        MOVQ    (10*8)(DI), R13 // a10
-       MOVQ    R10, (1*8)(SP)  // a7
-       MOVQ    R11, (2*8)(SP)  // a8
-       MOVQ    R12, (3*8)(SP)  // a9
-       MOVQ    R13, (4*8)(SP)  // a10
+       MOVQ    R10, (0*8)(SP)  // a7
+       MOVQ    R11, (1*8)(SP)  // a8
+       MOVQ    R12, (2*8)(SP)  // a9
+       MOVQ    R13, (3*8)(SP)  // a10
        MOVQ    (0*8)(DI), R11  // fn
        MOVQ    (2*8)(DI), SI   // a2
        MOVQ    (3*8)(DI), DX   // a3
        MOVQ    (4*8)(DI), CX   // a4
        MOVQ    (5*8)(DI), R8   // a5
        MOVQ    (6*8)(DI), R9   // a6
-       MOVQ    DI, (SP)
+       MOVQ    DI, (4*8)(SP)
        MOVQ    (1*8)(DI), DI   // a1
        XORL    AX, AX          // vararg: say "no float args"
 
        CALL    R11
 
-       MOVQ    (SP), DI
+       MOVQ    (4*8)(SP), DI
        MOVQ    AX, (11*8)(DI) // r1
        MOVQ    DX, (12*8)(DI) // r2
 
@@ -705,7 +709,7 @@ TEXT runtime·syscall10(SB),NOSPLIT,$0
 
        CALL    libc_errno(SB)
        MOVLQSX (AX), AX
-       MOVQ    (SP), DI
+       MOVQ    (4*8)(SP), DI
        MOVQ    AX, (13*8)(DI) // err
 
 ok:
@@ -741,27 +745,31 @@ TEXT runtime·syscall10X(SB),NOSPLIT,$0
        PUSHQ   BP
        MOVQ    SP, BP
        SUBQ    $48, SP
+
+       // Arguments a1 to a6 get passed in registers, with a7 onwards being
+       // passed via the stack per the x86-64 System V ABI
+       // (https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf).
        MOVQ    (7*8)(DI), R10  // a7
        MOVQ    (8*8)(DI), R11  // a8
        MOVQ    (9*8)(DI), R12  // a9
        MOVQ    (10*8)(DI), R13 // a10
-       MOVQ    R10, (1*8)(SP)  // a7
-       MOVQ    R11, (2*8)(SP)  // a8
-       MOVQ    R12, (3*8)(SP)  // a9
-       MOVQ    R13, (4*8)(SP)  // a10
+       MOVQ    R10, (0*8)(SP)  // a7
+       MOVQ    R11, (1*8)(SP)  // a8
+       MOVQ    R12, (2*8)(SP)  // a9
+       MOVQ    R13, (3*8)(SP)  // a10
        MOVQ    (0*8)(DI), R11  // fn
        MOVQ    (2*8)(DI), SI   // a2
        MOVQ    (3*8)(DI), DX   // a3
        MOVQ    (4*8)(DI), CX   // a4
        MOVQ    (5*8)(DI), R8   // a5
        MOVQ    (6*8)(DI), R9   // a6
-       MOVQ    DI, (SP)
+       MOVQ    DI, (4*8)(SP)
        MOVQ    (1*8)(DI), DI   // a1
        XORL    AX, AX          // vararg: say "no float args"
 
        CALL    R11
 
-       MOVQ    (SP), DI
+       MOVQ    (4*8)(SP), DI
        MOVQ    AX, (11*8)(DI) // r1
        MOVQ    DX, (12*8)(DI) // r2
 
@@ -770,7 +778,7 @@ TEXT runtime·syscall10X(SB),NOSPLIT,$0
 
        CALL    libc_errno(SB)
        MOVLQSX (AX), AX
-       MOVQ    (SP), DI
+       MOVQ    (4*8)(SP), DI
        MOVQ    AX, (13*8)(DI) // err
 
 ok: