runtime/internal/syscall: use ABIInternal for Syscall6 on amd64
This is an exact copy of CL 401096 after fixing #52472 in CL 401654.
For #51087
For #52472
Change-Id: Ib3c914949a15517aacdca2d72e69e1c7b217e430
Reviewed-on: https://go-review.googlesource.com/c/go/+/401656
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
diff --git a/src/runtime/internal/syscall/asm_linux_amd64.s b/src/runtime/internal/syscall/asm_linux_amd64.s
index 961d9bd..3740ef1 100644
--- a/src/runtime/internal/syscall/asm_linux_amd64.s
+++ b/src/runtime/internal/syscall/asm_linux_amd64.s
@@ -6,28 +6,42 @@
// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
//
-// Syscall # in AX, args in DI SI DX R10 R8 R9, return in AX DX.
+// We need to convert to the syscall ABI.
+//
+// arg | ABIInternal | Syscall
+// ---------------------------
+// num | AX | AX
+// a1 | BX | DI
+// a2 | CX | SI
+// a3 | DI | DX
+// a4 | SI | R10
+// a5 | R8 | R8
+// a6 | R9 | R9
+//
+// r1 | AX | AX
+// r2 | BX | DX
+// err | CX | part of AX
//
// Note that this differs from "standard" ABI convention, which would pass 4th
// arg in CX, not R10.
-TEXT ·Syscall6(SB),NOSPLIT,$0-80
- MOVQ num+0(FP), AX // syscall entry
- MOVQ a1+8(FP), DI
- MOVQ a2+16(FP), SI
- MOVQ a3+24(FP), DX
- MOVQ a4+32(FP), R10
- MOVQ a5+40(FP), R8
- MOVQ a6+48(FP), R9
+TEXT ·Syscall6<ABIInternal>(SB),NOSPLIT,$0
+ // a6 already in R9.
+ // a5 already in R8.
+ MOVQ SI, R10 // a4
+ MOVQ DI, DX // a3
+ MOVQ CX, SI // a2
+ MOVQ BX, DI // a1
+ // num already in AX.
SYSCALL
CMPQ AX, $0xfffffffffffff001
JLS ok
- MOVQ $-1, r1+56(FP)
- MOVQ $0, r2+64(FP)
NEGQ AX
- MOVQ AX, errno+72(FP)
+ MOVQ AX, CX // errno
+ MOVQ $-1, AX // r1
+ MOVQ $0, BX // r2
RET
ok:
- MOVQ AX, r1+56(FP)
- MOVQ DX, r2+64(FP)
- MOVQ $0, errno+72(FP)
+ // r1 already in AX.
+ MOVQ DX, BX // r2
+ MOVQ $0, CX // errno
RET
