runtime/internal/syscall: use ABIInternal for Syscall6 on riscv64

Change-Id: Iceed0f55038c87f261b60309e025132142946364
Reviewed-on: https://go-review.googlesource.com/c/go/+/443557
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Wayne Zuo <wdvxdr@golangcn.org>

diff --git a/src/runtime/internal/syscall/asm_linux_riscv64.s b/src/runtime/internal/syscall/asm_linux_riscv64.s
index a8652fdd6b33dc9ddb343a2612d5eb1abfc80981..15e50ec15379533b070ff1b54b26840d1d76efda 100644 (file)
--- a/src/runtime/internal/syscall/asm_linux_riscv64.s
+++ b/src/runtime/internal/syscall/asm_linux_riscv64.s
@@ -5,25 +5,39 @@
 #include "textflag.h"
 
 // func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
-TEXT ·Syscall6(SB),NOSPLIT,$0-80
-       MOV     num+0(FP), A7   // syscall entry
-       MOV     a1+8(FP), A0
-       MOV     a2+16(FP), A1
-       MOV     a3+24(FP), A2
-       MOV     a4+32(FP), A3
-       MOV     a5+40(FP), A4
-       MOV     a6+48(FP), A5
+//
+// We need to convert to the syscall ABI.
+//
+// arg | ABIInternal | Syscall
+// ---------------------------
+// num | A0          | A7
+// a1  | A1          | A0
+// a2  | A2          | A1
+// a3  | A3          | A2
+// a4  | A4          | A3
+// a5  | A5          | A4
+// a6  | A6          | A5
+//
+// r1  | A0          | A0
+// r2  | A1          | A1
+// err | A2          | part of A0
+TEXT ·Syscall6<ABIInternal>(SB),NOSPLIT,$0-80
+       MOV     A0, A7
+       MOV     A1, A0
+       MOV     A2, A1
+       MOV     A3, A2
+       MOV     A4, A3
+       MOV     A5, A4
+       MOV     A6, A5
        ECALL
        MOV     $-4096, T0
        BLTU    T0, A0, err
-       MOV     A0, r1+56(FP)
-       MOV     A1, r2+64(FP)
-       MOV     ZERO, errno+72(FP)
+       // r1 already in A0
+       // r2 already in A1
+       MOV     ZERO, A2 // errno
        RET
 err:
-       MOV     $-1, T0
-       MOV     T0, r1+56(FP)
-       MOV     ZERO, r2+64(FP)
-       SUB     A0, ZERO, A0
-       MOV     A0, errno+72(FP)
+       SUB     A0, ZERO, A2 // errno
+       MOV     $-1, A0      // r1
+       MOV     ZERO, A1     // r2
        RET