runtime: fix a register save/restore bug in sigtramp of arm-darwin

In sigtramp of sys_darwin_arm.s, the callee-save register R4 is
saved to the stack, but later R2 is also saved to the save position.

That CL fixes the unexpected lost of the value in R4.

fixes #32744

Change-Id: Ifaeb99f11e4abf0c79bec9da67e0db97c358010c
Reviewed-on: https://go-review.googlesource.com/c/go/+/183517
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/runtime/sys_darwin_arm.s b/src/runtime/sys_darwin_arm.s
index 82470bc4df2b3704eed7b36627a82e1d41bd2bf8..b1c22b32423840084f19d9af0a6cd43db4f0452e 100644 (file)
--- a/src/runtime/sys_darwin_arm.s
+++ b/src/runtime/sys_darwin_arm.s
@@ -160,14 +160,14 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-16
 
 TEXT runtime·sigtramp(SB),NOSPLIT,$0
        // Reserve space for callee-save registers and arguments.
-       SUB     $36, R13
+       SUB     $40, R13
 
-       MOVW    R4, 12(R13)
-       MOVW    R5, 16(R13)
-       MOVW    R6, 20(R13)
-       MOVW    R7, 24(R13)
-       MOVW    R8, 28(R13)
-       MOVW    R11, 32(R13)
+       MOVW    R4, 16(R13)
+       MOVW    R5, 20(R13)
+       MOVW    R6, 24(R13)
+       MOVW    R7, 28(R13)
+       MOVW    R8, 32(R13)
+       MOVW    R11, 36(R13)
 
        // Save arguments.
        MOVW    R0, 4(R13)      // sig
@@ -216,14 +216,14 @@ nog:
        MOVW    R5, R13
 
        // Restore callee-save registers.
-       MOVW    12(R13), R4
-       MOVW    16(R13), R5
-       MOVW    20(R13), R6
-       MOVW    24(R13), R7
-       MOVW    28(R13), R8
-       MOVW    32(R13), R11
-
-       ADD $36, R13
+       MOVW    16(R13), R4
+       MOVW    20(R13), R5
+       MOVW    24(R13), R6
+       MOVW    28(R13), R7
+       MOVW    32(R13), R8
+       MOVW    36(R13), R11
+
+       ADD     $40, R13
 
        RET