runtime: save/restore callee-save registers in arm's sigtramp

ARM's R4-R8 & R10-R11 are callee-save registers, and R9
may be callee-save or not. This CL saves them at the beginning
of sigtramp and restores them in the end.

fixes #32738

Change-Id: Ib7eb80836bc074e2e6a46ae4602ba8a3b96c5456
Reviewed-on: https://go-review.googlesource.com/c/go/+/183777Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/runtime/sys_darwin_arm.s

@@ -182,14 +182,8 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-16
 
 TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	// Reserve space for callee-save registers and arguments.
-	SUB	$40, 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)
+	MOVM.DB.W [R4-R11], (R13)
+	SUB	$16, R13
 
 	// Save arguments.
 	MOVW	R0, 4(R13)	// sig
@@ -238,14 +232,8 @@ nog:
 	MOVW	R5, R13
 
 	// Restore callee-save registers.
-	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
+	ADD	$16, R13
+	MOVM.IA.W (R13), [R4-R11]
 
 	RET
 

src/runtime/sys_freebsd_arm.s

@@ -246,7 +246,11 @@ TEXT runtime·asmSigaction(SB),NOSPLIT|NOFRAME,$0
 	MOVW	R0, ret+12(FP)
 	RET
 
-TEXT runtime·sigtramp(SB),NOSPLIT,$12
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
+	// Reserve space for callee-save registers and arguments.
+	MOVM.DB.W [R4-R11], (R13)
+	SUB	$16, R13
+
 	// this might be called in external code context,
 	// where g is not set.
 	// first save R0, because runtime·load_g will clobber it
@@ -258,6 +262,11 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$12
 	MOVW	R1, 8(R13)
 	MOVW	R2, 12(R13)
 	BL	runtime·sigtrampgo(SB)
+
+	// Restore callee-save registers.
+	ADD	$16, R13
+	MOVM.IA.W (R13), [R4-R11]
+
 	RET
 
 TEXT runtime·mmap(SB),NOSPLIT,$16

src/runtime/sys_linux_arm.s

@@ -493,7 +493,11 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-16
 	MOVW	R4, R13
 	RET
 
-TEXT runtime·sigtramp(SB),NOSPLIT,$12
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
+	// Reserve space for callee-save registers and arguments.
+	MOVM.DB.W [R4-R11], (R13)
+	SUB	$16, R13
+
 	// this might be called in external code context,
 	// where g is not set.
 	// first save R0, because runtime·load_g will clobber it
@@ -506,6 +510,11 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$12
 	MOVW	R2, 12(R13)
 	MOVW  	$runtime·sigtrampgo(SB), R11
 	BL	(R11)
+
+	// Restore callee-save registers.
+	ADD	$16, R13
+	MOVM.IA.W (R13), [R4-R11]
+
 	RET
 
 TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0

src/runtime/sys_netbsd_arm.s

@@ -300,7 +300,11 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-16
 	MOVW	R4, R13
 	RET
 
-TEXT runtime·sigtramp(SB),NOSPLIT,$12
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
+	// Reserve space for callee-save registers and arguments.
+	MOVM.DB.W [R4-R11], (R13)
+	SUB	$16, R13
+
 	// this might be called in external code context,
 	// where g is not set.
 	// first save R0, because runtime·load_g will clobber it
@@ -312,6 +316,11 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$12
 	MOVW	R1, 8(R13)
 	MOVW	R2, 12(R13)
 	BL	runtime·sigtrampgo(SB)
+
+	// Restore callee-save registers.
+	ADD	$16, R13
+	MOVM.IA.W (R13), [R4-R11]
+
 	RET
 
 TEXT runtime·mmap(SB),NOSPLIT,$12

src/runtime/sys_openbsd_arm.s

@@ -247,7 +247,11 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-16
 	MOVW	R4, R13
 	RET
 
-TEXT runtime·sigtramp(SB),NOSPLIT,$12
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
+	// Reserve space for callee-save registers and arguments.
+	MOVM.DB.W [R4-R11], (R13)
+	SUB	$16, R13
+
 	// If called from an external code context, g will not be set.
 	// Save R0, since runtime·load_g will clobber it.
 	MOVW	R0, 4(R13)		// signum
@@ -258,6 +262,11 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$12
 	MOVW	R1, 8(R13)
 	MOVW	R2, 12(R13)
 	BL	runtime·sigtrampgo(SB)
+
+	// Restore callee-save registers.
+	ADD	$16, R13
+	MOVM.IA.W (R13), [R4-R11]
+
 	RET
 
 // int32 tfork(void *param, uintptr psize, M *mp, G *gp, void (*fn)(void));