runtime: improve sigtramp on aix/ppc64 to handle SIGPROF

R14, R15 must be saved in sigtramp because they might be modified by Go
code when a SIGPROF occurs.

Fixes #28555

Change-Id: I573541f108d7d6aac8e60d33c649e5db943f3ef5
Reviewed-on: https://go-review.googlesource.com/c/go/+/169117
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/crash_cgo_test.go

@@ -229,9 +229,6 @@ func TestCgoPanicDeadlock(t *testing.T) {
 }
 
 func TestCgoCCodeSIGPROF(t *testing.T) {
-	if runtime.GOOS == "aix" {
-		t.Skip("pprof not yet available on AIX (see golang.org/issue/28555)")
-	}
 	t.Parallel()
 	got := runTestProg(t, "testprogcgo", "CgoCCodeSIGPROF")
 	want := "OK\n"

src/runtime/crash_test.go

@@ -623,9 +623,6 @@ func TestBadTraceback(t *testing.T) {
 }
 
 func TestTimePprof(t *testing.T) {
-	if runtime.GOOS == "aix" {
-		t.Skip("pprof not yet available on AIX (see golang.org/issue/28555)")
-	}
 	fn := runTestProg(t, "testprog", "TimeProf")
 	fn = strings.TrimSpace(fn)
 	defer os.Remove(fn)

src/runtime/os_aix.go

@@ -233,6 +233,8 @@ func setSignalstackSP(s *stackt, sp uintptr) {
 func (c *sigctxt) fixsigcode(sig uint32) {
 }
 
+//go:nosplit
+//go:nowritebarrierrec
 func sigaddset(mask *sigset, i int) {
 	(*mask)[(i-1)/64] |= 1 << ((uint32(i) - 1) & 63)
 }

src/runtime/pprof/pprof_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !aix,!nacl,!js
+// +build !nacl,!js
 
 package pprof
 

src/runtime/pprof/proto_test.go

@@ -312,10 +312,6 @@ func TestMapping(t *testing.T) {
 	testenv.MustHaveGoRun(t)
 	testenv.MustHaveCGO(t)
 
-	if runtime.GOOS == "aix" {
-		t.Skip("pprof not yet available on AIX (see golang.org/issue/28555)")
-	}
-
 	prog := "./testdata/mappingtest/main.go"
 
 	// GoOnly includes only Go symbols that runtime will symbolize.

src/runtime/proc.go

@@ -3758,7 +3758,7 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
 		// Normal traceback is impossible or has failed.
 		// See if it falls into several common cases.
 		n = 0
-		if (GOOS == "windows" || GOOS == "solaris" || GOOS == "darwin") && mp.libcallg != 0 && mp.libcallpc != 0 && mp.libcallsp != 0 {
+		if (GOOS == "windows" || GOOS == "solaris" || GOOS == "darwin" || GOOS == "aix") && mp.libcallg != 0 && mp.libcallpc != 0 && mp.libcallsp != 0 {
 			// Libcall, i.e. runtime syscall on windows.
 			// Collect Go stack that leads to the call.
 			n = gentraceback(mp.libcallpc, mp.libcallsp, 0, mp.libcallg.ptr(), 0, &stk[0], len(stk), nil, nil, 0)

src/runtime/sys_aix_ppc64.s

@@ -97,6 +97,7 @@ GLOBL	runtime·sigtramp(SB), NOPTR, $24
 
 // This funcion must not have any frame as we want to control how
 // every registers are used.
+// TODO(aix): Implement SetCgoTraceback handler.
 TEXT runtime·_sigtramp(SB),NOSPLIT|NOFRAME,$0
 	MOVD	LR, R0
 	MOVD	R0, 16(R1)
@@ -107,89 +108,86 @@ TEXT runtime·_sigtramp(SB),NOSPLIT|NOFRAME,$0
 	// more stack available than NOSPLIT would have us believe.
 	// To defeat the linker, we make our own stack frame with
 	// more space.
-	SUB	   $128+FIXED_FRAME, R1
+	SUB	$144+FIXED_FRAME, R1
 
 	// Save registers
 	MOVD	R31, 56(R1)
 	MOVD	g, 64(R1)
 	MOVD	R29, 72(R1)
+	MOVD	R14, 80(R1)
+	MOVD	R15, 88(R1)
 
 	BL	runtime·load_g(SB)
 
 	CMP	$0, g
-	BEQ	sigtrampnog // g == nil
+	BEQ	sigtramp // g == nil
+	MOVD	g_m(g), R6
+	CMP	$0, R6
+	BEQ	sigtramp	// g.m == nil
 
 	// Save m->libcall. We need to do this because we
 	// might get interrupted by a signal in runtime·asmcgocall.
-
-	// save m->libcall
-	MOVD	g_m(g), R6
 	MOVD	(m_libcall+libcall_fn)(R6), R7
-	MOVD	R7, 80(R1)
+	MOVD	R7, 96(R1)
 	MOVD	(m_libcall+libcall_args)(R6), R7
-	MOVD	R7, 88(R1)
+	MOVD	R7, 104(R1)
 	MOVD	(m_libcall+libcall_n)(R6), R7
-	MOVD	R7, 96(R1)
+	MOVD	R7, 112(R1)
 	MOVD	(m_libcall+libcall_r1)(R6), R7
-	MOVD	R7, 104(R1)
+	MOVD	R7, 120(R1)
 	MOVD	(m_libcall+libcall_r2)(R6), R7
-	MOVD	R7, 112(R1)
+	MOVD	R7, 128(R1)
 
 	// save errno, it might be EINTR; stuff we do here might reset it.
 	MOVD	(m_mOS+mOS_perrno)(R6), R8
 	MOVD	0(R8), R8
-	MOVD	R8, 120(R1)
+	MOVD	R8, 136(R1)
 
+sigtramp:
 	MOVW	R3, FIXED_FRAME+0(R1)
 	MOVD	R4, FIXED_FRAME+8(R1)
 	MOVD	R5, FIXED_FRAME+16(R1)
 	MOVD	$runtime·sigtrampgo(SB), R12
 	MOVD	R12, CTR
 	BL	(CTR)
 
+	CMP	$0, g
+	BEQ	exit // g == nil
 	MOVD	g_m(g), R6
+	CMP	$0, R6
+	BEQ	exit	// g.m == nil
+
 	// restore libcall
-	MOVD	80(R1), R7
+	MOVD	96(R1), R7
 	MOVD	R7, (m_libcall+libcall_fn)(R6)
-	MOVD	88(R1), R7
+	MOVD	104(R1), R7
 	MOVD	R7, (m_libcall+libcall_args)(R6)
-	MOVD	96(R1), R7
+	MOVD	112(R1), R7
 	MOVD	R7, (m_libcall+libcall_n)(R6)
-	MOVD	104(R1), R7
+	MOVD	120(R1), R7
 	MOVD	R7, (m_libcall+libcall_r1)(R6)
-	MOVD	112(R1), R7
+	MOVD	128(R1), R7
 	MOVD	R7, (m_libcall+libcall_r2)(R6)
 
 	// restore errno
 	MOVD	(m_mOS+mOS_perrno)(R6), R7
-	MOVD	120(R1), R8
+	MOVD	136(R1), R8
 	MOVD	R8, 0(R7)
 
 exit:
 	// restore registers
 	MOVD	56(R1),R31
 	MOVD	64(R1),g
 	MOVD	72(R1),R29
+	MOVD	80(R1), R14
+	MOVD	88(R1), R15
 
 	// Don't use RET because we need to restore R31 !
-	ADD $128+FIXED_FRAME, R1
+	ADD $144+FIXED_FRAME, R1
 	MOVD	16(R1), R0
 	MOVD	R0, LR
 	BR (LR)
 
-sigtrampnog:
-	// Signal arrived on a non-Go thread.
-	// SIGPROF handler is not yet available so simply call badsignal,
-	// after having created *sigctxt.
-	MOVD	R4, 80(R1)
-	MOVD	R5, 88(R1)
-	MOVD	R1, R4
-	ADD		$80, R4
-	MOVD	R4, FIXED_FRAME+8(R1)
-	MOVD	R3, FIXED_FRAME+0(R1)
-	BL runtime·badsignal(SB)
-	JMP	exit
-
 // runtime.tstart is a function descriptor to the real tstart.
 DATA	runtime·tstart+0(SB)/8, $runtime·_tstart(SB)
 DATA	runtime·tstart+8(SB)/8, $TOC(SB)