cmd/internal/obj, cmd/link, runtime: use a larger stack frame on ppc64

The larger stack frames causes the nosplit stack to overflow so the next change
increases the stackguard.

Change-Id: Ib2b4f24f0649eb1d13e3a58d265f13d1b6cc9bf9
Reviewed-on: https://go-review.googlesource.com/15964Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/internal/obj/link.go

@@ -585,6 +585,10 @@ func (ctxt *Link) FixedFrameSize() int64 {
 	switch ctxt.Arch.Thechar {
 	case '6', '8':
 		return 0
+	case '9':
+		// PIC code on ppc64le requires 32 bytes of stack, and it's easier to
+		// just use that much stack always on ppc64x.
+		return int64(4 * ctxt.Arch.Ptrsize)
 	default:
 		return int64(ctxt.Arch.Ptrsize)
 	}

src/cmd/link/internal/ld/link.go

@@ -168,6 +168,10 @@ func (ctxt *Link) FixedFrameSize() int64 {
 	switch ctxt.Arch.Thechar {
 	case '6', '8':
 		return 0
+	case '9':
+		// PIC code on ppc64le requires 32 bytes of stack, and it's easier to
+		// just use that much stack always on ppc64x.
+		return int64(4 * ctxt.Arch.Ptrsize)
 	default:
 		return int64(ctxt.Arch.Ptrsize)
 	}

src/runtime/asm_ppc64x.h

@@ -18,14 +18,8 @@
 // with arguments (the arguments should be stored at FIXED_FRAME+0(R1),
 // FIXED_FRAME+8(R1) etc) and some other low-level places.
 //
-// The reason for using a constant is when code is compiled as PIC on ppc64le
-// the fixed part of the stack is 32 bytes large (although PIC is not actually
-// supported yet).
+// The reason for using a constant is to make supporting PIC easier (although
+// we only support PIC on ppc64le which has a minimum 32 bytes of stack frame,
+// and currently always use that much, PIC on ppc64 would need to use 48).
 
-#ifdef GOARCH_ppc64
-#define FIXED_FRAME 8
-#endif
-
-#ifdef GOARCH_ppc64le
-#define FIXED_FRAME 8
-#endif
+#define FIXED_FRAME 32

src/runtime/asm_ppc64x.s

@@ -74,8 +74,11 @@ nocgo:
 	MOVDU	R3, -8(R1)
 	MOVDU	R0, -8(R1)
 	MOVDU	R0, -8(R1)
+	MOVDU	R0, -8(R1)
+	MOVDU	R0, -8(R1)
+	MOVDU	R0, -8(R1)
 	BL	runtime·newproc(SB)
-	ADD	$24, R1
+	ADD	$(16+FIXED_FRAME), R1
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -174,6 +177,9 @@ TEXT runtime·mcall(SB), NOSPLIT|NOFRAME, $0-8
 	MOVD	(g_sched+gobuf_sp)(g), R1	// sp = m->g0->sched.sp
 	MOVDU	R3, -8(R1)
 	MOVDU	R0, -8(R1)
+	MOVDU	R0, -8(R1)
+	MOVDU	R0, -8(R1)
+	MOVDU	R0, -8(R1)
 	BL	(CTR)
 	BR	runtime·badmcall2(SB)
 

src/runtime/internal/sys/arch_ppc64.go

@@ -12,7 +12,7 @@ const (
 	PCQuantum     = 4
 	Int64Align    = 8
 	HugePageSize  = 0
-	MinFrameSize  = 8
+	MinFrameSize  = 32
 )
 
 type Uintreg uint64

src/runtime/internal/sys/arch_ppc64le.go

@@ -12,7 +12,7 @@ const (
 	PCQuantum     = 4
 	Int64Align    = 8
 	HugePageSize  = 0
-	MinFrameSize  = 8
+	MinFrameSize  = 32
 )
 
 type Uintreg uint64