reflect, runtime, runtime/cgo: use ppc64 asm constant for fixed frame size

Shared libraries on ppc64le will require a larger minimum stack frame (because
the ABI mandates that the TOC pointer is available at 24(R1)). Part 3 of that
is using a #define in the ppc64 assembly to refer to the size of the fixed
part of the stack (finding all these took me about a week!).

Change-Id: I50f22fe1c47af1ec59da1bd7ea8f84a4750df9b7
Reviewed-on: https://go-review.googlesource.com/15525Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/build.go

@@ -626,6 +626,8 @@ func install(dir string) {
 			pathf("%s/src/runtime/textflag.h", goroot), 0)
 		copyfile(pathf("%s/pkg/include/funcdata.h", goroot),
 			pathf("%s/src/runtime/funcdata.h", goroot), 0)
+		copyfile(pathf("%s/pkg/include/asm_ppc64x.h", goroot),
+			pathf("%s/src/runtime/asm_ppc64x.h", goroot), 0)
 	}
 
 	// Generate any missing files; regenerate existing ones.

src/reflect/asm_ppc64x.s

@@ -6,6 +6,7 @@
 
 #include "textflag.h"
 #include "funcdata.h"
+#include "asm_ppc64x.h"
 
 // makeFuncStub is the code half of the function returned by MakeFunc.
 // See the comment on the declaration of makeFuncStub in makefunc.go
@@ -13,9 +14,9 @@
 // No arg size here, runtime pulls arg map out of the func value.
 TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$16
 	NO_LOCAL_POINTERS
-	MOVD	R11, 8(R1)
+	MOVD	R11, FIXED_FRAME+0(R1)
 	MOVD	$argframe+0(FP), R3
-	MOVD	R3, 16(R1)
+	MOVD	R3, FIXED_FRAME+8(R1)
 	BL	·callReflect(SB)
 	RET
 
@@ -25,8 +26,8 @@ TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$16
 // No arg size here; runtime pulls arg map out of the func value.
 TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$16
 	NO_LOCAL_POINTERS
-	MOVD	R11, 8(R1)
+	MOVD	R11, FIXED_FRAME+0(R1)
 	MOVD	$argframe+0(FP), R3
-	MOVD	R3, 16(R1)
+	MOVD	R3, FIXED_FRAME+8(R1)
 	BL	·callMethod(SB)
 	RET

src/runtime/asm_ppc64x.h

+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// FIXED_FRAME defines the size of the fixed part of a stack frame. A stack
+// frame looks like this:
+//
+// +---------------------+
+// | local variable area |
+// +---------------------+
+// | argument area       |
+// +---------------------+ <- R1+FIXED_FRAME
+// | fixed area          |
+// +---------------------+ <- R1
+//
+// So a function that sets up a stack frame at all uses as least FIXED_FRAME
+// bytes of stack.  This mostly affects assembly that calls other functions
+// 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).
+
+#ifdef GOARCH_ppc64
+#define FIXED_FRAME 8
+#endif
+
+#ifdef GOARCH_ppc64le
+#define FIXED_FRAME 8
+#endif

src/runtime/asm_ppc64x.s

@@ -8,6 +8,7 @@
 #include "go_tls.h"
 #include "funcdata.h"
 #include "textflag.h"
+#include "asm_ppc64x.h"
 
 TEXT runtime·rt0_go(SB),NOSPLIT,$0
 	// R1 = stack; R3 = argc; R4 = argv; R13 = C TLS base pointer
@@ -15,9 +16,9 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
 	// initialize essential registers
 	BL	runtime·reginit(SB)
 
-	SUB	$24, R1
-	MOVW	R3, 8(R1) // argc
-	MOVD	R4, 16(R1) // argv
+	SUB	$(FIXED_FRAME+16), R1
+	MOVW	R3, FIXED_FRAME+0(R1) // argc
+	MOVD	R4, FIXED_FRAME+8(R1) // argv
 
 	// create istack out of the given (operating system) stack.
 	// _cgo_init may update stackguard.
@@ -225,7 +226,7 @@ switch:
 	BL	runtime·save_g(SB)
 	MOVD	(g_sched+gobuf_sp)(g), R3
 	// make it look like mstart called systemstack on g0, to stop traceback
-	SUB	$8, R3
+	SUB	$FIXED_FRAME, R3
 	MOVD	$runtime·mstart(SB), R4
 	MOVD	R4, 0(R3)
 	MOVD	R3, R1
@@ -381,7 +382,7 @@ TEXT NAME(SB), WRAPPER, $MAXSIZE-24;		\
 	MOVD	arg+16(FP), R3;			\
 	MOVWZ	argsize+24(FP), R4;			\
 	MOVD	R1, R5;				\
-	ADD	$(8-1), R5;			\
+	ADD	$(FIXED_FRAME-1), R5;			\
 	SUB	$1, R3;				\
 	ADD	R5, R4;				\
 	CMP	R5, R4;				\
@@ -403,7 +404,7 @@ TEXT NAME(SB), WRAPPER, $MAXSIZE-24;		\
 	ADD	R6, R5; 			\
 	ADD	R6, R3;				\
 	SUB	R6, R4;				\
-	ADD	$(8-1), R5;			\
+	ADD	$(FIXED_FRAME-1), R5;			\
 	SUB	$1, R3;				\
 	ADD	R5, R4;				\
 loop:						\
@@ -418,10 +419,10 @@ end:						\
 	MOVD	arg+16(FP), R3;			\
 	MOVWZ	n+24(FP), R4;			\
 	MOVWZ	retoffset+28(FP), R6;		\
-	MOVD	R7, 8(R1);			\
-	MOVD	R3, 16(R1);			\
-	MOVD	R4, 24(R1);			\
-	MOVD	R6, 32(R1);			\
+	MOVD	R7, FIXED_FRAME+0(R1);			\
+	MOVD	R3, FIXED_FRAME+8(R1);			\
+	MOVD	R4, FIXED_FRAME+16(R1);			\
+	MOVD	R6, FIXED_FRAME+24(R1);			\
 	BL	runtime·callwritebarrier(SB);	\
 	RET
 
@@ -676,7 +677,7 @@ TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
 
 	MOVD	fv+0(FP), R11
 	MOVD	argp+8(FP), R1
-	SUB	$8, R1
+	SUB	$FIXED_FRAME, R1
 	MOVD	0(R11), R3
 	MOVD	R3, CTR
 	BR	(CTR)
@@ -750,11 +751,11 @@ g0:
 // cgocallback_gofunc.
 TEXT runtime·cgocallback(SB),NOSPLIT,$24-24
 	MOVD	$fn+0(FP), R3
-	MOVD	R3, 8(R1)
+	MOVD	R3, FIXED_FRAME+0(R1)
 	MOVD	frame+8(FP), R3
-	MOVD	R3, 16(R1)
+	MOVD	R3, FIXED_FRAME+8(R1)
 	MOVD	framesize+16(FP), R3
-	MOVD	R3, 24(R1)
+	MOVD	R3, FIXED_FRAME+16(R1)
 	MOVD	$runtime·cgocallback_gofunc(SB), R3
 	MOVD	R3, CTR
 	BL	(CTR)
@@ -831,14 +832,14 @@ havem:
 	BL	runtime·save_g(SB)
 	MOVD	(g_sched+gobuf_sp)(g), R4 // prepare stack as R4
 	MOVD	(g_sched+gobuf_pc)(g), R5
-	MOVD	R5, -24(R4)
-	MOVD	$-24(R4), R1
+	MOVD	R5, -(FIXED_FRAME+16)(R4)
+	MOVD	$-(FIXED_FRAME+16)(R4), R1
 	BL	runtime·cgocallbackg(SB)
 
 	// Restore g->sched (== m->curg->sched) from saved values.
 	MOVD	0(R1), R5
 	MOVD	R5, (g_sched+gobuf_pc)(g)
-	MOVD	$24(R1), R4
+	MOVD	$(FIXED_FRAME+16)(R1), R4
 	MOVD	R4, (g_sched+gobuf_sp)(g)
 
 	// Switch back to m->g0's stack and restore m->g0->sched.sp.
@@ -890,34 +891,34 @@ TEXT setg_gcc<>(SB),NOSPLIT|NOFRAME,$0-0
 	RET
 
 TEXT runtime·getcallerpc(SB),NOSPLIT,$8-16
-	MOVD	16(R1), R3		// LR saved by caller
+	MOVD	FIXED_FRAME+8(R1), R3		// LR saved by caller
 	MOVD	runtime·stackBarrierPC(SB), R4
 	CMP	R3, R4
 	BNE	nobar
 	// Get original return PC.
 	BL	runtime·nextBarrierPC(SB)
-	MOVD	8(R1), R3
+	MOVD	FIXED_FRAME+0(R1), R3
 nobar:
 	MOVD	R3, ret+8(FP)
 	RET
 
 TEXT runtime·setcallerpc(SB),NOSPLIT,$8-16
 	MOVD	pc+8(FP), R3
-	MOVD	16(R1), R4
+	MOVD	FIXED_FRAME+8(R1), R4
 	MOVD	runtime·stackBarrierPC(SB), R5
 	CMP	R4, R5
 	BEQ	setbar
-	MOVD	R3, 16(R1)		// set LR in caller
+	MOVD	R3, FIXED_FRAME+8(R1)		// set LR in caller
 	RET
 setbar:
 	// Set the stack barrier return PC.
-	MOVD	R3, 8(R1)
+	MOVD	R3, FIXED_FRAME+0(R1)
 	BL	runtime·setNextBarrierPC(SB)
 	RET
 
 TEXT runtime·getcallersp(SB),NOSPLIT,$0-16
 	MOVD	argp+0(FP), R3
-	SUB	$8, R3
+	SUB	$FIXED_FRAME, R3
 	MOVD	R3, ret+8(FP)
 	RET
 
@@ -949,11 +950,11 @@ TEXT runtime·memhash_varlen(SB),NOSPLIT,$40-24
 	MOVD	p+0(FP), R3
 	MOVD	h+8(FP), R4
 	MOVD	8(R11), R5
-	MOVD	R3, 8(R1)
-	MOVD	R4, 16(R1)
-	MOVD	R5, 24(R1)
+	MOVD	R3, FIXED_FRAME+0(R1)
+	MOVD	R4, FIXED_FRAME+8(R1)
+	MOVD	R5, FIXED_FRAME+16(R1)
 	BL	runtime·memhash(SB)
-	MOVD	32(R1), R3
+	MOVD	FIXED_FRAME+24(R1), R3
 	MOVD	R3, ret+16(FP)
 	RET
 
@@ -996,11 +997,11 @@ TEXT runtime·memequal_varlen(SB),NOSPLIT,$40-17
 	CMP	R3, R4
 	BEQ	eq
 	MOVD	8(R11), R5    // compiler stores size at offset 8 in the closure
-	MOVD	R3, 8(R1)
-	MOVD	R4, 16(R1)
-	MOVD	R5, 24(R1)
+	MOVD	R3, FIXED_FRAME+0(R1)
+	MOVD	R4, FIXED_FRAME+8(R1)
+	MOVD	R5, FIXED_FRAME+16(R1)
 	BL	runtime·memeq(SB)
-	MOVBZ	32(R1), R3
+	MOVBZ	FIXED_FRAME+24(R1), R3
 	MOVB	R3, ret+16(FP)
 	RET
 eq:

src/runtime/cgo/asm_ppc64x.s

@@ -5,6 +5,7 @@
 // +build ppc64 ppc64le
 
 #include "textflag.h"
+#include "asm_ppc64x.h"
 
 /*
  * void crosscall2(void (*fn)(void*, int32), void*, int32)
@@ -21,18 +22,18 @@ TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
 
 	BL	saveregs2<>(SB)
 
-	MOVDU	R1, (-288-3*8)(R1)
+	MOVDU	R1, (-288-2*8-FIXED_FRAME)(R1)
 
 	// Initialize Go ABI environment
 	BL	runtime·reginit(SB)
 	BL	runtime·load_g(SB)
 
 	MOVD	R3, CTR
-	MOVD	R4, 8(R1)
-	MOVD	R5, 16(R1)
+	MOVD	R4, FIXED_FRAME+0(R1)
+	MOVD	R5, FIXED_FRAME+8(R1)
 	BL	(CTR)
 
-	ADD	$(288+3*8), R1
+	ADD	$(288+2*8+FIXED_FRAME), R1
 
 	BL	restoreregs2<>(SB)
 

src/runtime/sys_linux_ppc64x.s

@@ -12,6 +12,7 @@
 #include "go_asm.h"
 #include "go_tls.h"
 #include "textflag.h"
+#include "asm_ppc64x.h"
 
 #define SYS_exit		  1
 #define SYS_read		  3
@@ -231,9 +232,9 @@ TEXT runtime·_sigtramp(SB),NOSPLIT,$64
 	BEQ	2(PC)
 	BL	runtime·load_g(SB)
 
-	MOVW	R3, 8(R1)
-	MOVD	R4, 16(R1)
-	MOVD	R5, 24(R1)
+	MOVW	R3, FIXED_FRAME+0(R1)
+	MOVD	R4, FIXED_FRAME+8(R1)
+	MOVD	R5, FIXED_FRAME+16(R1)
 	MOVD	$runtime·sigtrampgo(SB), R31
 	MOVD	R31, CTR
 	BL	(CTR)