powerpc: tracing: Give hypervisor call tracepoints access to arguments

While most users of the hcall tracepoints will only want the opcode
and return code, some will want all the arguments.  To avoid the
complexity of using varargs we pass a pointer to the register save
area, which contains all the arguments.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/include/asm/trace.h

@@ -82,9 +82,9 @@ extern void hcall_tracepoint_unregfunc(void);
 
 TRACE_EVENT_FN(hcall_entry,
 
-	TP_PROTO(unsigned long opcode),
+	TP_PROTO(unsigned long opcode, unsigned long *args),
 
-	TP_ARGS(opcode),
+	TP_ARGS(opcode, args),
 
 	TP_STRUCT__entry(
 		__field(unsigned long, opcode)
@@ -101,9 +101,10 @@ TRACE_EVENT_FN(hcall_entry,
 
 TRACE_EVENT_FN(hcall_exit,
 
-	TP_PROTO(unsigned long opcode, unsigned long retval),
+	TP_PROTO(unsigned long opcode, unsigned long retval,
+		unsigned long *retbuf),
 
-	TP_ARGS(opcode, retval),
+	TP_ARGS(opcode, retval, retbuf),
 
 	TP_STRUCT__entry(
 		__field(unsigned long, opcode)

arch/powerpc/platforms/pseries/hvCall.S

@@ -30,7 +30,7 @@ hcall_tracepoint_refcount:
  * in early init (eg when populating the MMU hashtable) by using an
  * unconditional cpu feature.
  */
-#define HCALL_INST_PRECALL					\
+#define HCALL_INST_PRECALL(FIRST_REG)				\
 BEGIN_FTR_SECTION;						\
 	b	1f;						\
 END_FTR_SECTION(0, 1);						\
@@ -47,6 +47,7 @@ END_FTR_SECTION(0, 1);						\
 	std	r9,STK_PARM(r9)(r1);				\
 	std	r10,STK_PARM(r10)(r1);				\
 	std	r0,16(r1);					\
+	addi	r4,r1,STK_PARM(FIRST_REG);			\
 	stdu	r1,-STACK_FRAME_OVERHEAD(r1);			\
 	bl	.__trace_hcall_entry;				\
 	addi	r1,r1,STACK_FRAME_OVERHEAD;			\
@@ -68,7 +69,7 @@ END_FTR_SECTION(0, 1);						\
  * in early init (eg when populating the MMU hashtable) by using an
  * unconditional cpu feature.
  */
-#define HCALL_INST_POSTCALL					\
+#define __HCALL_INST_POSTCALL					\
 BEGIN_FTR_SECTION;						\
 	b	1f;						\
 END_FTR_SECTION(0, 1);						\
@@ -88,9 +89,19 @@ END_FTR_SECTION(0, 1);						\
 	ld	r3,STK_PARM(r3)(r1);				\
 	mtlr	r0;						\
 1:
+
+#define HCALL_INST_POSTCALL_NORETS				\
+	li	r5,0;						\
+	__HCALL_INST_POSTCALL
+
+#define HCALL_INST_POSTCALL(BUFREG)				\
+	mr	r5,BUFREG;					\
+	__HCALL_INST_POSTCALL
+
 #else
-#define HCALL_INST_PRECALL
-#define HCALL_INST_POSTCALL
+#define HCALL_INST_PRECALL(FIRST_ARG)
+#define HCALL_INST_POSTCALL_NORETS
+#define HCALL_INST_POSTCALL(BUFREG)
 #endif
 
 	.text
@@ -101,11 +112,11 @@ _GLOBAL(plpar_hcall_norets)
 	mfcr	r0
 	stw	r0,8(r1)
 
-	HCALL_INST_PRECALL
+	HCALL_INST_PRECALL(r4)
 
 	HVSC				/* invoke the hypervisor */
 
-	HCALL_INST_POSTCALL
+	HCALL_INST_POSTCALL_NORETS
 
 	lwz	r0,8(r1)
 	mtcrf	0xff,r0
@@ -117,7 +128,7 @@ _GLOBAL(plpar_hcall)
 	mfcr	r0
 	stw	r0,8(r1)
 
-	HCALL_INST_PRECALL
+	HCALL_INST_PRECALL(r5)
 
 	std     r4,STK_PARM(r4)(r1)     /* Save ret buffer */
 
@@ -136,7 +147,7 @@ _GLOBAL(plpar_hcall)
 	std	r6, 16(r12)
 	std	r7, 24(r12)
 
-	HCALL_INST_POSTCALL
+	HCALL_INST_POSTCALL(r12)
 
 	lwz	r0,8(r1)
 	mtcrf	0xff,r0
@@ -183,7 +194,7 @@ _GLOBAL(plpar_hcall9)
 	mfcr	r0
 	stw	r0,8(r1)
 
-	HCALL_INST_PRECALL
+	HCALL_INST_PRECALL(r5)
 
 	std     r4,STK_PARM(r4)(r1)     /* Save ret buffer */
 
@@ -211,7 +222,7 @@ _GLOBAL(plpar_hcall9)
 	std	r11,56(r12)
 	std	r0, 64(r12)
 
-	HCALL_INST_POSTCALL
+	HCALL_INST_POSTCALL(r12)
 
 	lwz	r0,8(r1)
 	mtcrf	0xff,r0

arch/powerpc/platforms/pseries/hvCall_inst.c

@@ -102,7 +102,7 @@ static const struct file_operations hcall_inst_seq_fops = {
 #define CPU_NAME_BUF_SIZE	32
 
 
-static void probe_hcall_entry(unsigned long opcode)
+static void probe_hcall_entry(unsigned long opcode, unsigned long *args)
 {
 	struct hcall_stats *h;
 
@@ -114,7 +114,8 @@ static void probe_hcall_entry(unsigned long opcode)
 	h->purr_start = mfspr(SPRN_PURR);
 }
 
-static void probe_hcall_exit(unsigned long opcode, unsigned long retval)
+static void probe_hcall_exit(unsigned long opcode, unsigned long retval,
+			     unsigned long *retbuf)
 {
 	struct hcall_stats *h;
 

arch/powerpc/platforms/pseries/lpar.c

@@ -683,13 +683,14 @@ void hcall_tracepoint_unregfunc(void)
 	hcall_tracepoint_refcount--;
 }
 
-void __trace_hcall_entry(unsigned long opcode)
+void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
 {
-	trace_hcall_entry(opcode);
+	trace_hcall_entry(opcode, args);
 }
 
-void __trace_hcall_exit(long opcode, unsigned long retval)
+void __trace_hcall_exit(long opcode, unsigned long retval,
+			unsigned long *retbuf)
 {
-	trace_hcall_exit(opcode, retval);
+	trace_hcall_exit(opcode, retval, retbuf);
 }
 #endif