Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c8cd093a authored by Anton Blanchard's avatar Anton Blanchard Committed by Paul Mackerras
Browse files

powerpc: tracing: Add hypervisor call tracepoints 



Add hcall_entry and hcall_exit tracepoints.  This replaces the inline
assembly HCALL_STATS code and converts it to use the new tracepoints.

To keep the disabled case as quick as possible, we embed a status word
in the TOC so we can get at it with a single load.  By doing so we
keep the overhead at a minimum.  Time taken for a null hcall:

No tracepoint code:	135.79 cycles
Disabled tracepoints:	137.95 cycles

For reference, before this patch enabling HCALL_STATS resulted in a null
hcall of 201.44 cycles!

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 6795b85c

arch/powerpc/Kconfig.debug

+1 −1
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ config DEBUG_STACK_USAGE 


config HCALL_STATS

	bool "Hypervisor call instrumentation"

	depends on PPC_PSERIES && DEBUG_FS

	depends on PPC_PSERIES && DEBUG_FS && TRACEPOINTS

	help

	  Adds code to keep track of the number of hypervisor calls made and

	  the amount of time spent in hypervisor calls.  Wall time spent in

arch/powerpc/include/asm/hvcall.h

+2 −0
Original line number Diff line number Diff line
@@ -274,6 +274,8 @@ struct hcall_stats { 
	unsigned long	num_calls;	/* number of calls (on this CPU) */

	unsigned long	tb_total;	/* total wall time (mftb) of calls. */

	unsigned long	purr_total;	/* total cpu time (PURR) of calls. */

	unsigned long	tb_start;

	unsigned long	purr_start;

};

#define HCALL_STAT_ARRAY_SIZE	((MAX_HCALL_OPCODE >> 2) + 1)

arch/powerpc/include/asm/trace.h

+45 −0
Original line number Diff line number Diff line
@@ -76,6 +76,51 @@ TRACE_EVENT(timer_interrupt_exit, 
	TP_printk("pt_regs=%p", __entry->regs)

);



#ifdef CONFIG_PPC_PSERIES

extern void hcall_tracepoint_regfunc(void);

extern void hcall_tracepoint_unregfunc(void);



TRACE_EVENT_FN(hcall_entry,



	TP_PROTO(unsigned long opcode),



	TP_ARGS(opcode),



	TP_STRUCT__entry(

		__field(unsigned long, opcode)

	),



	TP_fast_assign(

		__entry->opcode = opcode;

	),



	TP_printk("opcode=%lu", __entry->opcode),



	hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc

);



TRACE_EVENT_FN(hcall_exit,



	TP_PROTO(unsigned long opcode, unsigned long retval),



	TP_ARGS(opcode, retval),



	TP_STRUCT__entry(

		__field(unsigned long, opcode)

		__field(unsigned long, retval)

	),



	TP_fast_assign(

		__entry->opcode = opcode;

		__entry->retval = retval;

	),



	TP_printk("opcode=%lu retval=%lu", __entry->opcode, __entry->retval),



	hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc

);

#endif



#endif /* _TRACE_POWERPC_H */



#undef TRACE_INCLUDE_PATH

arch/powerpc/platforms/pseries/hvCall.S

+58 −43
Original line number Diff line number Diff line
@@ -14,19 +14,53 @@ 
	

#define STK_PARM(i)     (48 + ((i)-3)*8)



#ifdef CONFIG_HCALL_STATS

#ifdef CONFIG_TRACEPOINTS



	.section	".toc","aw"



	.globl hcall_tracepoint_refcount

hcall_tracepoint_refcount:

	.llong	0



	.section	".text"



/*

 * precall must preserve all registers.  use unused STK_PARM()

 * areas to save snapshots and opcode.

 * areas to save snapshots and opcode. We branch around this

 * in early init (eg when populating the MMU hashtable) by using an

 * unconditional cpu feature.

 */

#define HCALL_INST_PRECALL					\

	std	r3,STK_PARM(r3)(r1);	/* save opcode */	\

	mftb	r0;			/* get timebase and */	\

	std     r0,STK_PARM(r5)(r1);	/* save for later */	\

BEGIN_FTR_SECTION;						\

	mfspr	r0,SPRN_PURR;		/* get PURR and */	\

	std	r0,STK_PARM(r6)(r1);	/* save for later */	\

END_FTR_SECTION_IFSET(CPU_FTR_PURR);

	b	1f;						\

END_FTR_SECTION(0, 1);						\

	ld      r12,hcall_tracepoint_refcount@toc(r2);		\

	cmpdi	r12,0;						\

	beq+	1f;						\

	mflr	r0;						\

	std	r3,STK_PARM(r3)(r1);				\

	std	r4,STK_PARM(r4)(r1);				\

	std	r5,STK_PARM(r5)(r1);				\

	std	r6,STK_PARM(r6)(r1);				\

	std	r7,STK_PARM(r7)(r1);				\

	std	r8,STK_PARM(r8)(r1);				\

	std	r9,STK_PARM(r9)(r1);				\

	std	r10,STK_PARM(r10)(r1);				\

	std	r0,16(r1);					\

	stdu	r1,-STACK_FRAME_OVERHEAD(r1);			\

	bl	.__trace_hcall_entry;				\

	addi	r1,r1,STACK_FRAME_OVERHEAD;			\

	ld	r0,16(r1);					\

	ld	r3,STK_PARM(r3)(r1);				\

	ld	r4,STK_PARM(r4)(r1);				\

	ld	r5,STK_PARM(r5)(r1);				\

	ld	r6,STK_PARM(r6)(r1);				\

	ld	r7,STK_PARM(r7)(r1);				\

	ld	r8,STK_PARM(r8)(r1);				\

	ld	r9,STK_PARM(r9)(r1);				\

	ld	r10,STK_PARM(r10)(r1);				\

	mtlr	r0;						\

1:



/*

 * postcall is performed immediately before function return which
@@ -38,40 +72,21 @@ END_FTR_SECTION_IFSET(CPU_FTR_PURR); 
BEGIN_FTR_SECTION;						\

	b	1f;						\

END_FTR_SECTION(0, 1);						\

	ld	r4,STK_PARM(r3)(r1);	/* validate opcode */	\

	cmpldi	cr7,r4,MAX_HCALL_OPCODE;			\

	bgt-	cr7,1f;						\

								\

	/* get time and PURR snapshots after hcall */		\

	mftb	r7;			/* timebase after */	\

BEGIN_FTR_SECTION;						\

	mfspr	r8,SPRN_PURR;		/* PURR after */	\

	ld	r6,STK_PARM(r6)(r1);	/* PURR before */	\

	subf	r6,r6,r8;		/* delta */		\

END_FTR_SECTION_IFSET(CPU_FTR_PURR);				\

	ld	r5,STK_PARM(r5)(r1);	/* timebase before */	\

	subf	r5,r5,r7;		/* time delta */	\

								\

	/* calculate address of stat structure r4 = opcode */	\

	srdi	r4,r4,2;		/* index into array */	\

	mulli	r4,r4,HCALL_STAT_SIZE;				\

	LOAD_REG_ADDR(r7, per_cpu__hcall_stats);		\

	add	r4,r4,r7;					\

	ld	r7,PACA_DATA_OFFSET(r13); /* per cpu offset */	\

	add	r4,r4,r7;					\

								\

	/* update stats	*/					\

	ld	r7,HCALL_STAT_CALLS(r4); /* count */		\

	addi	r7,r7,1;					\

	std	r7,HCALL_STAT_CALLS(r4);			\

	ld      r7,HCALL_STAT_TB(r4);	/* timebase */		\

	add	r7,r7,r5;					\

	std	r7,HCALL_STAT_TB(r4);				\

BEGIN_FTR_SECTION;						\

	ld	r7,HCALL_STAT_PURR(r4);	/* PURR */		\

	add	r7,r7,r6;					\

	std	r7,HCALL_STAT_PURR(r4);				\

END_FTR_SECTION_IFSET(CPU_FTR_PURR);				\

	ld      r12,hcall_tracepoint_refcount@toc(r2);		\

	cmpdi	r12,0;						\

	beq+	1f;						\

	mflr	r0;						\

	ld	r6,STK_PARM(r3)(r1);				\

	std	r3,STK_PARM(r3)(r1);				\

	mr	r4,r3;						\

	mr	r3,r6;						\

	std	r0,16(r1);					\

	stdu	r1,-STACK_FRAME_OVERHEAD(r1);			\

	bl	.__trace_hcall_exit;				\

	addi	r1,r1,STACK_FRAME_OVERHEAD;			\

	ld	r0,16(r1);					\

	ld	r3,STK_PARM(r3)(r1);				\

	mtlr	r0;						\

1:

#else

#define HCALL_INST_PRECALL

arch/powerpc/platforms/pseries/hvCall_inst.c

+37 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <asm/hvcall.h>

#include <asm/firmware.h>

#include <asm/cputable.h>

#include <asm/trace.h>



DEFINE_PER_CPU(struct hcall_stats[HCALL_STAT_ARRAY_SIZE], hcall_stats);
@@ -100,6 +101,34 @@ static const struct file_operations hcall_inst_seq_fops = { 
#define	HCALL_ROOT_DIR		"hcall_inst"

#define CPU_NAME_BUF_SIZE	32





static void probe_hcall_entry(unsigned long opcode)

{

	struct hcall_stats *h;



	if (opcode > MAX_HCALL_OPCODE)

		return;



	h = &get_cpu_var(hcall_stats)[opcode / 4];

	h->tb_start = mftb();

	h->purr_start = mfspr(SPRN_PURR);

}



static void probe_hcall_exit(unsigned long opcode, unsigned long retval)

{

	struct hcall_stats *h;



	if (opcode > MAX_HCALL_OPCODE)

		return;



	h = &__get_cpu_var(hcall_stats)[opcode / 4];

	h->num_calls++;

	h->tb_total = mftb() - h->tb_start;

	h->purr_total = mfspr(SPRN_PURR) - h->purr_start;



	put_cpu_var(hcall_stats);

}



static int __init hcall_inst_init(void)

{

	struct dentry *hcall_root;
@@ -110,6 +139,14 @@ static int __init hcall_inst_init(void) 
	if (!firmware_has_feature(FW_FEATURE_LPAR))

		return 0;



	if (register_trace_hcall_entry(probe_hcall_entry))

		return -EINVAL;



	if (register_trace_hcall_exit(probe_hcall_exit)) {

		unregister_trace_hcall_entry(probe_hcall_entry);

		return -EINVAL;

	}



	hcall_root = debugfs_create_dir(HCALL_ROOT_DIR, NULL);

	if (!hcall_root)

		return -ENOMEM;