Commit cd99ddbe authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/8xx: Only perform perf counting when perf is in use. 



In TLB miss handlers, updating the perf counter is only useful
when performing a perf analysis. As it has a noticeable overhead,
let's only do it when needed.

In order to do so, the exit of the miss handlers will be patched
when starting/stopping 'perf': the first register restore
instruction of each exit point will be replaced by a jump to
the counting code.

Once this is done, CONFIG_PPC_8xx_PERF_EVENT becomes useless as
this feature doesn't add any overhead.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent bb9b5a83

arch/powerpc/include/asm/ppc-opcode.h

+2 −0
Original line number Diff line number Diff line
@@ -236,6 +236,7 @@ 
#define PPC_INST_RFCI			0x4c000066

#define PPC_INST_RFDI			0x4c00004e

#define PPC_INST_RFMCI			0x4c00004c

#define PPC_INST_MFSPR			0x7c0002a6

#define PPC_INST_MFSPR_DSCR		0x7c1102a6

#define PPC_INST_MFSPR_DSCR_MASK	0xfc1ffffe

#define PPC_INST_MTSPR_DSCR		0x7c1103a6
@@ -383,6 +384,7 @@ 
#define __PPC_ME64(s)	__PPC_MB64(s)

#define __PPC_BI(s)	(((s) & 0x1f) << 16)

#define __PPC_CT(t)	(((t) & 0x0f) << 21)

#define __PPC_SPR(r)	((((r) & 0x1f) << 16) | ((((r) >> 5) & 0x1f) << 11))



/*

 * Only use the larx hint bit on 64bit CPUs. e500v1/v2 based CPUs will treat a

arch/powerpc/kernel/entry_32.S

+5 −5
Original line number Diff line number Diff line
@@ -211,7 +211,7 @@ transfer_to_handler_cont: 
	mflr	r9

	lwz	r11,0(r9)		/* virtual address of handler */

	lwz	r9,4(r9)		/* where to go when done */

#ifdef CONFIG_PPC_8xx_PERF_EVENT

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

	mtspr	SPRN_NRI, r0

#endif

#ifdef CONFIG_TRACE_IRQFLAGS
@@ -301,7 +301,7 @@ stack_ovf: 
	lis	r9,StackOverflow@ha

	addi	r9,r9,StackOverflow@l

	LOAD_MSR_KERNEL(r10,MSR_KERNEL)

#ifdef CONFIG_PPC_8xx_PERF_EVENT

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

	mtspr	SPRN_NRI, r0

#endif

	mtspr	SPRN_SRR0,r9
@@ -430,7 +430,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) 
	lwz	r7,_NIP(r1)

	lwz	r2,GPR2(r1)

	lwz	r1,GPR1(r1)

#ifdef CONFIG_PPC_8xx_PERF_EVENT

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

	mtspr	SPRN_NRI, r0

#endif

	mtspr	SPRN_SRR0,r7
@@ -727,7 +727,7 @@ fast_exception_return: 
	lwz	r10,_LINK(r11)

	mtlr	r10

	REST_GPR(10, r11)

#ifdef CONFIG_PPC_8xx_PERF_EVENT

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

	mtspr	SPRN_NRI, r0

#endif

	mtspr	SPRN_SRR1,r9
@@ -978,7 +978,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) 
	.globl exc_exit_restart

exc_exit_restart:

	lwz	r12,_NIP(r1)

#ifdef CONFIG_PPC_8xx_PERF_EVENT

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

	mtspr	SPRN_NRI, r0

#endif

	mtspr	SPRN_SRR0,r12

arch/powerpc/kernel/head_8xx.S

+32 −15
Original line number Diff line number Diff line
@@ -304,12 +304,6 @@ InstructionTLBMiss: 
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)

	mtspr	SPRN_SPRG_SCRATCH2, r12

#endif

#ifdef CONFIG_PPC_8xx_PERF_EVENT

	lis	r10, (itlb_miss_counter - PAGE_OFFSET)@ha

	lwz	r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)

	addi	r11, r11, 1

	stw	r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)

#endif



	/* If we are faulting a kernel address, we have to use the

	 * kernel page tables.
@@ -392,6 +386,20 @@ _ENTRY(ITLBMiss_cmp) 
	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */



	/* Restore registers */

_ENTRY(itlb_miss_exit_1)

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)

	mfspr	r12, SPRN_SPRG_SCRATCH2

#endif

	rfi

#ifdef CONFIG_PERF_EVENTS

_ENTRY(itlb_miss_perf)

	lis	r10, (itlb_miss_counter - PAGE_OFFSET)@ha

	lwz	r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)

	addi	r11, r11, 1

	stw	r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)

#endif

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
@@ -429,12 +437,6 @@ DataStoreTLBMiss: 
	mtspr	SPRN_SPRG_SCRATCH0, r10

	mtspr	SPRN_SPRG_SCRATCH1, r11

	mtspr	SPRN_SPRG_SCRATCH2, r12

#ifdef CONFIG_PPC_8xx_PERF_EVENT

	lis	r10, (dtlb_miss_counter - PAGE_OFFSET)@ha

	lwz	r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)

	addi	r11, r11, 1

	stw	r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)

#endif

	mfcr	r12



	/* If we are faulting a kernel address, we have to use the
@@ -526,6 +528,18 @@ _ENTRY(DTLBMiss_jmp) 


	/* Restore registers */

	mtspr	SPRN_DAR, r11	/* Tag DAR */

_ENTRY(dtlb_miss_exit_1)

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

	mfspr	r12, SPRN_SPRG_SCRATCH2

	rfi

#ifdef CONFIG_PERF_EVENTS

_ENTRY(dtlb_miss_perf)

	lis	r10, (dtlb_miss_counter - PAGE_OFFSET)@ha

	lwz	r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)

	addi	r11, r11, 1

	stw	r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)

#endif

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

	mfspr	r12, SPRN_SPRG_SCRATCH2
@@ -635,7 +649,7 @@ DataBreakpoint: 
	mfspr	r11, SPRN_SPRG_SCRATCH1

	rfi



#ifdef CONFIG_PPC_8xx_PERF_EVENT

#ifdef CONFIG_PERF_EVENTS

	. = 0x1d00

InstructionBreakpoint:

	mtspr	SPRN_SPRG_SCRATCH0, r10
@@ -675,6 +689,7 @@ DTLBMissIMMR: 


	li	r11, RPN_PATTERN

	mtspr	SPRN_DAR, r11	/* Tag DAR */

_ENTRY(dtlb_miss_exit_2)

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

	mfspr	r12, SPRN_SPRG_SCRATCH2
@@ -692,6 +707,7 @@ DTLBMissLinear: 


	li	r11, RPN_PATTERN

	mtspr	SPRN_DAR, r11	/* Tag DAR */

_ENTRY(dtlb_miss_exit_3)

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

	mfspr	r12, SPRN_SPRG_SCRATCH2
@@ -708,6 +724,7 @@ ITLBMissLinear: 
			  _PAGE_PRESENT

	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */



_ENTRY(itlb_miss_exit_2)

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r11, SPRN_SPRG_SCRATCH1

	mfspr	r12, SPRN_SPRG_SCRATCH2
@@ -1039,7 +1056,7 @@ initial_mmu: 
#endif

	/* Disable debug mode entry on breakpoints */

	mfspr	r8, SPRN_DER

#ifdef CONFIG_PPC_8xx_PERF_EVENT

#ifdef CONFIG_PERF_EVENTS

	rlwinm	r8, r8, 0, ~0xc

#else

	rlwinm	r8, r8, 0, ~0x8
@@ -1072,7 +1089,7 @@ swapper_pg_dir: 
abatron_pteptrs:

	.space	8



#ifdef CONFIG_PPC_8xx_PERF_EVENT

#ifdef CONFIG_PERF_EVENTS

	.globl	itlb_miss_counter

itlb_miss_counter:

	.space	4

arch/powerpc/perf/8xx-pmu.c

+48 −4
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <asm/machdep.h>

#include <asm/firmware.h>

#include <asm/ptrace.h>

#include <asm/code-patching.h>



#define PERF_8xx_ID_CPU_CYCLES		1

#define PERF_8xx_ID_HW_INSTRUCTIONS	2
@@ -30,8 +31,13 @@ 


extern unsigned long itlb_miss_counter, dtlb_miss_counter;

extern atomic_t instruction_counter;

extern unsigned int itlb_miss_perf, dtlb_miss_perf;

extern unsigned int itlb_miss_exit_1, itlb_miss_exit_2;

extern unsigned int dtlb_miss_exit_1, dtlb_miss_exit_2, dtlb_miss_exit_3;



static atomic_t insn_ctr_ref;

static atomic_t itlb_miss_ref;

static atomic_t dtlb_miss_ref;



static s64 get_insn_ctr(void)

{
@@ -96,9 +102,24 @@ static int mpc8xx_pmu_add(struct perf_event *event, int flags) 
		val = get_insn_ctr();

		break;

	case PERF_8xx_ID_ITLB_LOAD_MISS:

		if (atomic_inc_return(&itlb_miss_ref) == 1) {

			unsigned long target = (unsigned long)&itlb_miss_perf;



			patch_branch(&itlb_miss_exit_1, target, 0);

#ifndef CONFIG_PIN_TLB_TEXT

			patch_branch(&itlb_miss_exit_2, target, 0);

#endif

		}

		val = itlb_miss_counter;

		break;

	case PERF_8xx_ID_DTLB_LOAD_MISS:

		if (atomic_inc_return(&dtlb_miss_ref) == 1) {

			unsigned long target = (unsigned long)&dtlb_miss_perf;



			patch_branch(&dtlb_miss_exit_1, target, 0);

			patch_branch(&dtlb_miss_exit_2, target, 0);

			patch_branch(&dtlb_miss_exit_3, target, 0);

		}

		val = dtlb_miss_counter;

		break;

	}
@@ -143,13 +164,36 @@ static void mpc8xx_pmu_read(struct perf_event *event) 


static void mpc8xx_pmu_del(struct perf_event *event, int flags)

{

	/* mfspr r10, SPRN_SPRG_SCRATCH0 */

	unsigned int insn = PPC_INST_MFSPR | __PPC_RS(R10) |

			    __PPC_SPR(SPRN_SPRG_SCRATCH0);



	mpc8xx_pmu_read(event);

	if (event_type(event) != PERF_8xx_ID_HW_INSTRUCTIONS)

		return;



	/* If it was the last user, stop counting to avoid useles overhead */

	switch (event_type(event)) {

	case PERF_8xx_ID_CPU_CYCLES:

		break;

	case PERF_8xx_ID_HW_INSTRUCTIONS:

		if (atomic_dec_return(&insn_ctr_ref) == 0)

			mtspr(SPRN_ICTRL, 7);

		break;

	case PERF_8xx_ID_ITLB_LOAD_MISS:

		if (atomic_dec_return(&itlb_miss_ref) == 0) {

			patch_instruction(&itlb_miss_exit_1, insn);

#ifndef CONFIG_PIN_TLB_TEXT

			patch_instruction(&itlb_miss_exit_2, insn);

#endif

		}

		break;

	case PERF_8xx_ID_DTLB_LOAD_MISS:

		if (atomic_dec_return(&dtlb_miss_ref) == 0) {

			patch_instruction(&dtlb_miss_exit_1, insn);

			patch_instruction(&dtlb_miss_exit_2, insn);

			patch_instruction(&dtlb_miss_exit_3, insn);

		}

		break;

	}

}



static struct pmu mpc8xx_pmu = {

arch/powerpc/perf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ obj-$(CONFIG_FSL_EMB_PERF_EVENT_E500) += e500-pmu.o e6500-pmu.o 


obj-$(CONFIG_HV_PERF_CTRS) += hv-24x7.o hv-gpci.o hv-common.o



obj-$(CONFIG_PPC_8xx_PERF_EVENT) += 8xx-pmu.o

obj-$(CONFIG_PPC_8xx) += 8xx-pmu.o



obj-$(CONFIG_PPC64)		+= $(obj64-y)

obj-$(CONFIG_PPC32)		+= $(obj32-y)

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