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powerpc/perf: Add basic assembly code to read BHRB entries on POWER8 

This patch adds the basic assembly code to read BHRB buffer. BHRB entries
are valid only after a PMU interrupt has happened (when MMCR0[PMAO]=1)
and BHRB has been freezed. BHRB read should not be attempted when it is
still enabled (MMCR0[PMAE]=1) and getting updated, as this can produce
non-deterministic results.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Anshuman Khandual 2013-04-22 19:42:41 +00:00 committed by Benjamin Herrenschmidt
parent 95213959ae
commit 73760931dc
2 changed files with 45 additions and 1 deletions
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2
arch/powerpc/perf/Makefile
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@ -2,7 +2,7 @@ subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
obj-$(CONFIG_PERF_EVENTS) += callchain.o
obj-$(CONFIG_PPC_PERF_CTRS) += core-book3s.o
obj-$(CONFIG_PPC_PERF_CTRS) += core-book3s.o bhrb.o
obj64-$(CONFIG_PPC_PERF_CTRS) += power4-pmu.o ppc970-pmu.o power5-pmu.o \
power5+-pmu.o power6-pmu.o power7-pmu.o \
power8-pmu.o

44
arch/powerpc/perf/bhrb.S Normal file
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@ -0,0 +1,44 @@
/*
* Basic assembly code to read BHRB entries
*
* Copyright 2013 Anshuman Khandual, IBM Corporation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/ppc_asm.h>
#include <asm/ppc-opcode.h>
.text
.balign 8
/* r3 = n (where n = [0-31])
* The maximum number of BHRB entries supported with PPC_MFBHRBE instruction
* is 1024. We have limited number of table entries here as POWER8 implements
* 32 BHRB entries.
*/
/* .global read_bhrb */
_GLOBAL(read_bhrb)
cmpldi r3,31
bgt 1f
ld r4,bhrb_table@got(r2)
sldi r3,r3,3
add r3,r4,r3
mtctr r3
bctr
1: li r3,0
blr
#define MFBHRB_TABLE1(n) PPC_MFBHRBE(R3,n); blr
#define MFBHRB_TABLE2(n) MFBHRB_TABLE1(n); MFBHRB_TABLE1(n+1)
#define MFBHRB_TABLE4(n) MFBHRB_TABLE2(n); MFBHRB_TABLE2(n+2)
#define MFBHRB_TABLE8(n) MFBHRB_TABLE4(n); MFBHRB_TABLE4(n+4)
#define MFBHRB_TABLE16(n) MFBHRB_TABLE8(n); MFBHRB_TABLE8(n+8)
#define MFBHRB_TABLE32(n) MFBHRB_TABLE16(n); MFBHRB_TABLE16(n+16)
bhrb_table:
MFBHRB_TABLE32(0)