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authorMichael Neuling <mikey@neuling.org>2013-05-13 18:44:58 (GMT)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-05-14 06:00:22 (GMT)
commit691231846cebfe1fbbcf898c8af17a569dbb5463 (patch)
treeedb500ca27ae25cfdae8526a9efb884143a12f5c /arch/powerpc/perf
parent506e70d13236dfdb0bc15e0914298ab0a7b7f4df (diff)
powerpc/perf: Fix setting of "to" addresses for BHRB
Currently we only set the "to" address in the branch stack when the CPU explicitly gives us a value. Unfortunately it only does this for XL form branches (eg blr, bctr, bctar) and not I and B form branches (eg b, bc). Fortunately if we read the instruction from memory we can extract the offset of a branch and calculate the target address. This adds a function power_pmu_bhrb_to() to calculate the target/to address of the corresponding I and B form branches. It handles branches in both user and kernel spaces. It also plumbs this into the perf brhb reading code. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/perf')
-rw-r--r--arch/powerpc/perf/core-book3s.c31
1 files changed, 30 insertions, 1 deletions
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 3fdfe45..426180b 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -13,11 +13,13 @@
#include <linux/perf_event.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
+#include <linux/uaccess.h>
#include <asm/reg.h>
#include <asm/pmc.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/ptrace.h>
+#include <asm/code-patching.h>
#define BHRB_MAX_ENTRIES 32
#define BHRB_TARGET 0x0000000000000002
@@ -362,6 +364,32 @@ void power_pmu_flush_branch_stack(void)
if (ppmu->bhrb_nr)
power_pmu_bhrb_reset();
}
+/* Calculate the to address for a branch */
+static __u64 power_pmu_bhrb_to(u64 addr)
+{
+ unsigned int instr;
+ int ret;
+ __u64 target;
+
+ if (is_kernel_addr(addr))
+ return branch_target((unsigned int *)addr);
+
+ /* Userspace: need copy instruction here then translate it */
+ pagefault_disable();
+ ret = __get_user_inatomic(instr, (unsigned int __user *)addr);
+ if (ret) {
+ pagefault_enable();
+ return 0;
+ }
+ pagefault_enable();
+
+ target = branch_target(&instr);
+ if ((!target) || (instr & BRANCH_ABSOLUTE))
+ return target;
+
+ /* Translate relative branch target from kernel to user address */
+ return target - (unsigned long)&instr + addr;
+}
/* Processing BHRB entries */
void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw)
@@ -426,7 +454,8 @@ void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw)
/* Branches to immediate field
(ie I or B form) */
cpuhw->bhrb_entries[u_index].from = addr;
- cpuhw->bhrb_entries[u_index].to = 0;
+ cpuhw->bhrb_entries[u_index].to =
+ power_pmu_bhrb_to(addr);
cpuhw->bhrb_entries[u_index].mispred = pred;
cpuhw->bhrb_entries[u_index].predicted = ~pred;
}

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