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authorAndi Kleen <ak@linux.intel.com>2015-10-20 11:46:33 -0700
committerIngo Molnar <mingo@kernel.org>2015-11-23 09:44:57 +0100
commitb28ae9560b693bcd2e9f4d6d9c415d5380b7c3c5 (patch)
tree44d175d2ef3b8a3a596d93510f8f31db4d3cd5e6
parentdaecbd267daad36c1cd90254f502610f82efcb30 (diff)
downloadop-kernel-dev-b28ae9560b693bcd2e9f4d6d9c415d5380b7c3c5.zip
op-kernel-dev-b28ae9560b693bcd2e9f4d6d9c415d5380b7c3c5.tar.gz
perf/x86: Fix LBR call stack save/restore
This fixes a bug I added in the following commit: 90405aa02247 ("perf/x86/intel/lbr: Limit LBR accesses to TOS in callstack mode") The bug could lead to lost LBR call stacks. When restoring the LBR state we need to use the TOS of the previous context, not the current context. To do that we need to save/restore the TOS. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: acme@kernel.org Cc: jolsa@kernel.org Link: http://lkml.kernel.org/r/1445366797-30894-1-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/kernel/cpu/perf_event.h1
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel_lbr.c4
2 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 499f533..ffa7a92 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -627,6 +627,7 @@ struct x86_perf_task_context {
u64 lbr_from[MAX_LBR_ENTRIES];
u64 lbr_to[MAX_LBR_ENTRIES];
u64 lbr_info[MAX_LBR_ENTRIES];
+ int tos;
int lbr_callstack_users;
int lbr_stack_state;
};
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index bfd0b71..659f01e 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -239,7 +239,7 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
}
mask = x86_pmu.lbr_nr - 1;
- tos = intel_pmu_lbr_tos();
+ tos = task_ctx->tos;
for (i = 0; i < tos; i++) {
lbr_idx = (tos - i) & mask;
wrmsrl(x86_pmu.lbr_from + lbr_idx, task_ctx->lbr_from[i]);
@@ -247,6 +247,7 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
wrmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]);
}
+ wrmsrl(x86_pmu.lbr_tos, tos);
task_ctx->lbr_stack_state = LBR_NONE;
}
@@ -270,6 +271,7 @@ static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
rdmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]);
}
+ task_ctx->tos = tos;
task_ctx->lbr_stack_state = LBR_VALID;
}
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