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Date: Wed, 11 Dec 2013 15:10:58 +0800
From: "Yan, Zheng" <zheng.z.yan@...el.com>
To: linux-kernel@...r.kernel.org
Cc: a.p.zijlstra@...llo.nl, eranian@...gle.com, andi@...stfloor.org,
"Yan, Zheng" <zheng.z.yan@...el.com>
Subject: [PATCH 13/15] perf, x86: Use LBR call stack to get user callchain
From: "Yan, Zheng" <zheng.z.yan@...el.com>
Try utilizing the LBR call stack to get user callchain in case of
there is no frame pointer
Signed-off-by: Yan, Zheng <zheng.z.yan@...el.com>
---
arch/x86/kernel/cpu/perf_event.c | 33 ++++++++++++++++++++++++++----
arch/x86/kernel/cpu/perf_event_intel.c | 12 ++++++++++-
arch/x86/kernel/cpu/perf_event_intel_lbr.c | 2 ++
include/linux/perf_event.h | 1 +
4 files changed, 43 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 49128e6..1509340 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1965,12 +1965,28 @@ static unsigned long get_segment_base(unsigned int segment)
return get_desc_base(desc + idx);
}
+static inline void
+perf_callchain_lbr_callstack(struct perf_callchain_entry *entry,
+ struct perf_sample_data *data)
+{
+ struct perf_branch_stack *br_stack = data->br_stack;
+
+ if (br_stack && br_stack->user_callstack) {
+ int i = 0;
+ while (i < br_stack->nr && entry->nr < PERF_MAX_STACK_DEPTH) {
+ perf_callchain_store(entry, br_stack->entries[i].from);
+ i++;
+ }
+ }
+}
+
#ifdef CONFIG_COMPAT
#include <asm/compat.h>
static inline int
-perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
+perf_callchain_user32(struct perf_callchain_entry *entry,
+ struct pt_regs *regs, struct perf_sample_data *data)
{
/* 32-bit process in 64-bit kernel. */
unsigned long ss_base, cs_base;
@@ -1999,11 +2015,16 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
perf_callchain_store(entry, cs_base + frame.return_address);
fp = compat_ptr(ss_base + frame.next_frame);
}
+
+ if (fp == compat_ptr(regs->bp))
+ perf_callchain_lbr_callstack(entry, data);
+
return 1;
}
#else
static inline int
-perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
+perf_callchain_user32(struct perf_callchain_entry *entry,
+ struct pt_regs *regs, struct perf_sample_data *data)
{
return 0;
}
@@ -2033,12 +2054,12 @@ void perf_callchain_user(struct perf_callchain_entry *entry,
if (!current->mm)
return;
- if (perf_callchain_user32(regs, entry))
+ if (perf_callchain_user32(entry, regs, data))
return;
while (entry->nr < PERF_MAX_STACK_DEPTH) {
unsigned long bytes;
- frame.next_frame = NULL;
+ frame.next_frame = NULL;
frame.return_address = 0;
bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
@@ -2051,6 +2072,10 @@ void perf_callchain_user(struct perf_callchain_entry *entry,
perf_callchain_store(entry, frame.return_address);
fp = frame.next_frame;
}
+
+ /* try LBR callstack if there is no frame pointer */
+ if (fp == (void __user *)regs->bp)
+ perf_callchain_lbr_callstack(entry, data);
}
/*
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 722171c..e0f658a 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1030,6 +1030,15 @@ static __initconst const u64 slm_hw_cache_event_ids
},
};
+static inline bool intel_pmu_needs_lbr_callstack(struct perf_event *event)
+{
+ if ((event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
+ (event->attr.branch_sample_type & PERF_SAMPLE_BRANCH_CALL_STACK))
+ return true;
+
+ return false;
+}
+
static void intel_pmu_disable_all(void)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
@@ -1398,7 +1407,8 @@ again:
perf_sample_data_init(&data, 0, event->hw.last_period);
- if (has_branch_stack(event))
+ if (has_branch_stack(event) ||
+ (event->ctx->task && intel_pmu_needs_lbr_callstack(event)))
data.br_stack = &cpuc->lbr_stack;
if (perf_event_overflow(event, &data, regs))
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index 80bb097..a879910 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -722,6 +722,8 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
int i, j, type;
bool compress = false;
+ cpuc->lbr_stack.user_callstack = branch_user_callstack(br_sel);
+
/* if sampling all branches, then nothing to filter */
if ((br_sel & X86_BR_ALL) == X86_BR_ALL)
return;
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c442276..d2f0488 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -74,6 +74,7 @@ struct perf_raw_record {
* recent branch.
*/
struct perf_branch_stack {
+ bool user_callstack;
__u64 nr;
struct perf_branch_entry entries[0];
};
--
1.8.1.4
--
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