From: "Yan, Zheng" <[email protected]> Try utilizing the LBR call stack to get user callchain in case of there is no frame pointer
Signed-off-by: Yan, Zheng <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
