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authorFrederic Weisbecker <fweisbec@gmail.com>2010-03-04 21:15:56 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2010-03-10 14:39:35 +0100
commit5331d7b84613b8325362dde53dc2bff2fb87d351 (patch)
tree60f4bf4fdaf31b612eefc291bf6b558dc4c8d947 /arch/x86
parent61e67fb9d3ed13e6a7f58652ae4979b9c872fa57 (diff)
perf: Introduce new perf_fetch_caller_regs() for hot regs snapshot
Events that trigger overflows by interrupting a context can use get_irq_regs() or task_pt_regs() to retrieve the state when the event triggered. But this is not the case for some other class of events like trace events as tracepoints are executed in the same context than the code that triggered the event. It means we need a different api to capture the regs there, namely we need a hot snapshot to get the most important informations for perf: the instruction pointer to get the event origin, the frame pointer for the callchain, the code segment for user_mode() tests (we always use __KERNEL_CS as trace events always occur from the kernel) and the eflags for further purposes. v2: rename perf_save_regs to perf_fetch_caller_regs as per Masami's suggestion. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Masami Hiramatsu <mhiramat@redhat.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Archs <linux-arch@vger.kernel.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c12
-rw-r--r--arch/x86/kernel/dumpstack.h15
2 files changed, 27 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 1d665a0b202..c6bde7d7afd 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1707,3 +1707,15 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
return entry;
}
+
+void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip)
+{
+ regs->ip = ip;
+ /*
+ * perf_arch_fetch_caller_regs adds another call, we need to increment
+ * the skip level
+ */
+ regs->bp = rewind_frame_pointer(skip + 1);
+ regs->cs = __KERNEL_CS;
+ local_save_flags(regs->flags);
+}
diff --git a/arch/x86/kernel/dumpstack.h b/arch/x86/kernel/dumpstack.h
index 4fd1420faff..29e5f7c845b 100644
--- a/arch/x86/kernel/dumpstack.h
+++ b/arch/x86/kernel/dumpstack.h
@@ -29,4 +29,19 @@ struct stack_frame {
struct stack_frame *next_frame;
unsigned long return_address;
};
+
+static inline unsigned long rewind_frame_pointer(int n)
+{
+ struct stack_frame *frame;
+
+ get_bp(frame);
+
+#ifdef CONFIG_FRAME_POINTER
+ while (n--)
+ frame = frame->next_frame;
#endif
+
+ return (unsigned long)frame;
+}
+
+#endif /* DUMPSTACK_H */