From 9d23a90a67261e73b2fcac04d8ca963c6b496afb Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 14 May 2009 21:48:08 +1000 Subject: [PATCH] perf_counter: allow arch to supply event misc flags and instruction pointer At present the values we put in overflow events for the misc flags indicating processor mode and the instruction pointer are obtained using the standard user_mode() and instruction_pointer() functions. Those functions tell you where the performance monitor interrupt was taken, which might not be exactly where the counter overflow occurred, for example because interrupts were disabled at the point where the overflow occurred, or because the processor had many instructions in flight and chose to complete some more instructions beyond the one that caused the counter overflow. Some architectures (e.g. powerpc) can supply more precise information about where the counter overflow occurred and the processor mode at that point. This introduces new functions, perf_misc_flags() and perf_instruction_pointer(), which arch code can override to provide more precise information if available. They have default implementations which are identical to the existing code. This also adds a new misc flag value, PERF_EVENT_MISC_HYPERVISOR, for the case where a counter overflow occurred in the hypervisor. We encode the processor mode in the 2 bits previously used to indicate user or kernel mode; the values for user and kernel mode are unchanged and hypervisor mode is indicated by both bits being set. [ Impact: generalize perfcounter core facilities ] Signed-off-by: Paul Mackerras Acked-by: Peter Zijlstra Cc: Corey Ashford Cc: Arnaldo Carvalho de Melo LKML-Reference: <18956.1272.818511.561835@cargo.ozlabs.ibm.com> Signed-off-by: Ingo Molnar --- include/linux/perf_counter.h | 11 ++++++++++- kernel/perf_counter.c | 5 ++--- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index 004b6e162b9..c8c1dfc22c9 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -215,8 +215,11 @@ struct perf_counter_mmap_page { __u32 data_head; /* head in the data section */ }; +#define PERF_EVENT_MISC_CPUMODE_MASK (3 << 0) +#define PERF_EVENT_MISC_CPUMODE_UNKNOWN (0 << 0) #define PERF_EVENT_MISC_KERNEL (1 << 0) -#define PERF_EVENT_MISC_USER (1 << 1) +#define PERF_EVENT_MISC_USER (2 << 0) +#define PERF_EVENT_MISC_HYPERVISOR (3 << 0) #define PERF_EVENT_MISC_OVERFLOW (1 << 2) struct perf_event_header { @@ -596,6 +599,12 @@ extern int sysctl_perf_counter_mlock; extern void perf_counter_init(void); +#ifndef perf_misc_flags +#define perf_misc_flags(regs) (user_mode(regs) ? PERF_EVENT_MISC_USER : \ + PERF_EVENT_MISC_KERNEL) +#define perf_instruction_pointer(regs) instruction_pointer(regs) +#endif + #else static inline void perf_counter_task_sched_in(struct task_struct *task, int cpu) { } diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 728a595399b..57840a94b16 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -2042,11 +2042,10 @@ static void perf_counter_output(struct perf_counter *counter, header.size = sizeof(header); header.misc = PERF_EVENT_MISC_OVERFLOW; - header.misc |= user_mode(regs) ? - PERF_EVENT_MISC_USER : PERF_EVENT_MISC_KERNEL; + header.misc |= perf_misc_flags(regs); if (record_type & PERF_RECORD_IP) { - ip = instruction_pointer(regs); + ip = perf_instruction_pointer(regs); header.type |= PERF_RECORD_IP; header.size += sizeof(ip); }