From ab608344bcbde4f55ec4cd911b686b0ce3eae076 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 8 Apr 2010 23:03:20 +0200 Subject: perf, x86: Improve the PEBS ABI Rename perf_event_attr::precise to perf_event_attr::precise_ip and widen it to 2 bits. This new field describes the required precision of the PERF_SAMPLE_IP field: 0 - SAMPLE_IP can have arbitrary skid 1 - SAMPLE_IP must have constant skid 2 - SAMPLE_IP requested to have 0 skid 3 - SAMPLE_IP must have 0 skid And modify the Intel PEBS code accordingly. The PEBS implementation now supports up to precise_ip == 2, where we perform the IP fixup. Also s/PERF_RECORD_MISC_EXACT/&_IP/ to clarify its meaning, this bit should be set for each PERF_SAMPLE_IP field known to match the actual instruction triggering the event. This new scheme allows for a PEBS mode that uses the buffer for more than a single event. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Cc: Stephane Eranian LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu/perf_event.c') diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 4a3f1f2b9b9..27fa9eeed02 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -488,6 +488,21 @@ static int x86_setup_perfctr(struct perf_event *event) static int x86_pmu_hw_config(struct perf_event *event) { + if (event->attr.precise_ip) { + int precise = 0; + + /* Support for constant skid */ + if (x86_pmu.pebs) + precise++; + + /* Support for IP fixup */ + if (x86_pmu.lbr_nr) + precise++; + + if (event->attr.precise_ip > precise) + return -EOPNOTSUPP; + } + /* * Generate PMC IRQs: * (keep 'enabled' bit clear for now) @@ -1780,7 +1795,7 @@ unsigned long perf_misc_flags(struct pt_regs *regs) } if (regs->flags & PERF_EFLAGS_EXACT) - misc |= PERF_RECORD_MISC_EXACT; + misc |= PERF_RECORD_MISC_EXACT_IP; return misc; } -- cgit v1.2.3-70-g09d2