[tip:perf/fast] perf, x86: Implement user-space RDPMC support, to allow fast, user-space access to self-monitoring counters

[tip-bot for Peter Zijlstra <a.p.zijlstra@chello.nl>]

Commit-ID:  fe4a330885aee20f233de36085fb15c38094e635
Gitweb:     http://git.kernel.org/tip/fe4a330885aee20f233de36085fb15c38094e635
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Sun, 20 Nov 2011 20:44:06 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 21 Dec 2011 11:01:10 +0100

perf, x86: Implement user-space RDPMC support, to allow fast, user-space access to self-monitoring counters

Implement a correct pmu::event_idx for the x86 counter index rules and
set CR4.PCE on CPU_STARTING.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arun Sharma <asharma@fb.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/n/tip-mwxab34dibqgzk5zywutfnha@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/cpu/perf_event.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 5adce10..53b5699 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1210,6 +1210,7 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
 		break;
 
 	case CPU_STARTING:
+		set_in_cr4(X86_CR4_PCE);
 		if (x86_pmu.cpu_starting)
 			x86_pmu.cpu_starting(cpu);
 		break;
@@ -1542,6 +1543,18 @@ static int x86_pmu_event_init(struct perf_event *event)
 	return err;
 }
 
+static int x86_pmu_event_idx(struct perf_event *event)
+{
+	int idx = event->hw.idx;
+
+	if (x86_pmu.num_counters_fixed && idx >= X86_PMC_IDX_FIXED) {
+		idx -= X86_PMC_IDX_FIXED;
+		idx |= 1 << 30;
+	}
+
+	return idx + 1;
+}
+
 static struct pmu pmu = {
 	.pmu_enable	= x86_pmu_enable,
 	.pmu_disable	= x86_pmu_disable,
@@ -1557,6 +1570,8 @@ static struct pmu pmu = {
 	.start_txn	= x86_pmu_start_txn,
 	.cancel_txn	= x86_pmu_cancel_txn,
 	.commit_txn	= x86_pmu_commit_txn,
+
+	.event_idx	= x86_pmu_event_idx,
 };
 
 /*