unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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perf, x86: Implement user-space RDPMC support, to allow fast, user-space access to self-monitoring counters

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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>
This commit is contained in:
Peter Zijlstra 2011-11-20 20:44:06 +01:00 committed by Ingo Molnar
parent 365a403848
commit fe4a330885
1 changed files with 15 additions and 0 deletions
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15
arch/x86/kernel/cpu/perf_event.c
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@ -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,
};
/*