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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-11-20 23:30:47 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-12-21 11:01:11 +0100 |
| commit | 0c9d42ed4cee2aa1dfc3a260b741baae8615744f (patch) | |
| tree | 393a3a3d0be5cbd57e1d03490b3f6a5a15d5367d /arch/x86/kernel/cpu/perf_event.c | |
| parent | fe4a330885aee20f233de36085fb15c38094e635 (diff) | |
| download | linux-0c9d42ed4cee2aa1dfc3a260b741baae8615744f.tar.gz | |
perf, x86: Provide means for disabling userspace RDPMC
Allow the disabling of RDPMC via a pmu specific attribute: echo 0 > /sys/bus/event_source/devices/cpu/rdpmc Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Stephane Eranian <eranian@google.com> Cc: Arun Sharma <asharma@fb.com> Link: http://lkml.kernel.org/n/tip-pqeog465zo5hsimtkfz73f27@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 55 |
1 files changed, 54 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 53b569910175..116b040a73a8 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -24,6 +24,7 @@ #include <linux/slab.h> #include <linux/cpu.h> #include <linux/bitops.h> +#include <linux/device.h> #include <asm/apic.h> #include <asm/stacktrace.h> @@ -1210,7 +1211,8 @@ 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.attr_rdpmc) + set_in_cr4(X86_CR4_PCE); if (x86_pmu.cpu_starting) x86_pmu.cpu_starting(cpu); break; @@ -1320,6 +1322,8 @@ static int __init init_hw_perf_events(void) } } + x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */ + pr_info("... version: %d\n", x86_pmu.version); pr_info("... bit width: %d\n", x86_pmu.cntval_bits); pr_info("... generic registers: %d\n", x86_pmu.num_counters); @@ -1555,10 +1559,59 @@ static int x86_pmu_event_idx(struct perf_event *event) return idx + 1; } +static ssize_t get_attr_rdpmc(struct device *cdev, + struct device_attribute *attr, + char *buf) +{ + return snprintf(buf, 40, "%d\n", x86_pmu.attr_rdpmc); +} + +static void change_rdpmc(void *info) +{ + bool enable = !!(unsigned long)info; + + if (enable) + set_in_cr4(X86_CR4_PCE); + else + clear_in_cr4(X86_CR4_PCE); +} + +static ssize_t set_attr_rdpmc(struct device *cdev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + unsigned long val = simple_strtoul(buf, NULL, 0); + + if (!!val != !!x86_pmu.attr_rdpmc) { + x86_pmu.attr_rdpmc = !!val; + smp_call_function(change_rdpmc, (void *)val, 1); + } + + return count; +} + +static DEVICE_ATTR(rdpmc, S_IRUSR | S_IWUSR, get_attr_rdpmc, set_attr_rdpmc); + +static struct attribute *x86_pmu_attrs[] = { + &dev_attr_rdpmc.attr, + NULL, +}; + +static struct attribute_group x86_pmu_attr_group = { + .attrs = x86_pmu_attrs, +}; + +static const struct attribute_group *x86_pmu_attr_groups[] = { + &x86_pmu_attr_group, + NULL, +}; + static struct pmu pmu = { .pmu_enable = x86_pmu_enable, .pmu_disable = x86_pmu_disable, + .attr_groups = x86_pmu_attr_groups, + .event_init = x86_pmu_event_init, .add = x86_pmu_add, |