The userspace RDPMC is a data leak since people can poke at random counters that are not their own, therefore provide a pmu specific attribute to turn it off. XXX: we probably want a perf_pmu_add_option() function but all this sysfs stuff gives me a head-ache. Cc: Stephane Eranian Cc: Arun Sharma Signed-off-by: Peter Zijlstra --- arch/x86/kernel/cpu/perf_event.c | 55 ++++++++++++++++++++++++++++++++++++++- arch/x86/kernel/cpu/perf_event.h | 8 +++++ include/linux/perf_event.h | 1 kernel/events/core.c | 1 4 files changed, 64 insertions(+), 1 deletion(-) Index: linux-2.6/include/linux/perf_event.h =================================================================== --- linux-2.6.orig/include/linux/perf_event.h +++ linux-2.6/include/linux/perf_event.h @@ -614,6 +614,7 @@ struct pmu { struct list_head entry; struct device *dev; + const struct attribute_group **attr_groups; char *name; int type; Index: linux-2.6/kernel/events/core.c =================================================================== --- linux-2.6.orig/kernel/events/core.c +++ linux-2.6/kernel/events/core.c @@ -5421,6 +5421,7 @@ static int pmu_dev_alloc(struct pmu *pmu if (!pmu->dev) goto out; + pmu->dev->groups = pmu->attr_groups; device_initialize(pmu->dev); ret = dev_set_name(pmu->dev, "%s", pmu->name); if (ret) Index: linux-2.6/arch/x86/kernel/cpu/perf_event.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/cpu/perf_event.c +++ linux-2.6/arch/x86/kernel/cpu/perf_event.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include @@ -1211,7 +1212,8 @@ x86_pmu_notifier(struct notifier_block * 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; @@ -1314,6 +1316,8 @@ static int __init init_hw_perf_events(vo } } + 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); @@ -1549,10 +1553,59 @@ static int x86_pmu_event_idx(struct perf 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, Index: linux-2.6/arch/x86/kernel/cpu/perf_event.h =================================================================== --- linux-2.6.orig/arch/x86/kernel/cpu/perf_event.h +++ linux-2.6/arch/x86/kernel/cpu/perf_event.h @@ -302,6 +302,14 @@ struct x86_pmu { void (*quirks)(void); int perfctr_second_write; + /* + * sysfs attrs + */ + int attr_rdpmc; + + /* + * CPU Hotplug hooks + */ int (*cpu_prepare)(int cpu); void (*cpu_starting)(int cpu); void (*cpu_dying)(int cpu); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/