3.16.66-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Jiri Olsa <[email protected]> commit 81ec3f3c4c4d78f2d3b6689c9816bfbdf7417dbb upstream. Vince (and later on Ravi) reported crashes in the BTS code during fuzzing with the following backtrace: general protection fault: 0000 [#1] SMP PTI ... RIP: 0010:perf_prepare_sample+0x8f/0x510 ... Call Trace: <IRQ> ? intel_pmu_drain_bts_buffer+0x194/0x230 intel_pmu_drain_bts_buffer+0x160/0x230 ? tick_nohz_irq_exit+0x31/0x40 ? smp_call_function_single_interrupt+0x48/0xe0 ? call_function_single_interrupt+0xf/0x20 ? call_function_single_interrupt+0xa/0x20 ? x86_schedule_events+0x1a0/0x2f0 ? x86_pmu_commit_txn+0xb4/0x100 ? find_busiest_group+0x47/0x5d0 ? perf_event_set_state.part.42+0x12/0x50 ? perf_mux_hrtimer_restart+0x40/0xb0 intel_pmu_disable_event+0xae/0x100 ? intel_pmu_disable_event+0xae/0x100 x86_pmu_stop+0x7a/0xb0 x86_pmu_del+0x57/0x120 event_sched_out.isra.101+0x83/0x180 group_sched_out.part.103+0x57/0xe0 ctx_sched_out+0x188/0x240 ctx_resched+0xa8/0xd0 __perf_event_enable+0x193/0x1e0 event_function+0x8e/0xc0 remote_function+0x41/0x50 flush_smp_call_function_queue+0x68/0x100 generic_smp_call_function_single_interrupt+0x13/0x30 smp_call_function_single_interrupt+0x3e/0xe0 call_function_single_interrupt+0xf/0x20 </IRQ> The reason is that while event init code does several checks for BTS events and prevents several unwanted config bits for BTS event (like precise_ip), the PERF_EVENT_IOC_PERIOD allows to create BTS event without those checks being done. Following sequence will cause the crash: If we create an 'almost' BTS event with precise_ip and callchains, and it into a BTS event it will crash the perf_prepare_sample() function because precise_ip events are expected to come in with callchain data initialized, but that's not the case for intel_pmu_drain_bts_buffer() caller. Adding a check_period callback to be called before the period is changed via PERF_EVENT_IOC_PERIOD. It will deny the change if the event would become BTS. Plus adding also the limit_period check as well. Reported-by: Vince Weaver <[email protected]> Signed-off-by: Jiri Olsa <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Naveen N. Rao <[email protected]> Cc: Ravi Bangoria <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/20190204123532.GA4794@krava Signed-off-by: Ingo Molnar <[email protected]> [bwh: Backported to 3.16: - Don't call limit_period operation, which doesn't exist and isn't needed here - Add the intel_pmu_has_bts() function, which didn't previously exist here - Adjust filenames, context] Signed-off-by: Ben Hutchings <[email protected]> --- --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1920,6 +1920,14 @@ void perf_check_microcode(void) } EXPORT_SYMBOL_GPL(perf_check_microcode); +static int x86_pmu_check_period(struct perf_event *event, u64 value) +{ + if (x86_pmu.check_period && x86_pmu.check_period(event, value)) + return -EINVAL; + + return 0; +} + static struct pmu pmu = { .pmu_enable = x86_pmu_enable, .pmu_disable = x86_pmu_disable, @@ -1940,6 +1948,7 @@ static struct pmu pmu = { .event_idx = x86_pmu_event_idx, .flush_branch_stack = x86_pmu_flush_branch_stack, + .check_period = x86_pmu_check_period, }; void arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now) --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -473,6 +473,11 @@ struct x86_pmu { * Intel host/guest support (KVM) */ struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr); + + /* + * Check period value for PERF_EVENT_IOC_PERIOD ioctl. + */ + int (*check_period) (struct perf_event *event, u64 period); }; #define x86_add_quirk(func_) \ @@ -634,6 +639,22 @@ static inline int amd_pmu_init(void) #ifdef CONFIG_CPU_SUP_INTEL +static inline bool intel_pmu_has_bts_period(struct perf_event *event, u64 period) +{ + if (event->attr.config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS && + !event->attr.freq && period == 1) + return true; + + return false; +} + +static inline bool intel_pmu_has_bts(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + + return intel_pmu_has_bts_period(event, hwc->sample_period); +} + int intel_pmu_save_and_restart(struct perf_event *event); struct event_constraint * --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1969,6 +1969,11 @@ ssize_t intel_event_sysfs_show(char *pag return x86_event_sysfs_show(page, config, event); } +static int intel_pmu_check_period(struct perf_event *event, u64 value) +{ + return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0; +} + static __initconst const struct x86_pmu core_pmu = { .name = "core", .handle_irq = x86_pmu_handle_irq, @@ -1995,6 +2000,8 @@ static __initconst const struct x86_pmu .guest_get_msrs = core_guest_get_msrs, .format_attrs = intel_arch_formats_attr, .events_sysfs_show = intel_event_sysfs_show, + + .check_period = intel_pmu_check_period, }; struct intel_shared_regs *allocate_shared_regs(int cpu) @@ -2145,6 +2152,8 @@ static __initconst const struct x86_pmu .cpu_dying = intel_pmu_cpu_dying, .guest_get_msrs = intel_guest_get_msrs, .flush_branch_stack = intel_pmu_flush_branch_stack, + + .check_period = intel_pmu_check_period, }; static __init void intel_clovertown_quirk(void) --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -262,6 +262,11 @@ struct pmu { * flush branch stack on context-switches (needed in cpu-wide mode) */ void (*flush_branch_stack) (void); + + /* + * Check period value for PERF_EVENT_IOC_PERIOD ioctl. + */ + int (*check_period) (struct perf_event *event, u64 value); /* optional */ }; /** --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3805,6 +3805,11 @@ static int __perf_event_period(void *inf return 0; } +static int perf_event_check_period(struct perf_event *event, u64 value) +{ + return event->pmu->check_period(event, value); +} + static int perf_event_period(struct perf_event *event, u64 __user *arg) { struct period_event pe = { .event = event, }; @@ -3824,6 +3829,9 @@ static int perf_event_period(struct perf if (event->attr.freq && value > sysctl_perf_event_sample_rate) return -EINVAL; + if (perf_event_check_period(event, value)) + return -EINVAL; + task = ctx->task; pe.value = value; @@ -6649,6 +6657,11 @@ static int perf_pmu_nop_int(struct pmu * return 0; } +static int perf_event_nop_int(struct perf_event *event, u64 value) +{ + return 0; +} + static void perf_pmu_start_txn(struct pmu *pmu) { perf_pmu_disable(pmu); @@ -6903,6 +6916,9 @@ got_cpu_context: pmu->pmu_disable = perf_pmu_nop_void; } + if (!pmu->check_period) + pmu->check_period = perf_event_nop_int; + if (!pmu->event_idx) pmu->event_idx = perf_event_idx_default;
