From b371b594317869971af326adcf7cd65cabdb4087 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 21 May 2015 10:57:13 +0200 Subject: [PATCH] perf/x86: Fix event/group validation Commit 43b4578071c0 ("perf/x86: Reduce stack usage of x86_schedule_events()") violated the rule that 'fake' scheduling; as used for event/group validation; should not change the event state. This went mostly un-noticed because repeated calls of x86_pmu::get_event_constraints() would give the same result. And x86_pmu::put_event_constraints() would mostly not do anything. Commit e979121b1b15 ("perf/x86/intel: Implement cross-HT corruption bug workaround") made the situation much worse by actually setting the event->hw.constraint value to NULL, so when validation and actual scheduling interact we get NULL ptr derefs. Fix it by removing the constraint pointer from the event and move it back to an array, this time in cpuc instead of on the stack. validate_group() x86_schedule_events() event->hw.constraint = c; # store perf_task_event_sched_in() ... x86_schedule_events(); event->hw.constraint = c2; # store ... put_event_constraints(event); # assume failure to schedule intel_put_event_constraints() event->hw.constraint = NULL; c = event->hw.constraint; # read -> NULL if (!test_bit(hwc->idx, c->idxmsk)) # <- *BOOM* NULL deref This in particular is possible when the event in question is a cpu-wide event and group-leader, where the validate_group() tries to add an event to the group. Reported-by: Vince Weaver Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Hunter Cc: Linus Torvalds Cc: Maria Dimakopoulou Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 43b4578071c0 ("perf/x86: Reduce stack usage of x86_schedule_events()") Fixes: e979121b1b15 ("perf/x86/intel: Implement cross-HT corruption bug workaround") Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 33 ++++++++++--------- arch/x86/kernel/cpu/perf_event.h | 9 ++--- arch/x86/kernel/cpu/perf_event_intel.c | 15 +++------ arch/x86/kernel/cpu/perf_event_intel_ds.c | 4 +-- arch/x86/kernel/cpu/perf_event_intel_uncore.c | 7 ++-- arch/x86/kernel/cpu/perf_event_intel_uncore.h | 1 + include/linux/perf_event.h | 4 --- 7 files changed, 33 insertions(+), 40 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 87848ebe2bb7..1664eeea65e0 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -620,7 +620,7 @@ struct sched_state { struct perf_sched { int max_weight; int max_events; - struct perf_event **events; + struct event_constraint **constraints; struct sched_state state; int saved_states; struct sched_state saved[SCHED_STATES_MAX]; @@ -629,7 +629,7 @@ struct perf_sched { /* * Initialize interator that runs through all events and counters. */ -static void perf_sched_init(struct perf_sched *sched, struct perf_event **events, +static void perf_sched_init(struct perf_sched *sched, struct event_constraint **constraints, int num, int wmin, int wmax) { int idx; @@ -637,10 +637,10 @@ static void perf_sched_init(struct perf_sched *sched, struct perf_event **events memset(sched, 0, sizeof(*sched)); sched->max_events = num; sched->max_weight = wmax; - sched->events = events; + sched->constraints = constraints; for (idx = 0; idx < num; idx++) { - if (events[idx]->hw.constraint->weight == wmin) + if (constraints[idx]->weight == wmin) break; } @@ -687,7 +687,7 @@ static bool __perf_sched_find_counter(struct perf_sched *sched) if (sched->state.event >= sched->max_events) return false; - c = sched->events[sched->state.event]->hw.constraint; + c = sched->constraints[sched->state.event]; /* Prefer fixed purpose counters */ if (c->idxmsk64 & (~0ULL << INTEL_PMC_IDX_FIXED)) { idx = INTEL_PMC_IDX_FIXED; @@ -745,7 +745,7 @@ static bool perf_sched_next_event(struct perf_sched *sched) if (sched->state.weight > sched->max_weight) return false; } - c = sched->events[sched->state.event]->hw.constraint; + c = sched->constraints[sched->state.event]; } while (c->weight != sched->state.weight); sched->state.counter = 0; /* start with first counter */ @@ -756,12 +756,12 @@ static bool perf_sched_next_event(struct perf_sched *sched) /* * Assign a counter for each event. */ -int perf_assign_events(struct perf_event **events, int n, +int perf_assign_events(struct event_constraint **constraints, int n, int wmin, int wmax, int *assign) { struct perf_sched sched; - perf_sched_init(&sched, events, n, wmin, wmax); + perf_sched_init(&sched, constraints, n, wmin, wmax); do { if (!perf_sched_find_counter(&sched)) @@ -788,9 +788,9 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) x86_pmu.start_scheduling(cpuc); for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) { - hwc = &cpuc->event_list[i]->hw; + cpuc->event_constraint[i] = NULL; c = x86_pmu.get_event_constraints(cpuc, i, cpuc->event_list[i]); - hwc->constraint = c; + cpuc->event_constraint[i] = c; wmin = min(wmin, c->weight); wmax = max(wmax, c->weight); @@ -801,7 +801,7 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) */ for (i = 0; i < n; i++) { hwc = &cpuc->event_list[i]->hw; - c = hwc->constraint; + c = cpuc->event_constraint[i]; /* never assigned */ if (hwc->idx == -1) @@ -821,9 +821,10 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) } /* slow path */ - if (i != n) - unsched = perf_assign_events(cpuc->event_list, n, wmin, + if (i != n) { + unsched = perf_assign_events(cpuc->event_constraint, n, wmin, wmax, assign); + } /* * In case of success (unsched = 0), mark events as committed, @@ -840,7 +841,7 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) e = cpuc->event_list[i]; e->hw.flags |= PERF_X86_EVENT_COMMITTED; if (x86_pmu.commit_scheduling) - x86_pmu.commit_scheduling(cpuc, e, assign[i]); + x86_pmu.commit_scheduling(cpuc, i, assign[i]); } } @@ -1292,8 +1293,10 @@ static void x86_pmu_del(struct perf_event *event, int flags) x86_pmu.put_event_constraints(cpuc, event); /* Delete the array entry. */ - while (++i < cpuc->n_events) + while (++i < cpuc->n_events) { cpuc->event_list[i-1] = cpuc->event_list[i]; + cpuc->event_constraint[i-1] = cpuc->event_constraint[i]; + } --cpuc->n_events; perf_event_update_userpage(event); diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index 6ac5cb7a9e14..fdfaab7c5e55 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -172,7 +172,10 @@ struct cpu_hw_events { added in the current transaction */ int assign[X86_PMC_IDX_MAX]; /* event to counter assignment */ u64 tags[X86_PMC_IDX_MAX]; + struct perf_event *event_list[X86_PMC_IDX_MAX]; /* in enabled order */ + struct event_constraint *event_constraint[X86_PMC_IDX_MAX]; + unsigned int group_flag; int is_fake; @@ -519,9 +522,7 @@ struct x86_pmu { void (*put_event_constraints)(struct cpu_hw_events *cpuc, struct perf_event *event); - void (*commit_scheduling)(struct cpu_hw_events *cpuc, - struct perf_event *event, - int cntr); + void (*commit_scheduling)(struct cpu_hw_events *cpuc, int idx, int cntr); void (*start_scheduling)(struct cpu_hw_events *cpuc); @@ -717,7 +718,7 @@ static inline void __x86_pmu_enable_event(struct hw_perf_event *hwc, void x86_pmu_enable_all(int added); -int perf_assign_events(struct perf_event **events, int n, +int perf_assign_events(struct event_constraint **constraints, int n, int wmin, int wmax, int *assign); int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign); diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 3998131d1a68..7a58fb5df15c 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -2106,7 +2106,7 @@ static struct event_constraint * intel_get_event_constraints(struct cpu_hw_events *cpuc, int idx, struct perf_event *event) { - struct event_constraint *c1 = event->hw.constraint; + struct event_constraint *c1 = cpuc->event_constraint[idx]; struct event_constraint *c2; /* @@ -2188,8 +2188,6 @@ intel_put_shared_regs_event_constraints(struct cpu_hw_events *cpuc, static void intel_put_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event) { - struct event_constraint *c = event->hw.constraint; - intel_put_shared_regs_event_constraints(cpuc, event); /* @@ -2197,19 +2195,14 @@ static void intel_put_event_constraints(struct cpu_hw_events *cpuc, * all events are subject to and must call the * put_excl_constraints() routine */ - if (c && cpuc->excl_cntrs) + if (cpuc->excl_cntrs) intel_put_excl_constraints(cpuc, event); - - /* cleanup dynamic constraint */ - if (c && (c->flags & PERF_X86_EVENT_DYNAMIC)) - event->hw.constraint = NULL; } -static void intel_commit_scheduling(struct cpu_hw_events *cpuc, - struct perf_event *event, int cntr) +static void intel_commit_scheduling(struct cpu_hw_events *cpuc, int idx, int cntr) { struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; - struct event_constraint *c = event->hw.constraint; + struct event_constraint *c = cpuc->event_constraint[idx]; struct intel_excl_states *xlo, *xl; int tid = cpuc->excl_thread_id; int o_tid = 1 - tid; diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index 813f75d71175..7f73b3553e2e 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -706,9 +706,9 @@ void intel_pmu_pebs_disable(struct perf_event *event) cpuc->pebs_enabled &= ~(1ULL << hwc->idx); - if (event->hw.constraint->flags & PERF_X86_EVENT_PEBS_LDLAT) + if (event->hw.flags & PERF_X86_EVENT_PEBS_LDLAT) cpuc->pebs_enabled &= ~(1ULL << (hwc->idx + 32)); - else if (event->hw.constraint->flags & PERF_X86_EVENT_PEBS_ST) + else if (event->hw.flags & PERF_X86_EVENT_PEBS_ST) cpuc->pebs_enabled &= ~(1ULL << 63); if (cpuc->enabled) diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c index c635b8b49e93..ec2ba578d286 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c @@ -365,9 +365,8 @@ static int uncore_assign_events(struct intel_uncore_box *box, int assign[], int bitmap_zero(used_mask, UNCORE_PMC_IDX_MAX); for (i = 0, wmin = UNCORE_PMC_IDX_MAX, wmax = 0; i < n; i++) { - hwc = &box->event_list[i]->hw; c = uncore_get_event_constraint(box, box->event_list[i]); - hwc->constraint = c; + box->event_constraint[i] = c; wmin = min(wmin, c->weight); wmax = max(wmax, c->weight); } @@ -375,7 +374,7 @@ static int uncore_assign_events(struct intel_uncore_box *box, int assign[], int /* fastpath, try to reuse previous register */ for (i = 0; i < n; i++) { hwc = &box->event_list[i]->hw; - c = hwc->constraint; + c = box->event_constraint[i]; /* never assigned */ if (hwc->idx == -1) @@ -395,7 +394,7 @@ static int uncore_assign_events(struct intel_uncore_box *box, int assign[], int } /* slow path */ if (i != n) - ret = perf_assign_events(box->event_list, n, + ret = perf_assign_events(box->event_constraint, n, wmin, wmax, assign); if (!assign || ret) { diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.h b/arch/x86/kernel/cpu/perf_event_intel_uncore.h index 6c8c1e7e69d8..f789ec9a0133 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.h +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.h @@ -97,6 +97,7 @@ struct intel_uncore_box { atomic_t refcnt; struct perf_event *events[UNCORE_PMC_IDX_MAX]; struct perf_event *event_list[UNCORE_PMC_IDX_MAX]; + struct event_constraint *event_constraint[UNCORE_PMC_IDX_MAX]; unsigned long active_mask[BITS_TO_LONGS(UNCORE_PMC_IDX_MAX)]; u64 tags[UNCORE_PMC_IDX_MAX]; struct pci_dev *pci_dev; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 61992cf2e977..d8a82a89f35a 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -92,8 +92,6 @@ struct hw_perf_event_extra { int idx; /* index in shared_regs->regs[] */ }; -struct event_constraint; - /** * struct hw_perf_event - performance event hardware details: */ @@ -112,8 +110,6 @@ struct hw_perf_event { struct hw_perf_event_extra extra_reg; struct hw_perf_event_extra branch_reg; - - struct event_constraint *constraint; }; struct { /* software */ struct hrtimer hrtimer; -- GitLab