diff options
Diffstat (limited to 'kernel/hw_breakpoint.c')
| -rw-r--r-- | kernel/hw_breakpoint.c | 196 |
1 files changed, 148 insertions, 48 deletions
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index 03808ed342a6..7a56b22e0602 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -40,23 +40,29 @@ #include <linux/percpu.h> #include <linux/sched.h> #include <linux/init.h> +#include <linux/slab.h> #include <linux/cpu.h> #include <linux/smp.h> #include <linux/hw_breakpoint.h> + /* * Constraints data */ /* Number of pinned cpu breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned); +static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]); /* Number of pinned task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_task_bp_pinned[HBP_NUM]); +static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]); /* Number of non-pinned cpu/task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_bp_flexible); +static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]); + +static int nr_slots[TYPE_MAX]; + +static int constraints_initialized; /* Gather the number of total pinned and un-pinned bp in a cpuset */ struct bp_busy_slots { @@ -67,16 +73,29 @@ struct bp_busy_slots { /* Serialize accesses to the above constraints */ static DEFINE_MUTEX(nr_bp_mutex); +__weak int hw_breakpoint_weight(struct perf_event *bp) +{ + return 1; +} + +static inline enum bp_type_idx find_slot_idx(struct perf_event *bp) +{ + if (bp->attr.bp_type & HW_BREAKPOINT_RW) + return TYPE_DATA; + + return TYPE_INST; +} + /* * Report the maximum number of pinned breakpoints a task * have in this cpu */ -static unsigned int max_task_bp_pinned(int cpu) +static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) { int i; - unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned, cpu); + unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); - for (i = HBP_NUM -1; i >= 0; i--) { + for (i = nr_slots[type] - 1; i >= 0; i--) { if (tsk_pinned[i] > 0) return i + 1; } @@ -84,7 +103,7 @@ static unsigned int max_task_bp_pinned(int cpu) return 0; } -static int task_bp_pinned(struct task_struct *tsk) +static int task_bp_pinned(struct task_struct *tsk, enum bp_type_idx type) { struct perf_event_context *ctx = tsk->perf_event_ctxp; struct list_head *list; @@ -105,7 +124,8 @@ static int task_bp_pinned(struct task_struct *tsk) */ list_for_each_entry(bp, list, event_entry) { if (bp->attr.type == PERF_TYPE_BREAKPOINT) - count++; + if (find_slot_idx(bp) == type) + count += hw_breakpoint_weight(bp); } raw_spin_unlock_irqrestore(&ctx->lock, flags); @@ -118,18 +138,19 @@ static int task_bp_pinned(struct task_struct *tsk) * a given cpu (cpu > -1) or in all of them (cpu = -1). */ static void -fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) +fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp, + enum bp_type_idx type) { int cpu = bp->cpu; struct task_struct *tsk = bp->ctx->task; if (cpu >= 0) { - slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu); + slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu); if (!tsk) - slots->pinned += max_task_bp_pinned(cpu); + slots->pinned += max_task_bp_pinned(cpu, type); else - slots->pinned += task_bp_pinned(tsk); - slots->flexible = per_cpu(nr_bp_flexible, cpu); + slots->pinned += task_bp_pinned(tsk, type); + slots->flexible = per_cpu(nr_bp_flexible[type], cpu); return; } @@ -137,16 +158,16 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) for_each_online_cpu(cpu) { unsigned int nr; - nr = per_cpu(nr_cpu_bp_pinned, cpu); + nr = per_cpu(nr_cpu_bp_pinned[type], cpu); if (!tsk) - nr += max_task_bp_pinned(cpu); + nr += max_task_bp_pinned(cpu, type); else - nr += task_bp_pinned(tsk); + nr += task_bp_pinned(tsk, type); if (nr > slots->pinned) slots->pinned = nr; - nr = per_cpu(nr_bp_flexible, cpu); + nr = per_cpu(nr_bp_flexible[type], cpu); if (nr > slots->flexible) slots->flexible = nr; @@ -154,31 +175,49 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) } /* + * For now, continue to consider flexible as pinned, until we can + * ensure no flexible event can ever be scheduled before a pinned event + * in a same cpu. + */ +static void +fetch_this_slot(struct bp_busy_slots *slots, int weight) +{ + slots->pinned += weight; +} + +/* * Add a pinned breakpoint for the given task in our constraint table */ -static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable) +static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable, + enum bp_type_idx type, int weight) { unsigned int *tsk_pinned; - int count = 0; + int old_count = 0; + int old_idx = 0; + int idx = 0; - count = task_bp_pinned(tsk); + old_count = task_bp_pinned(tsk, type); + old_idx = old_count - 1; + idx = old_idx + weight; - tsk_pinned = per_cpu(nr_task_bp_pinned, cpu); + tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); if (enable) { - tsk_pinned[count]++; - if (count > 0) - tsk_pinned[count-1]--; + tsk_pinned[idx]++; + if (old_count > 0) + tsk_pinned[old_idx]--; } else { - tsk_pinned[count]--; - if (count > 0) - tsk_pinned[count-1]++; + tsk_pinned[idx]--; + if (old_count > 0) + tsk_pinned[old_idx]++; } } /* * Add/remove the given breakpoint in our constraint table */ -static void toggle_bp_slot(struct perf_event *bp, bool enable) +static void +toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, + int weight) { int cpu = bp->cpu; struct task_struct *tsk = bp->ctx->task; @@ -186,20 +225,20 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) /* Pinned counter task profiling */ if (tsk) { if (cpu >= 0) { - toggle_bp_task_slot(tsk, cpu, enable); + toggle_bp_task_slot(tsk, cpu, enable, type, weight); return; } for_each_online_cpu(cpu) - toggle_bp_task_slot(tsk, cpu, enable); + toggle_bp_task_slot(tsk, cpu, enable, type, weight); return; } /* Pinned counter cpu profiling */ if (enable) - per_cpu(nr_cpu_bp_pinned, bp->cpu)++; + per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight; else - per_cpu(nr_cpu_bp_pinned, bp->cpu)--; + per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight; } /* @@ -246,14 +285,29 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) static int __reserve_bp_slot(struct perf_event *bp) { struct bp_busy_slots slots = {0}; + enum bp_type_idx type; + int weight; - fetch_bp_busy_slots(&slots, bp); + /* We couldn't initialize breakpoint constraints on boot */ + if (!constraints_initialized) + return -ENOMEM; + + /* Basic checks */ + if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY || + bp->attr.bp_type == HW_BREAKPOINT_INVALID) + return -EINVAL; + + type = find_slot_idx(bp); + weight = hw_breakpoint_weight(bp); + + fetch_bp_busy_slots(&slots, bp, type); + fetch_this_slot(&slots, weight); /* Flexible counters need to keep at least one slot */ - if (slots.pinned + (!!slots.flexible) == HBP_NUM) + if (slots.pinned + (!!slots.flexible) > nr_slots[type]) return -ENOSPC; - toggle_bp_slot(bp, true); + toggle_bp_slot(bp, true, type, weight); return 0; } @@ -273,7 +327,12 @@ int reserve_bp_slot(struct perf_event *bp) static void __release_bp_slot(struct perf_event *bp) { - toggle_bp_slot(bp, false); + enum bp_type_idx type; + int weight; + + type = find_slot_idx(bp); + weight = hw_breakpoint_weight(bp); + toggle_bp_slot(bp, false, type, weight); } void release_bp_slot(struct perf_event *bp) @@ -308,6 +367,28 @@ int dbg_release_bp_slot(struct perf_event *bp) return 0; } +static int validate_hw_breakpoint(struct perf_event *bp) +{ + int ret; + + ret = arch_validate_hwbkpt_settings(bp); + if (ret) + return ret; + + if (arch_check_bp_in_kernelspace(bp)) { + if (bp->attr.exclude_kernel) + return -EINVAL; + /* + * Don't let unprivileged users set a breakpoint in the trap + * path to avoid trap recursion attacks. + */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + } + + return 0; +} + int register_perf_hw_breakpoint(struct perf_event *bp) { int ret; @@ -316,17 +397,7 @@ int register_perf_hw_breakpoint(struct perf_event *bp) if (ret) return ret; - /* - * Ptrace breakpoints can be temporary perf events only - * meant to reserve a slot. In this case, it is created disabled and - * we don't want to check the params right now (as we put a null addr) - * But perf tools create events as disabled and we want to check - * the params for them. - * This is a quick hack that will be removed soon, once we remove - * the tmp breakpoints from ptrace - */ - if (!bp->attr.disabled || !bp->overflow_handler) - ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task); + ret = validate_hw_breakpoint(bp); /* if arch_validate_hwbkpt_settings() fails then release bp slot */ if (ret) @@ -373,7 +444,7 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att if (attr->disabled) goto end; - err = arch_validate_hwbkpt_settings(bp, bp->ctx->task); + err = validate_hw_breakpoint(bp); if (!err) perf_event_enable(bp); @@ -480,7 +551,36 @@ static struct notifier_block hw_breakpoint_exceptions_nb = { static int __init init_hw_breakpoint(void) { + unsigned int **task_bp_pinned; + int cpu, err_cpu; + int i; + + for (i = 0; i < TYPE_MAX; i++) + nr_slots[i] = hw_breakpoint_slots(i); + + for_each_possible_cpu(cpu) { + for (i = 0; i < TYPE_MAX; i++) { + task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu); + *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i], + GFP_KERNEL); + if (!*task_bp_pinned) + goto err_alloc; + } + } + + constraints_initialized = 1; + return register_die_notifier(&hw_breakpoint_exceptions_nb); + + err_alloc: + for_each_possible_cpu(err_cpu) { + if (err_cpu == cpu) + break; + for (i = 0; i < TYPE_MAX; i++) + kfree(per_cpu(nr_task_bp_pinned[i], cpu)); + } + + return -ENOMEM; } core_initcall(init_hw_breakpoint); |