X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fhw_breakpoint.c;h=967e66143e117096262c65fa646a1570e5f035d3;hb=3041f5170751e3522aa1bd6e8ca5d98e846720b0;hp=e662dc991c967a702a327bb44a4812b0df1c09bf;hpb=ba1c813a6b9a0ef14d7112daf51270eff326f037;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index e662dc9..967e661 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -18,6 +18,10 @@ * Copyright (C) 2009, Frederic Weisbecker * * Thanks to Ingo Molnar for his many suggestions. + * + * Authors: Alan Stern + * K.Prasad + * Frederic Weisbecker */ /* @@ -36,16 +40,11 @@ #include #include #include +#include #include #include -#include - -#ifdef CONFIG_X86 -#include -#endif - /* * Constraints data */ @@ -54,7 +53,7 @@ static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned); /* Number of pinned task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, task_bp_pinned[HBP_NUM]); +static DEFINE_PER_CPU(unsigned int, nr_task_bp_pinned[HBP_NUM]); /* Number of non-pinned cpu/task breakpoints in a cpu */ static DEFINE_PER_CPU(unsigned int, nr_bp_flexible); @@ -75,7 +74,7 @@ static DEFINE_MUTEX(nr_bp_mutex); static unsigned int max_task_bp_pinned(int cpu) { int i; - unsigned int *tsk_pinned = per_cpu(task_bp_pinned, cpu); + unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned, cpu); for (i = HBP_NUM -1; i >= 0; i--) { if (tsk_pinned[i] > 0) @@ -85,15 +84,51 @@ static unsigned int max_task_bp_pinned(int cpu) return 0; } +static int task_bp_pinned(struct task_struct *tsk) +{ + struct perf_event_context *ctx = tsk->perf_event_ctxp; + struct list_head *list; + struct perf_event *bp; + unsigned long flags; + int count = 0; + + if (WARN_ONCE(!ctx, "No perf context for this task")) + return 0; + + list = &ctx->event_list; + + raw_spin_lock_irqsave(&ctx->lock, flags); + + /* + * The current breakpoint counter is not included in the list + * at the open() callback time + */ + list_for_each_entry(bp, list, event_entry) { + if (bp->attr.type == PERF_TYPE_BREAKPOINT) + count++; + } + + raw_spin_unlock_irqrestore(&ctx->lock, flags); + + return count; +} + /* * Report the number of pinned/un-pinned breakpoints we have in * a given cpu (cpu > -1) or in all of them (cpu = -1). */ -static void fetch_bp_busy_slots(struct bp_busy_slots *slots, int cpu) +static void +fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) { + 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 += max_task_bp_pinned(cpu); + if (!tsk) + slots->pinned += max_task_bp_pinned(cpu); + else + slots->pinned += task_bp_pinned(tsk); slots->flexible = per_cpu(nr_bp_flexible, cpu); return; @@ -103,7 +138,10 @@ static void fetch_bp_busy_slots(struct bp_busy_slots *slots, int cpu) unsigned int nr; nr = per_cpu(nr_cpu_bp_pinned, cpu); - nr += max_task_bp_pinned(cpu); + if (!tsk) + nr += max_task_bp_pinned(cpu); + else + nr += task_bp_pinned(tsk); if (nr > slots->pinned) slots->pinned = nr; @@ -120,43 +158,20 @@ static void fetch_bp_busy_slots(struct bp_busy_slots *slots, int cpu) */ static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable) { + unsigned int *tsk_pinned; int count = 0; - struct perf_event *bp; - struct perf_event_context *ctx = tsk->perf_event_ctxp; - unsigned int *task_bp_pinned; - struct list_head *list; - unsigned long flags; - - if (WARN_ONCE(!ctx, "No perf context for this task")) - return; - - list = &ctx->event_list; - spin_lock_irqsave(&ctx->lock, flags); + count = task_bp_pinned(tsk); - /* - * The current breakpoint counter is not included in the list - * at the open() callback time - */ - list_for_each_entry(bp, list, event_entry) { - if (bp->attr.type == PERF_TYPE_BREAKPOINT) - count++; - } - - spin_unlock_irqrestore(&ctx->lock, flags); - - if (WARN_ONCE(count < 0, "No breakpoint counter found in the counter list")) - return; - - task_bp_pinned = per_cpu(task_bp_pinned, cpu); + tsk_pinned = per_cpu(nr_task_bp_pinned, cpu); if (enable) { - task_bp_pinned[count]++; + tsk_pinned[count]++; if (count > 0) - task_bp_pinned[count-1]--; + tsk_pinned[count-1]--; } else { - task_bp_pinned[count]--; + tsk_pinned[count]--; if (count > 0) - task_bp_pinned[count-1]++; + tsk_pinned[count-1]++; } } @@ -195,7 +210,7 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) * - If attached to a single cpu, check: * * (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu) - * + max(per_cpu(task_bp_pinned, cpu)))) < HBP_NUM + * + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM * * -> If there are already non-pinned counters in this cpu, it means * there is already a free slot for them. @@ -206,7 +221,7 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) * - If attached to every cpus, check: * * (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *)) - * + max(per_cpu(task_bp_pinned, *)))) < HBP_NUM + * + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM * * -> This is roughly the same, except we check the number of per cpu * bp for every cpu and we keep the max one. Same for the per tasks @@ -218,7 +233,7 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) * - If attached to a single cpu, check: * * ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu) - * + max(per_cpu(task_bp_pinned, cpu))) < HBP_NUM + * + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM * * -> Same checks as before. But now the nr_bp_flexible, if any, must keep * one register at least (or they will never be fed). @@ -226,156 +241,156 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) * - If attached to every cpus, check: * * ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *)) - * + max(per_cpu(task_bp_pinned, *))) < HBP_NUM + * + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM */ -int reserve_bp_slot(struct perf_event *bp) +static int __reserve_bp_slot(struct perf_event *bp) { struct bp_busy_slots slots = {0}; - int ret = 0; - - mutex_lock(&nr_bp_mutex); - fetch_bp_busy_slots(&slots, bp->cpu); + fetch_bp_busy_slots(&slots, bp); /* Flexible counters need to keep at least one slot */ - if (slots.pinned + (!!slots.flexible) == HBP_NUM) { - ret = -ENOSPC; - goto end; - } + if (slots.pinned + (!!slots.flexible) == HBP_NUM) + return -ENOSPC; toggle_bp_slot(bp, true); -end: + return 0; +} + +int reserve_bp_slot(struct perf_event *bp) +{ + int ret; + + mutex_lock(&nr_bp_mutex); + + ret = __reserve_bp_slot(bp); + mutex_unlock(&nr_bp_mutex); return ret; } +static void __release_bp_slot(struct perf_event *bp) +{ + toggle_bp_slot(bp, false); +} + void release_bp_slot(struct perf_event *bp) { mutex_lock(&nr_bp_mutex); - toggle_bp_slot(bp, false); + __release_bp_slot(bp); mutex_unlock(&nr_bp_mutex); } - -int __register_perf_hw_breakpoint(struct perf_event *bp) +/* + * Allow the kernel debugger to reserve breakpoint slots without + * taking a lock using the dbg_* variant of for the reserve and + * release breakpoint slots. + */ +int dbg_reserve_bp_slot(struct perf_event *bp) { - int ret; + if (mutex_is_locked(&nr_bp_mutex)) + return -1; - ret = reserve_bp_slot(bp); - if (ret) - return ret; - - if (!bp->attr.disabled) - ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task); - - return ret; + return __reserve_bp_slot(bp); } -int register_perf_hw_breakpoint(struct perf_event *bp) +int dbg_release_bp_slot(struct perf_event *bp) { - bp->callback = perf_bp_event; + if (mutex_is_locked(&nr_bp_mutex)) + return -1; - return __register_perf_hw_breakpoint(bp); + __release_bp_slot(bp); + + return 0; } -/* - * Register a breakpoint bound to a task and a given cpu. - * If cpu is -1, the breakpoint is active for the task in every cpu - * If the task is -1, the breakpoint is active for every tasks in the given - * cpu. - */ -static struct perf_event * -register_user_hw_breakpoint_cpu(unsigned long addr, - int len, - int type, - perf_callback_t triggered, - pid_t pid, - int cpu, - bool active) +int register_perf_hw_breakpoint(struct perf_event *bp) { - struct perf_event_attr *attr; - struct perf_event *bp; + int ret; - attr = kzalloc(sizeof(*attr), GFP_KERNEL); - if (!attr) - return ERR_PTR(-ENOMEM); + ret = reserve_bp_slot(bp); + if (ret) + return ret; - attr->type = PERF_TYPE_BREAKPOINT; - attr->size = sizeof(*attr); - attr->bp_addr = addr; - attr->bp_len = len; - attr->bp_type = type; /* - * Such breakpoints are used by debuggers to trigger signals when - * we hit the excepted memory op. We can't miss such events, they - * must be pinned. + * 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 */ - attr->pinned = 1; - - if (!active) - attr->disabled = 1; + if (!bp->attr.disabled || !bp->overflow_handler) + ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task); - bp = perf_event_create_kernel_counter(attr, cpu, pid, triggered); - kfree(attr); + /* if arch_validate_hwbkpt_settings() fails then release bp slot */ + if (ret) + release_bp_slot(bp); - return bp; + return ret; } /** * register_user_hw_breakpoint - register a hardware breakpoint for user space - * @addr: is the memory address that triggers the breakpoint - * @len: the length of the access to the memory (1 byte, 2 bytes etc...) - * @type: the type of the access to the memory (read/write/exec) + * @attr: breakpoint attributes * @triggered: callback to trigger when we hit the breakpoint * @tsk: pointer to 'task_struct' of the process to which the address belongs - * @active: should we activate it while registering it - * */ struct perf_event * -register_user_hw_breakpoint(unsigned long addr, - int len, - int type, - perf_callback_t triggered, - struct task_struct *tsk, - bool active) +register_user_hw_breakpoint(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + struct task_struct *tsk) { - return register_user_hw_breakpoint_cpu(addr, len, type, triggered, - tsk->pid, -1, active); + return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered); } EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); /** * modify_user_hw_breakpoint - modify a user-space hardware breakpoint * @bp: the breakpoint structure to modify - * @addr: is the memory address that triggers the breakpoint - * @len: the length of the access to the memory (1 byte, 2 bytes etc...) - * @type: the type of the access to the memory (read/write/exec) + * @attr: new breakpoint attributes * @triggered: callback to trigger when we hit the breakpoint * @tsk: pointer to 'task_struct' of the process to which the address belongs - * @active: should we activate it while registering it */ -struct perf_event * -modify_user_hw_breakpoint(struct perf_event *bp, - unsigned long addr, - int len, - int type, - perf_callback_t triggered, - struct task_struct *tsk, - bool active) +int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) { - /* - * FIXME: do it without unregistering - * - We don't want to lose our slot - * - If the new bp is incorrect, don't lose the older one - */ - unregister_hw_breakpoint(bp); + u64 old_addr = bp->attr.bp_addr; + u64 old_len = bp->attr.bp_len; + int old_type = bp->attr.bp_type; + int err = 0; + + perf_event_disable(bp); + + bp->attr.bp_addr = attr->bp_addr; + bp->attr.bp_type = attr->bp_type; + bp->attr.bp_len = attr->bp_len; + + if (attr->disabled) + goto end; + + err = arch_validate_hwbkpt_settings(bp, bp->ctx->task); + if (!err) + perf_event_enable(bp); - return register_user_hw_breakpoint(addr, len, type, triggered, - tsk, active); + if (err) { + bp->attr.bp_addr = old_addr; + bp->attr.bp_type = old_type; + bp->attr.bp_len = old_len; + if (!bp->attr.disabled) + perf_event_enable(bp); + + return err; + } + +end: + bp->attr.disabled = attr->disabled; + + return 0; } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); @@ -391,34 +406,16 @@ void unregister_hw_breakpoint(struct perf_event *bp) } EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); -static struct perf_event * -register_kernel_hw_breakpoint_cpu(unsigned long addr, - int len, - int type, - perf_callback_t triggered, - int cpu, - bool active) -{ - return register_user_hw_breakpoint_cpu(addr, len, type, triggered, - -1, cpu, active); -} - /** * register_wide_hw_breakpoint - register a wide breakpoint in the kernel - * @addr: is the memory address that triggers the breakpoint - * @len: the length of the access to the memory (1 byte, 2 bytes etc...) - * @type: the type of the access to the memory (read/write/exec) + * @attr: breakpoint attributes * @triggered: callback to trigger when we hit the breakpoint - * @active: should we activate it while registering it * * @return a set of per_cpu pointers to perf events */ struct perf_event ** -register_wide_hw_breakpoint(unsigned long addr, - int len, - int type, - perf_callback_t triggered, - bool active) +register_wide_hw_breakpoint(struct perf_event_attr *attr, + perf_overflow_handler_t triggered) { struct perf_event **cpu_events, **pevent, *bp; long err; @@ -428,32 +425,35 @@ register_wide_hw_breakpoint(unsigned long addr, if (!cpu_events) return ERR_PTR(-ENOMEM); - for_each_possible_cpu(cpu) { + get_online_cpus(); + for_each_online_cpu(cpu) { pevent = per_cpu_ptr(cpu_events, cpu); - bp = register_kernel_hw_breakpoint_cpu(addr, len, type, - triggered, cpu, active); + bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered); *pevent = bp; - if (IS_ERR(bp) || !bp) { + if (IS_ERR(bp)) { err = PTR_ERR(bp); goto fail; } } + put_online_cpus(); return cpu_events; fail: - for_each_possible_cpu(cpu) { + for_each_online_cpu(cpu) { pevent = per_cpu_ptr(cpu_events, cpu); - if (IS_ERR(*pevent) || !*pevent) + if (IS_ERR(*pevent)) break; unregister_hw_breakpoint(*pevent); } + put_online_cpus(); + free_percpu(cpu_events); - /* return the error if any */ return ERR_PTR(err); } +EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); /** * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel @@ -470,7 +470,7 @@ void unregister_wide_hw_breakpoint(struct perf_event **cpu_events) } free_percpu(cpu_events); } - +EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); static struct notifier_block hw_breakpoint_exceptions_nb = { .notifier_call = hw_breakpoint_exceptions_notify,