hw-breakpoints: Use overflow handler instead of the event callback
struct perf_event::event callback was called when a breakpoint triggers. But this is a rather opaque callback, pretty tied-only to the breakpoint API and not really integrated into perf as it triggers even when we don't overflow. We prefer to use overflow_handler() as it fits into the perf events rules, being called only when we overflow. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
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@ -362,8 +362,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
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return ret;
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}
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if (bp->callback)
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ret = arch_store_info(bp);
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ret = arch_store_info(bp);
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if (ret < 0)
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return ret;
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@ -519,7 +518,7 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
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break;
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}
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(bp->callback)(bp, args->regs);
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perf_bp_event(bp, args->regs);
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rcu_read_unlock();
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}
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@ -555,7 +555,9 @@ static int genregs_set(struct task_struct *target,
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return ret;
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}
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static void ptrace_triggered(struct perf_event *bp, void *data)
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static void ptrace_triggered(struct perf_event *bp, int nmi,
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struct perf_sample_data *data,
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struct pt_regs *regs)
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{
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int i;
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struct thread_struct *thread = &(current->thread);
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@ -599,7 +601,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
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{
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int err;
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int gen_len, gen_type;
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DEFINE_BREAKPOINT_ATTR(attr);
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struct perf_event_attr attr;
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/*
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* We shoud have at least an inactive breakpoint at this
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@ -721,9 +723,10 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
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{
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struct perf_event *bp;
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struct thread_struct *t = &tsk->thread;
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DEFINE_BREAKPOINT_ATTR(attr);
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struct perf_event_attr attr;
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if (!t->ptrace_bps[nr]) {
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hw_breakpoint_init(&attr);
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/*
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* Put stub len and type to register (reserve) an inactive but
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* correct bp
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@ -20,19 +20,16 @@ enum {
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#ifdef CONFIG_HAVE_HW_BREAKPOINT
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/* As it's for in-kernel or ptrace use, we want it to be pinned */
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#define DEFINE_BREAKPOINT_ATTR(name) \
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struct perf_event_attr name = { \
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.type = PERF_TYPE_BREAKPOINT, \
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.size = sizeof(name), \
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.pinned = 1, \
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};
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static inline void hw_breakpoint_init(struct perf_event_attr *attr)
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{
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attr->type = PERF_TYPE_BREAKPOINT;
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attr->size = sizeof(*attr);
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/*
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* As it's for in-kernel or ptrace use, we want it to be pinned
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* and to call its callback every hits.
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*/
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attr->pinned = 1;
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attr->sample_period = 1;
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}
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static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
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@ -52,7 +49,7 @@ static inline int hw_breakpoint_len(struct perf_event *bp)
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extern struct perf_event *
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register_user_hw_breakpoint(struct perf_event_attr *attr,
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perf_callback_t triggered,
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perf_overflow_handler_t triggered,
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struct task_struct *tsk);
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/* FIXME: only change from the attr, and don't unregister */
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@ -64,12 +61,12 @@ modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr);
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*/
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extern struct perf_event *
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register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
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perf_callback_t triggered,
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perf_overflow_handler_t triggered,
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int cpu);
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extern struct perf_event **
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register_wide_hw_breakpoint(struct perf_event_attr *attr,
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perf_callback_t triggered);
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perf_overflow_handler_t triggered);
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extern int register_perf_hw_breakpoint(struct perf_event *bp);
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extern int __register_perf_hw_breakpoint(struct perf_event *bp);
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@ -90,18 +87,18 @@ static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
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static inline struct perf_event *
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register_user_hw_breakpoint(struct perf_event_attr *attr,
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perf_callback_t triggered,
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perf_overflow_handler_t triggered,
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struct task_struct *tsk) { return NULL; }
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static inline struct perf_event *
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modify_user_hw_breakpoint(struct perf_event *bp,
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struct perf_event_attr *attr) { return NULL; }
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static inline struct perf_event *
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register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
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perf_callback_t triggered,
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perf_overflow_handler_t triggered,
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int cpu) { return NULL; }
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static inline struct perf_event **
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register_wide_hw_breakpoint(struct perf_event_attr *attr,
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perf_callback_t triggered) { return NULL; }
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perf_overflow_handler_t triggered) { return NULL; }
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static inline int
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register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
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static inline int
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@ -565,10 +565,13 @@ struct perf_pending_entry {
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void (*func)(struct perf_pending_entry *);
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};
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typedef void (*perf_callback_t)(struct perf_event *, void *);
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struct perf_sample_data;
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typedef void (*perf_callback_t)(struct perf_event *, void *);
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typedef void (*perf_overflow_handler_t)(struct perf_event *, int,
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struct perf_sample_data *,
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struct pt_regs *regs);
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/**
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* struct perf_event - performance event kernel representation:
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*/
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@ -660,9 +663,7 @@ struct perf_event {
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struct pid_namespace *ns;
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u64 id;
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void (*overflow_handler)(struct perf_event *event,
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int nmi, struct perf_sample_data *data,
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struct pt_regs *regs);
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perf_overflow_handler_t overflow_handler;
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#ifdef CONFIG_EVENT_PROFILE
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struct event_filter *filter;
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@ -779,7 +780,7 @@ extern struct perf_event *
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perf_event_create_kernel_counter(struct perf_event_attr *attr,
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int cpu,
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pid_t pid,
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perf_callback_t callback);
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perf_overflow_handler_t callback);
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extern u64 perf_event_read_value(struct perf_event *event,
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u64 *enabled, u64 *running);
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@ -259,7 +259,7 @@ void release_bp_slot(struct perf_event *bp)
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}
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int __register_perf_hw_breakpoint(struct perf_event *bp)
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int register_perf_hw_breakpoint(struct perf_event *bp)
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{
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int ret;
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@ -276,19 +276,12 @@ int __register_perf_hw_breakpoint(struct perf_event *bp)
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* This is a quick hack that will be removed soon, once we remove
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* the tmp breakpoints from ptrace
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*/
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if (!bp->attr.disabled || bp->callback == perf_bp_event)
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if (!bp->attr.disabled || !bp->overflow_handler)
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ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
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return ret;
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}
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int register_perf_hw_breakpoint(struct perf_event *bp)
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{
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bp->callback = perf_bp_event;
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return __register_perf_hw_breakpoint(bp);
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}
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/**
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* register_user_hw_breakpoint - register a hardware breakpoint for user space
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* @attr: breakpoint attributes
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@ -297,7 +290,7 @@ int register_perf_hw_breakpoint(struct perf_event *bp)
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*/
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struct perf_event *
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register_user_hw_breakpoint(struct perf_event_attr *attr,
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perf_callback_t triggered,
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perf_overflow_handler_t triggered,
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struct task_struct *tsk)
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{
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return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
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unregister_hw_breakpoint(bp);
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return perf_event_create_kernel_counter(attr, -1, bp->ctx->task->pid,
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bp->callback);
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bp->overflow_handler);
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}
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EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
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@ -347,7 +340,7 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
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*/
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struct perf_event **
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register_wide_hw_breakpoint(struct perf_event_attr *attr,
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perf_callback_t triggered)
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perf_overflow_handler_t triggered)
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{
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struct perf_event **cpu_events, **pevent, *bp;
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long err;
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@ -4286,15 +4286,8 @@ static void bp_perf_event_destroy(struct perf_event *event)
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static const struct pmu *bp_perf_event_init(struct perf_event *bp)
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{
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int err;
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/*
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* The breakpoint is already filled if we haven't created the counter
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* through perf syscall
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* FIXME: manage to get trigerred to NULL if it comes from syscalls
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*/
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if (!bp->callback)
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err = register_perf_hw_breakpoint(bp);
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else
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err = __register_perf_hw_breakpoint(bp);
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err = register_perf_hw_breakpoint(bp);
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if (err)
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return ERR_PTR(err);
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struct perf_event_context *ctx,
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struct perf_event *group_leader,
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struct perf_event *parent_event,
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perf_callback_t callback,
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perf_overflow_handler_t overflow_handler,
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gfp_t gfpflags)
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{
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const struct pmu *pmu;
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event->state = PERF_EVENT_STATE_INACTIVE;
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if (!callback && parent_event)
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callback = parent_event->callback;
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if (!overflow_handler && parent_event)
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overflow_handler = parent_event->overflow_handler;
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event->callback = callback;
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event->overflow_handler = overflow_handler;
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if (attr->disabled)
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event->state = PERF_EVENT_STATE_OFF;
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*/
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struct perf_event *
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perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
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pid_t pid, perf_callback_t callback)
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pid_t pid,
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perf_overflow_handler_t overflow_handler)
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{
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struct perf_event *event;
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struct perf_event_context *ctx;
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}
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event = perf_event_alloc(attr, cpu, ctx, NULL,
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NULL, callback, GFP_KERNEL);
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NULL, overflow_handler, GFP_KERNEL);
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if (IS_ERR(event)) {
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err = PTR_ERR(event);
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goto err_put_context;
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@ -79,11 +79,12 @@ void ksym_collect_stats(unsigned long hbp_hit_addr)
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}
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#endif /* CONFIG_PROFILE_KSYM_TRACER */
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void ksym_hbp_handler(struct perf_event *hbp, void *data)
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void ksym_hbp_handler(struct perf_event *hbp, int nmi,
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struct perf_sample_data *data,
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struct pt_regs *regs)
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{
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struct ring_buffer_event *event;
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struct ksym_trace_entry *entry;
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struct pt_regs *regs = data;
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struct ring_buffer *buffer;
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int pc;
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@ -41,7 +41,9 @@ module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
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MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
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" write operations on the kernel symbol");
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static void sample_hbp_handler(struct perf_event *temp, void *data)
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static void sample_hbp_handler(struct perf_event *bp, int nmi,
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struct perf_sample_data *data,
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struct pt_regs *regs)
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{
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printk(KERN_INFO "%s value is changed\n", ksym_name);
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dump_stack();
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static int __init hw_break_module_init(void)
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{
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int ret;
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DEFINE_BREAKPOINT_ATTR(attr);
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struct perf_event_attr attr;
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hw_breakpoint_init(&attr);
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attr.bp_addr = kallsyms_lookup_name(ksym_name);
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attr.bp_len = HW_BREAKPOINT_LEN_4;
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attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
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