From b326e9560a28fc3e950637ef51847ed8f05c1335 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sat, 5 Dec 2009 09:44:31 +0100 Subject: [PATCH] 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 Signed-off-by: Frederic Weisbecker Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: "K. Prasad" --- arch/x86/kernel/hw_breakpoint.c | 5 ++--- arch/x86/kernel/ptrace.c | 9 ++++++--- include/linux/hw_breakpoint.h | 25 +++++++++++-------------- include/linux/perf_event.h | 13 +++++++------ kernel/hw_breakpoint.c | 17 +++++------------ kernel/perf_event.c | 24 +++++++++--------------- kernel/trace/trace_ksym.c | 5 +++-- samples/hw_breakpoint/data_breakpoint.c | 7 +++++-- 8 files changed, 48 insertions(+), 57 deletions(-) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index d42f65ac492..05d5fec64a9 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -362,8 +362,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp, return ret; } - if (bp->callback) - ret = arch_store_info(bp); + ret = arch_store_info(bp); if (ret < 0) return ret; @@ -519,7 +518,7 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args) break; } - (bp->callback)(bp, args->regs); + perf_bp_event(bp, args->regs); rcu_read_unlock(); } diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index dbb395572ae..b361d28061d 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -555,7 +555,9 @@ static int genregs_set(struct task_struct *target, return ret; } -static void ptrace_triggered(struct perf_event *bp, void *data) +static void ptrace_triggered(struct perf_event *bp, int nmi, + struct perf_sample_data *data, + struct pt_regs *regs) { int i; struct thread_struct *thread = &(current->thread); @@ -599,7 +601,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, { int err; int gen_len, gen_type; - DEFINE_BREAKPOINT_ATTR(attr); + struct perf_event_attr attr; /* * We shoud have at least an inactive breakpoint at this @@ -721,9 +723,10 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, { struct perf_event *bp; struct thread_struct *t = &tsk->thread; - DEFINE_BREAKPOINT_ATTR(attr); + struct perf_event_attr attr; if (!t->ptrace_bps[nr]) { + hw_breakpoint_init(&attr); /* * Put stub len and type to register (reserve) an inactive but * correct bp diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index d33096e0dbd..4d14a384a01 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -20,19 +20,16 @@ enum { #ifdef CONFIG_HAVE_HW_BREAKPOINT -/* As it's for in-kernel or ptrace use, we want it to be pinned */ -#define DEFINE_BREAKPOINT_ATTR(name) \ -struct perf_event_attr name = { \ - .type = PERF_TYPE_BREAKPOINT, \ - .size = sizeof(name), \ - .pinned = 1, \ -}; - static inline void hw_breakpoint_init(struct perf_event_attr *attr) { attr->type = PERF_TYPE_BREAKPOINT; attr->size = sizeof(*attr); + /* + * As it's for in-kernel or ptrace use, we want it to be pinned + * and to call its callback every hits. + */ attr->pinned = 1; + attr->sample_period = 1; } static inline unsigned long hw_breakpoint_addr(struct perf_event *bp) @@ -52,7 +49,7 @@ static inline int hw_breakpoint_len(struct perf_event *bp) extern struct perf_event * register_user_hw_breakpoint(struct perf_event_attr *attr, - perf_callback_t triggered, + perf_overflow_handler_t triggered, struct task_struct *tsk); /* FIXME: only change from the attr, and don't unregister */ @@ -64,12 +61,12 @@ modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr); */ extern struct perf_event * register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, - perf_callback_t triggered, + perf_overflow_handler_t triggered, int cpu); extern struct perf_event ** register_wide_hw_breakpoint(struct perf_event_attr *attr, - perf_callback_t triggered); + perf_overflow_handler_t triggered); extern int register_perf_hw_breakpoint(struct perf_event *bp); extern int __register_perf_hw_breakpoint(struct perf_event *bp); @@ -90,18 +87,18 @@ static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp) static inline struct perf_event * register_user_hw_breakpoint(struct perf_event_attr *attr, - perf_callback_t triggered, + perf_overflow_handler_t triggered, struct task_struct *tsk) { return NULL; } static inline struct perf_event * modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) { return NULL; } static inline struct perf_event * register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, - perf_callback_t triggered, + perf_overflow_handler_t triggered, int cpu) { return NULL; } static inline struct perf_event ** register_wide_hw_breakpoint(struct perf_event_attr *attr, - perf_callback_t triggered) { return NULL; } + perf_overflow_handler_t triggered) { return NULL; } static inline int register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; } static inline int diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 84bd28a0ffa..d2f2667430d 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -565,10 +565,13 @@ struct perf_pending_entry { void (*func)(struct perf_pending_entry *); }; -typedef void (*perf_callback_t)(struct perf_event *, void *); - struct perf_sample_data; +typedef void (*perf_callback_t)(struct perf_event *, void *); +typedef void (*perf_overflow_handler_t)(struct perf_event *, int, + struct perf_sample_data *, + struct pt_regs *regs); + /** * struct perf_event - performance event kernel representation: */ @@ -660,9 +663,7 @@ struct perf_event { struct pid_namespace *ns; u64 id; - void (*overflow_handler)(struct perf_event *event, - int nmi, struct perf_sample_data *data, - struct pt_regs *regs); + perf_overflow_handler_t overflow_handler; #ifdef CONFIG_EVENT_PROFILE struct event_filter *filter; @@ -779,7 +780,7 @@ extern struct perf_event * perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, pid_t pid, - perf_callback_t callback); + perf_overflow_handler_t callback); extern u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running); diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index 2d10b012828..b600fc27f16 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -259,7 +259,7 @@ void release_bp_slot(struct perf_event *bp) } -int __register_perf_hw_breakpoint(struct perf_event *bp) +int register_perf_hw_breakpoint(struct perf_event *bp) { int ret; @@ -276,19 +276,12 @@ int __register_perf_hw_breakpoint(struct perf_event *bp) * This is a quick hack that will be removed soon, once we remove * the tmp breakpoints from ptrace */ - if (!bp->attr.disabled || bp->callback == perf_bp_event) + if (!bp->attr.disabled || !bp->overflow_handler) ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task); return ret; } -int register_perf_hw_breakpoint(struct perf_event *bp) -{ - bp->callback = perf_bp_event; - - return __register_perf_hw_breakpoint(bp); -} - /** * register_user_hw_breakpoint - register a hardware breakpoint for user space * @attr: breakpoint attributes @@ -297,7 +290,7 @@ int register_perf_hw_breakpoint(struct perf_event *bp) */ struct perf_event * register_user_hw_breakpoint(struct perf_event_attr *attr, - perf_callback_t triggered, + perf_overflow_handler_t triggered, struct task_struct *tsk) { return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered); @@ -322,7 +315,7 @@ modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) unregister_hw_breakpoint(bp); return perf_event_create_kernel_counter(attr, -1, bp->ctx->task->pid, - bp->callback); + bp->overflow_handler); } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); @@ -347,7 +340,7 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); */ struct perf_event ** register_wide_hw_breakpoint(struct perf_event_attr *attr, - perf_callback_t triggered) + perf_overflow_handler_t triggered) { struct perf_event **cpu_events, **pevent, *bp; long err; diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 6b7ddba1dd6..fd43ff4ac86 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -4286,15 +4286,8 @@ static void bp_perf_event_destroy(struct perf_event *event) static const struct pmu *bp_perf_event_init(struct perf_event *bp) { int err; - /* - * The breakpoint is already filled if we haven't created the counter - * through perf syscall - * FIXME: manage to get trigerred to NULL if it comes from syscalls - */ - if (!bp->callback) - err = register_perf_hw_breakpoint(bp); - else - err = __register_perf_hw_breakpoint(bp); + + err = register_perf_hw_breakpoint(bp); if (err) return ERR_PTR(err); @@ -4390,7 +4383,7 @@ perf_event_alloc(struct perf_event_attr *attr, struct perf_event_context *ctx, struct perf_event *group_leader, struct perf_event *parent_event, - perf_callback_t callback, + perf_overflow_handler_t overflow_handler, gfp_t gfpflags) { const struct pmu *pmu; @@ -4433,10 +4426,10 @@ perf_event_alloc(struct perf_event_attr *attr, event->state = PERF_EVENT_STATE_INACTIVE; - if (!callback && parent_event) - callback = parent_event->callback; + if (!overflow_handler && parent_event) + overflow_handler = parent_event->overflow_handler; - event->callback = callback; + event->overflow_handler = overflow_handler; if (attr->disabled) event->state = PERF_EVENT_STATE_OFF; @@ -4776,7 +4769,8 @@ err_put_context: */ struct perf_event * perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, - pid_t pid, perf_callback_t callback) + pid_t pid, + perf_overflow_handler_t overflow_handler) { struct perf_event *event; struct perf_event_context *ctx; @@ -4793,7 +4787,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, } event = perf_event_alloc(attr, cpu, ctx, NULL, - NULL, callback, GFP_KERNEL); + NULL, overflow_handler, GFP_KERNEL); if (IS_ERR(event)) { err = PTR_ERR(event); goto err_put_context; diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c index ddfa0fd43bc..acb87d4a4ac 100644 --- a/kernel/trace/trace_ksym.c +++ b/kernel/trace/trace_ksym.c @@ -79,11 +79,12 @@ void ksym_collect_stats(unsigned long hbp_hit_addr) } #endif /* CONFIG_PROFILE_KSYM_TRACER */ -void ksym_hbp_handler(struct perf_event *hbp, void *data) +void ksym_hbp_handler(struct perf_event *hbp, int nmi, + struct perf_sample_data *data, + struct pt_regs *regs) { struct ring_buffer_event *event; struct ksym_trace_entry *entry; - struct pt_regs *regs = data; struct ring_buffer *buffer; int pc; diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c index 29525500df0..c69cbe9b242 100644 --- a/samples/hw_breakpoint/data_breakpoint.c +++ b/samples/hw_breakpoint/data_breakpoint.c @@ -41,7 +41,9 @@ module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO); MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any" " write operations on the kernel symbol"); -static void sample_hbp_handler(struct perf_event *temp, void *data) +static void sample_hbp_handler(struct perf_event *bp, int nmi, + struct perf_sample_data *data, + struct pt_regs *regs) { printk(KERN_INFO "%s value is changed\n", ksym_name); dump_stack(); @@ -51,8 +53,9 @@ static void sample_hbp_handler(struct perf_event *temp, void *data) static int __init hw_break_module_init(void) { int ret; - DEFINE_BREAKPOINT_ATTR(attr); + struct perf_event_attr attr; + hw_breakpoint_init(&attr); attr.bp_addr = kallsyms_lookup_name(ksym_name); attr.bp_len = HW_BREAKPOINT_LEN_4; attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;