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389 lines
8.9 KiB
389 lines
8.9 KiB
/* |
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* trace event based perf event profiling/tracing |
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* |
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* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra |
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* Copyright (C) 2009-2010 Frederic Weisbecker <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/kprobes.h> |
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#include "trace.h" |
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static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS]; |
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/* |
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* Force it to be aligned to unsigned long to avoid misaligned accesses |
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* suprises |
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*/ |
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typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)]) |
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perf_trace_t; |
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/* Count the events in use (per event id, not per instance) */ |
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static int total_ref_count; |
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static int perf_trace_event_perm(struct trace_event_call *tp_event, |
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struct perf_event *p_event) |
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{ |
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if (tp_event->perf_perm) { |
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int ret = tp_event->perf_perm(tp_event, p_event); |
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if (ret) |
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return ret; |
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} |
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/* |
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* We checked and allowed to create parent, |
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* allow children without checking. |
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*/ |
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if (p_event->parent) |
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return 0; |
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/* |
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* It's ok to check current process (owner) permissions in here, |
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* because code below is called only via perf_event_open syscall. |
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*/ |
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/* The ftrace function trace is allowed only for root. */ |
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if (ftrace_event_is_function(tp_event)) { |
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if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) |
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return -EPERM; |
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if (!is_sampling_event(p_event)) |
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return 0; |
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/* |
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* We don't allow user space callchains for function trace |
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* event, due to issues with page faults while tracing page |
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* fault handler and its overall trickiness nature. |
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*/ |
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if (!p_event->attr.exclude_callchain_user) |
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return -EINVAL; |
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/* |
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* Same reason to disable user stack dump as for user space |
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* callchains above. |
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*/ |
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if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER) |
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return -EINVAL; |
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} |
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/* No tracing, just counting, so no obvious leak */ |
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if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW)) |
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return 0; |
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/* Some events are ok to be traced by non-root users... */ |
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if (p_event->attach_state == PERF_ATTACH_TASK) { |
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if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY) |
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return 0; |
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} |
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/* |
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* ...otherwise raw tracepoint data can be a severe data leak, |
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* only allow root to have these. |
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*/ |
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if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) |
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return -EPERM; |
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return 0; |
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} |
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static int perf_trace_event_reg(struct trace_event_call *tp_event, |
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struct perf_event *p_event) |
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{ |
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struct hlist_head __percpu *list; |
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int ret = -ENOMEM; |
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int cpu; |
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p_event->tp_event = tp_event; |
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if (tp_event->perf_refcount++ > 0) |
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return 0; |
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list = alloc_percpu(struct hlist_head); |
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if (!list) |
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goto fail; |
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for_each_possible_cpu(cpu) |
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INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); |
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tp_event->perf_events = list; |
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if (!total_ref_count) { |
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char __percpu *buf; |
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int i; |
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for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
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buf = (char __percpu *)alloc_percpu(perf_trace_t); |
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if (!buf) |
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goto fail; |
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perf_trace_buf[i] = buf; |
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} |
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} |
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ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL); |
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if (ret) |
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goto fail; |
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total_ref_count++; |
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return 0; |
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fail: |
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if (!total_ref_count) { |
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int i; |
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for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
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free_percpu(perf_trace_buf[i]); |
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perf_trace_buf[i] = NULL; |
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} |
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} |
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if (!--tp_event->perf_refcount) { |
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free_percpu(tp_event->perf_events); |
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tp_event->perf_events = NULL; |
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} |
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return ret; |
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} |
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static void perf_trace_event_unreg(struct perf_event *p_event) |
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{ |
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struct trace_event_call *tp_event = p_event->tp_event; |
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int i; |
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if (--tp_event->perf_refcount > 0) |
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goto out; |
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tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); |
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/* |
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* Ensure our callback won't be called anymore. The buffers |
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* will be freed after that. |
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*/ |
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tracepoint_synchronize_unregister(); |
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free_percpu(tp_event->perf_events); |
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tp_event->perf_events = NULL; |
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if (!--total_ref_count) { |
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for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
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free_percpu(perf_trace_buf[i]); |
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perf_trace_buf[i] = NULL; |
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} |
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} |
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out: |
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module_put(tp_event->mod); |
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} |
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static int perf_trace_event_open(struct perf_event *p_event) |
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{ |
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struct trace_event_call *tp_event = p_event->tp_event; |
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return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event); |
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} |
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static void perf_trace_event_close(struct perf_event *p_event) |
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{ |
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struct trace_event_call *tp_event = p_event->tp_event; |
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tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event); |
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} |
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static int perf_trace_event_init(struct trace_event_call *tp_event, |
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struct perf_event *p_event) |
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{ |
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int ret; |
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ret = perf_trace_event_perm(tp_event, p_event); |
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if (ret) |
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return ret; |
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ret = perf_trace_event_reg(tp_event, p_event); |
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if (ret) |
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return ret; |
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ret = perf_trace_event_open(p_event); |
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if (ret) { |
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perf_trace_event_unreg(p_event); |
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return ret; |
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} |
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return 0; |
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} |
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int perf_trace_init(struct perf_event *p_event) |
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{ |
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struct trace_event_call *tp_event; |
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u64 event_id = p_event->attr.config; |
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int ret = -EINVAL; |
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mutex_lock(&event_mutex); |
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list_for_each_entry(tp_event, &ftrace_events, list) { |
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if (tp_event->event.type == event_id && |
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tp_event->class && tp_event->class->reg && |
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try_module_get(tp_event->mod)) { |
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ret = perf_trace_event_init(tp_event, p_event); |
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if (ret) |
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module_put(tp_event->mod); |
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break; |
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} |
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} |
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mutex_unlock(&event_mutex); |
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return ret; |
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} |
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void perf_trace_destroy(struct perf_event *p_event) |
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{ |
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mutex_lock(&event_mutex); |
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perf_trace_event_close(p_event); |
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perf_trace_event_unreg(p_event); |
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mutex_unlock(&event_mutex); |
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} |
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int perf_trace_add(struct perf_event *p_event, int flags) |
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{ |
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struct trace_event_call *tp_event = p_event->tp_event; |
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struct hlist_head __percpu *pcpu_list; |
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struct hlist_head *list; |
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pcpu_list = tp_event->perf_events; |
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if (WARN_ON_ONCE(!pcpu_list)) |
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return -EINVAL; |
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if (!(flags & PERF_EF_START)) |
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p_event->hw.state = PERF_HES_STOPPED; |
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list = this_cpu_ptr(pcpu_list); |
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hlist_add_head_rcu(&p_event->hlist_entry, list); |
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return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event); |
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} |
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void perf_trace_del(struct perf_event *p_event, int flags) |
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{ |
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struct trace_event_call *tp_event = p_event->tp_event; |
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hlist_del_rcu(&p_event->hlist_entry); |
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tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event); |
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} |
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void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp) |
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{ |
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char *raw_data; |
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int rctx; |
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BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
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if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, |
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"perf buffer not large enough")) |
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return NULL; |
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*rctxp = rctx = perf_swevent_get_recursion_context(); |
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if (rctx < 0) |
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return NULL; |
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if (regs) |
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*regs = this_cpu_ptr(&__perf_regs[rctx]); |
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raw_data = this_cpu_ptr(perf_trace_buf[rctx]); |
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/* zero the dead bytes from align to not leak stack to user */ |
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memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
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return raw_data; |
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} |
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EXPORT_SYMBOL_GPL(perf_trace_buf_alloc); |
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NOKPROBE_SYMBOL(perf_trace_buf_alloc); |
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void perf_trace_buf_update(void *record, u16 type) |
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{ |
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struct trace_entry *entry = record; |
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int pc = preempt_count(); |
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unsigned long flags; |
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local_save_flags(flags); |
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tracing_generic_entry_update(entry, flags, pc); |
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entry->type = type; |
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} |
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NOKPROBE_SYMBOL(perf_trace_buf_update); |
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#ifdef CONFIG_FUNCTION_TRACER |
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static void |
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perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, |
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struct ftrace_ops *ops, struct pt_regs *pt_regs) |
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{ |
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struct ftrace_entry *entry; |
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struct hlist_head *head; |
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struct pt_regs regs; |
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int rctx; |
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head = this_cpu_ptr(event_function.perf_events); |
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if (hlist_empty(head)) |
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return; |
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#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ |
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sizeof(u64)) - sizeof(u32)) |
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BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); |
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memset(®s, 0, sizeof(regs)); |
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perf_fetch_caller_regs(®s); |
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entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx); |
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if (!entry) |
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return; |
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entry->ip = ip; |
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entry->parent_ip = parent_ip; |
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perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN, |
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1, ®s, head, NULL); |
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#undef ENTRY_SIZE |
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} |
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static int perf_ftrace_function_register(struct perf_event *event) |
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{ |
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struct ftrace_ops *ops = &event->ftrace_ops; |
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ops->flags |= FTRACE_OPS_FL_PER_CPU | FTRACE_OPS_FL_RCU; |
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ops->func = perf_ftrace_function_call; |
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return register_ftrace_function(ops); |
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} |
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static int perf_ftrace_function_unregister(struct perf_event *event) |
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{ |
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struct ftrace_ops *ops = &event->ftrace_ops; |
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int ret = unregister_ftrace_function(ops); |
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ftrace_free_filter(ops); |
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return ret; |
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} |
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static void perf_ftrace_function_enable(struct perf_event *event) |
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{ |
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ftrace_function_local_enable(&event->ftrace_ops); |
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} |
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static void perf_ftrace_function_disable(struct perf_event *event) |
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{ |
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ftrace_function_local_disable(&event->ftrace_ops); |
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} |
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int perf_ftrace_event_register(struct trace_event_call *call, |
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enum trace_reg type, void *data) |
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{ |
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switch (type) { |
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case TRACE_REG_REGISTER: |
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case TRACE_REG_UNREGISTER: |
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break; |
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case TRACE_REG_PERF_REGISTER: |
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case TRACE_REG_PERF_UNREGISTER: |
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return 0; |
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case TRACE_REG_PERF_OPEN: |
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return perf_ftrace_function_register(data); |
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case TRACE_REG_PERF_CLOSE: |
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return perf_ftrace_function_unregister(data); |
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case TRACE_REG_PERF_ADD: |
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perf_ftrace_function_enable(data); |
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return 0; |
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case TRACE_REG_PERF_DEL: |
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perf_ftrace_function_disable(data); |
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return 0; |
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} |
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return -EINVAL; |
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} |
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#endif /* CONFIG_FUNCTION_TRACER */
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