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-rw-r--r--kernel/trace/trace_event_perf.c175
1 files changed, 175 insertions, 0 deletions
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
new file mode 100644
index 00000000000..0565bb42566
--- /dev/null
+++ b/kernel/trace/trace_event_perf.c
@@ -0,0 +1,175 @@
+/*
+ * trace event based perf event profiling/tracing
+ *
+ * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
+ * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include "trace.h"
+
+DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
+EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
+
+EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
+
+static char *perf_trace_buf;
+static char *perf_trace_buf_nmi;
+
+/*
+ * Force it to be aligned to unsigned long to avoid misaligned accesses
+ * suprises
+ */
+typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
+ perf_trace_t;
+
+/* Count the events in use (per event id, not per instance) */
+static int total_ref_count;
+
+static int perf_trace_event_enable(struct ftrace_event_call *event)
+{
+ char *buf;
+ int ret = -ENOMEM;
+
+ if (event->perf_refcount++ > 0)
+ return 0;
+
+ if (!total_ref_count) {
+ buf = (char *)alloc_percpu(perf_trace_t);
+ if (!buf)
+ goto fail_buf;
+
+ rcu_assign_pointer(perf_trace_buf, buf);
+
+ buf = (char *)alloc_percpu(perf_trace_t);
+ if (!buf)
+ goto fail_buf_nmi;
+
+ rcu_assign_pointer(perf_trace_buf_nmi, buf);
+ }
+
+ ret = event->perf_event_enable(event);
+ if (!ret) {
+ total_ref_count++;
+ return 0;
+ }
+
+fail_buf_nmi:
+ if (!total_ref_count) {
+ free_percpu(perf_trace_buf_nmi);
+ free_percpu(perf_trace_buf);
+ perf_trace_buf_nmi = NULL;
+ perf_trace_buf = NULL;
+ }
+fail_buf:
+ event->perf_refcount--;
+
+ return ret;
+}
+
+int perf_trace_enable(int event_id)
+{
+ struct ftrace_event_call *event;
+ int ret = -EINVAL;
+
+ mutex_lock(&event_mutex);
+ list_for_each_entry(event, &ftrace_events, list) {
+ if (event->id == event_id && event->perf_event_enable &&
+ try_module_get(event->mod)) {
+ ret = perf_trace_event_enable(event);
+ break;
+ }
+ }
+ mutex_unlock(&event_mutex);
+
+ return ret;
+}
+
+static void perf_trace_event_disable(struct ftrace_event_call *event)
+{
+ char *buf, *nmi_buf;
+
+ if (--event->perf_refcount > 0)
+ return;
+
+ event->perf_event_disable(event);
+
+ if (!--total_ref_count) {
+ buf = perf_trace_buf;
+ rcu_assign_pointer(perf_trace_buf, NULL);
+
+ nmi_buf = perf_trace_buf_nmi;
+ rcu_assign_pointer(perf_trace_buf_nmi, NULL);
+
+ /*
+ * Ensure every events in profiling have finished before
+ * releasing the buffers
+ */
+ synchronize_sched();
+
+ free_percpu(buf);
+ free_percpu(nmi_buf);
+ }
+}
+
+void perf_trace_disable(int event_id)
+{
+ struct ftrace_event_call *event;
+
+ mutex_lock(&event_mutex);
+ list_for_each_entry(event, &ftrace_events, list) {
+ if (event->id == event_id) {
+ perf_trace_event_disable(event);
+ module_put(event->mod);
+ break;
+ }
+ }
+ mutex_unlock(&event_mutex);
+}
+
+__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
+ int *rctxp, unsigned long *irq_flags)
+{
+ struct trace_entry *entry;
+ char *trace_buf, *raw_data;
+ int pc, cpu;
+
+ BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
+
+ pc = preempt_count();
+
+ /* Protect the per cpu buffer, begin the rcu read side */
+ local_irq_save(*irq_flags);
+
+ *rctxp = perf_swevent_get_recursion_context();
+ if (*rctxp < 0)
+ goto err_recursion;
+
+ cpu = smp_processor_id();
+
+ if (in_nmi())
+ trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
+ else
+ trace_buf = rcu_dereference_sched(perf_trace_buf);
+
+ if (!trace_buf)
+ goto err;
+
+ raw_data = per_cpu_ptr(trace_buf, cpu);
+
+ /* zero the dead bytes from align to not leak stack to user */
+ memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
+
+ entry = (struct trace_entry *)raw_data;
+ tracing_generic_entry_update(entry, *irq_flags, pc);
+ entry->type = type;
+
+ return raw_data;
+err:
+ perf_swevent_put_recursion_context(*rctxp);
+err_recursion:
+ local_irq_restore(*irq_flags);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);