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Diffstat (limited to 'kernel/trace/trace_hw_branches.c')
-rw-r--r--kernel/trace/trace_hw_branches.c179
1 files changed, 144 insertions, 35 deletions
diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c
index 649df22d435..3561aace075 100644
--- a/kernel/trace/trace_hw_branches.c
+++ b/kernel/trace/trace_hw_branches.c
@@ -1,7 +1,8 @@
/*
* h/w branch tracer for x86 based on bts
*
- * Copyright (C) 2008 Markus Metzger <markus.t.metzger@gmail.com>
+ * Copyright (C) 2008-2009 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
*
*/
@@ -10,21 +11,44 @@
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include <linux/kallsyms.h>
+#include <linux/mutex.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
#include <asm/ds.h>
#include "trace.h"
+#include "trace_output.h"
#define SIZEOF_BTS (1 << 13)
+/* The tracer mutex protects the below per-cpu tracer array.
+ It needs to be held to:
+ - start tracing on all cpus
+ - stop tracing on all cpus
+ - start tracing on a single hotplug cpu
+ - stop tracing on a single hotplug cpu
+ - read the trace from all cpus
+ - read the trace from a single cpu
+*/
+static DEFINE_MUTEX(bts_tracer_mutex);
static DEFINE_PER_CPU(struct bts_tracer *, tracer);
static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
#define this_tracer per_cpu(tracer, smp_processor_id())
#define this_buffer per_cpu(buffer, smp_processor_id())
+static int __read_mostly trace_hw_branches_enabled;
+static struct trace_array *hw_branch_trace __read_mostly;
+
+/*
+ * Start tracing on the current cpu.
+ * The argument is ignored.
+ *
+ * pre: bts_tracer_mutex must be locked.
+ */
static void bts_trace_start_cpu(void *arg)
{
if (this_tracer)
@@ -42,14 +66,20 @@ static void bts_trace_start_cpu(void *arg)
static void bts_trace_start(struct trace_array *tr)
{
- int cpu;
+ mutex_lock(&bts_tracer_mutex);
- tracing_reset_online_cpus(tr);
+ on_each_cpu(bts_trace_start_cpu, NULL, 1);
+ trace_hw_branches_enabled = 1;
- for_each_cpu(cpu, cpu_possible_mask)
- smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
+ mutex_unlock(&bts_tracer_mutex);
}
+/*
+ * Stop tracing on the current cpu.
+ * The argument is ignored.
+ *
+ * pre: bts_tracer_mutex must be locked.
+ */
static void bts_trace_stop_cpu(void *arg)
{
if (this_tracer) {
@@ -60,26 +90,62 @@ static void bts_trace_stop_cpu(void *arg)
static void bts_trace_stop(struct trace_array *tr)
{
- int cpu;
+ mutex_lock(&bts_tracer_mutex);
+
+ trace_hw_branches_enabled = 0;
+ on_each_cpu(bts_trace_stop_cpu, NULL, 1);
+
+ mutex_unlock(&bts_tracer_mutex);
+}
+
+static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+
+ mutex_lock(&bts_tracer_mutex);
+
+ if (!trace_hw_branches_enabled)
+ goto out;
- for_each_cpu(cpu, cpu_possible_mask)
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_DOWN_FAILED:
+ smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
+ break;
+ case CPU_DOWN_PREPARE:
smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
+ break;
+ }
+
+ out:
+ mutex_unlock(&bts_tracer_mutex);
+ return NOTIFY_DONE;
}
-static int bts_trace_init(struct trace_array *tr)
+static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
+ .notifier_call = bts_hotcpu_handler
+};
+
+static int __cpuinit bts_trace_init(struct trace_array *tr)
{
- tracing_reset_online_cpus(tr);
+ hw_branch_trace = tr;
+
+ register_hotcpu_notifier(&bts_hotcpu_notifier);
bts_trace_start(tr);
return 0;
}
+static void __cpuinit bts_trace_reset(struct trace_array *tr)
+{
+ bts_trace_stop(tr);
+ unregister_hotcpu_notifier(&bts_hotcpu_notifier);
+}
+
static void bts_trace_print_header(struct seq_file *m)
{
- seq_puts(m,
- "# CPU# FROM TO FUNCTION\n");
- seq_puts(m,
- "# | | | |\n");
+ seq_puts(m, "# CPU# TO <- FROM\n");
}
static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
@@ -87,15 +153,15 @@ static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
struct trace_entry *entry = iter->ent;
struct trace_seq *seq = &iter->seq;
struct hw_branch_entry *it;
+ unsigned long symflags = TRACE_ITER_SYM_OFFSET;
trace_assign_type(it, entry);
if (entry->type == TRACE_HW_BRANCHES) {
- if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
- trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
- it->from, it->to) &&
- (!it->from ||
- seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
+ if (trace_seq_printf(seq, "%4d ", iter->cpu) &&
+ seq_print_ip_sym(seq, it->to, symflags) &&
+ trace_seq_printf(seq, "\t <- ") &&
+ seq_print_ip_sym(seq, it->from, symflags) &&
trace_seq_printf(seq, "\n"))
return TRACE_TYPE_HANDLED;
return TRACE_TYPE_PARTIAL_LINE;;
@@ -103,26 +169,42 @@ static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
return TRACE_TYPE_UNHANDLED;
}
-void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
+void trace_hw_branch(u64 from, u64 to)
{
+ struct trace_array *tr = hw_branch_trace;
struct ring_buffer_event *event;
struct hw_branch_entry *entry;
- unsigned long irq;
+ unsigned long irq1;
+ int cpu;
- event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
- if (!event)
+ if (unlikely(!tr))
return;
+
+ if (unlikely(!trace_hw_branches_enabled))
+ return;
+
+ local_irq_save(irq1);
+ cpu = raw_smp_processor_id();
+ if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
+ goto out;
+
+ event = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES,
+ sizeof(*entry), 0, 0);
+ if (!event)
+ goto out;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, from);
entry->ent.type = TRACE_HW_BRANCHES;
- entry->ent.cpu = smp_processor_id();
entry->from = from;
entry->to = to;
- ring_buffer_unlock_commit(tr->buffer, event, irq);
+ trace_buffer_unlock_commit(tr, event, 0, 0);
+
+ out:
+ atomic_dec(&tr->data[cpu]->disabled);
+ local_irq_restore(irq1);
}
-static void trace_bts_at(struct trace_array *tr,
- const struct bts_trace *trace, void *at)
+static void trace_bts_at(const struct bts_trace *trace, void *at)
{
struct bts_struct bts;
int err = 0;
@@ -137,18 +219,29 @@ static void trace_bts_at(struct trace_array *tr,
switch (bts.qualifier) {
case BTS_BRANCH:
- trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
+ trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
break;
}
}
+/*
+ * Collect the trace on the current cpu and write it into the ftrace buffer.
+ *
+ * pre: bts_tracer_mutex must be locked
+ */
static void trace_bts_cpu(void *arg)
{
struct trace_array *tr = (struct trace_array *) arg;
const struct bts_trace *trace;
unsigned char *at;
- if (!this_tracer)
+ if (unlikely(!tr))
+ return;
+
+ if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
+ return;
+
+ if (unlikely(!this_tracer))
return;
ds_suspend_bts(this_tracer);
@@ -158,11 +251,11 @@ static void trace_bts_cpu(void *arg)
for (at = trace->ds.top; (void *)at < trace->ds.end;
at += trace->ds.size)
- trace_bts_at(tr, trace, at);
+ trace_bts_at(trace, at);
for (at = trace->ds.begin; (void *)at < trace->ds.top;
at += trace->ds.size)
- trace_bts_at(tr, trace, at);
+ trace_bts_at(trace, at);
out:
ds_resume_bts(this_tracer);
@@ -170,22 +263,38 @@ out:
static void trace_bts_prepare(struct trace_iterator *iter)
{
- int cpu;
+ mutex_lock(&bts_tracer_mutex);
+
+ on_each_cpu(trace_bts_cpu, iter->tr, 1);
+
+ mutex_unlock(&bts_tracer_mutex);
+}
+
+static void trace_bts_close(struct trace_iterator *iter)
+{
+ tracing_reset_online_cpus(iter->tr);
+}
+
+void trace_hw_branch_oops(void)
+{
+ mutex_lock(&bts_tracer_mutex);
+
+ trace_bts_cpu(hw_branch_trace);
- for_each_cpu(cpu, cpu_possible_mask)
- smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
+ mutex_unlock(&bts_tracer_mutex);
}
struct tracer bts_tracer __read_mostly =
{
.name = "hw-branch-tracer",
.init = bts_trace_init,
- .reset = bts_trace_stop,
+ .reset = bts_trace_reset,
.print_header = bts_trace_print_header,
.print_line = bts_trace_print_line,
.start = bts_trace_start,
.stop = bts_trace_stop,
- .open = trace_bts_prepare
+ .open = trace_bts_prepare,
+ .close = trace_bts_close
};
__init static int init_bts_trace(void)