Commit b1818748 authored by Markus Metzger's avatar Markus Metzger Committed by Ingo Molnar
Browse files

x86, ftrace, hw-branch-tracer: dump trace on oops



Dump the branch trace on an oops (based on ftrace_dump_on_oops).
Signed-off-by: default avatarMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5c5317de
......@@ -14,6 +14,7 @@
#include <linux/bug.h>
#include <linux/nmi.h>
#include <linux/sysfs.h>
#include <linux/ftrace.h>
#include <asm/stacktrace.h>
......@@ -195,6 +196,11 @@ unsigned __kprobes long oops_begin(void)
int cpu;
unsigned long flags;
/* notify the hw-branch tracer so it may disable tracing and
add the last trace to the trace buffer -
the earlier this happens, the more useful the trace. */
trace_hw_branch_oops();
oops_enter();
/* racy, but better than risking deadlock. */
......
......@@ -496,4 +496,17 @@ static inline int test_tsk_trace_graph(struct task_struct *tsk)
#endif /* CONFIG_TRACING */
#ifdef CONFIG_HW_BRANCH_TRACER
void trace_hw_branch(u64 from, u64 to);
void trace_hw_branch_oops(void);
#else /* CONFIG_HW_BRANCH_TRACER */
static inline void trace_hw_branch(u64 from, u64 to) {}
static inline void trace_hw_branch_oops(void) {}
#endif /* CONFIG_HW_BRANCH_TRACER */
#endif /* _LINUX_FTRACE_H */
......@@ -438,7 +438,6 @@ void trace_function(struct trace_array *tr,
void trace_graph_return(struct ftrace_graph_ret *trace);
int trace_graph_entry(struct ftrace_graph_ent *trace);
void trace_hw_branch(struct trace_array *tr, u64 from, u64 to);
void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
......
......@@ -40,6 +40,7 @@ static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
#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;
/*
......@@ -128,6 +129,8 @@ static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
static int bts_trace_init(struct trace_array *tr)
{
hw_branch_trace = tr;
register_hotcpu_notifier(&bts_hotcpu_notifier);
tracing_reset_online_cpus(tr);
bts_trace_start(tr);
......@@ -170,8 +173,9 @@ 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 irq1, irq2;
......@@ -204,8 +208,7 @@ void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
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;
......@@ -220,7 +223,7 @@ 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;
}
}
......@@ -236,12 +239,15 @@ static void trace_bts_cpu(void *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);
trace = ds_read_bts(this_tracer);
if (!trace)
......@@ -249,11 +255,11 @@ 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);
......@@ -268,6 +274,15 @@ static void trace_bts_prepare(struct trace_iterator *iter)
mutex_unlock(&bts_tracer_mutex);
}
void trace_hw_branch_oops(void)
{
mutex_lock(&bts_tracer_mutex);
trace_bts_cpu(hw_branch_trace);
mutex_unlock(&bts_tracer_mutex);
}
struct tracer bts_tracer __read_mostly =
{
.name = "hw-branch-tracer",
......
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