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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

arch/x86/kernel/dumpstack.c

+6 −0
Original line number Diff line number Diff line
@@ -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. */

include/linux/ftrace.h

+13 −0
Original line number Diff line number Diff line
@@ -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 */

kernel/trace/trace.h

+0 −1
Original line number Diff line number Diff line
@@ -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);

kernel/trace/trace_hw_branches.c

+22 −7
Original line number Diff line number Diff line
@@ -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",