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: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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5c5317de14
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@ -14,6 +14,7 @@
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#include <linux/bug.h>
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#include <linux/bug.h>
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#include <linux/nmi.h>
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#include <linux/nmi.h>
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#include <linux/sysfs.h>
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#include <linux/sysfs.h>
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#include <linux/ftrace.h>
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#include <asm/stacktrace.h>
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#include <asm/stacktrace.h>
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@ -195,6 +196,11 @@ unsigned __kprobes long oops_begin(void)
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int cpu;
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int cpu;
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unsigned long flags;
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unsigned long flags;
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/* notify the hw-branch tracer so it may disable tracing and
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add the last trace to the trace buffer -
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the earlier this happens, the more useful the trace. */
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trace_hw_branch_oops();
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oops_enter();
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oops_enter();
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/* racy, but better than risking deadlock. */
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/* racy, but better than risking deadlock. */
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@ -496,4 +496,17 @@ static inline int test_tsk_trace_graph(struct task_struct *tsk)
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#endif /* CONFIG_TRACING */
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#endif /* CONFIG_TRACING */
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#ifdef CONFIG_HW_BRANCH_TRACER
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void trace_hw_branch(u64 from, u64 to);
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void trace_hw_branch_oops(void);
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#else /* CONFIG_HW_BRANCH_TRACER */
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static inline void trace_hw_branch(u64 from, u64 to) {}
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static inline void trace_hw_branch_oops(void) {}
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#endif /* CONFIG_HW_BRANCH_TRACER */
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#endif /* _LINUX_FTRACE_H */
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#endif /* _LINUX_FTRACE_H */
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@ -438,7 +438,6 @@ void trace_function(struct trace_array *tr,
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void trace_graph_return(struct ftrace_graph_ret *trace);
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void trace_graph_return(struct ftrace_graph_ret *trace);
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int trace_graph_entry(struct ftrace_graph_ent *trace);
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int trace_graph_entry(struct ftrace_graph_ent *trace);
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void trace_hw_branch(struct trace_array *tr, u64 from, u64 to);
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void tracing_start_cmdline_record(void);
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void tracing_start_cmdline_record(void);
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void tracing_stop_cmdline_record(void);
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void tracing_stop_cmdline_record(void);
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@ -40,6 +40,7 @@ static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
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#define this_buffer per_cpu(buffer, smp_processor_id())
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#define this_buffer per_cpu(buffer, smp_processor_id())
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static int __read_mostly trace_hw_branches_enabled;
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static int __read_mostly trace_hw_branches_enabled;
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static struct trace_array *hw_branch_trace __read_mostly;
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/*
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/*
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@ -128,6 +129,8 @@ static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
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static int bts_trace_init(struct trace_array *tr)
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static int bts_trace_init(struct trace_array *tr)
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{
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{
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hw_branch_trace = tr;
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register_hotcpu_notifier(&bts_hotcpu_notifier);
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register_hotcpu_notifier(&bts_hotcpu_notifier);
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tracing_reset_online_cpus(tr);
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tracing_reset_online_cpus(tr);
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bts_trace_start(tr);
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bts_trace_start(tr);
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@ -170,8 +173,9 @@ static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
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return TRACE_TYPE_UNHANDLED;
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return TRACE_TYPE_UNHANDLED;
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}
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}
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void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
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void trace_hw_branch(u64 from, u64 to)
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{
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{
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struct trace_array *tr = hw_branch_trace;
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struct ring_buffer_event *event;
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struct ring_buffer_event *event;
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struct hw_branch_entry *entry;
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struct hw_branch_entry *entry;
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unsigned long irq1, irq2;
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unsigned long irq1, irq2;
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@ -204,8 +208,7 @@ void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
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local_irq_restore(irq1);
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local_irq_restore(irq1);
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}
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}
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static void trace_bts_at(struct trace_array *tr,
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static void trace_bts_at(const struct bts_trace *trace, void *at)
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const struct bts_trace *trace, void *at)
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{
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{
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struct bts_struct bts;
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struct bts_struct bts;
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int err = 0;
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int err = 0;
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@ -220,7 +223,7 @@ static void trace_bts_at(struct trace_array *tr,
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switch (bts.qualifier) {
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switch (bts.qualifier) {
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case BTS_BRANCH:
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case BTS_BRANCH:
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trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
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trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
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break;
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break;
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}
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}
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}
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}
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@ -236,12 +239,15 @@ static void trace_bts_cpu(void *arg)
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const struct bts_trace *trace;
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const struct bts_trace *trace;
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unsigned char *at;
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unsigned char *at;
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if (!this_tracer)
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if (unlikely(!tr))
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return;
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return;
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if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
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if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
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return;
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return;
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if (unlikely(!this_tracer))
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return;
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ds_suspend_bts(this_tracer);
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ds_suspend_bts(this_tracer);
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trace = ds_read_bts(this_tracer);
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trace = ds_read_bts(this_tracer);
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if (!trace)
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if (!trace)
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@ -249,11 +255,11 @@ static void trace_bts_cpu(void *arg)
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for (at = trace->ds.top; (void *)at < trace->ds.end;
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for (at = trace->ds.top; (void *)at < trace->ds.end;
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at += trace->ds.size)
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at += trace->ds.size)
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trace_bts_at(tr, trace, at);
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trace_bts_at(trace, at);
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for (at = trace->ds.begin; (void *)at < trace->ds.top;
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for (at = trace->ds.begin; (void *)at < trace->ds.top;
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at += trace->ds.size)
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at += trace->ds.size)
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trace_bts_at(tr, trace, at);
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trace_bts_at(trace, at);
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out:
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out:
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ds_resume_bts(this_tracer);
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ds_resume_bts(this_tracer);
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@ -268,6 +274,15 @@ static void trace_bts_prepare(struct trace_iterator *iter)
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mutex_unlock(&bts_tracer_mutex);
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mutex_unlock(&bts_tracer_mutex);
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}
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}
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void trace_hw_branch_oops(void)
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{
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mutex_lock(&bts_tracer_mutex);
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trace_bts_cpu(hw_branch_trace);
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mutex_unlock(&bts_tracer_mutex);
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}
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struct tracer bts_tracer __read_mostly =
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struct tracer bts_tracer __read_mostly =
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{
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{
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.name = "hw-branch-tracer",
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.name = "hw-branch-tracer",
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