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Commit 88f7a890 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

ksym_tracer: Fix to make the tracer work 



ksym tracer doesn't work:

 # echo tasklist_lock:rw- > ksym_trace_filter
 -bash: echo: write error: No such device

It's because we pass to perf_event_create_kernel_counter()
a cpu number which is not present.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B3AF19E.1010201@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 40892367

kernel/hw_breakpoint.c

+7 −3
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#include <linux/percpu.h>

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/cpu.h>

#include <linux/smp.h>



#include <linux/hw_breakpoint.h>
@@ -388,7 +389,8 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, 
	if (!cpu_events)

		return ERR_PTR(-ENOMEM);



	for_each_possible_cpu(cpu) {

	get_online_cpus();

	for_each_online_cpu(cpu) {

		pevent = per_cpu_ptr(cpu_events, cpu);

		bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered);
@@ -399,18 +401,20 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, 
			goto fail;

		}

	}

	put_online_cpus();



	return cpu_events;



fail:

	for_each_possible_cpu(cpu) {

	for_each_online_cpu(cpu) {

		pevent = per_cpu_ptr(cpu_events, cpu);

		if (IS_ERR(*pevent))

			break;

		unregister_hw_breakpoint(*pevent);

	}

	put_online_cpus();



	free_percpu(cpu_events);

	/* return the error if any */

	return ERR_PTR(err);

}

EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);

kernel/trace/trace_ksym.c

+0 −1
Original line number Diff line number Diff line
@@ -197,7 +197,6 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr) 
	entry->attr.bp_addr = addr;

	entry->attr.bp_len = HW_BREAKPOINT_LEN_4;



	ret = -EAGAIN;

	entry->ksym_hbp = register_wide_hw_breakpoint(&entry->attr,

					ksym_hbp_handler);