![Robert Richter](/assets/img/avatar_default.png)
Oprofile may crash in a KVM guest while unlaoding modules. This happens if oprofile_arch_init() fails and oprofile switches to the hr timer mode as a fallback. In this case oprofile_arch_exit() is called, but it never was initialized properly which causes the crash. This patch fixes this. oprofile: using timer interrupt. BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [<ffffffff8123c226>] unregister_syscore_ops+0x41/0x58 PGD 41da3f067 PUD 41d80e067 PMD 0 Oops: 0002 [#1] PREEMPT SMP CPU 5 Modules linked in: oprofile(-) Pid: 2382, comm: modprobe Not tainted 3.1.0-rc7-00018-g709a39d #18 Advanced Micro Device Anaheim/Anaheim RIP: 0010:[<ffffffff8123c226>] [<ffffffff8123c226>] unregister_syscore_ops+0x41/0x58 RSP: 0018:ffff88041de1de98 EFLAGS: 00010296 RAX: 0000000000000000 RBX: ffffffffa00060e0 RCX: dead000000200200 RDX: 0000000000000000 RSI: dead000000100100 RDI: ffffffff8178c620 RBP: ffff88041de1dea8 R08: 0000000000000001 R09: 0000000000000082 R10: 0000000000000000 R11: ffff88041de1dde8 R12: 0000000000000080 R13: fffffffffffffff5 R14: 0000000000000001 R15: 0000000000610210 FS: 00007f9ae5bef700(0000) GS:ffff88042fd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000008 CR3: 000000041ca44000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process modprobe (pid: 2382, threadinfo ffff88041de1c000, task ffff88042db6d040) Stack: ffff88041de1deb8 ffffffffa0006770 ffff88041de1deb8 ffffffffa000251e ffff88041de1dec8 ffffffffa00022c2 ffff88041de1ded8 ffffffffa0004993 ffff88041de1df78 ffffffff81073115 656c69666f72706f 0000000000610200 Call Trace: [<ffffffffa000251e>] op_nmi_exit+0x15/0x17 [oprofile] [<ffffffffa00022c2>] oprofile_arch_exit+0xe/0x10 [oprofile] [<ffffffffa0004993>] oprofile_exit+0x13/0x15 [oprofile] [<ffffffff81073115>] sys_delete_module+0x1c3/0x22f [<ffffffff811bf09e>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff8148070b>] system_call_fastpath+0x16/0x1b Code: 20 c6 78 81 e8 c5 cc 23 00 48 8b 13 48 8b 43 08 48 be 00 01 10 00 00 00 ad de 48 b9 00 02 20 00 00 00 ad de 48 c7 c7 20 c6 78 81 89 42 08 48 89 10 48 89 33 48 89 4b 08 e8 a6 c0 23 00 5a 5b RIP [<ffffffff8123c226>] unregister_syscore_ops+0x41/0x58 RSP <ffff88041de1de98> CR2: 0000000000000008 ---[ end trace 06d4e95b6aa3b437 ]--- CC: stable@kernel.org # 2.6.37+ Signed-off-by: Robert Richter <robert.richter@amd.com>
293 lines
5.1 KiB
C
293 lines
5.1 KiB
C
/**
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* @file oprof.c
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*
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* @remark Copyright 2002 OProfile authors
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* @remark Read the file COPYING
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*
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* @author John Levon <levon@movementarian.org>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/oprofile.h>
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#include <linux/moduleparam.h>
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#include <linux/workqueue.h>
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#include <linux/time.h>
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#include <linux/mutex.h>
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#include "oprof.h"
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#include "event_buffer.h"
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#include "cpu_buffer.h"
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#include "buffer_sync.h"
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#include "oprofile_stats.h"
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struct oprofile_operations oprofile_ops;
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unsigned long oprofile_started;
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unsigned long oprofile_backtrace_depth;
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static unsigned long is_setup;
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static DEFINE_MUTEX(start_mutex);
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/* timer
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0 - use performance monitoring hardware if available
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1 - use the timer int mechanism regardless
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*/
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static int timer = 0;
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int oprofile_setup(void)
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{
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int err;
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mutex_lock(&start_mutex);
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if ((err = alloc_cpu_buffers()))
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goto out;
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if ((err = alloc_event_buffer()))
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goto out1;
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if (oprofile_ops.setup && (err = oprofile_ops.setup()))
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goto out2;
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/* Note even though this starts part of the
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* profiling overhead, it's necessary to prevent
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* us missing task deaths and eventually oopsing
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* when trying to process the event buffer.
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*/
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if (oprofile_ops.sync_start) {
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int sync_ret = oprofile_ops.sync_start();
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switch (sync_ret) {
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case 0:
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goto post_sync;
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case 1:
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goto do_generic;
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case -1:
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goto out3;
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default:
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goto out3;
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}
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}
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do_generic:
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if ((err = sync_start()))
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goto out3;
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post_sync:
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is_setup = 1;
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mutex_unlock(&start_mutex);
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return 0;
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out3:
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if (oprofile_ops.shutdown)
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oprofile_ops.shutdown();
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out2:
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free_event_buffer();
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out1:
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free_cpu_buffers();
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out:
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mutex_unlock(&start_mutex);
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return err;
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}
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#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
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static void switch_worker(struct work_struct *work);
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static DECLARE_DELAYED_WORK(switch_work, switch_worker);
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static void start_switch_worker(void)
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{
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if (oprofile_ops.switch_events)
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schedule_delayed_work(&switch_work, oprofile_time_slice);
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}
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static void stop_switch_worker(void)
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{
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cancel_delayed_work_sync(&switch_work);
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}
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static void switch_worker(struct work_struct *work)
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{
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if (oprofile_ops.switch_events())
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return;
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atomic_inc(&oprofile_stats.multiplex_counter);
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start_switch_worker();
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}
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/* User inputs in ms, converts to jiffies */
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int oprofile_set_timeout(unsigned long val_msec)
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{
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int err = 0;
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unsigned long time_slice;
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mutex_lock(&start_mutex);
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if (oprofile_started) {
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err = -EBUSY;
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goto out;
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}
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if (!oprofile_ops.switch_events) {
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err = -EINVAL;
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goto out;
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}
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time_slice = msecs_to_jiffies(val_msec);
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if (time_slice == MAX_JIFFY_OFFSET) {
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err = -EINVAL;
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goto out;
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}
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oprofile_time_slice = time_slice;
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out:
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mutex_unlock(&start_mutex);
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return err;
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}
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#else
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static inline void start_switch_worker(void) { }
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static inline void stop_switch_worker(void) { }
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#endif
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/* Actually start profiling (echo 1>/dev/oprofile/enable) */
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int oprofile_start(void)
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{
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int err = -EINVAL;
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mutex_lock(&start_mutex);
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if (!is_setup)
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goto out;
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err = 0;
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if (oprofile_started)
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goto out;
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oprofile_reset_stats();
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if ((err = oprofile_ops.start()))
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goto out;
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start_switch_worker();
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oprofile_started = 1;
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out:
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mutex_unlock(&start_mutex);
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return err;
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}
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/* echo 0>/dev/oprofile/enable */
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void oprofile_stop(void)
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{
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mutex_lock(&start_mutex);
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if (!oprofile_started)
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goto out;
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oprofile_ops.stop();
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oprofile_started = 0;
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stop_switch_worker();
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/* wake up the daemon to read what remains */
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wake_up_buffer_waiter();
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out:
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mutex_unlock(&start_mutex);
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}
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void oprofile_shutdown(void)
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{
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mutex_lock(&start_mutex);
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if (oprofile_ops.sync_stop) {
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int sync_ret = oprofile_ops.sync_stop();
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switch (sync_ret) {
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case 0:
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goto post_sync;
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case 1:
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goto do_generic;
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default:
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goto post_sync;
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}
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}
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do_generic:
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sync_stop();
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post_sync:
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if (oprofile_ops.shutdown)
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oprofile_ops.shutdown();
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is_setup = 0;
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free_event_buffer();
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free_cpu_buffers();
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mutex_unlock(&start_mutex);
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}
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int oprofile_set_ulong(unsigned long *addr, unsigned long val)
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{
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int err = -EBUSY;
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mutex_lock(&start_mutex);
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if (!oprofile_started) {
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*addr = val;
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err = 0;
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}
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mutex_unlock(&start_mutex);
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return err;
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}
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static int timer_mode;
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static int __init oprofile_init(void)
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{
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int err;
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/* always init architecture to setup backtrace support */
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err = oprofile_arch_init(&oprofile_ops);
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timer_mode = err || timer; /* fall back to timer mode on errors */
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if (timer_mode) {
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if (!err)
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oprofile_arch_exit();
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err = oprofile_timer_init(&oprofile_ops);
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if (err)
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return err;
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}
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err = oprofilefs_register();
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if (!err)
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return 0;
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/* failed */
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if (timer_mode)
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oprofile_timer_exit();
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else
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oprofile_arch_exit();
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return err;
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}
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static void __exit oprofile_exit(void)
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{
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oprofilefs_unregister();
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if (timer_mode)
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oprofile_timer_exit();
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else
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oprofile_arch_exit();
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}
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module_init(oprofile_init);
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module_exit(oprofile_exit);
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module_param_named(timer, timer, int, 0644);
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MODULE_PARM_DESC(timer, "force use of timer interrupt");
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("John Levon <levon@movementarian.org>");
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MODULE_DESCRIPTION("OProfile system profiler");
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