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Steven Rostedt 1085a87765 ftrace: Be first to run code modification on modules 
commit c1bf08ac26 upstream.

If some other kernel subsystem has a module notifier, and adds a kprobe
to a ftrace mcount point (now that kprobes work on ftrace points),
when the ftrace notifier runs it will fail and disable ftrace, as well
as kprobes that are attached to ftrace points.

Here's the error:

 WARNING: at kernel/trace/ftrace.c:1618 ftrace_bug+0x239/0x280()
 Hardware name: Bochs
 Modules linked in: fat(+) stap_56d28a51b3fe546293ca0700b10bcb29__8059(F) nfsv4 auth_rpcgss nfs dns_resolver fscache xt_nat iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack lockd sunrpc ppdev parport_pc parport microcode virtio_net i2c_piix4 drm_kms_helper ttm drm i2c_core [last unloaded: bid_shared]
 Pid: 8068, comm: modprobe Tainted: GF            3.7.0-0.rc8.git0.1.fc19.x86_64 #1
 Call Trace:
  [<ffffffff8105e70f>] warn_slowpath_common+0x7f/0xc0
  [<ffffffff81134106>] ? __probe_kernel_read+0x46/0x70
  [<ffffffffa0180000>] ? 0xffffffffa017ffff
  [<ffffffffa0180000>] ? 0xffffffffa017ffff
  [<ffffffff8105e76a>] warn_slowpath_null+0x1a/0x20
  [<ffffffff810fd189>] ftrace_bug+0x239/0x280
  [<ffffffff810fd626>] ftrace_process_locs+0x376/0x520
  [<ffffffff810fefb7>] ftrace_module_notify+0x47/0x50
  [<ffffffff8163912d>] notifier_call_chain+0x4d/0x70
  [<ffffffff810882f8>] __blocking_notifier_call_chain+0x58/0x80
  [<ffffffff81088336>] blocking_notifier_call_chain+0x16/0x20
  [<ffffffff810c2a23>] sys_init_module+0x73/0x220
  [<ffffffff8163d719>] system_call_fastpath+0x16/0x1b
 ---[ end trace 9ef46351e53bbf80 ]---
 ftrace failed to modify [<ffffffffa0180000>] init_once+0x0/0x20 [fat]
  actual: cc:bb:d2:4b:e1

A kprobe was added to the init_once() function in the fat module on load.
But this happened before ftrace could have touched the code. As ftrace
didn't run yet, the kprobe system had no idea it was a ftrace point and
simply added a breakpoint to the code (0xcc in the cc:bb:d2:4b:e1).

Then when ftrace went to modify the location from a call to mcount/fentry
into a nop, it didn't see a call op, but instead it saw the breakpoint op
and not knowing what to do with it, ftrace shut itself down.

The solution is to simply give the ftrace module notifier the max priority.
This should have been done regardless, as the core code ftrace modification
also happens very early on in boot up. This makes the module modification
closer to core modification.

Link: http://lkml.kernel.org/r/20130107140333.593683061@goodmis.org

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reported-by: Frank Ch. Eigler <fche@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-01-27 20:46:28 -08:00
..
debug kgdb,debug_core: pass the breakpoint struct instead of address and memory 2012-04-13 08:14:07 -07:00
events perf_event: Switch to internal refcount, fix race with close() 2012-10-02 09:47:24 -07:00
gcov gcov: disable CONFIG_CONSTRUCTORS when not needed by CONFIG_GCOV_KERNEL 2011-06-15 20:04:01 -07:00
irq genirq: Always force thread affinity 2013-01-11 09:03:38 -08:00
power ftrace: Disable function tracing during suspend/resume and hibernation, again 2012-08-09 08:27:35 -07:00
time time: Move ktime_t overflow checking into timespec_valid_strict 2012-10-02 09:47:52 -07:00
trace ftrace: Be first to run code modification on modules 2013-01-27 20:46:28 -08:00
.gitignore
acct.c
async.c Fix a dead loop in async_synchronize_full() 2012-10-02 09:47:41 -07:00
audit.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
audit.h
audit_tree.c audit: fix refcounting in audit-tree 2012-09-14 10:00:38 -07:00
audit_watch.c kill path_lookup() 2011-03-14 09:15:23 -04:00
auditfilter.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
auditsc.c audit: acquire creds selectively to reduce atomic op overhead 2011-04-27 15:11:03 +02:00
backtracetest.c
bounds.c memcg: remove direct page_cgroup-to-page pointer 2011-03-23 19:46:28 -07:00
capability.c Merge branch 'master' into next 2011-05-19 18:51:57 +10:00
cgroup.c cgroup: remove incorrect dget/dput() pair in cgroup_create_dir() 2013-01-11 09:03:47 -08:00
cgroup_freezer.c cgroup_freezer: fix freezing groups with stopped tasks 2011-12-09 08:52:27 -08:00
compat.c compat: Fix RT signal mask corruption via sigprocmask 2012-05-21 09:40:04 -07:00
configs.c
cpu.c PM / Sleep: Fix race between CPU hotplug and freezer 2012-01-12 11:35:46 -08:00
cpuset.c CPU hotplug, cpusets, suspend: Don't modify cpusets during suspend/resume 2012-10-13 05:28:15 +09:00
crash_dump.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
cred.c cred: copy_process() should clear child->replacement_session_keyring 2012-04-13 08:14:08 -07:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c sched: Fix ancient race in do_exit() 2012-10-02 09:47:55 -07:00
extable.c extable, core_kernel_data(): Make sure all archs define _sdata 2011-05-20 08:56:56 +02:00
fork.c cpuset: mm: reduce large amounts of memory barrier related damage v3 2012-08-01 12:27:20 -07:00
freezer.c Freezer: Use SMP barriers 2011-05-17 23:19:17 +02:00
futex.c futex: avoid wake_futex() for a PI futex_q 2012-12-03 12:59:14 -08:00
futex_compat.c futex: Do not leak robust list to unprivileged process 2012-04-22 16:21:45 -07:00
groups.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
hrtimer.c hrtimer: Update hrtimer base offsets each hrtimer_interrupt 2012-07-19 08:58:46 -07:00
hung_task.c hung_task: fix false positive during vfork 2012-01-06 14:14:13 -08:00
irq_work.c irq_work: Use per cpu atomics instead of regular atomics 2010-12-18 15:54:48 +01:00
itimer.c
jump_label.c jump_label: jump_label_inc may return before the code is patched 2011-12-09 08:52:50 -08:00
kallsyms.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-25 17:52:22 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks arch:Kconfig.locks Remove unused config option. 2011-04-10 17:01:05 +02:00
Kconfig.preempt
kexec.c PM: Remove sysdev suspend, resume and shutdown operations 2011-05-11 21:37:15 +02:00
kfifo.c
kmod.c kmod: prevent kmod_loop_msg overflow in __request_module() 2011-11-11 09:35:48 -08:00
kprobes.c kprobes: adjust "fix a memory leak in function pre_handler_kretprobe()" 2012-03-12 10:32:57 -07:00
ksysfs.c kernel/ksysfs.c: expose file_caps_enabled in sysfs 2011-04-19 16:45:51 -07:00
kthread.c cpuset: Fix cpuset_cpus_allowed_fallback(), don't update tsk->rt.nr_cpus_allowed 2011-05-28 17:02:57 +02:00
latencytop.c Fix common misspellings 2011-03-31 11:26:23 -03:00
lockdep.c lockdep: Fix lock_is_held() on recursion 2011-06-07 12:25:50 +02:00
lockdep_internals.h
lockdep_proc.c lockdep: Remove unused 'factor' variable from lockdep_stats_show() 2011-03-23 13:54:47 +01:00
lockdep_states.h
Makefile cgroup: remove the ns_cgroup 2011-05-26 17:12:34 -07:00
module.c module: taint kernel when lve module is loaded 2012-10-21 09:17:10 -07:00
mutex-debug.c mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
mutex-debug.h mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
mutex.c lockdep, mutex: provide mutex_lock_nest_lock 2011-05-25 08:39:17 -07:00
mutex.h mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
notifier.c
nsproxy.c cgroup: remove the ns_cgroup 2011-05-26 17:12:34 -07:00
padata.c Fix common misspellings 2011-03-31 11:26:23 -03:00
panic.c lockdep, bug: Exclude TAINT_FIRMWARE_WORKAROUND from disabling lockdep 2012-02-13 11:06:10 -08:00
params.c params.c: Use new strtobool function to process boolean inputs 2011-05-19 16:55:28 +09:30
pid.c next_pidmap: fix overflow condition 2011-04-18 10:35:30 -07:00
pid_namespace.c pidns: call pid_ns_prepare_proc() from create_pid_namespace() 2011-03-23 19:46:58 -07:00
pm_qos_params.c Merge branch 'idle-release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6 2011-05-29 11:18:09 -07:00
posix-cpu-timers.c cputimer: Cure lock inversion 2011-10-25 07:10:14 +02:00
posix-timers.c posix-timers: RCU conversion 2011-05-24 12:10:51 +02:00
printk.c cap_syslog: don't use WARN_ONCE for CAP_SYS_ADMIN deprecation warning 2012-02-03 09:18:57 -08:00
profile.c kernel/profile.c: remove some duplicate code from profile_hits() 2011-05-26 17:12:37 -07:00
ptrace.c ptrace: ptrace_resume() shouldn't wake up !TASK_TRACED thread 2011-05-25 19:20:21 +02:00
range.c
rcupdate.c rcu: Use WARN_ON_ONCE for DEBUG_OBJECTS_RCU_HEAD warnings 2011-05-05 23:16:57 -07:00
rcutiny.c sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00
rcutiny_plugin.h rcu: Converge TINY_RCU expedited and normal boosting 2011-05-05 23:16:58 -07:00
rcutorture.c rcu: mark rcutorture boosting callback as being on-stack 2011-05-05 23:16:57 -07:00
rcutree.c rcu: Fix day-one dyntick-idle stall-warning bug 2012-10-13 05:28:11 +09:00
rcutree.h rcu: Move RCU_BOOST #ifdefs to header file 2011-06-16 16:12:05 -07:00
rcutree_plugin.h softirq,rcu: Inform RCU of irq_exit() activity 2011-07-20 10:50:12 -07:00
rcutree_trace.c rcu: use softirq instead of kthreads except when RCU_BOOST=y 2011-06-15 23:07:21 -07:00
relay.c relay: prevent integer overflow in relay_open() 2012-02-20 12:48:10 -08:00
res_counter.c memcg: res_counter_read_u64(): fix potential races on 32-bit machines 2011-03-23 19:46:22 -07:00
resource.c Resource: fix wrong resource window calculation 2012-11-26 11:34:58 -08:00
rtmutex-debug.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.h
rtmutex-tester.c rtmutex: tester: Remove the remaining BKL leftovers 2011-02-22 22:07:22 +01:00
rtmutex.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex.h
rtmutex_common.h rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rwsem.c
sched.c CPU hotplug, cpusets, suspend: Don't modify cpusets during suspend/resume 2012-10-13 05:28:15 +09:00
sched_autogroup.c Revert "sched, autogroup: Stop going ahead if autogroup is disabled" 2012-12-10 10:45:08 -08:00
sched_autogroup.h Revert "sched, autogroup: Stop going ahead if autogroup is disabled" 2012-12-10 10:45:08 -08:00
sched_clock.c
sched_cpupri.c
sched_cpupri.h
sched_debug.c sched: Get rid of lock_depth 2011-04-24 13:18:38 +02:00
sched_fair.c sched: Break out cpu_power from the sched_group structure 2011-07-20 18:32:40 +02:00
sched_features.h sched: Allow for overlapping sched_domain spans 2011-07-20 18:32:41 +02:00
sched_idletask.c sched: Drop the rq argument to sched_class::select_task_rq() 2011-04-14 08:52:36 +02:00
sched_rt.c sched/rt: Fix task stack corruption under __ARCH_WANT_INTERRUPTS_ON_CTXSW 2012-02-13 11:06:08 -08:00
sched_stats.h sched: More sched_domain iterations fixes 2011-05-28 17:02:54 +02:00
sched_stoptask.c sched: Drop the rq argument to sched_class::select_task_rq() 2011-04-14 08:52:36 +02:00
seccomp.c
semaphore.c
signal.c ptrace: don't clear GROUP_STOP_SIGMASK on double-stop 2011-11-11 09:36:23 -08:00
smp.c generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts 2011-06-17 10:17:12 +02:00
softirq.c softirq,rcu: Inform RCU of irq_exit() activity 2011-07-20 10:50:12 -07:00
spinlock.c
srcu.c rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status 2011-01-14 04:56:49 -08:00
stacktrace.c
stop_machine.c x86, mtrr: lock stop machine during MTRR rendezvous sequence 2011-08-29 13:29:08 -07:00
sys.c use clamp_t in UNAME26 fix 2012-10-28 10:02:11 -07:00
sys_ni.c ipc: Add missing sys_ni entries for ipc/compat.c functions 2011-05-20 13:53:02 -07:00
sysctl.c sysctl: fix write access to dmesg_restrict/kptr_restrict 2012-04-13 08:14:07 -07:00
sysctl_binary.c binary_sysctl(): fix memory leak 2012-01-06 14:13:50 -08:00
sysctl_check.c sysctl_check: drop dead code 2011-03-23 19:46:51 -07:00
taskstats.c Make TASKSTATS require root access 2011-12-21 12:57:40 -08:00
test_kprobes.c
time.c time: Change jiffies_to_clock_t() argument type to unsigned long 2011-11-11 09:35:52 -08:00
timeconst.pl
timer.c timers: Fix endless looping between cascade() and internal_add_timer() 2012-10-21 09:17:10 -07:00
tracepoint.c jump label: Introduce static_branch() interface 2011-04-04 12:48:08 -04:00
tsacct.c
uid16.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
up.c
user-return-notifier.c Fix common misspellings 2011-03-31 11:26:23 -03:00
user.c userns: add a user_namespace as creator/owner of uts_namespace 2011-03-23 19:46:59 -07:00
user_namespace.c user_ns: improve the user_ns on-the-slab packaging 2011-01-13 08:03:18 -08:00
utsname.c ns proc: Add support for the uts namespace 2011-05-10 14:35:35 -07:00
utsname_sysctl.c
wait.c Fix common misspellings 2011-03-31 11:26:23 -03:00
watchdog.c watchdog: using u64 in get_sample_period() 2012-12-03 12:59:15 -08:00
workqueue.c workqueue: convert BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s 2012-12-17 10:49:02 -08:00
workqueue_sched.h