If a failure occurs while enabling a trace, it bails out and will remove
the tracepoints to be back to what the code originally was. But the fix
up had some bugs in it. By injecting a failure in the code, the fix up
ran to completion, but shortly afterward the system rebooted.
There was two bugs here.
The first was that there was no final sync run across the CPUs after the
fix up was done, and before the ftrace int3 handler flag was reset. That
means that other CPUs could still see the breakpoint and trigger on it
long after the flag was cleared, and the int3 handler would think it was
a spurious interrupt. Worse yet, the int3 handler could hit other breakpoints
because the ftrace int3 handler flag would have prevented the int3 handler
from going further.
Here's a description of the issue:
CPU0 CPU1
---- ----
remove_breakpoint();
modifying_ftrace_code = 0;
[still sees breakpoint]
<takes trap>
[sees modifying_ftrace_code as zero]
[no breakpoint handler]
[goto failed case]
[trap exception - kernel breakpoint, no
handler]
BUG()
The second bug was that the removal of the breakpoints required the
"within()" logic updates instead of accessing the ip address directly.
As the kernel text is mapped read-only when CONFIG_DEBUG_RODATA is set, and
the removal of the breakpoint is a modification of the kernel text.
The ftrace_write() includes the "within()" logic, where as, the
probe_kernel_write() does not. This prevented the breakpoint from being
removed at all.
Link: http://lkml.kernel.org/r/1392650573-3390-1-git-send-email-pmladek@suse.cz
Reported-by: Petr Mladek <pmladek@suse.cz>
Tested-by: Petr Mladek <pmladek@suse.cz>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The ENABLED flag needs to be cleared when a ftrace_ops is unregistered
otherwise it wont be able to be registered again.
This is only for static tracing and does not affect DYNAMIC_FTRACE at
all.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Being able to change the trace clock at boot can be advantageous if
you need a better source of when things happen across CPUs. The default
trace clock is the fastest, but it uses local clocks which may not be
synced across CPUs and it does not let you know when events took place
with respect to events on other CPUs.
The global trace clock can help in this case, and if you do not care
about timings, the counter "clock" is the best, as that is just a simple
atomic counter that is incremented for every event.
Usage is to add "trace_clock=counter" on the kernel command line. You
can replace counter with "global" or any of the clocks listed in
/sys/kernel/debug/tracing/trace_clock
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Appreciated-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Support multi-buffer on uprobe-based dynamic events by
using ftrace_event_file.
This patch is based kprobe-based dynamic events multibuffer
support work initially, commited by Masami(commit 41a7dd420c),
but revised as below:
Oleg changed the kprobe-based multibuffer design from
array-pointers of ftrace_event_file into simple list,
so this patch also change to the list design.
rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
to synchronize with ftrace_event_file list add and delete.
Even though we allow multi-uprobes instances now,
but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
in probe_event_enable currently, this means we cannot allow
one user is using uprobe-tracer, and another user is using
perf-probe on same uprobe concurrently.
(Perhaps this will be fix in future, kprobe don't have this
limitation now)
Link: http://lkml.kernel.org/r/1389946120-19610-4-git-send-email-namhyung@kernel.org
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Create a "set_ftrace_filter" and "set_ftrace_notrace" files in the instance
directories to let users filter of functions to trace for the given instance.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In preparation for having the function tracing instances be able to
filter on functions, the generic filter functions must first be
converted to take in the global_ops as a parameter.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Allow instances (sub-buffers) to enable function tracing.
Each instance will have its own function tracing capability.
For now, instances will not have function stack tracing, or will
they be able to pick and choose what functions they can trace.
Picking and choosing their own functions will come later.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As tracers will soon be used by instances, the tracer enabled field
needs to be converted to a counter instead of a boolean.
This counter is protected by the trace_types_lock mutex.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When an instance is about to be deleted, make sure the tracer
is set to nop. If it isn't reset the tracer and set it to the nop
tracer, otherwise memory leaks and bad pointers may result.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If global_ops function is being called directly, instead of the global_ops
list function, set the global_ops private to be the same as the ops private
that's being called directly.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Passing data to the function callback was originally done by adding the
ftrace_ops in another structure, and using the container_of() to get
the field. But this adds a bit more complexity than it is worth, and
adding a simple .private field to ftrace_ops makes things a lot easier.
But be warned, the .private data should not be freed once it is used
unless the ftrace_ops itself has gone through the necessary freeing
routines. A simple synchronize_sched() is not enough as functions
can be traced that are called outside the view of RCU and all its
concoctions.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently the tracers (function, function_graph, irqsoff, etc) can only
be used by the top level tracing directory (not for instances).
This sets up the infrastructure to allow instances to be able to
run a separate tracer apart from the what the top level tracing is
doing.
As tracers need to adapt for being used by instances, the tracers
must flag if they can be used by instances or not. Currently only the
'nop' tracer can be used by all instances.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As options (flags) may affect instances instead of being global
the flag_changed() callbacks need to receive the trace_array descriptor
of the instance they will be modifying.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As options (flags) may affect instances instead of being global
the set_flag() callbacks need to receive the trace_array descriptor
of the instance they will be modifying.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull btrfs fixes from Chris Mason:
"We have a small collection of fixes in my for-linus branch.
The big thing that stands out is a revert of a new ioctl. Users
haven't shipped yet in btrfs-progs, and Dave Sterba found a better way
to export the information"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: use right clone root offset for compressed extents
btrfs: fix null pointer deference at btrfs_sysfs_add_one+0x105
Btrfs: unset DCACHE_DISCONNECTED when mounting default subvol
Btrfs: fix max_inline mount option
Btrfs: fix a lockdep warning when cleaning up aborted transaction
Revert "btrfs: add ioctl to export size of global metadata reservation"
Pull devicetree fixes from Rob Herring:
"Fix booting on PPC boards. Changes to of_match_node matching caused
the serial port on some PPC boards to stop working. Reverted the
change and reimplement to split matching between new style compatible
only matching and fallback to old matching algorithm"
* tag 'dt-fixes-for-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
of: search the best compatible match first in __of_match_node()
Revert "OF: base: match each node compatible against all given matches first"
Currently, of_match_node compares each given match against all node's
compatible strings with of_device_is_compatible.
To achieve multiple compatible strings per node with ordering from
specific to generic, this requires given matches to be ordered from
specific to generic. For most of the drivers this is not true and also
an alphabetical ordering is more sane there.
Therefore, this patch introduces a function to match each of the node's
compatible strings against all given compatible matches without type and
name first, before checking the next compatible string. This implies
that node's compatibles are ordered from specific to generic while
given matches can be in any order. If we fail to find such a match
entry, then fall-back to the old method in order to keep compatibility.
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Tested-by: Stephen Chivers <schivers@csc.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Pull SCSI target fixes from Nicholas Bellinger:
"Mostly minor fixes this time to v3.14-rc1 related changes. Also
included is one fix for a free after use regression in persistent
reservations UNREGISTER logic that is CC'ed to >= v3.11.y stable"
* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
Target/sbc: Fix protection copy routine
IB/srpt: replace strict_strtoul() with kstrtoul()
target: Simplify command completion by removing CMD_T_FAILED flag
iser-target: Fix leak on failure in isert_conn_create_fastreg_pool
iscsi-target: Fix SNACK Type 1 + BegRun=0 handling
target: Fix missing length check in spc_emulate_evpd_83()
qla2xxx: Remove last vestiges of qla_tgt_cmd.cmd_list
target: Fix 32-bit + CONFIG_LBDAF=n link error w/ sector_div
target: Fix free-after-use regression in PR unregister
Pull i2c fixes from Wolfram Sang:
"i2c has a bugfix and documentation improvements for you"
* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
Documentation: i2c: mention ACPI method for instantiating devices
Documentation: i2c: describe devicetree method for instantiating devices
i2c: mv64xxx: refactor message start to ensure proper initialization
Steven Rostedt (Red Hat)
Namhyung Kim
zhangwei(Jovi)
Linus Torvalds
Kevin Hao