- Allow kernel trace instance creation to specify what events are created
Inside the kernel, a subsystem may create a tracing instance that it can
use to send events to user space. This sub-system may not care about the
thousands of events that exist in eventfs. Allow the sub-system to specify
what sub-systems of events it cares about, and only those events are exposed
to this instance.
- Allow the ring buffer to be broken up into bigger sub-buffers than just the
architecture page size. A new tracefs file called "buffer_subbuf_size_kb"
is created. The user can now specify a minimum size the sub-buffer may be
in kilobytes. Note, that the implementation currently make the sub-buffer
size a power of 2 pages (1, 2, 4, 8, 16, ...) but the user only writes in
kilobyte size, and the sub-buffer will be updated to the next size that
it will can accommodate it. If the user writes in 10, it will change the
size to be 4 pages on x86 (16K), as that is the next available size that
can hold 10K pages.
- Update the debug output when a corrupt time is detected in the ring buffer.
If the ring buffer detects inconsistent timestamps, there's a debug config
options that will dump the contents of the meta data of the sub-buffer that
is used for debugging. Add some more information to this dump that helps
with debugging.
- Add more timestamp debugging checks (only triggers when the config is enabled)
- Increase the trace_seq iterator to 2 page sizes.
- Allow strings written into tracefs_marker to be larger. Up to just under
2 page sizes (based on what trace_seq can hold).
- Increase the trace_maker_raw write to be as big as a sub-buffer can hold.
- Remove 32 bit time stamp logic, now that the rb_time_cmpxchg() has been
removed.
- More selftests were added.
- Some code clean ups as well.
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Merge tag 'trace-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt:
- Allow kernel trace instance creation to specify what events are
created
Inside the kernel, a subsystem may create a tracing instance that it
can use to send events to user space. This sub-system may not care
about the thousands of events that exist in eventfs. Allow the
sub-system to specify what sub-systems of events it cares about, and
only those events are exposed to this instance.
- Allow the ring buffer to be broken up into bigger sub-buffers than
just the architecture page size.
A new tracefs file called "buffer_subbuf_size_kb" is created. The
user can now specify a minimum size the sub-buffer may be in
kilobytes. Note, that the implementation currently make the
sub-buffer size a power of 2 pages (1, 2, 4, 8, 16, ...) but the user
only writes in kilobyte size, and the sub-buffer will be updated to
the next size that it will can accommodate it. If the user writes in
10, it will change the size to be 4 pages on x86 (16K), as that is
the next available size that can hold 10K pages.
- Update the debug output when a corrupt time is detected in the ring
buffer. If the ring buffer detects inconsistent timestamps, there's a
debug config options that will dump the contents of the meta data of
the sub-buffer that is used for debugging. Add some more information
to this dump that helps with debugging.
- Add more timestamp debugging checks (only triggers when the config is
enabled)
- Increase the trace_seq iterator to 2 page sizes.
- Allow strings written into tracefs_marker to be larger. Up to just
under 2 page sizes (based on what trace_seq can hold).
- Increase the trace_maker_raw write to be as big as a sub-buffer can
hold.
- Remove 32 bit time stamp logic, now that the rb_time_cmpxchg() has
been removed.
- More selftests were added.
- Some code clean ups as well.
* tag 'trace-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (29 commits)
ring-buffer: Remove stale comment from ring_buffer_size()
tracing histograms: Simplify parse_actions() function
tracing/selftests: Remove exec permissions from trace_marker.tc test
ring-buffer: Use subbuf_order for buffer page masking
tracing: Update subbuffer with kilobytes not page order
ringbuffer/selftest: Add basic selftest to test changing subbuf order
ring-buffer: Add documentation on the buffer_subbuf_order file
ring-buffer: Just update the subbuffers when changing their allocation order
ring-buffer: Keep the same size when updating the order
tracing: Stop the tracing while changing the ring buffer subbuf size
tracing: Update snapshot order along with main buffer order
ring-buffer: Make sure the spare sub buffer used for reads has same size
ring-buffer: Do no swap cpu buffers if order is different
ring-buffer: Clear pages on error in ring_buffer_subbuf_order_set() failure
ring-buffer: Read and write to ring buffers with custom sub buffer size
ring-buffer: Set new size of the ring buffer sub page
ring-buffer: Add interface for configuring trace sub buffer size
ring-buffer: Page size per ring buffer
ring-buffer: Have ring_buffer_print_page_header() be able to access ring_buffer_iter
ring-buffer: Check if absolute timestamp goes backwards
...
When the buffer_percent file was added to the kernel, the documentation
should have been updated to document what that file does.
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Fixes: 03329f9939 ("tracing: Add tracefs file buffer_percentage")
Signed-off-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231229122402.537eb252@gandalf.local.home
Using page order for deciding what the size of the ring buffer sub buffers
are is exposing a bit too much of the implementation. Although the sub
buffers are only allocated in orders of pages, allow the user to specify
the minimum size of each sub-buffer via kilobytes like they can with the
buffer size itself.
If the user specifies 3 via:
echo 3 > buffer_subbuf_size_kb
Then the sub-buffer size will round up to 4kb (on a 4kb page size system).
If they specify:
echo 6 > buffer_subbuf_size_kb
The sub-buffer size will become 8kb.
and so on.
Link: https://lore.kernel.org/linux-trace-kernel/20231219185631.809766769@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add to the documentation how to use the buffer_subbuf_order file to change
the size and how it affects what events can be added to the ring buffer.
Link: https://lore.kernel.org/linux-trace-kernel/20231219185631.230636734@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The filename for setting the cpumask should be `tracing_cpumask`,
instead of `tracing_cpu_mask`.
Signed-off-by: Yuanhsi Chung <freshliver.cys@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20231104103329.215139-1-freshliver.cys@gmail.com>
Adding new available_filter_functions_addrs file that shows all available
functions (same as available_filter_functions) together with addresses,
like:
# cat available_filter_functions_addrs | head
ffffffff81000770 __traceiter_initcall_level
ffffffff810007c0 __traceiter_initcall_start
ffffffff81000810 __traceiter_initcall_finish
ffffffff81000860 trace_initcall_finish_cb
...
Note displayed address is the patch-site address and can differ from
/proc/kallsyms address.
It's useful to have address avilable for traceable symbols, so we don't
need to allways cross check kallsyms with available_filter_functions
(or the other way around) and have all the data in single file.
For backwards compatibility reasons we can't change the existing
available_filter_functions file output, but we need to add new file.
The problem is that we need to do 2 passes:
- through available_filter_functions and find out if the function is traceable
- through /proc/kallsyms to get the address for traceable function
Having available_filter_functions symbols together with addresses allow
us to skip the kallsyms step and we are ok with the address in
available_filter_functions_addr not being the function entry, because
kprobe_multi uses fprobe and that handles both entry and patch-site
address properly.
We have 2 interfaces how to create kprobe_multi link:
a) passing symbols to kernel
1) user gathers symbols and need to ensure that they are
trace-able -> pass through available_filter_functions file
2) kernel takes those symbols and translates them to addresses
through kallsyms api
3) addresses are passed to fprobe/ftrace through:
register_fprobe_ips
-> ftrace_set_filter_ips
b) passing addresses to kernel
1) user gathers symbols and needs to ensure that they are
trace-able -> pass through available_filter_functions file
2) user takes those symbols and translates them to addresses
through /proc/kallsyms
3) addresses are passed to the kernel and kernel calls:
register_fprobe_ips
-> ftrace_set_filter_ips
The new available_filter_functions_addrs file helps us with option b),
because we can make 'b 1' and 'b 2' in one step - while filtering traceable
functions, we get the address directly.
Link: https://lore.kernel.org/linux-trace-kernel/20230611130029.1202298-1-jolsa@kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Tested-by: Jackie Liu <liuyun01@kylinos.cn> # x86
Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add documentation for the two newly introduced options for the
function_graph tracer. The funcgraph-retval option is used to
control whether or not to display the return value, while the
funcgraph-retval-hex option is used to control the display
format of the return value.
Link: https://lkml.kernel.org/r/2b5635f05146161b54c9ea6307e25efe5ccebdad.1680954589.git.pengdonglin@sangfor.com.cn
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Donglin Peng <pengdonglin@sangfor.com.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
- Make buffer_percent read/write. The buffer_percent file is how users can
state how long to block on the tracing buffer depending on how much
is in the buffer. When it hits the "buffer_percent" it will wake the
task waiting on the buffer. For some reason it was set to read-only.
This was not noticed because testing was done as root without SELinux,
but with SELinux it will prevent even root to write to it without having
CAP_DAC_OVERRIDE.
- The "touched_functions" was added this merge window, but one of the
reasons for adding it was not implemented. That was to show what functions
were not only touched, but had either a direct trampoline attached to
it, or a kprobe or live kernel patching that can "hijack" the function
to run a different function. The point is to know if there's functions
in the kernel that may not be behaving as the kernel code shows. This can
be used for debugging. TODO: Add this information to kernel oops too.
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Merge tag 'trace-v6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull more tracing updates from Steven Rostedt:
- Make buffer_percent read/write.
The buffer_percent file is how users can state how long to block on
the tracing buffer depending on how much is in the buffer. When it
hits the "buffer_percent" it will wake the task waiting on the
buffer. For some reason it was set to read-only.
This was not noticed because testing was done as root without
SELinux, but with SELinux it will prevent even root to write to it
without having CAP_DAC_OVERRIDE.
- The "touched_functions" was added this merge window, but one of the
reasons for adding it was not implemented.
That was to show what functions were not only touched, but had either
a direct trampoline attached to it, or a kprobe or live kernel
patching that can "hijack" the function to run a different function.
The point is to know if there's functions in the kernel that may not
be behaving as the kernel code shows. This can be used for debugging.
TODO: Add this information to kernel oops too.
* tag 'trace-v6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ftrace: Add MODIFIED flag to show if IPMODIFY or direct was attached
tracing: Fix permissions for the buffer_percent file
If a function had ever had IPMODIFY or DIRECT attached to it, where this
is how live kernel patching and BPF overrides work, mark them and display
an "M" in the enabled_functions and touched_functions files. This can be
used for debugging. If a function had been modified and later there's a bug
in the code related to that function, this can be used to know if the cause
is possibly from a live kernel patch or a BPF program that changed the
behavior of the code.
Also update the documentation on the enabled_functions and
touched_functions output, as it was missing direct callers and CALL_OPS.
And include this new modify attribute.
Link: https://lore.kernel.org/linux-trace-kernel/20230502213233.004e3ae4@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
- User events are finally ready!
After lots of collaboration between various parties, we finally locked
down on a stable interface for user events that can also work with user
space only tracing. This is implemented by telling the kernel (or user
space library, but that part is user space only and not part of this
patch set), where the variable is that the application uses to know if
something is listening to the trace. There's also an interface to tell
the kernel about these events, which will show up in the
/sys/kernel/tracing/events/user_events/ directory, where it can be
enabled. When it's enabled, the kernel will update the variable, to tell
the application to start writing to the kernel.
See https://lwn.net/Articles/927595/
- Cleaned up the direct trampolines code to simplify arm64 addition of
direct trampolines. Direct trampolines use the ftrace interface but
instead of jumping to the ftrace trampoline, applications (mostly BPF)
can register their own trampoline for performance reasons.
- Some updates to the fprobe infrastructure. fprobes are more efficient than
kprobes, as it does not need to save all the registers that kprobes on
ftrace do. More work needs to be done before the fprobes will be exposed
as dynamic events.
- More updates to references to the obsolete path of
/sys/kernel/debug/tracing for the new /sys/kernel/tracing path.
- Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer line
by line instead of all at once. There's users in production kernels that
have a large data dump that originally used printk() directly, but the
data dump was larger than what printk() allowed as a single print.
Using seq_buf() to do the printing fixes that.
- Add /sys/kernel/tracing/touched_functions that shows all functions that
was every traced by ftrace or a direct trampoline. This is used for
debugging issues where a traced function could have caused a crash by
a bpf program or live patching.
- Add a "fields" option that is similar to "raw" but outputs the fields of
the events. It's easier to read by humans.
- Some minor fixes and clean ups.
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Merge tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt:
- User events are finally ready!
After lots of collaboration between various parties, we finally
locked down on a stable interface for user events that can also work
with user space only tracing.
This is implemented by telling the kernel (or user space library, but
that part is user space only and not part of this patch set), where
the variable is that the application uses to know if something is
listening to the trace.
There's also an interface to tell the kernel about these events,
which will show up in the /sys/kernel/tracing/events/user_events/
directory, where it can be enabled.
When it's enabled, the kernel will update the variable, to tell the
application to start writing to the kernel.
See https://lwn.net/Articles/927595/
- Cleaned up the direct trampolines code to simplify arm64 addition of
direct trampolines.
Direct trampolines use the ftrace interface but instead of jumping to
the ftrace trampoline, applications (mostly BPF) can register their
own trampoline for performance reasons.
- Some updates to the fprobe infrastructure. fprobes are more efficient
than kprobes, as it does not need to save all the registers that
kprobes on ftrace do. More work needs to be done before the fprobes
will be exposed as dynamic events.
- More updates to references to the obsolete path of
/sys/kernel/debug/tracing for the new /sys/kernel/tracing path.
- Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer
line by line instead of all at once.
There are users in production kernels that have a large data dump
that originally used printk() directly, but the data dump was larger
than what printk() allowed as a single print.
Using seq_buf() to do the printing fixes that.
- Add /sys/kernel/tracing/touched_functions that shows all functions
that was every traced by ftrace or a direct trampoline. This is used
for debugging issues where a traced function could have caused a
crash by a bpf program or live patching.
- Add a "fields" option that is similar to "raw" but outputs the fields
of the events. It's easier to read by humans.
- Some minor fixes and clean ups.
* tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (41 commits)
ring-buffer: Sync IRQ works before buffer destruction
tracing: Add missing spaces in trace_print_hex_seq()
ring-buffer: Ensure proper resetting of atomic variables in ring_buffer_reset_online_cpus
recordmcount: Fix memory leaks in the uwrite function
tracing/user_events: Limit max fault-in attempts
tracing/user_events: Prevent same address and bit per process
tracing/user_events: Ensure bit is cleared on unregister
tracing/user_events: Ensure write index cannot be negative
seq_buf: Add seq_buf_do_printk() helper
tracing: Fix print_fields() for __dyn_loc/__rel_loc
tracing/user_events: Set event filter_type from type
ring-buffer: Clearly check null ptr returned by rb_set_head_page()
tracing: Unbreak user events
tracing/user_events: Use print_format_fields() for trace output
tracing/user_events: Align structs with tabs for readability
tracing/user_events: Limit global user_event count
tracing/user_events: Charge event allocs to cgroups
tracing/user_events: Update documentation for ABI
tracing/user_events: Use write ABI in example
tracing/user_events: Add ABI self-test
...
There is a typo in the sentence "A kernel developer must be
conscience ...". The word conscience should be conscious.
This patch fixes it.
Signed-off-by: Lin Yu Chen <starpt.official@gmail.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230412183739.89894-1-starpt.official@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The canonical location for the tracefs filesystem is at /sys/kernel/tracing.
But, from Documentation/trace/ftrace.rst:
Before 4.1, all ftrace tracing control files were within the debugfs
file system, which is typically located at /sys/kernel/debug/tracing.
For backward compatibility, when mounting the debugfs file system,
the tracefs file system will be automatically mounted at:
/sys/kernel/debug/tracing
Many parts of Documentation still reference this older debugfs path, so
let's update them to avoid confusion.
Signed-off-by: Ross Zwisler <zwisler@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230125213251.2013791-1-zwisler@google.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Currently setgid stripping in file_remove_privs()'s should_remove_suid()
helper is inconsistent with other parts of the vfs. Specifically, it only
raises ATTR_KILL_SGID if the inode is S_ISGID and S_IXGRP but not if the
inode isn't in the caller's groups and the caller isn't privileged over the
inode although we require this already in setattr_prepare() and
setattr_copy() and so all filesystem implement this requirement implicitly
because they have to use setattr_{prepare,copy}() anyway.
But the inconsistency shows up in setgid stripping bugs for overlayfs in
xfstests (e.g., generic/673, generic/683, generic/685, generic/686,
generic/687). For example, we test whether suid and setgid stripping works
correctly when performing various write-like operations as an unprivileged
user (fallocate, reflink, write, etc.):
echo "Test 1 - qa_user, non-exec file $verb"
setup_testfile
chmod a+rws $junk_file
commit_and_check "$qa_user" "$verb" 64k 64k
The test basically creates a file with 6666 permissions. While the file has
the S_ISUID and S_ISGID bits set it does not have the S_IXGRP set. On a
regular filesystem like xfs what will happen is:
sys_fallocate()
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> setattr_copy()
In should_remove_suid() we can see that ATTR_KILL_SUID is raised
unconditionally because the file in the test has S_ISUID set.
But we also see that ATTR_KILL_SGID won't be set because while the file
is S_ISGID it is not S_IXGRP (see above) which is a condition for
ATTR_KILL_SGID being raised.
So by the time we call notify_change() we have attr->ia_valid set to
ATTR_KILL_SUID | ATTR_FORCE. Now notify_change() sees that
ATTR_KILL_SUID is set and does:
ia_valid = attr->ia_valid |= ATTR_MODE
attr->ia_mode = (inode->i_mode & ~S_ISUID);
which means that when we call setattr_copy() later we will definitely
update inode->i_mode. Note that attr->ia_mode still contains S_ISGID.
Now we call into the filesystem's ->setattr() inode operation which will
end up calling setattr_copy(). Since ATTR_MODE is set we will hit:
if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
vfsgid_t vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
if (!vfsgid_in_group_p(vfsgid) &&
!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
mode &= ~S_ISGID;
inode->i_mode = mode;
}
and since the caller in the test is neither capable nor in the group of the
inode the S_ISGID bit is stripped.
But assume the file isn't suid then ATTR_KILL_SUID won't be raised which
has the consequence that neither the setgid nor the suid bits are stripped
even though it should be stripped because the inode isn't in the caller's
groups and the caller isn't privileged over the inode.
If overlayfs is in the mix things become a bit more complicated and the bug
shows up more clearly. When e.g., ovl_setattr() is hit from
ovl_fallocate()'s call to file_remove_privs() then ATTR_KILL_SUID and
ATTR_KILL_SGID might be raised but because the check in notify_change() is
questioning the ATTR_KILL_SGID flag again by requiring S_IXGRP for it to be
stripped the S_ISGID bit isn't removed even though it should be stripped:
sys_fallocate()
-> vfs_fallocate()
-> ovl_fallocate()
-> file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> ovl_setattr()
// TAKE ON MOUNTER'S CREDS
-> ovl_do_notify_change()
-> notify_change()
// GIVE UP MOUNTER'S CREDS
// TAKE ON MOUNTER'S CREDS
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = attr_force | kill;
-> notify_change()
The fix for all of this is to make file_remove_privs()'s
should_remove_suid() helper to perform the same checks as we already
require in setattr_prepare() and setattr_copy() and have notify_change()
not pointlessly requiring S_IXGRP again. It doesn't make any sense in the
first place because the caller must calculate the flags via
should_remove_suid() anyway which would raise ATTR_KILL_SGID.
While we're at it we move should_remove_suid() from inode.c to attr.c
where it belongs with the rest of the iattr helpers. Especially since it
returns ATTR_KILL_S{G,U}ID flags. We also rename it to
setattr_should_drop_suidgid() to better reflect that it indicates both
setuid and setgid bit removal and also that it returns attr flags.
Running xfstests with this doesn't report any regressions. We should really
try and use consistent checks.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
The documentation gives an example for opening trace marker with
write-only mode, but the flag WR_ONLY is not defined by glibc.
Use O_WRONLY to replace it.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20221008083250.3160-1-leo.yan@linaro.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add documentation for newly introduced trace clock "tai".
This clock corresponds to CLOCK_TAI.
Link: https://lkml.kernel.org/r/20220414091805.89667-4-kurt@linutronix.de
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Delete "tracing" due to it has been included in /proc/mounts.
Delete "echo nop > $tracefs/tracing/current_tracer", maybe
this command is redundant.
Signed-off-by: Zhaoyu Liu <zackary.liu.pro@gmail.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().
Update the documentation accordingly.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210803141621.780504-2-bigeasy@linutronix.de
Add tracefs/options/hash-ptr option to show hashed pointer
value by %p in event printk format string.
For the security reason, normal printk will show the hashed
pointer value (encrypted by random number) with %p to printk
buffer to hide the real address. But the tracefs/trace always
shows real address for debug. To bridge those outputs, add an
option to switch the output format. Ftrace users can use it
to find the hashed value corresponding to the real address
in trace log.
Link: https://lkml.kernel.org/r/160277372504.29307.14909828808982012211.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
while to come. Changes include:
- Some new Chinese translations
- Progress on the battle against double words words and non-HTTPS URLs
- Some block-mq documentation
- More RST conversions from Mauro. At this point, that task is
essentially complete, so we shouldn't see this kind of churn again for a
while. Unless we decide to switch to asciidoc or something...:)
- Lots of typo fixes, warning fixes, and more.
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Merge tag 'docs-5.9' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"It's been a busy cycle for documentation - hopefully the busiest for a
while to come. Changes include:
- Some new Chinese translations
- Progress on the battle against double words words and non-HTTPS
URLs
- Some block-mq documentation
- More RST conversions from Mauro. At this point, that task is
essentially complete, so we shouldn't see this kind of churn again
for a while. Unless we decide to switch to asciidoc or
something...:)
- Lots of typo fixes, warning fixes, and more"
* tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits)
scripts/kernel-doc: optionally treat warnings as errors
docs: ia64: correct typo
mailmap: add entry for <alobakin@marvell.com>
doc/zh_CN: add cpu-load Chinese version
Documentation/admin-guide: tainted-kernels: fix spelling mistake
MAINTAINERS: adjust kprobes.rst entry to new location
devices.txt: document rfkill allocation
PCI: correct flag name
docs: filesystems: vfs: correct flag name
docs: filesystems: vfs: correct sync_mode flag names
docs: path-lookup: markup fixes for emphasis
docs: path-lookup: more markup fixes
docs: path-lookup: fix HTML entity mojibake
CREDITS: Replace HTTP links with HTTPS ones
docs: process: Add an example for creating a fixes tag
doc/zh_CN: add Chinese translation prefer section
doc/zh_CN: add clearing-warn-once Chinese version
doc/zh_CN: add admin-guide index
doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label
futex: MAINTAINERS: Re-add selftests directory
...
Some documents were converted from the plain text documentation
to reStructuredText format; update references to match.
Signed-off-by: Manbing <manbing3@gmail.com>
Link: https://lore.kernel.org/r/20200630185356.3467-1-manbing3@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
generic_make_request has always been very confusingly misnamed, so rename
it to submit_bio_noacct to make it clear that it is submit_bio minus
accounting and a few checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is and has been for a very long time been a lot more going on in
flush_old_exec than just flushing the old state. After the movement
of code from setup_new_exec there is a whole lot more going on than
just flushing the old executables state.
Rename flush_old_exec to begin_new_exec to more accurately reflect
what this function does.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Now that reading the trace file does not temporarly stop tracing while it is
open, update the document to reflect this fact.
Link: http://lkml.kernel.org/r/20200317213417.209675068@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When opening the "trace" file, it is no longer necessary to disable tracing.
Note, a new option is created called "pause-on-trace", when set, will cause
the trace file to emulate its original behavior.
Link: http://lkml.kernel.org/r/20200317213416.903351225@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The hwlat tracer runs a loop of width time during a given window. It then
reports the max latency over a given threshold and records a timestamp. But
this timestamp is the time after the width has finished, and not the time it
actually triggered.
Record the actual time when the latency was greater than the threshold as
well as the number of times it was greater in a given width per window.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The current text could mislead the user into believing that the number
of pages allocated by each CPU ring buffer is calculated by the round
up of the division: buffer_size_kb / PAGE_SIZE.
Clarifies that a few extra pages may be allocated to accommodate buffer
management meta-data.
Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Suggested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Frank A. Cancio Bello <frank@generalsoftwareinc.com>
Link: https://lore.kernel.org/r/6f33be5f3d60e5ffc061d8d2b329d3d3ccf22a8c.1577231751.git.frank@generalsoftwareinc.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Clarify a few places where the ring buffer and the "snapshot" buffer
are cleared as a side effect of an operation.
This will avoid users lost of tracing data because of these so far
undocumented behavior.
Signed-off-by: Frank A. Cancio Bello <frank@generalsoftwareinc.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20191218191553.q4lwyxmquvtjzjfz@frank-laptop
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Livepatch uses ftrace for redirection to new patched functions. It means
that if ftrace is disabled, all live patched functions are disabled as
well. Toggling global 'ftrace_enabled' sysctl thus affect it directly.
It is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.
Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be
disabled by disabling ftrace_enabled. Equally, a callback with the flag
set cannot be registered if ftrace_enabled is disabled.
Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The current text could mislead the user into believing that only read()
disables tracing. Clarify that any open() call that requests read access
disables tracing.
Link: https://lkml.kernel.org/r/CAADnVQ+hU6QOC_dPmpjnuv=9g4SQEeaMEMqXOS2WpMj=q=LdiQ@mail.gmail.com
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
- Removing of non-DYNAMIC_FTRACE from 32bit x86
- Removing of mcount support from x86
- Emulating a call from int3 on x86_64, fixes live kernel patching
- Consolidated Tracing Error logs file
Minor updates:
- Removal of klp_check_compiler_support()
- kdb ftrace dumping output changes
- Accessing and creating ftrace instances from inside the kernel
- Clean up of #define if macro
- Introduction of TRACE_EVENT_NOP() to disable trace events based on config
options
And other minor fixes and clean ups
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Merge tag 'trace-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"The major changes in this tracing update includes:
- Removal of non-DYNAMIC_FTRACE from 32bit x86
- Removal of mcount support from x86
- Emulating a call from int3 on x86_64, fixes live kernel patching
- Consolidated Tracing Error logs file
Minor updates:
- Removal of klp_check_compiler_support()
- kdb ftrace dumping output changes
- Accessing and creating ftrace instances from inside the kernel
- Clean up of #define if macro
- Introduction of TRACE_EVENT_NOP() to disable trace events based on
config options
And other minor fixes and clean ups"
* tag 'trace-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits)
x86: Hide the int3_emulate_call/jmp functions from UML
livepatch: Remove klp_check_compiler_support()
ftrace/x86: Remove mcount support
ftrace/x86_32: Remove support for non DYNAMIC_FTRACE
tracing: Simplify "if" macro code
tracing: Fix documentation about disabling options using trace_options
tracing: Replace kzalloc with kcalloc
tracing: Fix partial reading of trace event's id file
tracing: Allow RCU to run between postponed startup tests
tracing: Fix white space issues in parse_pred() function
tracing: Eliminate const char[] auto variables
ring-buffer: Fix mispelling of Calculate
tracing: probeevent: Fix to make the type of $comm string
tracing: probeevent: Do not accumulate on ret variable
tracing: uprobes: Re-enable $comm support for uprobe events
ftrace/x86_64: Emulate call function while updating in breakpoint handler
x86_64: Allow breakpoints to emulate call instructions
x86_64: Add gap to int3 to allow for call emulation
tracing: kdb: Allow ftdump to skip all but the last few entries
tracing: Add trace_total_entries() / trace_total_entries_cpu()
...
There are some warnings produced when building trace. Fix them.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Move most of the hist trigger extended error documentation to
ftrace.rst and expand on it to fully document tracing/error_log.
Link: http://lkml.kernel.org/r/c5d53c8f643ef6844d6ad8d0200c116936730b01.1554072478.git.tom.zanussi@linux.intel.com
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Enabling of large number of functions by echoing in a large subset of the
functions in available_filter_functions can take a very long time. The
process requires testing all functions registered by the function tracer
(which is in the 10s of thousands), and doing a kallsyms lookup to convert
the ip address into a name, then comparing that name with the string passed
in.
When a function causes the function tracer to crash the system, a binary
bisect of the available_filter_functions can be done to find the culprit.
But this requires passing in half of the functions in
available_filter_functions over and over again, which makes it basically a
O(n^2) operation. With 40,000 functions, that ends up bing 1,600,000,000
opertions! And enabling this can take over 20 minutes.
As a quick speed up, if a number is passed into one of the filter files,
instead of doing a search, it just enables the function at the corresponding
line of the available_filter_functions file. That is:
# echo 50 > set_ftrace_filter
# cat set_ftrace_filter
x86_pmu_commit_txn
# head -50 available_filter_functions | tail -1
x86_pmu_commit_txn
This allows setting of half the available_filter_functions to take place in
less than a second!
# time seq 20000 > set_ftrace_filter
real 0m0.042s
user 0m0.005s
sys 0m0.015s
# wc -l set_ftrace_filter
20000 set_ftrace_filter
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Trivial fixes to spelling mistakes in ftrace.rst
v2: tripple -> triple
Signed-off-by: Amir Livneh <alivneh@fb.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add a description of stacktrace filter command.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The name of the directory for per-cpu function statistics
is trace_stat, not trace_stats.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
triggers. For example:
# cd /sys/kernel/debug/tracing
# echo 'snapshot' > events/ftrace/print/trigger
# echo 'cause snapshot' > trace_marker
The rest of the changes are various clean ups and also one stable fix that
was added late in the cycle.
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Merge tag 'trace-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"One new feature was added to ftrace, which is the trace_marker now
supports triggers. For example:
# cd /sys/kernel/debug/tracing
# echo 'snapshot' > events/ftrace/print/trigger
# echo 'cause snapshot' > trace_marker
The rest of the changes are various clean ups and also one stable fix
that was added late in the cycle"
* tag 'trace-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (21 commits)
tracing: Use match_string() instead of open coding it in trace_set_options()
branch-check: fix long->int truncation when profiling branches
ring-buffer: Fix typo in comment
ring-buffer: Fix a bunch of typos in comments
tracing/selftest: Add test to test simple snapshot trigger for trace_marker
tracing/selftest: Add test to test hist trigger between kernel event and trace_marker
tracing/selftest: Add selftests to test trace_marker histogram triggers
ftrace/selftest: Fix reset_trigger() to handle triggers with filters
ftrace/selftest: Have the reset_trigger code be a bit more careful
tracing: Document trace_marker triggers
tracing: Allow histogram triggers to access ftrace internal events
tracing: Prevent further users of zero size static arrays in trace events
tracing: Have zero size length in filter logic be full string
tracing: Add trigger file for trace_markers tracefs/ftrace/print
tracing: Do not show filter file for ftrace internal events
tracing: Add brackets in ftrace event dynamic arrays
tracing: Have event_trace_init() called by trace_init_tracefs()
tracing: Add __find_event_file() to find event files without restrictions
tracing: Do not reference event data in post call triggers
tracepoints: Fix the descriptions of tracepoint_probe_register{_prio}
...
including:
- Extensive RST conversions and organizational work in the
memory-management docs thanks to Mike Rapoport.
- An update of Documentation/features from Andrea Parri and a script to
keep it updated.
- Various LICENSES updates from Thomas, along with a script to check SPDX
tags.
- Work to fix dangling references to documentation files; this involved a
fair number of one-liner comment changes outside of Documentation/
...and the usual list of documentation improvements, typo fixes, etc.
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Merge tag 'docs-4.18' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"There's been a fair amount of work in the docs tree this time around,
including:
- Extensive RST conversions and organizational work in the
memory-management docs thanks to Mike Rapoport.
- An update of Documentation/features from Andrea Parri and a script
to keep it updated.
- Various LICENSES updates from Thomas, along with a script to check
SPDX tags.
- Work to fix dangling references to documentation files; this
involved a fair number of one-liner comment changes outside of
Documentation/
... and the usual list of documentation improvements, typo fixes, etc"
* tag 'docs-4.18' of git://git.lwn.net/linux: (103 commits)
Documentation: document hung_task_panic kernel parameter
docs/admin-guide/mm: add high level concepts overview
docs/vm: move ksm and transhuge from "user" to "internals" section.
docs: Use the kerneldoc comments for memalloc_no*()
doc: document scope NOFS, NOIO APIs
docs: update kernel versions and dates in tables
docs/vm: transhuge: split userspace bits to admin-guide/mm/transhuge
docs/vm: transhuge: minor updates
docs/vm: transhuge: change sections order
Documentation: arm: clean up Marvell Berlin family info
Documentation: gpio: driver: Fix a typo and some odd grammar
docs: ranoops.rst: fix location of ramoops.txt
scripts/documentation-file-ref-check: rewrite it in perl with auto-fix mode
docs: uio-howto.rst: use a code block to solve a warning
mm, THP, doc: Add document for thp_swpout/thp_swpout_fallback
w1: w1_io.c: fix a kernel-doc warning
Documentation/process/posting: wrap text at 80 cols
docs: admin-guide: add cgroup-v2 documentation
Revert "Documentation/features/vm: Remove arch support status file for 'pte_special'"
Documentation: refcount-vs-atomic: Update reference to LKMM doc.
...
Add documentation and an example on how to use trace_marker triggers.
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Saurav Shah