tracing: Disable "other" permission bits in the tracefs files

When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for

tracing: Disable "other" permission bits in the tracefs files

When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.

As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing: Add a verifier to check string pointers for trace events

It is a common mistake for someone writing a trace event to save a pointer
to a string in the TP_fast_assign() and then display that

tracing: Add a verifier to check string pointers for trace events

It is a common mistake for someone writing a trace event to save a pointer
to a string in the TP_fast_assign() and then display that string pointer
in the TP_printk() with %s. The problem is that those two events may happen
a long time apart, where the source of the string may no longer exist.

The proper way to handle displaying any string that is not guaranteed to be
in the kernel core rodata section, is to copy it into the ring buffer via
the __string(), __assign_str() and __get_str() helper macros.

Add a check at run time while displaying the TP_printk() of events to make
sure that every %s referenced is safe to dereference, and if it is not,
trigger a warning and only show the address of the pointer, and the
dereferenced string if it can be safely retrieved with a
strncpy_from_kernel_nofault() call.

In order to not have to copy the parsing of vsnprintf() formats, or even
exporting its code, the verifier relies on vsnprintf() being able to
modify the va_list that is passed to it, and it remains modified after it
is called. This is the case for some architectures like x86_64, but other
architectures like x86_32 pass the va_list to vsnprintf() as a value not a
reference, and the verifier can not use it to parse the non string
arguments. Thus, at boot up, it is checked if vsnprintf() modifies the
passed in va_list or not, and a static branch will disable the verifier if
it's not compatible.

Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer

Current tracing_init_dentry() return a d_entry pointer, while is not
necessary. This function returns NULL on succ

tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer

Current tracing_init_dentry() return a d_entry pointer, while is not
necessary. This function returns NULL on success or error on failure,
which means there is no valid d_entry pointer return.

Let's return 0 on success and negative value for error.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Wei Yang <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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module: Fix up module_notifier return values

While auditing all module notifiers I noticed a whole bunch of fail
wrt the return value. Notifiers have a 'special' return semantics.

As is; NOTIFY_DON

module: Fix up module_notifier return values

While auditing all module notifiers I noticed a whole bunch of fail
wrt the return value. Notifiers have a 'special' return semantics.

As is; NOTIFY_DONE vs NOTIFY_OK is a bit vague; but
notifier_from_errno(0) results in NOTIFY_OK and NOTIFY_DONE has a
comment that says "Don't care".

From this I've used NOTIFY_DONE when the function completely ignores
the callback and notifier_to_error() isn't used.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Mathieu Desnoyers <[email protected]>
Reviewed-by: Joel Fernandes (Google) <[email protected]>
Reviewed-by: Robert Richter <[email protected]>
Acked-by: Steven Rostedt (VMware) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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tracing: Add locked_down checks to the open calls of files created for tracefs

Added various checks on open tracefs calls to see if tracefs is in lockdown
mode, and if so, to return -EPERM.

Note, t

tracing: Add locked_down checks to the open calls of files created for tracefs

Added various checks on open tracefs calls to see if tracefs is in lockdown
mode, and if so, to return -EPERM.

Note, the event format files (which are basically standard on all machines)
as well as the enabled_functions file (which shows what is currently being
traced) are not lockde down. Perhaps they should be, but it seems counter
intuitive to lockdown information to help you know if the system has been
modified.

Link: http://lkml.kernel.org/r/CAHk-=wj7fGPKUspr579Cii-w_y60PtRaiDgKuxVtBAMK0VNNkA@mail.gmail.com

Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing: Trivia spelling fix containerof() -> container_of()

This is the only location on kernel that has wrong spelling
of the container_of() helper. Fix it.

Signed-off-by: Andy Shevchenko <andriy

tracing: Trivia spelling fix containerof() -> container_of()

This is the only location on kernel that has wrong spelling
of the container_of() helper. Fix it.

Signed-off-by: Andy Shevchenko <[email protected]>
Acked-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>

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tracing: Add SPDX License format tags to tracing files

Add the SPDX License header to ease license compliance management.

Signed-off-by: Steven Rostedt (VMware) <[email protected]>

treewide: Align function definition open/close braces

Some functions definitions have either the initial open brace and/or
the closing brace outside of column 1.

Move those braces to column 1.

Thi

treewide: Align function definition open/close braces

Some functions definitions have either the initial open brace and/or
the closing brace outside of column 1.

Move those braces to column 1.

This allows various function analyzers like gnu complexity to work
properly for these modified functions.

Signed-off-by: Joe Perches <[email protected]>
Acked-by: Andy Shevchenko <[email protected]>
Acked-by: Paul Moore <[email protected]>
Acked-by: Alex Deucher <[email protected]>
Acked-by: Dave Chinner <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Acked-by: Alexandre Belloni <[email protected]>
Acked-by: Martin K. Petersen <[email protected]>
Acked-by: Takashi Iwai <[email protected]>
Acked-by: Mauro Carvalho Chehab <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Acked-by: Nicolin Chen <[email protected]>
Acked-by: Martin K. Petersen <[email protected]>
Acked-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

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tracing: Handle NULL formats in hold_module_trace_bprintk_format()

If a task uses a non constant string for the format parameter in
trace_printk(), then the trace_printk_fmt variable is set to NULL.

tracing: Handle NULL formats in hold_module_trace_bprintk_format()

If a task uses a non constant string for the format parameter in
trace_printk(), then the trace_printk_fmt variable is set to NULL. This
variable is then saved in the __trace_printk_fmt section.

The function hold_module_trace_bprintk_format() checks to see if duplicate
formats are used by modules, and reuses them if so (saves them to the list
if it is new). But this function calls lookup_format() that does a strcmp()
to the value (which is now NULL) and can cause a kernel oops.

This wasn't an issue till 3debb0a9ddb ("tracing: Fix trace_printk() to print
when not using bprintk()") which added "__used" to the trace_printk_fmt
variable, and before that, the kernel simply optimized it out (no NULL value
was saved).

The fix is simply to handle the NULL pointer in lookup_format() and have the
caller ignore the value if it was NULL.

Link: http://lkml.kernel.org/r/[email protected]

Reported-by: xingzhen <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Fixes: 3debb0a9ddb ("tracing: Fix trace_printk() to print when not using bprintk()")
Cc: [email protected] # v3.5+
Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Fix trace_printk() to print when not using bprintk()

The trace_printk() code will allocate extra buffers if the compile detects
that a trace_printk() is used. To do this, the format of the

tracing: Fix trace_printk() to print when not using bprintk()

The trace_printk() code will allocate extra buffers if the compile detects
that a trace_printk() is used. To do this, the format of the trace_printk()
is saved to the __trace_printk_fmt section, and if that section is bigger
than zero, the buffers are allocated (along with a message that this has
happened).

If trace_printk() uses a format that is not a constant, and thus something
not guaranteed to be around when the print happens, the compiler optimizes
the fmt out, as it is not used, and the __trace_printk_fmt section is not
filled. This means the kernel will not allocate the special buffers needed
for the trace_printk() and the trace_printk() will not write anything to the
tracing buffer.

Adding a "__used" to the variable in the __trace_printk_fmt section will
keep it around, even though it is set to NULL. This will keep the string
from being printed in the debugfs/tracing/printk_formats section as it is
not needed.

Reported-by: Vlastimil Babka <[email protected]>
Fixes: 07d777fe8c398 "tracing: Add percpu buffers for trace_printk()"
Cc: [email protected] # v3.5+
Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Fix setting of start_index in find_next()

When we do cat /sys/kernel/debug/tracing/printk_formats, we hit kernel
panic at t_show.

general protection fault: 0000 [#1] PREEMPT SMP
CPU: 0 PID

tracing: Fix setting of start_index in find_next()

When we do cat /sys/kernel/debug/tracing/printk_formats, we hit kernel
panic at t_show.

general protection fault: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 2957 Comm: sh Tainted: G W O 3.14.55-x86_64-01062-gd4acdc7 #2
RIP: 0010:[<ffffffff811375b2>]
[<ffffffff811375b2>] t_show+0x22/0xe0
RSP: 0000:ffff88002b4ebe80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004
RDX: 0000000000000004 RSI: ffffffff81fd26a6 RDI: ffff880032f9f7b1
RBP: ffff88002b4ebe98 R08: 0000000000001000 R09: 000000000000ffec
R10: 0000000000000000 R11: 000000000000000f R12: ffff880004d9b6c0
R13: 7365725f6d706400 R14: ffff880004d9b6c0 R15: ffffffff82020570
FS: 0000000000000000(0000) GS:ffff88003aa00000(0063) knlGS:00000000f776bc40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f6c02ff0 CR3: 000000002c2b3000 CR4: 00000000001007f0
Call Trace:
[<ffffffff811dc076>] seq_read+0x2f6/0x3e0
[<ffffffff811b749b>] vfs_read+0x9b/0x160
[<ffffffff811b7f69>] SyS_read+0x49/0xb0
[<ffffffff81a3a4b9>] ia32_do_call+0x13/0x13
---[ end trace 5bd9eb630614861e ]---
Kernel panic - not syncing: Fatal exception

When the first time find_next calls find_next_mod_format, it should
iterate the trace_bprintk_fmt_list to find the first print format of
the module. However in current code, start_index is smaller than *pos
at first, and code will not iterate the list. Latter container_of will
get the wrong address with former v, which will cause mod_fmt be a
meaningless object and so is the returned mod_fmt->fmt.

This patch will fix it by correcting the start_index. After fixed,
when the first time calls find_next_mod_format, start_index will be
equal to *pos, and code will iterate the trace_bprintk_fmt_list to
get the right module printk format, so is the returned mod_fmt->fmt.

Link: http://lkml.kernel.org/r/[email protected]

Cc: [email protected] # 3.12+
Fixes: 102c9323c35a8 "tracing: Add __tracepoint_string() to export string pointers"
Signed-off-by: Qiu Peiyang <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Remove access to trace_flags in trace_printk.c

In the effort to move the global trace_flags to the tracing instances, the
direct access to trace_flags must be removed from trace_printk.c

I

tracing: Remove access to trace_flags in trace_printk.c

In the effort to move the global trace_flags to the tracing instances, the
direct access to trace_flags must be removed from trace_printk.c

Instead, add a new trace_printk_enabled boolean that is set by a new access
function trace_printk_control(), that will enable or disable trace_printk.

Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Use IS_ERR() check for return value of tracing_init_dentry()

tracing_init_dentry() will soon return NULL as a valid pointer for the
top level tracing directroy. NULL can not be used as an e

tracing: Use IS_ERR() check for return value of tracing_init_dentry()

tracing_init_dentry() will soon return NULL as a valid pointer for the
top level tracing directroy. NULL can not be used as an error value.
Instead, switch to ERR_PTR() and check the return status with
IS_ERR().

Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Remove unneeded includes of debugfs.h and fs.h

The creation of tracing files and directories is for the most part
encapsulated in helper functions in trace.c. Other files do not need to
inc

tracing: Remove unneeded includes of debugfs.h and fs.h

The creation of tracing files and directories is for the most part
encapsulated in helper functions in trace.c. Other files do not need to
include debugfs.h or fs.h, as they may have needed to in the past.

Remove them from the files that do not need them.

Signed-off-by: Steven Rostedt <[email protected]>

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trace: Replace single-character seq_puts with seq_putc

Printing a single character to a seqfile might as well be done with
seq_putc instead of seq_puts; this avoids a strlen() call and a memory
acce

trace: Replace single-character seq_puts with seq_putc

Printing a single character to a seqfile might as well be done with
seq_putc instead of seq_puts; this avoids a strlen() call and a memory
access. It also shaves another few bytes off the generated code.

Link: http://lkml.kernel.org/r/[email protected]

Signed-off-by: Rasmus Villemoes <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Add __tracepoint_string() to export string pointers

There are several tracepoints (mostly in RCU), that reference a string
pointer and uses the print format of "%s" to display the string th

tracing: Add __tracepoint_string() to export string pointers

There are several tracepoints (mostly in RCU), that reference a string
pointer and uses the print format of "%s" to display the string that
exists in the kernel, instead of copying the actual string to the
ring buffer (saves time and ring buffer space).

But this has an issue with userspace tools that read the binary buffers
that has the address of the string but has no access to what the string
itself is. The end result is just output that looks like:

rcu_dyntick: ffffffff818adeaa 1 0
rcu_dyntick: ffffffff818adeb5 0 140000000000000
rcu_dyntick: ffffffff818adeb5 0 140000000000000
rcu_utilization: ffffffff8184333b
rcu_utilization: ffffffff8184333b

The above is pretty useless when read by the userspace tools. Ideally
we would want something that looks like this:

rcu_dyntick: Start 1 0
rcu_dyntick: End 0 140000000000000
rcu_dyntick: Start 140000000000000 0
rcu_callback: rcu_preempt rhp=0xffff880037aff710 func=put_cred_rcu 0/4
rcu_callback: rcu_preempt rhp=0xffff880078961980 func=file_free_rcu 0/5
rcu_dyntick: End 0 1

The trace_printk() which also only stores the address of the string
format instead of recording the string into the buffer itself, exports
the mapping of kernel addresses to format strings via the printk_format
file in the debugfs tracing directory.

The tracepoint strings can use this same method and output the format
to the same file and the userspace tools will be able to decipher
the address without any modification.

The tracepoint strings need its own section to save the strings because
the trace_printk section will cause the trace_printk() buffers to be
allocated if anything exists within the section. trace_printk() is only
used for debugging and should never exist in the kernel, we can not use
the trace_printk sections.

Add a new tracepoint_str section that will also be examined by the output
of the printk_format file.

Cc: Paul E. McKenney <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Add percpu buffers for trace_printk()

Currently, trace_printk() uses a single buffer to write into
to calculate the size and format needed to save the trace. To
do this safely in an SMP env

tracing: Add percpu buffers for trace_printk()

Currently, trace_printk() uses a single buffer to write into
to calculate the size and format needed to save the trace. To
do this safely in an SMP environment, a spin_lock() is taken
to only allow one writer at a time to the buffer. But this could
also affect what is being traced, and add synchronization that
would not be there otherwise.

Ideally, using percpu buffers would be useful, but since trace_printk()
is only used in development, having per cpu buffers for something
never used is a waste of space. Thus, the use of the trace_bprintk()
format section is changed to be used for static fmts as well as dynamic ones.
Then at boot up, we can check if the section that holds the trace_printk
formats is non-empty, and if it does contain something, then we
know a trace_printk() has been added to the kernel. At this time
the trace_printk per cpu buffers are allocated. A check is also
done at module load time in case a module is added that contains a
trace_printk().

Once the buffers are allocated, they are never freed. If you use
a trace_printk() then you should know what you are doing.

A buffer is made for each type of context:

normal
softirq
irq
nmi

The context is checked and the appropriate buffer is used.
This allows for totally lockless usage of trace_printk(),
and they no longer even disable interrupts.

Requested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Clean up tb_fmt to not give faulty compile warning

gcc incorrectly states that the variable "fmt" is uninitialized when
CC_OPITMIZE_FOR_SIZE is set.

Instead of just blindly setting fmt to

tracing: Clean up tb_fmt to not give faulty compile warning

gcc incorrectly states that the variable "fmt" is uninitialized when
CC_OPITMIZE_FOR_SIZE is set.

Instead of just blindly setting fmt to NULL, the code is cleaned up
a little to be a bit easier for humans to follow, as well as gcc
to know the variables are initialized.

Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Fix regression in printk_formats file

The fix to fix the printk_formats of modules broke the
printk_formats of trace_printks in the kernel.

The update of what to show via the seq_file was

tracing: Fix regression in printk_formats file

The fix to fix the printk_formats of modules broke the
printk_formats of trace_printks in the kernel.

The update of what to show via the seq_file was only updated
if the passed in fmt was NULL, which happens only on the first
iteration. The result was showing the first format every time
instead of iterating through the available formats.

Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Print trace_bprintk() formats for modules too

The file debugfs/tracing/printk_formats maps the addresses
to the formats that are used by trace_bprintk() so that userspace
tools can read the

tracing: Print trace_bprintk() formats for modules too

The file debugfs/tracing/printk_formats maps the addresses
to the formats that are used by trace_bprintk() so that userspace
tools can read the buffer and be able to decode trace_bprintk events
to get the format saved when reading the ring buffer directly.

This is because trace_bprintk() does not store the format into the
buffer, but just the address of the format, which is hidden in
the kernel memory.

But currently it only exports trace_bprintk()s from the kernel core
and not for modules. The modules need their formats exported
as well.

Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Convert trace_printk() formats for module to const char *

The trace_printk() formats for modules do not show up in the
debugfs/tracing/printk_formats file. Only the formats that are
for tra

tracing: Convert trace_printk() formats for module to const char *

The trace_printk() formats for modules do not show up in the
debugfs/tracing/printk_formats file. Only the formats that are
for trace_printk()s that are in the kernel core.

To facilitate the change to add trace_printk() formats from modules
into that file as well, we need to convert the structure that
holds the formats from char fmt[], into const char *fmt,
and allocate them separately.

Signed-off-by: Steven Rostedt <[email protected]>

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tracing: Remove markers

Now that the last users of markers have migrated to the event
tracer we can kill off the (now orphan) support code.

Signed-off-by: Christoph Hellwig <[email protected]>
Acked-by: M

tracing: Remove markers

Now that the last users of markers have migrated to the event
tracer we can kill off the (now orphan) support code.

Signed-off-by: Christoph Hellwig <[email protected]>
Acked-by: Mathieu Desnoyers <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

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tracing: show proper address for trace-printk format

Since the trace_printk may use pointers to the format fields
in the buffer, they are exported via debugfs/tracing/printk_formats.
This is used by

tracing: show proper address for trace-printk format

Since the trace_printk may use pointers to the format fields
in the buffer, they are exported via debugfs/tracing/printk_formats.
This is used by utilities that read the ring buffer in binary format.
It helps the utilities map the address of the format in the binary
buffer to what the printf format looks like.

Unfortunately, the way the output code works, it exports the address
of the pointer to the format address, and not the format address
itself. This makes the file totally useless in trying to figure
out what format string a binary address belongs to.

Signed-off-by: Steven Rostedt <[email protected]>

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tracing_bprintk: Don't increment @pos in t_start()

It's wrong to increment @pos in t_start(), otherwise we'll lose
some entries when reading printk_formats, if the output is larger
than PAGE_SIZE.

tracing_bprintk: Don't increment @pos in t_start()

It's wrong to increment @pos in t_start(), otherwise we'll lose
some entries when reading printk_formats, if the output is larger
than PAGE_SIZE.

Reported-by: Lai Jiangshan <[email protected]>
Reviewed-by: Liming Wang <[email protected]>
Signed-off-by: Li Zefan <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

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tracing/ftrace: factorize the tracing files creation

Impact: cleanup

Most of the tracing files creation follow the same pattern:

ret = debugfs_create_file(...)
if (!ret)
pr_warning("Couldn't crea

tracing/ftrace: factorize the tracing files creation

Impact: cleanup

Most of the tracing files creation follow the same pattern:

ret = debugfs_create_file(...)
if (!ret)
pr_warning("Couldn't create ... entry\n")

Unify it!

Reported-by: Ingo Molnar <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

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