- 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.
-----BEGIN PGP SIGNATURE-----
iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCZFUcrxQccm9zdGVkdEBn
b29kbWlzLm9yZwAKCRAp5XQQmuv6qgOoAP0U2R6+jvA2ehQFb0UTCH9wEu2uEELA
g2CkdPNdn6wJjAD+O1+v5nVkqSpsArjHOhv5OGYrgh+VSXK3Z8EpQ9vUVgg=
=nfoh
-----END PGP SIGNATURE-----
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
e919a3f705