There's not much changes for the tracing system this release.
Mostly small clean ups and fixes.
The biggest change is to how bprintf works. bprintf is used by
trace_printk() to just save the format and args of a printf call,
and the formatting is done when the trace buffer is read. This is
done to keep the formatting out of the fast path (this was recommended
by you). The issue is when arguments are de-referenced.
If a pointer is saved, and the format has something like "%*pbl",
when the buffer is read, it will de-reference the argument then.
The problem is if the data no longer exists. This can cause the
kernel to oops.
The fix for this was to make these de-reference pointes do
the formatting at the time it is called (the fast path), as
this guarantees that the data exists (and doesn't change later)
-----BEGIN PGP SIGNATURE-----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=bmm/
-----END PGP SIGNATURE-----
Merge tag 'trace-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"There's not much changes for the tracing system this release. Mostly
small clean ups and fixes.
The biggest change is to how bprintf works. bprintf is used by
trace_printk() to just save the format and args of a printf call, and
the formatting is done when the trace buffer is read. This is done to
keep the formatting out of the fast path (this was recommended by
you). The issue is when arguments are de-referenced.
If a pointer is saved, and the format has something like "%*pbl", when
the buffer is read, it will de-reference the argument then. The
problem is if the data no longer exists. This can cause the kernel to
oops.
The fix for this was to make these de-reference pointes do the
formatting at the time it is called (the fast path), as this
guarantees that the data exists (and doesn't change later)"
* tag 'trace-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
vsprintf: Do not have bprintf dereference pointers
ftrace: Mark function tracer test functions noinline/noclone
trace_uprobe: Display correct offset in uprobe_events
tracing: Make sure the parsed string always terminates with '\0'
tracing: Clear parser->idx if only spaces are read
tracing: Detect the string nul character when parsing user input string
27529c891b