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e94fac3829
Jiri Olsa says:
====================
Add new helpers to access traced function arguments that
came out of the trampoline batch changes [1].
Get n-th argument of the traced function:
long bpf_get_func_arg(void *ctx, u32 n, u64 *value)
Get return value of the traced function:
long bpf_get_func_ret(void *ctx, u64 *value)
Get arguments count of the traced funtion:
long bpf_get_func_arg_cnt(void *ctx)
v2 changes:
- added acks
- updated stack diagram
- return -EOPNOTSUPP instead of -EINVAL in bpf_get_func_ret
- removed gpl_only for all helpers
- added verifier fix to allow proper arguments checks,
Andrii asked for checking also 'int *b' argument in
bpf_modify_return_test programs and it turned out that it's currently
not supported by verifier - we can't read argument that is int pointer,
so I had to add verifier change to allow that + adding verifier selftest
- checking all arguments in bpf_modify_return_test test programs
- moved helpers proto gets in tracing_prog_func_proto with attach type check
thanks,
jirka
[1] https://lore.kernel.org/bpf/20211118112455.475349-1-jolsa@kernel.org/
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.