79ef68c7e1
This is the start of having the raw_syscalls:sys_enter BPF handler collecting pointer arguments, namely pathnames, and with two syscalls that have that pointer in different arguments, "open" as it as its first argument, "openat" as the second. With this in place the existing beautifiers in 'perf trace' works, those args are shown instead of just the pointer that comes with the syscalls tracepoints. This also serves to show and document pitfalls in the process of using just that place in the kernel (raw_syscalls:sys_enter) plus tables provided by userspace to collect syscall pointer arguments. One is the need to use a barrier, as suggested by Edward, to avoid clang optimizations that make the kernel BPF verifier to refuse loading our pointer contents collector. The end result should be a generic eBPF program that works in all architectures, with the differences amongst archs resolved by the userspace component, 'perf trace', that should get all its tables created automatically from the kernel components where they are defined, via string table constructors for things not expressed in BTF/DWARF (enums, structs, etc), and otherwise using those observability files (BTF). Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David Ahern <dsahern@gmail.com> Cc: Edward Cree <ecree@solarflare.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Cc: Yonghong Song <yhs@fb.com> Link: https://lkml.kernel.org/n/tip-37dz54pmotgpnwg9tb6zuk9j@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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.