Add tests for the new O_EMPTYPATH flag of openat(2)/openat2(2).

Also, the current openat2 tests include a helper header file that
defines the necessary structs and constants to use openat2(2), such as
struct open_how. This may result in conflicting definitions when the
system header openat2.h is present as well.

So add openat2.h generated by 'make headers' to the uapi header
files in ./tools/include and remove the helper file definitions of
the current openat2 selftests.

Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20260424114611.1678641-3-jkoolstra@xs4all.nl
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

These were used to build perf to provide defines not available in older
distros, but this was back in 2017, nowadays all the distros that are
supported and I have build containers for work using just the system
headers, so ditch them.

Some of these older distros may not have things that are used in 'perf
trace', but then they also don't have libtraceevent packages, so don't
build 'perf trace'.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20240315204835.748716-5-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To pick the changes in:

  99668f618062816c ("fs: expose LOOKUP_CACHED through openat2() RESOLVE_CACHED")

That don't result in any change in tooling, only silences this perf
build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/openat2.h' differs from latest version at 'include/uapi/linux/openat2.h'
  diff -u tools/include/uapi/linux/openat2.h include/uapi/linux/openat2.h

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

  fddb5d430ad9 ("open: introduce openat2(2) syscall")
  9a2cef09c801 ("arch: wire up pidfd_getfd syscall")

We also need to grab a copy of uapi/linux/openat2.h since it is now
needed by fcntl.h, add it to tools/perf/check_headers.h.

  $ diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
  --- tools/perf/arch/x86/entry/syscalls/syscall_64.tbl	2019-12-20 16:43:57.662429958 -0300
  +++ arch/x86/entry/syscalls/syscall_64.tbl	2020-02-10 16:36:22.070012468 -0300
  @@ -357,6 +357,8 @@
   433	common	fspick			__x64_sys_fspick
   434	common	pidfd_open		__x64_sys_pidfd_open
   435	common	clone3			__x64_sys_clone3/ptregs
  +437	common	openat2			__x64_sys_openat2
  +438	common	pidfd_getfd		__x64_sys_pidfd_getfd

   #
   # x32-specific system call numbers start at 512 to avoid cache impact
  $

Update tools/'s copy of that file:

  $ cp arch/x86/entry/syscalls/syscall_64.tbl tools/perf/arch/x86/entry/syscalls/syscall_64.tbl

See the result:

  $ diff -u /tmp/build/perf/arch/x86/include/generated/asm/syscalls_64.c.before /tmp/build/perf/arch/x86/include/generated/asm/syscalls_64.c
  --- /tmp/build/perf/arch/x86/include/generated/asm/syscalls_64.c.before	2020-02-10 16:42:59.010636041 -0300
  +++ /tmp/build/perf/arch/x86/include/generated/asm/syscalls_64.c	2020-02-10 16:43:24.149958337 -0300
  @@ -346,5 +346,7 @@
   	[433] = "fspick",
   	[434] = "pidfd_open",
   	[435] = "clone3",
  +	[437] = "openat2",
  +	[438] = "pidfd_getfd",
   };
  -#define SYSCALLTBL_x86_64_MAX_ID 435
  +#define SYSCALLTBL_x86_64_MAX_ID 438
  $

Now one can use:

  perf trace -e openat2,pidfd_getfd

To get just those syscalls or use in things like:

  perf trace -e open*

To get all the open variant (open, openat, openat2, etc) or:

  perf trace pidfd*

To get the pidfd syscalls.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sargun Dhillon <sargun@sargun.me>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>