We have an augmenter for the "open" syscall, which has just one pointer,
in the first argument, a "const char *", so any other syscall that has
just one pointer and that is the first can reuse the "open" BPF
augmenter program.

Even more, syscalls that get two pointers with the first being a string
can reuse "open"'s BPF augmenter till we have an augmenter that better
matches that syscall with two pointers.

With this the few augmenters we have, for open (first arg is a string),
openat (2nd arg is a string), renameat (2nd and 4th are strings) can be
reused by a lot of syscalls, ditto for "bind" reusing "connect" because
both have the 2nd argument as a sockaddr and the 3rd as its len.

Lets see how this makes the "bind" syscall reuse the "connect" BPF prog
augmenter found in tools/perf/examples/bpf/augmented_raw_syscalls.c:

  # perf trace -e bind,connect systemctl restart sshd
  connect(3, { .family: PF_LOCAL, path: /run/systemd/private }, 23) = 0
  #

Oh, it just connects to some daemon, so we better do it system wide and then
stop/start sshd:

  # perf trace -e bind,connect
  systemctl/10124 connect(3, { .family: PF_LOCAL, path: /run/systemd/private }, 23) = 0
  sshd/10102 connect(7, { .family: PF_LOCAL, path: /dev/log }, 110) = 0
  systemctl/10126 connect(3, { .family: PF_LOCAL, path: /run/systemd/private }, 23) = 0
  systemd/10128  ... [continued]: connect())            = 0
  (sshd)/10128 connect(3, { .family: PF_LOCAL, path: /run/systemd/journal/stdout }, 30) ...
  sshd/10128 bind(3, { .family: PF_NETLINK }, 12)    = 0
  sshd/10128 connect(4, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 110) = -1 ENOENT (No such file or directory)
  sshd/10128 connect(3, { .family: PF_INET6, port: 22, addr: :: }, 28) = 0
  sshd/10128 connect(3, { .family: PF_UNSPEC }, 16)  = 0
  sshd/10128 connect(3, { .family: PF_INET, port: 22, addr: 0.0.0.0 }, 16) = 0
  sshd/10128 connect(3, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 110) = -1 ENOENT (No such file or directory)
  sshd/10128 connect(3, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 110) = -1 ENOENT (No such file or directory)
  sshd/10128 connect(5, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 110) = -1 ENOENT (No such file or directory)
  sshd/10128 connect(5, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 110) = -1 ENOENT (No such file or directory)
  sshd/10128 bind(4, { .family: PF_INET, port: 22, addr: 0.0.0.0 }, 16) = 0
  sshd/10128 connect(6, { .family: PF_LOCAL, path: /dev/log }, 110) = 0
  sshd/10128 bind(6, { .family: PF_INET6, port: 22, addr: :: }, 28) = 0
  sshd/10128 connect(7, { .family: PF_LOCAL, path: /dev/log }, 110) = 0
  ^C#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-zfley2ghs4nim1uq4nu6ed3l@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>