Yonghong Song 38261f369f selftests/bpf: Fix probe_user test failure with clang build kernel
clang build kernel failed the selftest probe_user.
  $ ./test_progs -t probe_user
  $ ...
  $ test_probe_user:PASS:get_kprobe_res 0 nsec
  $ test_probe_user:FAIL:check_kprobe_res wrong kprobe res from probe read: 0.0.0.0:0
  $ #94 probe_user:FAIL

The test attached to kernel function __sys_connect(). In net/socket.c, we have
  int __sys_connect(int fd, struct sockaddr __user *uservaddr, int addrlen)
  {
        ......
  }
  ...
  SYSCALL_DEFINE3(connect, int, fd, struct sockaddr __user *, uservaddr,
                  int, addrlen)
  {
        return __sys_connect(fd, uservaddr, addrlen);
  }

The gcc compiler (8.5.0) does not inline __sys_connect() in syscall entry
function. But latest clang trunk did the inlining. So the bpf program
is not triggered.

To make the test more reliable, let us kprobe the syscall entry function
instead. Note that x86_64, arm64 and s390 have syscall wrappers and they have
to be handled specially.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210929033000.3711921-1-yhs@fb.com
2021-09-28 23:17:22 -07:00
2021-09-15 13:56:37 -07:00
2021-09-28 00:18:35 +02:00

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.
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