linux-stable/tools/build/feature/test-bpf.c
Tiezhu Yang e32cb12ff5 bpf, mips: Fix build errors about __NR_bpf undeclared
Add the __NR_bpf definitions to fix the following build errors for mips:

  $ cd tools/bpf/bpftool
  $ make
  [...]
  bpf.c:54:4: error: #error __NR_bpf not defined. libbpf does not support your arch.
   #  error __NR_bpf not defined. libbpf does not support your arch.
      ^~~~~
  bpf.c: In function ‘sys_bpf’:
  bpf.c:66:17: error: ‘__NR_bpf’ undeclared (first use in this function); did you mean ‘__NR_brk’?
    return syscall(__NR_bpf, cmd, attr, size);
                   ^~~~~~~~
                   __NR_brk
  [...]
  In file included from gen_loader.c:15:0:
  skel_internal.h: In function ‘skel_sys_bpf’:
  skel_internal.h:53:17: error: ‘__NR_bpf’ undeclared (first use in this function); did you mean ‘__NR_brk’?
    return syscall(__NR_bpf, cmd, attr, size);
                   ^~~~~~~~
                   __NR_brk

We can see the following generated definitions:

  $ grep -r "#define __NR_bpf" arch/mips
  arch/mips/include/generated/uapi/asm/unistd_o32.h:#define __NR_bpf (__NR_Linux + 355)
  arch/mips/include/generated/uapi/asm/unistd_n64.h:#define __NR_bpf (__NR_Linux + 315)
  arch/mips/include/generated/uapi/asm/unistd_n32.h:#define __NR_bpf (__NR_Linux + 319)

The __NR_Linux is defined in arch/mips/include/uapi/asm/unistd.h:

  $ grep -r "#define __NR_Linux" arch/mips
  arch/mips/include/uapi/asm/unistd.h:#define __NR_Linux	4000
  arch/mips/include/uapi/asm/unistd.h:#define __NR_Linux	5000
  arch/mips/include/uapi/asm/unistd.h:#define __NR_Linux	6000

That is to say, __NR_bpf is:

  4000 + 355 = 4355 for mips o32,
  6000 + 319 = 6319 for mips n32,
  5000 + 315 = 5315 for mips n64.

So use the GCC pre-defined macro _ABIO32, _ABIN32 and _ABI64 [1] to define
the corresponding __NR_bpf.

This patch is similar with commit bad1926dd2 ("bpf, s390: fix build for
libbpf and selftest suite").

  [1] https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/config/mips/mips.h#l549

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1637804167-8323-1-git-send-email-yangtiezhu@loongson.cn
2021-11-26 22:11:25 +01:00

48 lines
1.1 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <asm/unistd.h>
#include <linux/bpf.h>
#include <unistd.h>
#ifndef __NR_bpf
# if defined(__i386__)
# define __NR_bpf 357
# elif defined(__x86_64__)
# define __NR_bpf 321
# elif defined(__aarch64__)
# define __NR_bpf 280
# elif defined(__sparc__)
# define __NR_bpf 349
# elif defined(__s390__)
# define __NR_bpf 351
# elif defined(__mips__) && defined(_ABIO32)
# define __NR_bpf 4355
# elif defined(__mips__) && defined(_ABIN32)
# define __NR_bpf 6319
# elif defined(__mips__) && defined(_ABI64)
# define __NR_bpf 5315
# else
# error __NR_bpf not defined. libbpf does not support your arch.
# endif
#endif
int main(void)
{
union bpf_attr attr;
/* Check fields in attr */
attr.prog_type = BPF_PROG_TYPE_KPROBE;
attr.insn_cnt = 0;
attr.insns = 0;
attr.license = 0;
attr.log_buf = 0;
attr.log_size = 0;
attr.log_level = 0;
attr.kern_version = 0;
attr.prog_flags = 0;
/*
* Test existence of __NR_bpf and BPF_PROG_LOAD.
* This call should fail if we run the testcase.
*/
return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
}