linux/tools/perf/tests/llvm.h
Wang Nan 7b6982ce4b perf test: Add libbpf relocation checker
There's a bug in LLVM that it can generate unneeded relocation
information. See [1] and [2]. Libbpf should check the target section of
a relocation symbol.

This patch adds a testcase which references a global variable (BPF
doesn't support global variables). Before fixing libbpf, the new test
case can be loaded into kernel, the global variable acts like the first
map. It is incorrect.

Result:

  # ~/perf test BPF
  37: Test BPF filter                                          :
  37.1: Test basic BPF filtering                               : Ok
  37.2: Test BPF prologue generation                           : Ok
  37.3: Test BPF relocation checker                            : FAILED!

  # ~/perf test -v BPF
  ...
  libbpf: loading object '[bpf_relocation_test]' from buffer
  libbpf: section .strtab, size 126, link 0, flags 0, type=3
  libbpf: section .text, size 0, link 0, flags 6, type=1
  libbpf: section .data, size 0, link 0, flags 3, type=1
  libbpf: section .bss, size 0, link 0, flags 3, type=8
  libbpf: section func=sys_write, size 104, link 0, flags 6, type=1
  libbpf: found program func=sys_write
  libbpf: section .relfunc=sys_write, size 16, link 10, flags 0, type=9
  libbpf: section maps, size 16, link 0, flags 3, type=1
  libbpf: maps in [bpf_relocation_test]: 16 bytes
  libbpf: section license, size 4, link 0, flags 3, type=1
  libbpf: license of [bpf_relocation_test] is GPL
  libbpf: section version, size 4, link 0, flags 3, type=1
  libbpf: kernel version of [bpf_relocation_test] is 40400
  libbpf: section .symtab, size 144, link 1, flags 0, type=2
  libbpf: map 0 is "my_table"
  libbpf: collecting relocating info for: 'func=sys_write'
  libbpf: relocation: insn_idx=7
  Success unexpectedly: libbpf error when dealing with relocation
  test child finished with -1
  ---- end ----
  Test BPF filter subtest 2: FAILED!

[1] https://llvm.org/bugs/show_bug.cgi?id=26243
[2] https://patchwork.ozlabs.org/patch/571385/

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1453715801-7732-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-01-26 12:10:55 -03:00

24 lines
650 B
C

#ifndef PERF_TEST_LLVM_H
#define PERF_TEST_LLVM_H
#include <stddef.h> /* for size_t */
#include <stdbool.h> /* for bool */
extern const char test_llvm__bpf_base_prog[];
extern const char test_llvm__bpf_test_kbuild_prog[];
extern const char test_llvm__bpf_test_prologue_prog[];
extern const char test_llvm__bpf_test_relocation[];
enum test_llvm__testcase {
LLVM_TESTCASE_BASE,
LLVM_TESTCASE_KBUILD,
LLVM_TESTCASE_BPF_PROLOGUE,
LLVM_TESTCASE_BPF_RELOCATION,
__LLVM_TESTCASE_MAX,
};
int test_llvm__fetch_bpf_obj(void **p_obj_buf, size_t *p_obj_buf_sz,
enum test_llvm__testcase index, bool force,
bool *should_load_fail);
#endif