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selftests/bpf: Define string const as global for test_sysctl_prog.c 

[ Upstream commit 6e057fc15a ]

When tweaking llvm optimizations, I found that selftest build failed
with the following error:
  libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1
  libbpf: prog 'sysctl_tcp_mem': bad map relo against '.L__const.is_tcp_mem.tcp_mem_name'
          in section '.rodata.str1.1'
  Error: failed to open BPF object file: Relocation failed
  make: *** [/work/net-next/tools/testing/selftests/bpf/test_sysctl_prog.skel.h] Error 255
  make: *** Deleting file `/work/net-next/tools/testing/selftests/bpf/test_sysctl_prog.skel.h'

The local string constant "tcp_mem_name" is put into '.rodata.str1.1' section
which libbpf cannot handle. Using untweaked upstream llvm, "tcp_mem_name"
is completely inlined after loop unrolling.

Commit 7fb5eefd76 ("selftests/bpf: Fix test_sysctl_loop{1, 2}
failure due to clang change") solved a similar problem by defining
the string const as a global. Let us do the same here
for test_sysctl_prog.c so it can weather future potential llvm changes.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910202718.956042-1-yhs@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Yonghong Song 2020-09-10 13:27:18 -07:00 committed by Greg Kroah-Hartman
parent 8f71fb76a3
commit 58c80462e4
1 changed files with 2 additions and 2 deletions
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4
tools/testing/selftests/bpf/progs/test_sysctl_prog.c
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@ -19,11 +19,11 @@
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#endif
const char tcp_mem_name[] = "net/ipv4/tcp_mem";
static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
{
char tcp_mem_name[] = "net/ipv4/tcp_mem";
unsigned char i;
char name[64];
char name[sizeof(tcp_mem_name)];
int ret;
memset(name, 0, sizeof(name));