From: Yonghong Song yhs@fb.com

[ Upstream commit 6e057fc15a2da4ee03eb1fa6889cf687e690106e ]

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 7fb5eefd7639 ("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 --- tools/testing/selftests/bpf/progs/test_sysctl_prog.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c index 5cbbff416998c..4396faf33394a 100644 --- a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c +++ b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c @@ -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));