This is a note to let you know that I've just added the patch titled selftests/bpf: Define string const as global for test_sysctl_prog.c to the 5.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: selftests-bpf-define-string-const-as-global-for-test.patch and it can be found in the queue-5.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 7a8d5d373a15da2f2dc92e51538fe69d2978ff5d Author: Yonghong Song <yhs@xxxxxx> Date: Thu Sep 10 13:27:18 2020 -0700 selftests/bpf: Define string const as global for test_sysctl_prog.c [ 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@xxxxxx> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Acked-by: Andrii Nakryiko <andriin@xxxxxx> Link: https://lore.kernel.org/bpf/20200910202718.956042-1-yhs@xxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c index 50525235380e8..5489823c83fc2 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));