Sorry, messed up the git submit with two unrelated patches. Please ignore this. Will submit the correct one soon. On 6/4/24 10:55 AM, Yonghong Song wrote:
I hit the following failure when running selftests with internal backported upstream kernel: test_ksyms:PASS:kallsyms_fopen 0 nsec test_ksyms:FAIL:ksym_find symbol 'bpf_link_fops' not found #123 ksyms:FAIL In /proc/kallsyms, we have $ cat /proc/kallsyms | grep bpf_link_fops ffffffff829f0cb0 d bpf_link_fops.llvm.12608678492448798416 The CONFIG_LTO_CLANG_THIN is enabled in the kernel which is responsible for bpf_link_fops.llvm.12608678492448798416 symbol name. In prog_tests/ksyms.c we have kallsyms_find("bpf_link_fops", &link_fops_addr) and kallsyms_find() compares "bpf_link_fops" with symbols in /proc/kallsyms in order to find the entry. With bpf_link_fops.llvm.<hash> in /proc/kallsyms, the kallsyms_find() failed. To fix the issue, in kallsyms_find(), if a symbol has suffix .llvm.<hash>, that suffix will be ignored for comparison. This fixed the test failure. Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx> --- tools/testing/selftests/bpf/trace_helpers.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index 70e29f316fe7..dc871e642ed5 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -221,6 +221,18 @@ int kallsyms_find(const char *sym, unsigned long long *addr) return -EINVAL;while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {+ /* If CONFIG_LTO_CLANG_THIN is enabled, static variable/function + * symbols could be promoted to global due to cross-file inlining. + * For such cases, clang compiler will add .llvm.<hash> suffix + * to those symbols to avoid potential naming conflict. + * Let us ignore .llvm.<hash> suffix during symbol comparison. + */ + if (type == 'd') { + char *res = strstr(name, ".llvm."); + + if (res) + *res = '\0'; + } if (strcmp(name, sym) == 0) { *addr = value; goto out;
