The syntax for POSIX regexes technically doesn't allow empty branches in conditional match groups. GNU libc accepts them as equivalent to `()', but other libc implementations (e.g. macOS libc) reject them with a parse error.
Changing to compliant syntax, `(|_sym)' to `(()|_sym)', lets the `relocs' tool run successfully when using a non-GNU platform as a build host for cross-compiling the kernel. Signed-off-by: John Millikin <[email protected]> --- Helper binary to verify behavior for the current platform: #include <regex.h> #include <stdio.h> int main(int argc, char **argv) { regex_t compiled; int err = regcomp(&compiled, argv[1], REG_EXTENDED|REG_NOSUB); if (err != 0) { char errbuf[128]; regerror(err, &compiled, errbuf, sizeof(errbuf)); printf("regcomp(\"%s\"): %s\n", argv[1], errbuf); return 1; } printf("regcomp(\"%s\"): OK\n", argv[1]); return 0; } Output from GNU libc 2.28 and a fussier non-GNU libc: debian:~$ ./regcomp '^a(|b)$' regcomp("^a(|b)$"): OK debian:~$ ./regcomp '^a(()|b)$' regcomp("^a(()|b)$"): OK darwin:~$ ./regcomp '^a(|b)$' regcomp("^a(|b)$"): empty (sub)expression darwin:~$ ./regcomp '^a(()|b)$' regcomp("^a(()|b)$"): OK arch/x86/tools/relocs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index ce7188cbdae5..e6f28616a625 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -57,12 +57,12 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = { [S_REL] = "^(__init_(begin|end)|" "__x86_cpu_dev_(start|end)|" - "(__parainstructions|__alt_instructions)(|_end)|" - "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|" + "(__parainstructions|__alt_instructions)(()|_end)|" + "(__iommu_table|__apicdrivers|__smp_locks)(()|_end)|" "__(start|end)_pci_.*|" "__(start|end)_builtin_fw|" - "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|" - "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|" + "__(start|stop)___ksymtab(()|_gpl|_unused|_unused_gpl|_gpl_future)|" + "__(start|stop)___kcrctab(()|_gpl|_unused|_unused_gpl|_gpl_future)|" "__(start|stop)___param|" "__(start|stop)___modver|" "__(start|stop)___bug_table|" -- 2.29.2
