The program below aborts even though it does nothing wrong. The reason is that the libgcc_s unwinder calls dl_iterate_phdr, which is not in the implementation namespace, so the application should be able to define it in a different way. #define _POSIX_SOURCE #include <pthread.h> #include <stdio.h> #include <stdlib.h> void dl_iterate_phdr (void) { abort (); } static void * thread_func (void *ignored) { pthread_exit (NULL); return NULL; } int main (void) { pthread_t thr; if (pthread_create (&thr, NULL, thread_func, NULL) != 0) { puts ("pthread_create failed"); return 1; } if (pthread_join (thr, NULL) != 0) { puts ("pthread_join failed"); return 1; } return 0; }
The master branch has been updated by Florian Weimer <fw@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5d28a8962dcb6ec056b81d730e3c6fb57185a210 commit 5d28a8962dcb6ec056b81d730e3c6fb57185a210 Author: Florian Weimer <fweimer@redhat.com> Date: Tue Dec 28 22:52:56 2021 +0100 elf: Add _dl_find_object function It can be used to speed up the libgcc unwinder, and the internal _dl_find_dso_for_object function (which is used for caller identification in dlopen and related functions, and in dladdr). _dl_find_object is in the internal namespace due to bug 28503. If libgcc switches to _dl_find_object, this namespace issue will be fixed. It is located in libc for two reasons: it is necessary to forward the call to the static libc after static dlopen, and there is a link ordering issue with -static-libgcc and libgcc_eh.a because libc.so is not a linker script that includes ld.so in the glibc build tree (so that GCC's internal -lc after libgcc_eh.a does not pick up ld.so). It is necessary to do the i386 customization in the sysdeps/x86/bits/dl_find_object.h header shared with x86-64 because otherwise, multilib installations are broken. The implementation uses software transactional memory, as suggested by Torvald Riegel. Two copies of the supporting data structures are used, also achieving full async-signal-safety. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>