From 5d28a8962dcb6ec056b81d730e3c6fb57185a210 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 28 Dec 2021 22:52:56 +0100 Subject: 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 --- dlfcn/dlfcn.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'dlfcn/dlfcn.h') diff --git a/dlfcn/dlfcn.h b/dlfcn/dlfcn.h index 4a3b870a48..a7e03c078a 100644 --- a/dlfcn/dlfcn.h +++ b/dlfcn/dlfcn.h @@ -28,6 +28,8 @@ #ifdef __USE_GNU +#include + /* If the first argument of `dlsym' or `dlvsym' is set to RTLD_NEXT the run-time address of the symbol called NAME in the next shared object is returned. The "next" relation is defined by the order @@ -194,6 +196,31 @@ typedef struct Dl_serpath dls_serpath[1]; /* Actually longer, dls_cnt elements. */ # endif } Dl_serinfo; + +struct dl_find_object +{ + __extension__ unsigned long long int dlfo_flags; + void *dlfo_map_start; /* Beginning of mapping containing address. */ + void *dlfo_map_end; /* End of mapping. */ + struct link_map *dlfo_link_map; + void *dlfo_eh_frame; /* Exception handling data of the object. */ +# if DLFO_STRUCT_HAS_EH_DBASE + void *dlfo_eh_dbase; /* Base address for DW_EH_PE_datarel. */ +# if __WORDSIZE == 32 + unsigned int __dlfo_eh_dbase_pad; +# endif +# endif +# if DLFO_STRUCT_HAS_EH_COUNT + int dlfo_eh_count; /* Number of exception handling entries. */ + unsigned int __dlfo_eh_count_pad; +# endif + __extension__ unsigned long long int __dflo_reserved[7]; +}; + +/* If ADDRESS is found in an object, fill in *RESULT and return 0. + Otherwise, return -1. */ +int _dl_find_object (void *__address, struct dl_find_object *__result) __THROW; + #endif /* __USE_GNU */ -- cgit v1.2.3