Another patch from Nathan. Ok to commit? Bernd ==
This patch fixes some fragileness in dlopen/do_dlopen wrapper & worker pair. do_dlopen contains __builtin_return_address to determine from whence it was called, and uses that to determine which dynamic object's data it should use to start the search. (In the bug I was tracking, this related to whether the application's RPATH was used or not.) For that to work, it has to have been inlined into the wrapper function. As it happens, it wasn't being inlined. That's an unfortunate compiler behaviour, but it isn't wrong and shouldn't have caused dlopen to fail. This patch changes things so the wrapper function determines the return address, and passes it to the worker. If the worker's inlined, the generated code should be exactly the same as before. nathan -- Nathan Sidwell
2013-03-21 Nathan Sidwell <[email protected]> * ldso/libdl/libdl.c (do_dlopen): Add FROM parameter. (dlopen): Determine return address here. Index: ldso/libdl/libdl.c =================================================================== --- ldso/libdl/libdl.c (revision 405512) +++ ldso/libdl/libdl.c (working copy) @@ -296,11 +296,10 @@ static ptrdiff_t _dl_build_local_scope ( return p - list; } -static void *do_dlopen(const char *libname, int flag) +static void *do_dlopen(const char *libname, int flag, ElfW(Addr) from) { struct elf_resolve *tpnt, *tfrom; struct dyn_elf *dyn_chain, *rpnt = NULL, *dyn_ptr, *relro_ptr, *handle; - ElfW(Addr) from; struct elf_resolve *tpnt1; void (*dl_brk) (void); int now_flag; @@ -320,8 +319,6 @@ static void *do_dlopen(const char *libna return NULL; } - from = (ElfW(Addr)) __builtin_return_address(0); - if (!_dl_init) { _dl_init = true; _dl_malloc_function = malloc; @@ -676,7 +673,8 @@ void *dlopen(const char *libname, int fl void *ret; __UCLIBC_MUTEX_CONDITIONAL_LOCK(_dl_mutex, 1); - ret = do_dlopen(libname, flag); + ret = do_dlopen(libname, flag, + (ElfW(Addr)) __builtin_return_address(0)); __UCLIBC_MUTEX_CONDITIONAL_UNLOCK(_dl_mutex, 1); return ret;
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