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 --- bits/dl_find_object.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 bits/dl_find_object.h (limited to 'bits') diff --git a/bits/dl_find_object.h b/bits/dl_find_object.h new file mode 100644 index 0000000000..5d652c9c71 --- /dev/null +++ b/bits/dl_find_object.h @@ -0,0 +1,32 @@ +/* System dependent definitions for finding objects by address. + Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef _DLFCN_H +# error "Never use directly; include instead." +#endif + +/* This implementation does not have a dlfo_eh_dbase member in struct + dl_find_object. */ +#define DLFO_STRUCT_HAS_EH_DBASE 0 + +/* This implementation does not have a dlfo_eh_count member in struct + dl_find_object. */ +#define DLFO_STRUCT_HAS_EH_COUNT 0 + +/* The ELF segment which contains the exception handling data. */ +#define DLFO_EH_SEGMENT_TYPE PT_GNU_EH_FRAME -- cgit 1.4.1