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| author | Florian Weimer <fweimer@redhat.com> | 2021-12-28 22:52:56 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2021-12-28 22:52:56 +0100 |
| commit | 5d28a8962dcb6ec056b81d730e3c6fb57185a210 (patch) | |
| tree | 3d714aaef575deba322fa5a1e29c76c6f96dc850 /bits | |
| parent | 83b8d5027d2f80c4603cd706da95d6c9a09a4e16 (diff) | |
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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>
Diffstat (limited to 'bits')
| -rw-r--r-- | bits/dl_find_object.h | 32 |
1 files changed, 32 insertions, 0 deletions
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 + <https://www.gnu.org/licenses/>. */ + +#ifndef _DLFCN_H +# error "Never use <bits/dl_find_object.h> directly; include <dlfcn.h> 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 |