lib/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2025-07-30 22:43:12 +03:00
Code Activity

elf: Introduce <elf_machine_sym_no_match.h>

Browse Source 
MIPS needs to ignore certain existing symbols during symbol lookup.
The old scheme uses the ELF_MACHINE_SYM_NO_MATCH macro, with an
inline function, within its own header, with a sysdeps override for
MIPS.  This allows re-use of the function from another file (without
having to include <dl-machine.h> or providing the default definition
for ELF_MACHINE_SYM_NO_MATCH).

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer
2020-04-24 22:13:03 +02:00
parent 781dacc4f4
commit 50a2d83c08
4 changed files with 79 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
elf/dl-lookup.c
View File

@ -28,18 +28,12 @@
#include <libc-lock.h>
#include <tls.h>
#include <atomic.h>
#include <elf_machine_sym_no_match.h>
#include <assert.h>
/* Return nonzero if check_match should consider SYM to fail to match a
symbol reference for some machine-specific reason. */
#ifndef ELF_MACHINE_SYM_NO_MATCH
# define ELF_MACHINE_SYM_NO_MATCH(sym) 0
#endif
#define VERSTAG(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag))
struct sym_val
{
const ElfW(Sym) *s;
@ -78,7 +72,7 @@ check_match (const char *const undef_name,
if (__glibc_unlikely ((sym->st_value == 0 /* No value. */
&& sym->st_shndx != SHN_ABS
&& stt != STT_TLS)
|| ELF_MACHINE_SYM_NO_MATCH (sym)
|| elf_machine_sym_no_match (sym)
|| (type_class & (sym->st_shndx == SHN_UNDEF))))
return NULL;

34
sysdeps/generic/elf_machine_sym_no_match.h Normal file
View File

@ -0,0 +1,34 @@
/* Function to ignore certain symbol matches for machine-specific reasons.
Copyright (C) 2020 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 _ELF_MACHINE_SYM_NO_MATCH_H
#define _ELF_MACHINE_SYM_NO_MATCH_H
#include <link.h>
#include <stdbool.h>
/* This can be customized to ignore certain symbols during lookup in
case there are machine-specific rules to disregard some
symbols. */
static inline bool
elf_machine_sym_no_match (const ElfW(Sym) *sym)
{
return false;
}
#endif /* _ELF_MACHINE_SYM_NO_MATCH_H */

15
sysdeps/mips/dl-machine.h
View File

@ -467,21 +467,6 @@ elf_machine_plt_value (struct link_map *map, const ElfW(Rel) *reloc,
return value;
}
/* The semantics of zero/non-zero values of undefined symbols differs
depending on whether the non-PIC ABI is in use. Under the non-PIC
ABI, a non-zero value indicates that there is an address reference
to the symbol and thus it must always be resolved (except when
resolving a jump slot relocation) to the PLT entry whose address is
provided as the symbol's value; a zero value indicates that this
canonical-address behaviour is not required. Yet under the classic
MIPS psABI, a zero value indicates that there is an address
reference to the function and the dynamic linker must resolve the
symbol immediately upon loading. To avoid conflict, symbols for
which the dynamic linker must assume the non-PIC ABI semantics are
marked with the STO_MIPS_PLT flag. */
#define ELF_MACHINE_SYM_NO_MATCH(sym) \
((sym)->st_shndx == SHN_UNDEF && !((sym)->st_other & STO_MIPS_PLT))
#endif /* !dl_machine_h */
#ifdef RESOLVE_MAP

43
sysdeps/mips/elf_machine_sym_no_match.h Normal file
View File

@ -0,0 +1,43 @@
/* MIPS-specific handling of undefined symbols.
Copyright (C) 2008-2020 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 _ELF_MACHINE_SYM_NO_MATCH_H
#define _ELF_MACHINE_SYM_NO_MATCH_H
#include <link.h>
#include <stdbool.h>
/* The semantics of zero/non-zero values of undefined symbols differs
depending on whether the non-PIC ABI is in use. Under the non-PIC
ABI, a non-zero value indicates that there is an address reference
to the symbol and thus it must always be resolved (except when
resolving a jump slot relocation) to the PLT entry whose address is
provided as the symbol's value; a zero value indicates that this
canonical-address behaviour is not required. Yet under the classic
MIPS psABI, a zero value indicates that there is an address
reference to the function and the dynamic linker must resolve the
symbol immediately upon loading. To avoid conflict, symbols for
which the dynamic linker must assume the non-PIC ABI semantics are
marked with the STO_MIPS_PLT flag. */
static inline bool
elf_machine_sym_no_match (const ElfW(Sym) *sym)
{
return sym->st_shndx == SHN_UNDEF && !(sym->st_other & STO_MIPS_PLT);
}
#endif /* _ELF_MACHINE_SYM_NO_MATCH_H */