commit 50a2d83c08a94a10f88a1fedeb7a6e3667a6b732

Author: Florian Weimer <fweimer@redhat.com>

Date:   Fri Apr 24 22:13:03 2020 +0200

    elf: Introduce <elf_machine_sym_no_match.h>

    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>

diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c

index e4c479de9a1fd6ec..47acd134600b44b5 100644

--- a/elf/dl-lookup.c

+++ b/elf/dl-lookup.c

@@ -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;

diff --git a/sysdeps/generic/elf_machine_sym_no_match.h b/sysdeps/generic/elf_machine_sym_no_match.h

new file mode 100644

index 0000000000000000..27155de4c0358460

--- /dev/null

+++ b/sysdeps/generic/elf_machine_sym_no_match.h

@@ -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 */

diff --git a/sysdeps/mips/dl-machine.h b/sysdeps/mips/dl-machine.h

index 91fc640388a735c7..b41e10647d81843b 100644

--- a/sysdeps/mips/dl-machine.h

+++ b/sysdeps/mips/dl-machine.h

@@ -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

diff --git a/sysdeps/mips/elf_machine_sym_no_match.h b/sysdeps/mips/elf_machine_sym_no_match.h

new file mode 100644

index 0000000000000000..9d09e5fa2db1ff6c

--- /dev/null

+++ b/sysdeps/mips/elf_machine_sym_no_match.h

@@ -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 */