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>

3 files changed, 77 insertions, 15 deletions

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 0000000000..27155de4c0
--- /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 06021ea9ab..e3b11a4f21 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 0000000000..9d09e5fa2d
--- /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 */