From f4349837d93b4dfe9ba09791e280ee2d6c99919f Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 18 Feb 2020 14:42:41 +0100 Subject: Introduce and ELF_INITFINI for all architectures This supersedes the init_array sysdeps directory. It allows us to check for ELF_INITFINI in both C and assembler code, and skip DT_INIT and DT_FINI processing completely on newer architectures. A new header file is needed because is incompatible with assembler code. is compatible with assembler code, but it cannot be included in all assembler files because on some architectures, it redefines register names, and some assembler files conflict with that. is replicated for legacy architectures which need DT_INIT/DT_FINI support. New architectures follow the generic default and disable it. --- sysdeps/generic/crti.S | 33 +++++++++++++++++++++++++++++++++ sysdeps/generic/crtn.S | 19 +++++++++++++++++++ sysdeps/generic/elf-initfini.h | 24 ++++++++++++++++++++++++ 3 files changed, 76 insertions(+) create mode 100644 sysdeps/generic/crti.S create mode 100644 sysdeps/generic/crtn.S create mode 100644 sysdeps/generic/elf-initfini.h (limited to 'sysdeps/generic') diff --git a/sysdeps/generic/crti.S b/sysdeps/generic/crti.S new file mode 100644 index 0000000000..82d6dc0d91 --- /dev/null +++ b/sysdeps/generic/crti.S @@ -0,0 +1,33 @@ +/* Dummy crti file. + + In this configuration, crti.o and crtn.o are both empty because the + .init_array/.fini_array sections are used exclusively. + + Older ports cannot use this because even if the linker used to + build libc itself has .init_array support, we don't want to produce + a crt[in].o that presume a linker that new will be used to link + other things later. + + But new configurations without compatibility concerns for + toolchains without .init_array support can use this to avoid the + superfluous .init and .fini boilerplate code. */ + +#include + +#if ELF_INITFINI +# error Cannot use default crti.S because it lacks _init code +#endif + +#ifdef PREINIT_FUNCTION + +# if PREINIT_FUNCTION_WEAK +# error PREINIT_FUNCTION_WEAK is unsupported +# endif + +/* This arranges for PREINIT_FUNCTION to be called upon loading a library that + contains crti.o. */ + + .section .init_array,"a",%init_array + .dc.a PREINIT_FUNCTION + +#endif diff --git a/sysdeps/generic/crtn.S b/sysdeps/generic/crtn.S new file mode 100644 index 0000000000..d92b07dd0b --- /dev/null +++ b/sysdeps/generic/crtn.S @@ -0,0 +1,19 @@ +/* Dummy crtn file. + + In this configuration, crti.o and crtn.o are both empty because the + .init_array/.fini_array sections are used exclusively. + + Older ports cannot use this because even if the linker used to + build libc itself has .init_array support, we don't want to produce + a crt[in].o that presume a linker that new will be used to link + other things later. + + But new configurations without compatibility concerns for + toolchains without .init_array support can use this to avoid the + superfluous .init and .fini boilerplate code. */ + +#include + +#if ELF_INITFINI +# error Cannot use genetric crtn.S because it lacks _fini code +#endif diff --git a/sysdeps/generic/elf-initfini.h b/sysdeps/generic/elf-initfini.h new file mode 100644 index 0000000000..75e920d283 --- /dev/null +++ b/sysdeps/generic/elf-initfini.h @@ -0,0 +1,24 @@ +/* Determine DT_INIT/DT_FINI support in the dynamic loader. + 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 + . */ + +/* Legacy platforms define this to 1. If 0, the dynamic linker + ignores the DT_INIT and DT_FINI tags, and static binaries will not + call the _init or _fini functions. If 1, the old constructor + mechanisms are used in addition to the initarray/finiarray + support. */ +#define ELF_INITFINI 0 -- cgit 1.4.1