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Diffstat (limited to 'sysdeps/riscv/start.S')
| -rw-r--r-- | sysdeps/riscv/start.S | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/sysdeps/riscv/start.S b/sysdeps/riscv/start.S new file mode 100644 index 0000000000..4635ddb5eb --- /dev/null +++ b/sysdeps/riscv/start.S @@ -0,0 +1,81 @@ +/* Startup code compliant to the ELF RISC-V ABI. + Copyright (C) 1995-2018 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. + + In addition to the permissions in the GNU Lesser General Public + License, the Free Software Foundation gives you unlimited + permission to link the compiled version of this file with other + programs, and to distribute those programs without any restriction + coming from the use of this file. (The GNU Lesser General Public + License restrictions do apply in other respects; for example, they + cover modification of the file, and distribution when not linked + into another program.) + + Note that people who make modified versions of this file are not + obligated to grant this special exception for their modified + versions; it is their choice whether to do so. The GNU Lesser + General Public License gives permission to release a modified + version without this exception; this exception also makes it + possible to release a modified version which carries forward this + exception. + + 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 + <http://www.gnu.org/licenses/>. */ + +#define __ASSEMBLY__ 1 +#include <entry.h> +#include <sysdep.h> +#include <sys/asm.h> + +/* The entry point's job is to call __libc_start_main. Per the ABI, + a0 contains the address of a function to be passed to atexit. + __libc_start_main wants this in a5. */ + +ENTRY (ENTRY_POINT) + call .Lload_gp + mv a5, a0 /* rtld_fini. */ + /* main may be in a shared library. */ + la a0, main + REG_L a1, 0(sp) /* argc. */ + addi a2, sp, SZREG /* argv. */ + andi sp, sp, ALMASK /* Align stack. */ + lla a3, __libc_csu_init + lla a4, __libc_csu_fini + mv a6, sp /* stack_end. */ + + tail __libc_start_main@plt +END (ENTRY_POINT) + +/* Dynamic links need the global pointer to be initialized prior to calling + any shared library's initializers, so we use preinit_array to load it. + This doesn't cut it for static links, though, since the global pointer + needs to be initialized before calling __libc_start_main in that case. + So we redundantly initialize it at the beginning of _start. */ + +.Lload_gp: +.option push +.option norelax + lla gp, __global_pointer$ +.option pop + ret + + .section .preinit_array,"aw" + .dc.a .Lload_gp + +/* Define a symbol for the first piece of initialized data. */ + .data + .globl __data_start +__data_start: + .weak data_start + data_start = __data_start |