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Diffstat (limited to 'sysdeps/mips/start.S')
| -rw-r--r-- | sysdeps/mips/start.S | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/sysdeps/mips/start.S b/sysdeps/mips/start.S new file mode 100644 index 0000000000..a454941e55 --- /dev/null +++ b/sysdeps/mips/start.S @@ -0,0 +1,181 @@ +/* Startup code compliant to the ELF Mips ABI. + Copyright (C) 1995-2014 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 <sgidefs.h> +#include <sys/asm.h> + +#ifndef ENTRY_POINT +#error ENTRY_POINT needs to be defined for start.S on MIPS/ELF. +#endif + +/* This is the canonical entry point, usually the first thing in the text + segment. The SVR4/Mips ABI (pages 3-31, 3-32) says that when the entry + point runs, most registers' values are unspecified, except for: + + v0 ($2) Contains a function pointer to be registered with `atexit'. + This is how the dynamic linker arranges to have DT_FINI + functions called for shared libraries that have been loaded + before this code runs. + + sp ($29) The stack contains the arguments and environment: + 0(%esp) argc + 4(%esp) argv[0] + ... + (4*argc)(%esp) NULL + (4*(argc+1))(%esp) envp[0] + ... + NULL + ra ($31) The return address register is set to zero so that programs + that search backword through stack frames recognize the last + stack frame. +*/ + + +/* We need to call: + __libc_start_main (int (*main) (int, char **, char **), int argc, + char **argv, void (*init) (void), void (*fini) (void), + void (*rtld_fini) (void), void *stack_end) +*/ + + .text + .globl ENTRY_POINT + .type ENTRY_POINT,@function +#ifndef __mips16 +ENTRY_POINT: +# ifdef __PIC__ + SETUP_GPX($0) + SETUP_GPX64($25,$0) +# else + PTR_LA $28, _gp /* Setup GP correctly if we're non-PIC. */ + move $31, $0 +# endif + + PTR_LA $4, main /* main */ + PTR_L $5, 0($29) /* argc */ + PTR_ADDIU $6, $29, PTRSIZE /* argv */ + + /* Allocate space on the stack for seven arguments (o32 only) + and make sure the stack is aligned to double words (8 bytes) + on o32 and quad words (16 bytes) on n32 and n64. */ + + and $29, -2 * SZREG +# if _MIPS_SIM == _ABIO32 + PTR_SUBIU $29, 32 +# endif + PTR_LA $7, __libc_csu_init /* init */ + PTR_LA $8, __libc_csu_fini +# if _MIPS_SIM == _ABIO32 + PTR_S $8, 16($29) /* fini */ + PTR_S $2, 20($29) /* rtld_fini */ + PTR_S $29, 24($29) /* stack_end */ +# else + move $9, $2 /* rtld_fini */ + move $10, $29 /* stack_end */ +# endif + jal __libc_start_main +hlt: b hlt /* Crash if somehow it does return. */ + +#elif _MIPS_SIM == _ABIO32 /* __mips16 */ + /* MIPS16 entry point. */ + .set mips16 +ENTRY_POINT: +# ifdef __PIC__ + li $3, %hi(_gp_disp) + addiu $4, $pc, %lo(_gp_disp) + sll $3, 16 + addu $3, $4 + move $gp, $3 +# else + li $3, %hi(_gp) + sll $3, 16 + addiu $3, %lo(_gp) + move $gp, $3 +# endif + /* Tie end of stack frames. */ + li $4, 0 + move $31, $4 + /* Create new SP value in $7, including alignment. */ + li $4, 2 * SZREG + neg $4, $4 + move $7, $sp + and $7, $4 + addiu $7, -32 + /* Load arguments with original SP. */ + lw $5, 0($sp) + addiu $6, $sp, PTRSIZE + /* Update SP. */ + move $sp, $7 + /* Lay out last arguments, and call __libc_start_main(). */ +# ifdef __PIC__ + sw $7, 24($sp) /* stack_end */ + lw $4, %got(__libc_csu_fini)($3) + lw $7, %got(__libc_csu_init)($3) /* init */ + sw $4, 16($sp) /* fini */ + lw $4, %got(main)($3) /* main */ + lw $3, %call16(__libc_start_main)($3) + sw $2, 20($sp) /* rtld_fini */ + move $25, $3 + jalr $3 +# else + lw $4, 1f + sw $7, 24($sp) /* stack_end */ + lw $7, 2f /* init */ + sw $4, 16($sp) /* fini */ + lw $4, 3f /* main */ + sw $2, 20($sp) /* rtld_fini */ + jal __libc_start_main +# endif +hlt: b hlt /* Crash if somehow it does return. */ +# ifndef __PIC__ + .align 2 +1: .word __libc_csu_fini +2: .word __libc_csu_init +3: .word main +# endif + +#else /* __mips16 && _MIPS_SIM != _ABIO32 */ +# error "MIPS16 support for N32/N64 not implemented" + +#endif /* __mips16 */ + +/* Define a symbol for the first piece of initialized data. */ + .data + .globl __data_start +__data_start: + .long 0 + .weak data_start + data_start = __data_start |