diff options
Diffstat (limited to 'libc/sysdeps/linux')
| -rw-r--r-- | libc/sysdeps/linux/arm/crt1.S | 207 |
1 files changed, 69 insertions, 138 deletions
diff --git a/libc/sysdeps/linux/arm/crt1.S b/libc/sysdeps/linux/arm/crt1.S index 65f27d0dc..8ae897c06 100644 --- a/libc/sysdeps/linux/arm/crt1.S +++ b/libc/sysdeps/linux/arm/crt1.S @@ -1,148 +1,80 @@ -/* When we enter this piece of code, the program stack looks like this: - argc argument counter (integer) - argv[0] program name (pointer) - argv[1...N] program args (pointers) - argv[argc-1] end of args (integer) - NULL - env[0...N] environment variables (pointers) - NULL - - For uClinux it looks like this: - - argc argument counter (integer) - argv char *argv[] - envp char *envp[] - argv[0] program name (pointer) - argv[1...N] program args (pointers) - argv[argc-1] end of args (integer) - NULL - env[0...N] environment variables (pointers) - NULL - - When we are done here, we want - a1=argc - a2=argv[0] - a3=argv[argc+1] - -ARM register quick reference: - - Name Number ARM Procedure Calling Standard Role - - a1 r0 argument 1 / integer result / scratch register / argc - a2 r1 argument 2 / scratch register / argv - a3 r2 argument 3 / scratch register / envp - a4 r3 argument 4 / scratch register - v1 r4 register variable - v2 r5 register variable - v3 r6 register variable - v4 r7 register variable - v5 r8 register variable - sb/v6 r9 static base / register variable - sl/v7 r10 stack limit / stack chunk handle / reg. variable - fp r11 frame pointer - ip r12 scratch register / new-sb in inter-link-unit calls - sp r13 lower end of current stack frame - lr r14 link address / scratch register - pc r15 program counter +/* Startup code for ARM & ELF + Copyright (C) 1995, 1996, 1997, 1998, 2001, 2002 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +/* This is the canonical entry point, usually the first thing in the text + segment. + + Note that the code in the .init section has already been run. + This includes _init and _libc_init + + + At this entry point, most registers' values are unspecified, except: + + a1 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 The stack contains the arguments and environment: + 0(sp) argc + 4(sp) argv[0] + ... + (4*argc)(sp) NULL + (4*(argc+1))(sp) envp[0] + ... + NULL */ -#include <features.h> + .text + .globl _start + .type _start,#function +_start: + /* Fetch address of fini */ + ldr ip, =_fini -.text - .global _start - .type _start,%function - .type _init,%function - .type _fini,%function - .type main,%function - .type __uClibc_main,%function + /* Clear the frame pointer since this is the outermost frame. */ + mov fp, #0 + /* Pop argc off the stack and save a pointer to argv */ + ldr a2, [sp], #4 + mov a3, sp -.text -_start: - /* Save a copy of rtld_fini before r0 gets nuked */ - mov r5, r0 - - /* clear the frame pointer */ - mov fp, #0 - - - /* Load register r0 with main */ -#ifdef __PIC__ - adr r8, .L_main - ldr r0, .L_main - add r0, r0, r8 -#else - ldr r0, =main -#endif - - -#ifdef __ARCH_HAS_MMU__ - - /* Load register r1 from the stack to its final resting place */ - ldr r1, [sp], #4 - - /* Copy argv pointer into r2 -- which its final resting place */ - mov r2, sp -#else - /* - * uClinux stacks look a little different from normal - * MMU-full Linux stacks (for no good reason) - */ - /* pull argc and argv off the stack */ - ldr r1,[sp, #0] - ldr r2,[sp, #4] -#endif - - /* Store _init and _fini to r3 and r4 */ -#ifdef __PIC__ - adr r8, .L_init - ldr r3, .L_init - add r3, r3, r8 - - ldr r4, .L_init + 4 - add r4, r4, r8 -#else - ldr r3, =_init - ldr r4, =_fini -#endif - - /* Store _fini(r4), rtld_fini(r5), and stack_end(r2) on the stack */ - str r2, [sp, #-4]! - str r5, [sp, #-4]! - str r4, [sp, #-4]! - - - /* We need to call __uClibc_main which should not return. - __uClibc_main (int (*main) (int, char **, char **), int argc, - char **argv, void (*init) (void), void (*fini) (void), - void (*rtld_fini) (void), void *stack_end) - */ - bl __uClibc_main + /* Push stack limit */ + str a3, [sp, #-4]! - /* Crash if somehow `exit' returns anyways. */ - bl abort + /* Push rtld_fini */ + str a1, [sp, #-4]! -#ifdef __PIC__ -.L_init: - .word _init - .word _fini -.L_main: - .word main -#endif + /* Set up the other arguments in registers */ + ldr a1, =main + ldr a4, =_init -/* We need this stuff to make gdb behave itself, otherwise - gdb will choke with SIGILL when trying to debug apps. -*/ - .section ".note.ABI-tag", "a" - .align 4 - .long 1f - 0f - .long 3f - 2f - .long 1 -0: .asciz "GNU" -1: .align 4 -2: .long 0 - .long 2,0,0 -3: .align 4 + /* Push fini */ + str ip, [sp, #-4]! + + /* __uClibc_main (main, argc, argv, init, fini, rtld_fini, stack_end) */ + + /* Let the libc call main and exit with its return code. */ + bl __uClibc_main + + /* should never get here....*/ + bl abort /* Define a symbol for the first piece of initialized data. */ .data @@ -151,4 +83,3 @@ __data_start: .long 0 .weak data_start data_start = __data_start - |