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(_start): Leave most of the initialisation for __libc_start_main().

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This commit is contained in:
Ulrich Drepper 1998-04-01 09:09:05 +00:00
parent c4dc6c456e
commit e7304fce4e
1 changed files with 20 additions and 53 deletions
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73
sysdeps/arm/elf/start.S
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@ -24,19 +24,19 @@
This includes _init and _libc_init
At this entry point, most registers' values are unspecified, except for:
At this entry point, most registers' values are unspecified, except:
r0 Contains a function pointer to be registered with `atexit'.
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(%esp) argc
4(%esp) argv[0]
0(sp) argc
4(sp) argv[0]
...
(4*argc)(%esp) NULL
(4*(argc+1))(%esp) envp[0]
(4*argc)(sp) NULL
(4*(argc+1))(sp) envp[0]
...
NULL
*/
@ -44,62 +44,29 @@
.text
.globl _start
_start:
/* Clear the frame pointer. The Intel ABI suggests this be done,
to mark the outermost frame obviously. This seems like a
sensible thing to do */
/* Clear the frame pointer since this is the outermost frame. */
mov fp, #0
/* r0 contains the address of the shared library termination
function, which we will register with `atexit' to be called by
`exit'. I suspect that on some systems, and when statically
linked, this will not be set by anything to any function
pointer; hopefully it will be zero so we don't try to call
random pointers. */
cmp r0,#0
blne atexit(PLT)
/* Pop argc off the stack and save a pointer to argv */
ldmfd sp!, {a2}
mov a3, sp
/* Do essential libc initialization. In statically linked
programs under the GNU Hurd, this is what sets up the
arguments on the stack for the code below. For dyn-link
programs, this has been run already, in the .init code. */
#ifndef PIC
bl __libc_init_first
/* Push the last arguments to main() onto the stack */
stmfd sp!, {a1}
ldr a1, =_fini
stmfd sp!, {a1}
/* Extract the arguments and environment as encoded on the stack
and set up the arguments for `main': argc, argv, envp. */
ldr r0,[sp]
add r1,sp,#4
add r2,r1,r0,lsl #2
add r2,r2,#4
/* save a copy of envp while we have it */
ldr r3,L_environ
str r2,[r3]
/* Set up the other arguments for main() that go in registers */
ldr a1, =main
ldr a4, =_init
/* Call `_init', which is the entry point to our own `.init'
section; and register with `atexit' to have `exit' call
`_fini', which is the entry point to our own `.fini' section. */
bl _init
ldr r0,L_fini
bl atexit
b L_pfini
/* __libc_start_main (main, argc, argv, init, fini, rtld_fini) */
L_fini: .word _fini
L_environ: .word _environ
L_pfini:
#endif
/* rebuild the arg list for main() */
ldr r0,[sp]
add r1,sp,#4
add r2,r1,r0,lsl #2
add r2,r2,#4
/* Call the user's main function, and exit with its value. */
bl main
bl exit
/* Let the libc call main and exit with its return code. */
bl __libc_start_main
/* should never get here....*/
bl abort
/* Define a symbol for the first piece of initialized data. */
.data
.globl __data_start