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authorRoland McGrath <roland@gnu.org>1995-05-02 06:35:55 +0000
committerRoland McGrath <roland@gnu.org>1995-05-02 06:35:55 +0000
commitd66e34cd423425c348bcc83df127dd19711b0b9a (patch)
tree97058e776d3b4fe06ef54bc4951596991652183f /sysdeps/i386/elf
parent08162fa888913a5153d2fcdc4e1a816b57b1fe56 (diff)
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* sysdeps/mach/i386/sysdep.h (SNARF_ARGS, CALL_WITH_SP): Rewritten.
* sysdeps/i386/dl-machine.h: New file. * sysdeps/stub/dl-machine.h: New file. * sysdeps/i386/dl-runtime.c: New file. * sysdeps/stub/dl-runtime.c: New file. * sysdeps/i386/elf/start.S: New file. * sysdeps/generic/dl-sysdep.c: New file. * sysdeps/mach/hurd/dl-sysdep.c: New file.
Diffstat (limited to 'sysdeps/i386/elf')
-rw-r--r--sysdeps/i386/elf/start.S86
1 files changed, 86 insertions, 0 deletions
diff --git a/sysdeps/i386/elf/start.S b/sysdeps/i386/elf/start.S
new file mode 100644
index 0000000000..5c29ce412a
--- /dev/null
+++ b/sysdeps/i386/elf/start.S
@@ -0,0 +1,86 @@
+/* Startup code compliant to the ELF i386 ABI.
+Copyright (C) 1995 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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+/* This is the canonical entry point, usually the first thing in the text
+ segment. The SVR4/i386 ABI (pages 3-31, 3-32) says that when the entry
+ point runs, most registers' values are unspecified, except for:
+
+ %edx 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.
+
+ %esp 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
+*/
+
+ .text
+ .globl _start
+_start:
+ /* Clear the frame pointer. The ABI suggests this be done, to mark
+ the outermost frame obviously. */
+ movl $0, %ebp
+
+ /* %edx 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. */
+ testl %edx
+ jeq nofini
+ pushl %edx
+ call atexit
+ addl $4, %esp
+nofini:
+
+ /* 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. */
+ call __libc_init_first
+
+ /* Extract the arguments and environment as encoded on the stack
+ and set up the arguments for `main': argc, argv, envp. */
+ popl %esi /* Pop the argument count. */
+ leal 4(%esp,%esi,4), %eax /* envp = &argv[argc + 1] */
+ movl %eax, _environ /* Store it in the global variable. */
+ pushl %eax /* Push third argument: envp. */
+ leal 4(%esp), %eax /* argv starts just above that word. */
+ pushl %eax /* Push second argument: argv. */
+ pushl %esi /* Push first argument: argc. */
+
+ /* 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. */
+ call _init
+ pushl $_fini
+ call atexit
+ addl $4, %esp
+
+ /* Call the user's main function, and exit with its value. */
+ call main
+ pushl %eax
+ call exit /* This should never return. */
+ hlt /* Crash if somehow it does return. */