Adapt x86 to new __uClibc_start_main.

1 files changed, 106 insertions, 96 deletions

diff --git a/libc/sysdeps/linux/i386/crt1.S b/libc/sysdeps/linux/i386/crt1.S
index 7eee8aea9..fa9174f3e 100644
--- a/libc/sysdeps/linux/i386/crt1.S
+++ b/libc/sysdeps/linux/i386/crt1.S
@@ -1,121 +1,132 @@
-/* Copyright (C) 1991, 1992 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.  */
-
-
-/*  Based on the code from GNU libc, but hacked up by John Beppu and Erik Andersen */
-/*  adapted by PaX Team for ET_DYN/PIE binaries */
-
-/*
-    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
+/* Startup code compliant to the ELF i386 ABI.
+   Copyright (C) 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2003, 2004
+   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, 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.  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
 */
 
-#include <features.h>
-
-.text
-	.align 4
-
-	.global	_start
-	.type	_start,%function
+	.text
+	.globl	_start
+	.type	_start,@function
 	.type	_init,%function
 	.type	_fini,%function
 	.type	main,%function
 	.type	__uClibc_start_main,%function
-
 _start:
-	/* locate the start of the environment variables */
-	popl %ecx	/* Store argc into %ecx */
-	movl %esp,%ebx  /* Store argv into ebx */
-	movl %esp,%eax  /* Store argv into eax as well*/
-	movl %edx,%esi	/* Store edx(FINI ptr) in %esi */
-	movl %ecx,%edx	/* Stick argc into %edx so we can do some math in a sec */
-	leal 4(%eax,%edx,4),%eax
-
-	/*  [ register layout ]
-
-	    sizeof(char*) == 4
-	    %ecx = argc	    ; 0(esp)
-	    %ebx = argv	    ; 4(esp)
-	    %eax = env	    ; argv + (argc * 4) + 4
-	*/
-	xorl %ebp,%ebp  /* NULL */
-	/*
-	Before pushing the arguments align the stack to a 16-byte
+	/* Clear the frame pointer.  The ABI suggests this be done, to mark
+	   the outermost frame obviously.  */
+	xorl %ebp, %ebp
+
+	/* Extract the arguments as encoded on the stack and set up
+	   the arguments for `main': argc, argv.  envp will be determined
+	   later in __libc_start_main.  */
+	popl %esi		/* Pop the argument count.  */
+	movl %esp, %ecx		/* argv starts just at the current stack top.*/
+
+	/* Before pushing the arguments align the stack to a 16-byte
 	(SSE needs 16-byte alignment) boundary to avoid penalties from
 	misaligned accesses.  Thanks to Edward Seidl <seidl@janed.com>
-	for pointing this out.
-	*/
+	for pointing this out.  */
 	andl $0xfffffff0, %esp
-	/* Push NULL to make sure stack ptr
-	   is 16 byte aligned when calling __uClibc_start_main */
-	pushl %ebp
-	
-	/* Set up an invalid (NULL return address, NULL frame pointer)
-	   callers stack frame so anybody unrolling the stack knows where
-	   to stop */
-	pushl %ebp      /* callers %cs */
-	pushl %ebp      /* callers %eip (return address) */
-	pushl %ebp      /* callers %ebp (frame pointer) */
-	movl %esp,%ebp  /* mark callers stack frame as invalid */
+	pushl %eax		/* Push garbage because we allocate
+				   28 more bytes.  */
+
+	/* Provide the highest stack address to the user code (for stacks
+	   which grow downwards).  */
+	pushl %esp
+
+	pushl %edx		/* Push address of the shared library
+				   termination function.  */
 
 #if defined L_Scrt1
-	call .L0
-.L0:
-	pop %edx
-	addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%edx
-#endif
-	pushl %esp	/* push stack ptr */
-	pushl %esi	/* Push FINI pointer */
+	/* Load PIC register.  */
+	call 1f
+	addl $_GLOBAL_OFFSET_TABLE_, %ebx
+
+	/* Push address of our own entry points to .fini and .init.  */
+	leal _fini@GOTOFF(%ebx), %eax
+	pushl %eax
+	leal _init@GOTOFF(%ebx), %eax
+	pushl %eax
 
-	/* Push apps .init, .fini and main arguments to __uClibc_start_main() on the stack */
-#ifdef L_Scrt1
-	pushl _fini@GOT(%edx)
-	pushl _init@GOT(%edx)
+	pushl %ecx		/* Push second argument: argv.  */
+	pushl %esi		/* Push first argument: argc.  */
+
+	pushl main@GOT(%ebx)
+
+	/* Call the user's main function, and exit with its value.
+	   But let the libc call main.    */
+	call __uClibc_start_main@PLT
 #else
+	/* Push address of our own entry points to .fini and .init.  */
 	pushl $_fini
 	pushl $_init
-#endif
 
-	/* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */
-	pushl %eax	/* Environment pointer */
-	pushl %ebx	/* Argument pointer */
-	pushl %ecx	/* And the argument count */
+	pushl %ecx		/* Push second argument: argv.  */
+	pushl %esi		/* Push first argument: argc.  */
 
-	/* Ok, now run uClibc's main() -- shouldn't return */
-#ifdef L_Scrt1
-	pushl main@GOT(%edx)
-	call *__uClibc_start_main@GOT(%edx)
-#else
 	pushl $main
+
+	/* Call the user's main function, and exit with its value.
+	   But let the libc call main.    */
 	call __uClibc_start_main
 #endif
 
-	/* Crash if somehow `exit' returns anyways.  */
-	hlt
-.size _start,.-_start
-
+	hlt			/* Crash if somehow `exit' does return.  */
 
+#if defined L_Scrt1
+1:	movl	(%esp), %ebx
+	ret
+#endif
 /* Define a symbol for the first piece of initialized data.  */
 	.data
 	.globl __data_start
@@ -123,4 +134,3 @@ __data_start:
 	.long 0
 	.weak data_start
 	data_start = __data_start
-