rename crt0.S to crt1.S and clean up so it actually works :)

1 files changed, 144 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/x86_64/crt1.S b/libc/sysdeps/linux/x86_64/crt1.S
new file mode 100644
index 000000000..04cf691ef
--- /dev/null
+++ b/libc/sysdeps/linux/x86_64/crt1.S
@@ -0,0 +1,144 @@
+/* Startup code compliant to the ELF x86-64 ABI.
+   Copyright (C) 2001, 2002, 2003, 2005 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 2001.
+
+   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.  */
+
+/* Originally based on glibc's sysdeps/x86_64/elf/start.S */
+
+/* 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:
+
+   %rdx		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.
+
+   %rsp		The stack contains the arguments and environment:
+		0(%rsp)			argc
+		8(%rsp)			argv[0]
+		...
+		(8*argc)(%rsp)		NULL
+		(8*(argc+1))(%rsp)	envp[0]
+		...
+					NULL
+*/
+
+#include <features.h>
+
+.text
+.global	_start
+.type   _start,@function
+#if defined(__UCLIBC_CTOR_DTOR__)
+.type	_init,@function
+.type	_fini,@function
+#else
+.weak	_init
+.weak	_fini
+#endif
+.type	__uClibc_main,@function
+/* Stick in a dummy reference to main(), so that if an application
+ * is linking when the main() function is in a static library (.a)
+ * we can be sure that main() actually gets linked in */
+.type	main,@function
+
+_start:
+	/* 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 __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).
+	   The arguments are passed via registers and on the stack:
+	main:		%rdi
+	argc:		%rsi
+	argv:		%rdx
+	init:		%rcx
+	fini:		%r8
+	rtld_fini:	%r9
+	stack_end:	stack.	*/
+
+	movq %rdx, %r9   /* Address of the shared library termination function. */
+	popq %rsi        /* Pop the argument count. */
+	movq %rsp, %rdx  /* argv starts just at the current stack top. */
+	movq %rsi, %rbx  /* now we calc envp ... envp = argc */
+	addq $8, %rbx
+	shl  $0x3, %rbx  /* envp *= 8 */
+	addq %rdx, %rbx  /* envp += argv */
+
+	/* Align the stack to a 16 byte boundary to follow the ABI. */
+	andq $~15, %rsp
+
+	pushq %rax		/* Push garbage because we push 8 more bytes.  */
+
+	/* Provide the highest stack address to the user code (for stacks
+	   which grow downwards).  */
+	pushq %rsp
+
+	/* Give address for main() */
+	movq $main, %rdi
+
+	/* setup init/fini address */
+	movq $_init, %rcx
+	movq $_fini, %r8
+
+/**************
+ * START TODO */
+#if defined(L_Scrt1)
+	call .L0
+.L0:
+	popq %rbx
+	addq $_GLOBAL_OFFSET_TABLE_+[.-.L0],%rbx
+
+	call *__uClibc_main@GOT(%rip)
+#else
+	call __uClibc_main
+#endif
+/* END TODO *
+ ************/
+
+	hlt			/* Crash if somehow `exit' does return.	 */
+.size _start,.-_start
+
+/* 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