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authorMike Frysinger <vapier@gentoo.org>2005-06-29 00:54:38 +0000
committerMike Frysinger <vapier@gentoo.org>2005-06-29 00:54:38 +0000
commit379712737e3a9a70b9c5db165efbe45446336df9 (patch)
treeef3c618af72f78c5c03fabb74600402e680bbf68 /libc/sysdeps/linux/x86_64/crt1.S
parent665f338e8679bd38c85f77162f773cf0669dbb2b (diff)
rename crt0.S to crt1.S and clean up so it actually works :)
Diffstat (limited to 'libc/sysdeps/linux/x86_64/crt1.S')
-rw-r--r--libc/sysdeps/linux/x86_64/crt1.S144
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