about summary refs log tree commit diff
path: root/sysdeps/arm/start.S
diff options
context:
space:
mode:
Diffstat (limited to 'sysdeps/arm/start.S')
-rw-r--r--sysdeps/arm/start.S148
1 files changed, 148 insertions, 0 deletions
diff --git a/sysdeps/arm/start.S b/sysdeps/arm/start.S
new file mode 100644
index 0000000000..adf6531892
--- /dev/null
+++ b/sysdeps/arm/start.S
@@ -0,0 +1,148 @@
+/* Startup code for ARM & ELF
+   Copyright (C) 1995-2014 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This is the canonical entry point, usually the first thing in the text
+   segment.
+
+	Note that the code in the .init section has already been run.
+	This includes _init and _libc_init
+
+
+	At this entry point, most registers' values are unspecified, except:
+
+   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(sp)			argc
+		4(sp)			argv[0]
+		...
+		(4*argc)(sp)		NULL
+		(4*(argc+1))(sp)	envp[0]
+		...
+					NULL
+*/
+
+/* Tag_ABI_align8_preserved: This code preserves 8-byte
+   alignment in any callee.  */
+	.eabi_attribute 25, 1
+/* Tag_ABI_align8_needed: This code may require 8-byte alignment from
+   the caller.  */
+	.eabi_attribute 24, 1
+
+#if defined(__thumb2__)
+	.thumb
+	.syntax unified
+#endif
+
+	.text
+	.globl _start
+	.type _start,#function
+_start:
+       /* Protect against unhandled exceptions.  */
+       .fnstart
+	/* Clear the frame pointer and link register since this is the outermost frame. */
+	mov fp, #0
+	mov lr, #0
+
+	/* Pop argc off the stack and save a pointer to argv */
+	pop { a2 }
+	mov a3, sp
+
+	/* Push stack limit */
+	push { a3 }
+
+	/* Push rtld_fini */
+	push { a1 }
+
+#ifdef SHARED
+	ldr sl, .L_GOT
+	adr a4, .L_GOT
+	add sl, sl, a4
+
+	ldr ip, .L_GOT+4	/* __libc_csu_fini */
+	ldr ip, [sl, ip]
+
+	push { ip }		/* Push __libc_csu_fini */
+
+	ldr a4, .L_GOT+8	/* __libc_csu_init */
+	ldr a4, [sl, a4]
+
+	ldr a1, .L_GOT+12	/* main */
+	ldr a1, [sl, a1]
+
+	/* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
+	/* Let the libc call main and exit with its return code.  */
+	bl __libc_start_main(PLT)
+#else
+	/* Fetch address of __libc_csu_fini */
+	ldr ip, =__libc_csu_fini
+
+	/* Push __libc_csu_fini */
+	push { ip }
+
+	/* Set up the other arguments in registers */
+	ldr a1, =main
+	ldr a4, =__libc_csu_init
+
+	/* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
+	/* Let the libc call main and exit with its return code.  */
+	bl __libc_start_main
+#endif
+
+	/* should never get here....*/
+	bl abort
+
+#ifdef SHARED
+	.align 2
+.L_GOT:
+	.word _GLOBAL_OFFSET_TABLE_ - .L_GOT
+	.word __libc_csu_fini(GOT)
+	.word __libc_csu_init(GOT)
+	.word main(GOT)
+#endif
+
+       .cantunwind
+       .fnend
+
+/* 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