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authorWaldemar Brodkorb <wbx@uclibc-ng.org>2016-10-04 06:51:35 +0200
committerWaldemar Brodkorb <wbx@openadk.org>2017-02-01 17:48:38 +0100
commitdba942c80dc2cfa5768a856fff98e22a755fdd27 (patch)
tree371e775cb6dfec085945f6834aeb9d3b6de36fbe /libc/sysdeps/linux/aarch64/crt1.S
parent9b457baf8d46329f7d7ee2aa084022bb0df88551 (diff)
add experimental aarch64 support
Ported over from GNU C Library and runtime tested in Qemu.
Diffstat (limited to 'libc/sysdeps/linux/aarch64/crt1.S')
-rw-r--r--libc/sysdeps/linux/aarch64/crt1.S89
1 files changed, 89 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/aarch64/crt1.S b/libc/sysdeps/linux/aarch64/crt1.S
new file mode 100644
index 000000000..09d0327ac
--- /dev/null
+++ b/libc/sysdeps/linux/aarch64/crt1.S
@@ -0,0 +1,89 @@
+/* Copyright (C) 1995-2016 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.
+
+ 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:
+
+ x0 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
+ 8(sp) argv[0]
+ ...
+ (8*argc)(sp) NULL
+ (8*(argc+1))(sp) envp[0]
+ ...
+ NULL
+ */
+
+ .text
+ .globl _start
+ .type _start,#function
+_start:
+ /* Create an initial frame with 0 LR and FP */
+ mov x29, #0
+ mov x30, #0
+
+ /* Setup _fini in argument register */
+ mov x5, x0
+
+ /* Load argc and a pointer to argv */
+ ldr x1, [sp, #0]
+ add x2, sp, #8
+
+ /* Setup stack limit in argument register */
+ mov x6, sp
+
+#ifdef __PIC__
+ adrp x0, :got:main
+ ldr x0, [x0, #:got_lo12:main]
+
+ adrp x3, :got:_init
+ ldr x3, [x3, #:got_lo12:_init]
+
+ adrp x4, :got:_fini
+ ldr x4, [x4, #:got_lo12:_fini]
+#else
+ /* Set up the other arguments in registers */
+ ldr x0, =main
+ ldr x3, =_init
+ ldr x4, =_fini
+#endif
+
+ /* Let the libc call main and exit with its return code. */
+ bl __uClibc_main
+
+ /* should never get here....*/
+ bl abort
+
+ /* 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