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authorWaldemar Brodkorb <wbrodkorb@conet.de>2018-05-31 01:04:17 +0200
committerWaldemar Brodkorb <wbrodkorb@conet.de>2018-06-10 06:35:18 +0200
commit9595fb8cd595028bece5174e7eddf660ae3dcc10 (patch)
tree56ffac7a96d15a2a9c825a4f96c3f1bcea7c4fa0 /libc/sysdeps/linux/riscv64/crt1.S
parentdf8caec1978cb5fe7d9a7e7ea9dd773605e89032 (diff)
risc-v: initial 64 bit port, static only (no TLS/NPTL)
Only a simple hello world is tested in qemu system emulation.
Diffstat (limited to 'libc/sysdeps/linux/riscv64/crt1.S')
-rw-r--r--libc/sysdeps/linux/riscv64/crt1.S83
1 files changed, 83 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/riscv64/crt1.S b/libc/sysdeps/linux/riscv64/crt1.S
new file mode 100644
index 000000000..872e0b12e
--- /dev/null
+++ b/libc/sysdeps/linux/riscv64/crt1.S
@@ -0,0 +1,83 @@
+/* Startup code compliant to the ELF RISC-V ABI.
+ Copyright (C) 1995-2018 Free Software Foundation, Inc.
+
+ 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/>. */
+
+#define __ASSEMBLY__ 1
+
+#include <sysdep.h>
+#include <sys/asm.h>
+
+/* The entry point's job is to call __uClibc_main. Per the ABI,
+ a0 contains the address of a function to be passed to atexit.
+ __uClibc_main wants this in a5. */
+
+.text
+ .globl _start
+ .type _start,%function
+
+_start:
+ call .Lload_gp
+ mv a5, a0 /* rtld_fini. */
+ /* main may be in a shared library. */
+ la a0, main
+ REG_L a1, 0(sp) /* argc. */
+ addi a2, sp, SZREG /* argv. */
+ andi sp, sp, ALMASK /* Align stack. */
+ mv a6, sp /* stack_end. */
+
+ tail __uClibc_main@plt
+
+ .size _start,.-_start
+
+/* Dynamic links need the global pointer to be initialized prior to calling
+ any shared library's initializers, so we use preinit_array to load it.
+ This doesn't cut it for static links, though, since the global pointer
+ needs to be initialized before calling __libc_start_main in that case.
+ So we redundantly initialize it at the beginning of _start. */
+
+.Lload_gp:
+.option push
+.option norelax
+ lla gp, __global_pointer$
+.option pop
+ ret
+
+ .section .preinit_array,"aw"
+ .dc.a .Lload_gp
+
+/* Define a symbol for the first piece of initialized data. */
+ .data
+ .globl __data_start
+__data_start:
+ .weak data_start
+ data_start = __data_start