ARC: startup and dynamic linking code

Code for C runtime startup and dynamic loading including PLT layout.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 74 insertions, 0 deletions

diff --git a/sysdeps/arc/start.S b/sysdeps/arc/start.S
new file mode 100644
index 0000000000..3c4144bd20
--- /dev/null
+++ b/sysdeps/arc/start.S
@@ -0,0 +1,74 @@
+/* Startup code for ARC.
+   Copyright (C) 2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+#define __ASSEMBLY__ 1
+#include <entry.h>
+#include <sysdep.h>
+
+#ifndef ENTRY_POINT
+# error ENTRY_POINT needs to be defined for ARC
+#endif
+
+/* When we enter this piece of code, the program stack looks like this:
+        argc            argument counter (integer)
+        argv[0]         program name (pointer)
+        argv[1...N]     program args (pointers)
+        argv[argc-1]    end of args (integer)
+        NULL
+        env[0...N]      environment variables (pointers)
+        NULL.  */
+
+ENTRY (ENTRY_POINT)
+
+	/* Needed to make gdb backtraces stop here.  */
+	.cfi_label .Ldummy
+	cfi_undefined (blink)
+
+	mov	fp, 0
+	ld_s	r1, [sp]	/* argc.  */
+
+	mov_s	r5, r0		/* rltd_fini.  */
+	add_s	r2, sp, 4	/* argv.  */
+	and	sp, sp, -8
+	mov	r6, sp
+
+	/* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end).  */
+
+#ifdef SHARED
+	ld	r0, [pcl, @main@gotpc]
+	ld	r3, [pcl, @__libc_csu_init@gotpc]
+	ld	r4, [pcl, @__libc_csu_fini@gotpc]
+	bl	__libc_start_main@plt
+#else
+	mov_s	r0, main
+	mov_s	r3, __libc_csu_init
+	mov	r4, __libc_csu_fini
+	bl	__libc_start_main
+#endif
+
+	/* Should never get here.  */
+	flag    1
+END (ENTRY_POINT)
+
+/* 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