From dba942c80dc2cfa5768a856fff98e22a755fdd27 Mon Sep 17 00:00:00 2001
From: Waldemar Brodkorb <wbx@uclibc-ng.org>
Date: Tue, 4 Oct 2016 06:51:35 +0200
Subject: add experimental aarch64 support

Ported over from GNU C Library and runtime tested in Qemu.
---
 ldso/ldso/aarch64/dl-startup.h | 98 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 ldso/ldso/aarch64/dl-startup.h

(limited to 'ldso/ldso/aarch64/dl-startup.h')

diff --git a/ldso/ldso/aarch64/dl-startup.h b/ldso/ldso/aarch64/dl-startup.h
new file mode 100644
index 000000000..1fac5ec35
--- /dev/null
+++ b/ldso/ldso/aarch64/dl-startup.h
@@ -0,0 +1,98 @@
+/*
+ * Architecture specific code used by dl-startup.c
+ * Copyright (C) 2016 Waldemar Brodkorb <wbx@uclibc-ng.org>
+ * Ported from GNU libc
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+/* Copyright (C) 1995-2016 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.
+
+   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/>.  */
+
+#include <features.h>
+
+__asm__("\
+.text									\n\
+.globl _start								\n\
+.type _start, %function							\n\
+.globl _dl_start_user							\n\
+.type _dl_start_user, %function						\n\
+_start:									\n\
+	mov	x0, sp							\n\
+	bl	_dl_start						\n\
+	// returns user entry point in x0				\n\
+	mov	x21, x0							\n\
+_dl_start_user:								\n\
+	// get the original arg count					\n\
+	ldr	x1, [sp]						\n\
+	// get the argv address						\n\
+	add	x2, sp, #(1<<3)						\n\
+	// get _dl_skip_args to see if we were				\n\
+	// invoked as an executable					\n\
+	adrp	x4, _dl_skip_args					\n\
+        ldr	w4, [x4, #:lo12:_dl_skip_args]				\n\
+	// do we need to adjust argc/argv				\n\
+        cmp	w4, 0							\n\
+	beq	.L_done_stack_adjust					\n\
+	// subtract _dl_skip_args from original arg count		\n\
+	sub	x1, x1, x4						\n\
+	// store adjusted argc back to stack				\n\
+	str	x1, [sp]						\n\
+	// find the first unskipped argument				\n\
+	mov	x3, x2							\n\
+	add	x4, x2, x4, lsl #3					\n\
+	// shuffle envp down						\n\
+1:	ldr	x5, [x4], #(1<<3)					\n\
+	str	x5, [x3], #(1<<3)					\n\
+	cmp	x5, #0							\n\
+	bne	1b							\n\
+	// shuffle auxv down						\n\
+1:	ldp	x0, x5, [x4, #(2<<3)]!					\n\
+	stp	x0, x5, [x3], #(2<<3)					\n\
+	cmp	x0, #0							\n\
+	bne	1b							\n\
+.L_done_stack_adjust:							\n\
+	// compute envp							\n\
+	add	x3, x2, x1, lsl #3					\n\
+	add	x3, x3, #(1<<3)						\n\
+	// load the finalizer function					\n\
+	adrp	x0, _dl_fini						\n\
+	add	x0, x0, #:lo12:_dl_fini					\n\
+	// jump to the user_s entry point				\n\
+	br      x21							\n\
+");
+
+/* Get a pointer to the argv array.  On many platforms this can be just
+ * the address of the first argument, on other platforms we need to
+ * do something a little more subtle here.  */
+#define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*)ARGS)+1)
+
+/* Handle relocation of the symbols in the dynamic loader. */
+static __always_inline
+void PERFORM_BOOTSTRAP_RELOC(ELF_RELOC *rpnt, ElfW(Addr) *reloc_addr,
+	ElfW(Addr) symbol_addr, ElfW(Addr) load_addr, ElfW(Addr) *sym)
+{
+	switch (ELF_R_TYPE(rpnt->r_info)) {
+		case R_AARCH64_NONE:
+			break;
+		case R_AARCH64_ABS64:
+		case R_AARCH64_GLOB_DAT:
+		case R_AARCH64_JUMP_SLOT:
+			*reloc_addr = symbol_addr + rpnt->r_addend;
+			break;
+		default:
+			_dl_exit(1);
+	}
+}
-- 
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