2 files changed, 87 insertions, 0 deletions

diff --git a/ldso/ldso/arm/dl-startup.h b/ldso/ldso/arm/dl-startup.h
index 8ebc0b288..fa7c9651e 100644
--- a/ldso/ldso/arm/dl-startup.h
+++ b/ldso/ldso/arm/dl-startup.h
@@ -4,6 +4,7 @@
  * Copyright (C) 2000-2004 by Erik Andersen <andersen@codepoet.org>
  */
 
+#if defined(__arm__)
 asm(
     "	.text\n"
     "	.globl	_start\n"
@@ -40,7 +41,11 @@ asm(
 	"	ldr	r0, .L_FINI_PROC\n"
 	"	ldr	r0, [sl, r0]\n"
 	"	@ jump to the user_s entry point\n"
+#if defined(__THUMB_INTERWORK__)
+	"	bx	r6\n"
+#else
 	"	mov	pc, r6\n"
+#endif
 	".L_GET_GOT:\n"
 	"	.word	_GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n"
 	".L_SKIP_ARGS:\n"
@@ -51,6 +56,70 @@ asm(
     "	.size	_start,.-_start\n"
 	".previous\n"
 );
+#else
+asm(
+    "	.text\n"
+    "	.arm\n"
+    "	.globl	_start\n"
+    "	.type	_start,%function\n"
+	"_start:\n"
+	"	@ dumb: can't persuade the linker to make the start address\n"
+	"	@ odd, so use an arm function and change to thumb (_dl_start\n"
+	"	@ is thumb)\n"
+	"	adr	r0, __dl_thumb_start+1\n"
+	"	bx	r0\n"
+	"\n\n"
+    "	.thumb\n"
+    "	.globl	__dl_thumb_start\n"
+    "	.thumb_func\n"
+    "	.type	__dl_thumb_start,%function\n"
+	"__dl_thumb_start:\n"
+	"	@ at start time, all the args are on the stack\n"
+	"	mov	r0, sp\n"
+	"	bl	_dl_start\n"
+	"	@ returns user entry point in r0\n"
+	"	mov	r6, r0\n"
+	"	@ we are PIC code, so get global offset table\n"
+	"	ldr	r7, .L_GET_GOT\n"
+	".L_GOT_GOT:\n"
+	"	add	r7, pc\n"
+	"	@ See if we were run as a command with the executable file\n"
+	"	@ name as an extra leading argument.\n"
+	"	ldr	r4, .L_SKIP_ARGS\n"
+	"	ldr	r4, [r7, r4]\n"
+	"	@ get the original arg count\n"
+	"	ldr	r1, [sp]\n"
+	"	@ subtract _dl_skip_args from it\n"
+	"	sub	r1, r1, r4\n"
+	"	@ adjust the stack pointer to skip them\n"
+	"	lsl	r4, r4, #2\n"
+	"	add	sp, r4\n"
+	"	@ get the argv address\n"
+	"	add	r2, sp, #4\n"
+	"	@ store the new argc in the new stack location\n"
+	"	str	r1, [sp]\n"
+	"	@ compute envp\n"
+	"	lsl	r3, r1, #2\n"
+	"	add	r3, r3, r2\n"
+	"	add	r3, #4\n"
+	"\n\n"
+	"	@ load the finalizer function\n"
+	"	ldr	r0, .L_FINI_PROC\n"
+	"	ldr	r0, [r7, r0]\n"
+	"	@ jump to the user_s entry point\n"
+	"	bx	r6\n"
+	"\n\n"
+	".L_GET_GOT:\n"
+	"	.word	_GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n"
+	".L_SKIP_ARGS:\n"
+	"	.word	_dl_skip_args(GOTOFF)\n"
+	".L_FINI_PROC:\n"
+	"	.word	_dl_fini(GOT)\n"
+	"\n\n"
+    "	.size	_start,.-_start\n"
+	".previous\n"
+);
+#endif
 
 
 /* Get a pointer to the argv array.  On many platforms this can be just
diff --git a/ldso/ldso/arm/dl-sysdep.h b/ldso/ldso/arm/dl-sysdep.h
index 794c86a0c..194fd2eb7 100644
--- a/ldso/ldso/arm/dl-sysdep.h
+++ b/ldso/ldso/arm/dl-sysdep.h
@@ -85,7 +85,25 @@ elf_machine_load_address (void)
 	extern void __dl_start asm ("_dl_start");
 	Elf32_Addr got_addr = (Elf32_Addr) &__dl_start;
 	Elf32_Addr pcrel_addr;
+#if !defined __thumb__
 	asm ("adr %0, _dl_start" : "=r" (pcrel_addr));
+#else
+	int tmp;
+	/* The above adr will not work on thumb because it
+	 * is negative.  The only safe way is to temporarily
+	 * swap to arm.
+	 */
+	asm(   ".align	2\n"
+	"	bx	pc\n"
+	"	nop	\n"
+	"	.arm	\n"
+	"	adr	%0, _dl_start\n"
+	"	.align	2\n"
+	"	orr	%1, pc, #1\n"
+	"	bx	%1\n"
+	"	.force_thumb\n"
+	: "=r" (pcrel_addr), "=&r" (tmp));
+#endif
 	return pcrel_addr - got_addr;
 }