From 80fc88f22dba0b213c208202807ee7311f6d7e9a Mon Sep 17 00:00:00 2001
From: robertmh <robertmh@localhost>
Date: Sat, 22 Nov 2008 15:00:39 +0000
Subject: [PATCH]         * kern/i386/loader.S
 (grub_multiboot_backward_relocator): Improve         comments.  Avoid copiing
 one more byte than necessary (just in case).

---
 ChangeLog          |  3 +++
 kern/i386/loader.S | 20 ++++++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 755112460..5a6d71773 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,9 @@
 	(grub_vga_text_term): Use grub_vga_text_init_fini() instead of
 	grub_vga_text_cls().
 
+	* kern/i386/loader.S (grub_multiboot_backward_relocator): Improve
+	comments.  Avoid copiing one more byte than necessary (just in case).
+
 2008-11-20  Robert Millan  <rmh@aybabtu.com>
 
 	* kern/i386/coreboot/init.c (grub_time_tics): Remove variable.
diff --git a/kern/i386/loader.S b/kern/i386/loader.S
index 8f146d92e..cacbbea73 100644
--- a/kern/i386/loader.S
+++ b/kern/i386/loader.S
@@ -141,24 +141,32 @@ VARIABLE(grub_multiboot_payload_entry_offset)
  * edx:	Offset of the entry point (relative to the beginning of the block).
  */
 VARIABLE(grub_multiboot_forward_relocator)
-	cld
+	/* Add entry offset.  */
 	addl	%edi, %edx
+
+	/* Forward copy.  */
+	cld
 	rep
 	movsb
+
 	jmp	*%edx
 VARIABLE(grub_multiboot_forward_relocator_end)
 
 VARIABLE(grub_multiboot_backward_relocator)
+	/* Add entry offset (before %edi is mangled).  */
+	addl	%edi, %edx
+
+	/* Backward movsb is implicitly off-by-one.  compensate that.  */
+	decl	%esi
+	decl	%edi
+
+	/* Backward copy.  */
 	std
 	addl	%ecx, %esi
 	addl	%ecx, %edi
-	/* backward movsb is implicitly off-by-one.  compensate that. */
-	incl	%ecx
 	rep
 	movsb
-	/* same problem again. */
-	incl	%edi
-	addl	%edi, %edx
+
 	jmp	*%edx
 VARIABLE(grub_multiboot_backward_relocator_end)