Eliminate fixed limit on reed solomon decoder length.

* grub-core/boot/i386/pc/lnxboot.S: Scan for multiboot signature
	rather than hardcoding the address.
	* grub-core/boot/i386/pc/startup_raw.S: Add new data field
	no_reed_solomon_length.
	Move gate_a20 to no-reed-solomon part.
	Don't force a particular size of no reed-solomon part.
	* include/grub/offsets.h (GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART):
	Removed.
	(GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH): New define.
	* util/grub-setup.c (setup): Read no_rs_length from the image itself.

ChangeLog

@@ -1,3 +1,18 @@
+2012-01-24  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	Eliminate fixed limit on reed solomon decoder length.
+
+	* grub-core/boot/i386/pc/lnxboot.S: Scan for multiboot signature
+	rather than hardcoding the address.
+	* grub-core/boot/i386/pc/startup_raw.S: Add new data field
+	no_reed_solomon_length.
+	Move gate_a20 to no-reed-solomon part.
+	Don't force a particular size of no reed-solomon part.
+	* include/grub/offsets.h (GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART):
+	Removed.
+	(GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH): New define.
+	* util/grub-setup.c (setup): Read no_rs_length from the image itself.
+
 2012-01-24  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	* grub-core/commands/wildcard.c (match_files): Handle filenames

grub-core/boot/i386/pc/lnxboot.S

@@ -177,20 +177,21 @@ real_code_2:
 	pushw	%es
 	popw	%ds
 
-#if GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART + 4 < 0x200
+	movl	$0x1000, %ecx
-	movl	$0x200, %ecx
-	addl	%ecx, %esi
-#else
-	movl	$(GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART + 4), %ecx
 	addl	$0x200, %esi
-#endif
 	movl	$DATA_ADDR, %edi
 
 	call	LOCAL(move_memory)
 
 	/* Check for multiboot signature.  */
-	cmpl	$MULTIBOOT_HEADER_MAGIC, %ss:(DATA_ADDR + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART)
+	movl	$DATA_ADDR, %edi
+3:
+	movl	%ss:(%edi), %eax
+	cmpl	$MULTIBOOT_HEADER_MAGIC, %eax
 	jz	1f
+	addl	$4, %edi
+	cmpl	$(DATA_ADDR + 0x1000), %edi
+	jne     3b
 
 	movl	(ramdisk_image - start), %esi
 	movl	(ramdisk_size - start), %ecx
@@ -199,8 +200,9 @@ real_code_2:
 
 1:
 
+	movl	$(DATA_ADDR + 0x1000), %edi
 	movl	%ss:(DATA_ADDR + GRUB_DECOMPRESSOR_MACHINE_COMPRESSED_SIZE), %ecx
-	addl	$((0x9000 - 0x8200) - (GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART + 4)), %ecx
+	addl	$(0x9000 - 0x8200), %ecx
 
 2:
 	call	LOCAL(move_memory)

grub-core/boot/i386/pc/startup_raw.S

@@ -60,6 +60,8 @@ LOCAL(uncompressed_size):
 	. = _start + GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY
 reed_solomon_redundancy:
 	.long	0
+	. = _start + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH
+	.short	(LOCAL(reed_solomon_part) - _start)
 
 /*
  *  This is the area for all of the special variables.
@@ -103,9 +105,9 @@ LOCAL (codestart):
 	call	grub_gate_a20
 
 	movl	LOCAL(compressed_size), %edx
-	addl    $(LOCAL(decompressor_end) - GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART - _start), %edx
+	addl    $(LOCAL(decompressor_end) - LOCAL(reed_solomon_part)), %edx
 	movl    reed_solomon_redundancy, %ecx
-	leal    _start + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART, %eax
+	leal    LOCAL(reed_solomon_part), %eax
 	cld
 	call    EXT_C (grub_reed_solomon_recover)
 	jmp	post_reed_solomon
@@ -116,82 +118,6 @@ LOCAL (codestart):
 
 	.text
 
-	. = _start + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART
-/*
- * Support for booting GRUB from a Multiboot boot loader (e.g. GRUB itself).
- * This uses the a.out kludge to load raw binary to the area starting at 1MB,
- * and relocates itself after loaded.
- */
-	.p2align	2	/* force 4-byte alignment */
-multiboot_header:
-	/* magic */
-	.long	0x1BADB002
-	/* flags */
-	.long	(1 << 16)
-	/* checksum */
-	.long	-0x1BADB002 - (1 << 16)
-	/* header addr */
-	.long	multiboot_header - _start + 0x100000 + 0x200
-	/* load addr */
-	.long	0x100000
-	/* load end addr */
-	.long	0
-	/* bss end addr */
-	.long	0
-	/* entry addr */
-	.long	multiboot_entry - _start + 0x100000 + 0x200
-
-multiboot_entry:
-	.code32
-	/* obtain the boot device */
-	movl	12(%ebx), %edx
-
-	movl	$GRUB_MEMORY_MACHINE_PROT_STACK, %ebp
-	movl	%ebp, %esp
-
-	/* relocate the code */
-	movl	$(LOCAL(decompressor_end) + 0x200), %ecx
-	addl	LOCAL(compressed_size) - _start + 0x100000 + 0x200, %ecx
-	movl	$0x100000, %esi
-	movl	$GRUB_BOOT_MACHINE_KERNEL_ADDR, %edi
-	cld
-	rep
-	movsb
-	/* jump to the real address */
-	movl	$multiboot_trampoline, %eax
-	jmp	*%eax
-
-multiboot_trampoline:
-	/* fill the boot information */
-	movl	%edx, LOCAL(boot_dev)
-	shrl	$24, %edx
-	/* enter the usual booting */
-	call	prot_to_real
-	.code16
-	jmp     LOCAL (codestart)
-	.code32
-
-post_reed_solomon:
-
-#ifdef ENABLE_LZMA
-	movl	$GRUB_MEMORY_MACHINE_DECOMPRESSION_ADDR, %edi
-	movl	$LOCAL(decompressor_end), %esi
-	pushl	%edi
-	movl	LOCAL (uncompressed_size), %ecx
-	leal	(%edi, %ecx), %ebx
-	/* Don't remove this push: it's an argument.  */
-	push 	%ecx
-	call	_LzmaDecodeA
-	pop	%ecx
-	/* _LzmaDecodeA clears DF, so no need to run cld */
-	popl	%esi
-#endif
-
-	movl	LOCAL(boot_dev), %edx
-	movl	$prot_to_real, %edi
-	movl	$real_to_prot, %ecx
-	jmp	*%esi
-
 /*
  * grub_gate_a20(int on)
  *
@@ -342,6 +268,83 @@ gate_a20_check_state:
 	popl	%ebx
 	ret
 
+LOCAL(reed_solomon_part):
+
+/*
+ * Support for booting GRUB from a Multiboot boot loader (e.g. GRUB itself).
+ * This uses the a.out kludge to load raw binary to the area starting at 1MB,
+ * and relocates itself after loaded.
+ */
+	.p2align	2	/* force 4-byte alignment */
+multiboot_header:
+	/* magic */
+	.long	0x1BADB002
+	/* flags */
+	.long	(1 << 16)
+	/* checksum */
+	.long	-0x1BADB002 - (1 << 16)
+	/* header addr */
+	.long	multiboot_header - _start + 0x100000 + 0x200
+	/* load addr */
+	.long	0x100000
+	/* load end addr */
+	.long	0
+	/* bss end addr */
+	.long	0
+	/* entry addr */
+	.long	multiboot_entry - _start + 0x100000 + 0x200
+
+multiboot_entry:
+	.code32
+	/* obtain the boot device */
+	movl	12(%ebx), %edx
+
+	movl	$GRUB_MEMORY_MACHINE_PROT_STACK, %ebp
+	movl	%ebp, %esp
+
+	/* relocate the code */
+	movl	$(LOCAL(decompressor_end) + 0x200), %ecx
+	addl	LOCAL(compressed_size) - _start + 0x100000 + 0x200, %ecx
+	movl	$0x100000, %esi
+	movl	$GRUB_BOOT_MACHINE_KERNEL_ADDR, %edi
+	cld
+	rep
+	movsb
+	/* jump to the real address */
+	movl	$multiboot_trampoline, %eax
+	jmp	*%eax
+
+multiboot_trampoline:
+	/* fill the boot information */
+	movl	%edx, LOCAL(boot_dev)
+	shrl	$24, %edx
+	/* enter the usual booting */
+	call	prot_to_real
+	.code16
+	jmp     LOCAL (codestart)
+	.code32
+
+post_reed_solomon:
+
+#ifdef ENABLE_LZMA
+	movl	$GRUB_MEMORY_MACHINE_DECOMPRESSION_ADDR, %edi
+	movl	$LOCAL(decompressor_end), %esi
+	pushl	%edi
+	movl	LOCAL (uncompressed_size), %ecx
+	leal	(%edi, %ecx), %ebx
+	/* Don't remove this push: it's an argument.  */
+	push 	%ecx
+	call	_LzmaDecodeA
+	pop	%ecx
+	/* _LzmaDecodeA clears DF, so no need to run cld */
+	popl	%esi
+#endif
+
+	movl	LOCAL(boot_dev), %edx
+	movl	$prot_to_real, %edi
+	movl	$real_to_prot, %ecx
+	jmp	*%esi
+
 #ifdef ENABLE_LZMA
 #include "lzma_decode.S"
 #endif

include/grub/offsets.h

@@ -28,7 +28,8 @@
 /* Offset of reed_solomon_redundancy.  */
 #define GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY	0x10
 
-#define GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART 0x7e0
+/* Offset of field holding no reed solomon length.  */
+#define GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH      0x14
 
 /* The segment where the kernel is loaded.  */
 #define GRUB_BOOT_I386_PC_KERNEL_SEG	0x800

util/grub-setup.c

@@ -444,14 +444,22 @@ setup (const char *dir,
 						  + GRUB_DISK_SECTOR_SIZE
 						  - sizeof (*block));
 
+    grub_size_t no_rs_length;
     *(grub_uint32_t *) (core_img + GRUB_DISK_SECTOR_SIZE
 			+ GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY)
       = grub_host_to_target32 (nsec * GRUB_DISK_SECTOR_SIZE - core_size);
+    no_rs_length = grub_target_to_host16 
+      (*(grub_uint16_t *) (core_img
+			   + GRUB_DISK_SECTOR_SIZE
+			   + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH));
+
+    if (no_rs_length == 0xffff)
+      grub_util_error ("core.img version mismatch");
 
     void *tmp = xmalloc (core_size);
     grub_memcpy (tmp, core_img, core_size);
-    grub_reed_solomon_add_redundancy (core_img + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART + GRUB_DISK_SECTOR_SIZE,
+    grub_reed_solomon_add_redundancy (core_img + no_rs_length + GRUB_DISK_SECTOR_SIZE,
-				      core_size - GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART - GRUB_DISK_SECTOR_SIZE,
+				      core_size - no_rs_length - GRUB_DISK_SECTOR_SIZE,
 				      nsec * GRUB_DISK_SECTOR_SIZE
 				      - core_size);
     assert (grub_memcmp (tmp, core_img, core_size) == 0);