grub-0.95-patch4-emulation

Grub for dos 0.2.0,system loader

diff -Naur grub-0.95_ntfs/ChangeLog grub-0.95_emulation/ChangeLog
--- grub-0.95_ntfs/ChangeLog	2004-10-22 14:26:29.333877624 +0800
+++ grub-0.95_emulation/ChangeLog	2004-10-22 17:43:06.671987456 +0800
@@ -1,5 +1,19 @@
 2004-07-13
 
+	From Tinybit  <[e-mail]>:
+	For disk drive emulation:
+	* stage2/asm.S (int13_handler, etc): floppy and harddisk emulation
+
+	* grub/asmstub.c: floppy and harddisk emulation
+
+	* stage2/builtins.c: floppy and harddisk emulation
+
+	* stage2/common.c: floppy and harddisk emulation
+
+	* stage2/disk_io.c: floppy and harddisk emulation
+
+	* stage2/shared.h: floppy and harddisk emulation
+
 	From Gandalf  <[e-mail]>:
 	NTFS support
 
diff -Naur grub-0.95_ntfs/grub/asmstub.c grub-0.95_emulation/grub/asmstub.c
--- grub-0.95_ntfs/grub/asmstub.c	2004-03-13 01:01:49.000000000 +0800
+++ grub-0.95_emulation/grub/asmstub.c	2004-10-22 17:33:28.547875680 +0800
@@ -338,11 +338,19 @@
 
 /* Copy MAP to the drive map and set up the int13 handler.  */
 void
-set_int13_handler (unsigned short *map)
+set_int13_handler (struct drive_map_slot *map)
 {
   /* Nothing to do in the simulator.  */
 }
 
+void
+unset_int13_handler (void)
+{
+  /* Nothing to do in the simulator.  */
+}
+
+struct drive_map_slot hooked_drive_map[DRIVE_MAP_SIZE + 1];
+
 int
 get_code_end (void)
 {
diff -Naur grub-0.95_ntfs/stage2/asm.S grub-0.95_emulation/stage2/asm.S
--- grub-0.95_ntfs/stage2/asm.S	2004-05-24 00:22:23.000000000 +0800
+++ grub-0.95_emulation/stage2/asm.S	2004-10-22 18:36:49.010117600 +0800
@@ -617,121 +617,1126 @@
 	pushl	%esi
 
 	/* copy MAP to the drive map */
-	movl	$(DRIVE_MAP_SIZE * 2), %ecx
-	movl	$ABS(drive_map), %edi
+	movl	$(DRIVE_MAP_SIZE * 12 / 4), %ecx /* sizeof(struct drive_map_slot) */
+	movl	$ABS(hooked_drive_map), %edi
 	movl	8(%ebp), %esi
 	cld
 	rep
-	movsb
+	movsl
 
 	/* save the original int13 handler */
 	movl	$0x4c, %edi
-	movw	(%edi), %ax
-	movw	%ax, ABS(int13_offset)
-	movw	2(%edi), %ax
-	movw	%ax, ABS(int13_segment)
+	movl	(%edi), %eax
+	movl	%eax, ABS(int13_offset)
 	
 	/* decrease the lower memory size and set it to the BIOS memory */
 	movl	$0x413, %edi
 	decw	(%edi)
+	decw	(%edi)
 	xorl	%eax, %eax
 	movw	(%edi), %ax
 	
-	/* compute the segment */
-	shll	$6, %eax
+	/* compute the segment(high word); the offset(low word) should be 0 */
+	shll	$(16 + 6), %eax
 
 	/* save the new int13 handler */
 	movl	$0x4c, %edi
-	movw	%ax, 2(%edi)
-	xorw	%cx, %cx
-	movw	%cx, (%edi)
+	movl	%eax, (%edi)
 
 	/* copy int13_handler to the reserved area */
-	shll	$4, %eax
+	shrl	$12, %eax
 	movl	%eax, %edi
 	movl	$ABS(int13_handler), %esi
-	movl	$(int13_handler_end - int13_handler), %ecx
+	movl	$((int13_handler_end - int13_handler) / 4), %ecx
 	rep
-	movsb
+	movsl
 
 	popl	%esi
 	popl	%edi
 	popl	%ebp
 	ret
 
+/*
+ * unset_int13_handler(void)
+ *
+ * Restore the original int13 handler
+ */
+ENTRY(unset_int13_handler)
+	pushl	%edi
 	
+	/* check if int13_handler is set */
+	movl	$0x413, %edi
+	xorl	%eax, %eax
+	movw	(%edi), %ax
+	cmpw	$640, %ax
+	jae	1f
+	cmpw	$632, %ax
+	jb	1f
+	shll	$(16 + 6), %eax
+	movl	$0x4c, %edi
+	cmpl	%eax, (%edi)
+	jne	1f
+	shrl	$12, %eax	/* segment absolute address */
+	movl	%eax, %edi
+	xorl	%eax, %eax
+	movw	$(int13_offset - int13_handler), %ax
+	addl	%eax, %edi
+	cmpl	$0x9a006e8b, -4(%edi) /* movw (%bp), %bp; lcall */
+	jnz	1f
+	movl	ABS(int13_offset), %eax
+	cmpl	(%edi), %eax
+	jnz	1f
+	cmpl	$0xc0000000, %eax /* is it a BIOS vector? */
+	jb	1f
+
+	/* restore the original int13 handler */
+	movl	$0x4c, %edi
+	stosl
+
+	/* increase the lower memory size and set it to the BIOS memory */
+	movl	$0x413, %edi
+	incw	(%edi)
+	incw	(%edi)
+1:
+	popl	%edi
+	ret
+
+
 /* 
- * Map a drive to another drive.
+ * Map a drive to another drive or a disk image file.
  */
 	
 	.code16
 	
 int13_handler:
-	pushw	%ax
+#if 0
+	/* for test only - direct far jmp to original int13 */
+	ljmp	%cs:*(int13_offset - int13_handler)
+#endif
+	cmpb	$0x1a, %ah	/* PS/2 low level format ESDI drive!!!! */
+	je	error_01_disable2	/* disabled in any case */
+	pushl	%eax
 	pushw	%bp
 	movw	%sp, %bp
 	
 	pushw	%si
 
 	/* set %si to the drive map */
-	movw	$(drive_map - int13_handler), %si
+	movw	$(hooked_drive_map - int13_handler), %si
 	/* find the drive number from the drive map */
 	cld
+	subw	$12, %sp
 1:	
-	lodsw	%cs:(%si), %ax
+	addw	$12, %sp
+	lodsl	%cs:(%si), %eax
+	pushl	%eax
+	lodsl	%cs:(%si), %eax
+	pushl	%eax
+	lodsl	%cs:(%si), %eax
+	pushl	%eax
+
+	movl	-6(%bp), %eax	/* FROM, TO, Hmax, Smax */
+
 	/* check if this is the end */
-	testw	%ax, %ax
-	jz	2f
-	/* check if this matches the drive number */
-	cmpb	%al, %dl
-	jne	1b
-	/* if so, perform the mapping */
-	movb	%ah, %dl
+	testl	%eax, %eax
+	jnz	3f		/* not end, continue */
+	movl	-10(%bp), %eax	/* StartLBA */
+	testl	%eax, %eax
+	jnz	3f		/* not end, continue */
+	movl	-14(%bp), %eax	/* S_count */
+	testl	%eax, %eax
+	jz	2f		/* map whole drive to itself signals the end */
+3:
+	/* Now this is a valid drive map slot */
+	movw	-6(%bp), %ax	/* AL=FROM, AH=TO */
+	cmpb	%al, %dl	/* check if this matches the drive number */
+	jne	1b		/* no, continue to check the next map */
+
+	/* yes, found the map corresponding to drive DL */
+	movl	-10(%bp), %eax	/* StartLBA */
+	testl	%eax, %eax
+	jnz	drive_emulation
+	movl	-14(%bp), %eax	/* S_count */
+	shrl	$1, %eax
+	jnz	drive_emulation
+	movw	-4(%bp), %ax	/* AL=Hmax, AH=Smax */
+	testb	$62, %ah	/* Sectors > 1 means force geom, this -- */
+	jnz	drive_emulation	/* -- also leads to drive emulation */
+
+	/* ignore geom and directly map a whole drive */
+	
+	/* bits of AH:
+	 *    7		bit set means readonly/fakewrite
+	 *    6		bit set means disable LBA
+	 *  5 - 1	bits already cleared(=0)
+	 *    0		bit cleared means disable CHS
+	 * So, if AH!=1, it is a restricted disk access;
+	 * and if AH=1, it is a normal disk access.
+	 */
+	cmpb	$1, %ah
+	je	1f
+	call	restricted_map
+1:
+	/* map a whole drive, normal access */
+	movw	-6(%bp), %ax	/* AL=FROM, AH=TO */
+	movb	%ah, %dl	/* Let DL access TO instead of FROM */
 2:
-	/* restore %si */
-	popw	%si
-	/* save %ax in the stack */
-	pushw	%ax
-	/* simulate the interrupt call */
-	pushw	8(%bp)
-	/* set %ax and %bp to the original values */
-	movw	2(%bp), %ax
-	movw	(%bp), %bp
-	/* lcall */
-	.byte	0x9a
+	/* might map to itself, i.e., acturally not mapped */
+	
+	movw	-2(%bp), %si	/* restore SI */
+
+	pushw	10(%bp)		/* pushfw, simulate the interrupt call */
+	
+	movl	2(%bp), %eax	/* restore EAX */
+	movw	(%bp), %bp	/* restore BP */
+	.byte	0x9a		/* lcall, simulate the interrupt call */
 int13_offset:	.word	0
 int13_segment:	.word	0
-	/* save flags */
-	pushf
-	/* restore %bp */
-	movw	%sp, %bp
-	/* save %ax */
+	pushw	%ax		/* save AX */
+	pushfw			/* save flags returned by int13 */
+	popw	%ax
+	movw	%sp, %bp	/* set new BP */
+	movw	%ax, 26(%bp)	/* update the flags in the stack */
+	
+	/* check if should restore(reversely map) the drive number */
+	jc	1f		/* restore DL on error */
+	movw	18(%bp), %ax	/* lower word of the saved EAX */
+	cmpb	$0x08, %ah	/* int13 AH=08h, read drive parameters */
+	je	3f		/* DL==number of drives, should not restore */
+	cmpb	$0x15, %ah	/* int13 AH=15h, read drive type */
+	je	3f		/* CX:DX==total sectors, should not restore */
+1:
+	/* try to restore DL if possible */
+	movw	10(%bp), %ax	/* get the drive mapping */
+	cmpb	%al, %ah	/* check if the mapping was performed */
+	je	3f		/* not performed, so need not restore DL */
+	cmpb	%dl, %ah
+	jne	3f		/* DL changed by int13, so do not restore */
+	movb	%al, %dl	/* restore DL back to the FROM drive */
+3:
+	movl	18(%bp), %eax	/* restore the original EAX */
+	popw	%ax		/* update the int13 status in AX */
+	movw	16(%bp), %bp	/* restore the original BP */
+	addw	$20, %sp
+	iret
+
+restricted_map:
+	movw	2(%bp), %ax	/* lower word of the saved EAX */
+
+	/* CHS read functions */
+	cmpb	$0x02, %ah	/* read sectors */
+	je	2f
+	cmpb	$0x04, %ah	/* verify sectors, also a read operation */
+	je	2f
+	cmpb	$0x0a, %ah	/* read long sectors */
+	je	2f
+	cmpb	$0x0c, %ah	/* seek to cylinder */
+	je	2f
+	cmpb	$0x21, %ah	/* PS/1 and newer PS/2 - read multiple disk sectors */
+	jne	1f
+2:
+	movb	-3(%bp), %ah	/* AH=Smax */
+	testb	$63, %ah	/* check if Sectors=0, i.e., disable CHS */
+	jz	error_01_disable
+	ret
+1:
+	/* CHS write functions */
+	cmpb	$0x03, %ah	/* CHS write sectors */
+	je	2f
+	cmpb	$0x05, %ah	/* PC/XT/AT/EISA format tracks */
+	je	2f
+	cmpb	$0x06, %ah	/* PC/XT format tracks with bad sectors */
+	je	2f
+	cmpb	$0x07, %ah	/* PC/XT format multiple cylinders */
+	je	2f
+	cmpb	$0x0b, %ah	/* PC/XT/AT/EISA write sectors with ECC */
+	je	2f
+	cmpb	$0x0f, %ah	/* PC/XT/PS/1 write sector buffer */
+	je	2f
+	cmpb	$0x22, %ah	/* PS/1 and newer PS/2 - write multiple disk sectors */
+	jne	1f
+2:
+	movb	-3(%bp), %ah	/* AH=Smax */
+	testb	$63, %ah	/* check if Sectors=0, i.e., disable CHS */
+	jz	error_01_disable
+	testb	$0x80, %ah	/* readonly access? */
+	jnz	readonly_fakewrite
+	ret
+1:
+	/* LBA read functions */
+	cmpb	$0x41, %ah	/* Extensions - INSTALLATION CHECK */
+	je	2f
+	cmpb	$0x42, %ah	/* Extensions - EXTENDED READ */
+	je	2f
+	cmpb	$0x44, %ah	/* Extensions - verify sectors */
+	je	2f
+	cmpb	$0x45, %ah	/* Extensions - LOCK/UNLOCK DRIVE */
+	je	2f
+	cmpb	$0x46, %ah	/* Extensions - EJECT MEDIA */
+	je	2f
+	cmpb	$0x47, %ah	/* Extensions - EXTENDED SEEK */
+	je	2f
+	cmpb	$0x48, %ah	/* Extensions - GET DRIVE PARAMETERS */
+	je	2f
+	cmpb	$0x49, %ah	/* Extensions - detect media change */
+	je	2f
+	cmpb	$0x4a, %ah	/* Bootable CDROM - INITIATE DISK EMULATION */
+	je	2f
+	cmpb	$0x4b, %ah	/* Bootable CDROM - TERMINATE DISK EMULATION */
+	je	2f
+	cmpb	$0x4c, %ah	/* Bootable CDROM - INITIATE DISK EMULATION AND BOOT */
+	je	2f
+	cmpb	$0x4d, %ah	/* Bootable CDROM - RETURN BOOT CATALOG */
+	je	2f
+	cmpb	$0x4e, %ah	/* Extensions v2.1 - SET HARDWARE CONFIGURATION */
+	jne	1f
+2:
+	movb	-3(%bp), %ah	/* AH=Smax */
+	testb	$64, %ah	/* disable LBA? */
+	jnz	error_01_disable
+	ret
+1:
+	/* LBA write functions */
+	cmpb	$0x43, %ah	/* Extensions - EXTENDED WRITE */
+	jne	1f
+2:
+	movb	-3(%bp), %ah	/* AH=Smax */
+	testb	$64, %ah	/* disable LBA? */
+	jnz	error_01_disable
+	testb	$0x80, %ah	/* readonly access? */
+	jnz	readonly_fakewrite
+1:
+	/* no restrictions, return and continue */
+	ret
+
+error_01_disable:
+	/* function not supported, or the input CHS is invalid */
+	addw	$14, %sp	/* adjust SP */
+	popw	%si
+	popw	%bp
+	popl	%eax
+error_01_disable2:
+	movb	$0x01, %ah	/* signal invalid function call */
+	stc			/* signal error */
+	lret	$2		/* far return discard the original flags */
+
+readonly_fakewrite:
+	addw	$14, %sp	/* adjust SP */
+	popw	%si
+	testb	$1, -14(%bp)	/* lowest bit of S_count */
+	popw	%bp
+	popl	%eax
+	jnz	1f
+	/* read only */
+	movb	$0x03, %ah	/* signal write protection */
+	stc			/* signal error */
+	lret	$2		/* far return discard the original flags */
+1:
+	/* fake write */
+	xorb	%ah, %ah	/* signal write succeeded */
+	/*clc*/			/* signal success, CF already cleared by XOR */
+	lret	$2		/* far return discard the original flags */
+
+
+drive_emulation:
+	movw	-4(%bp), %ax	/* AL=Hmax, AH=Smax */
+	testb	$63, %ah	/* disable CHS? */
+	jz	2f		/* yes, call restricted map */
+	testb	$0xc0, %ah	/* readonly or disable LBA? */
+	jz	1f
+2:
+	call	restricted_map
+1:
+	movw	2(%bp),	%ax	/* get original AX */
+
+	testb	%ah, %ah	/* reset disk system, always succeed */
+	jnz	1f
+	clc
+	jmp	int13_return
+1:
+	cmpb	$0x01, %ah /* get status of last operation, always succeed */
+	jnz	1f
+	xorb	%ah, %ah
+	clc