x86 boot enhancements, Clean up the 32bit entry points 6/11

diff -uNr linux-2.5.8.boot.heap/arch/i386/boot/compressed/head.S linux-2.5.8.boot.clean_32bit_entries/arch/i386/boot/compressed/head.S
@@ -25,24 +25,30 @@
 
 #include <linux/linkage.h>
 #include <asm/segment.h>
+#include <asm/boot.h>
 
 	.globl startup_32
 	
 startup_32:
 	cld
 	cli
-	movl $(__KERNEL_DS),%eax
-	movl %eax,%ds
-	movl %eax,%es
-	movl %eax,%fs
-	movl %eax,%gs
 
-	lss SYMBOL_NAME(stack_start),%esp
-	xorl %eax,%eax
-1:	incl %eax		# check that A20 really IS enabled
-	movl %eax,0x000000	# loop forever if it isn't
-	cmpl %eax,0x100000
-	je 1b
+	/*
+	 * Save the initial registers
+	 */
+	movl %eax, eax
+	movl %ebx, ebx
+	movl %ecx, ecx
+	movl %edx, edx
+	movl %esi, esi
+	movl %edi, edi
+	movl %esp, esp
+	movl %ebp, ebp
+
+	/*
+	 * Setup the stack
+	 */
+	movl SYMBOL_NAME(stack_start), %esp
 
 /*
  * Initialize eflags.  Some BIOS's leave bits like NT set.  This would

@@ -66,16 +72,10 @@
  */
 	subl $16,%esp	# place for structure on the stack
 	movl %esp,%eax
-	pushl %esi	# real mode pointer as second arg
 	pushl %eax	# address of structure as first arg
 	call SYMBOL_NAME(decompress_kernel)
 	orl  %eax,%eax 
-	jnz  3f
-	popl %esi	# discard address
-	popl %esi	# real mode pointer
-	xorl %ebx,%ebx
-	ljmp $(__KERNEL_CS), $0x100000
-
+	jz out
 /*
  * We come here, if we were loaded high.
  * We need to move the move-in-place routine down to 0x1000

@@ -83,8 +83,21 @@
  * which we got from the stack.
  */
 3:
-	movl $move_routine_start,%esi
-	movl $0x1000,%edi
+	/* Relocate the move routine */
+	movl $move_routine_start,%esi	#src
+	movl %eax,%edi			#dest
+	movl %eax, %ebp                 #saved dest
+	movl %edi, %eax 
+	subl %esi, %eax			# The relocation factor
+	addl %eax, reloc1
+	addl %eax, reloc2
+	addl %eax, reloc3
+	addl %eax, reloc4
+	addl %eax, reloc5
+	addl %eax, reloc6
+	addl %eax, reloc7
+	addl %eax, reloc8
+	addl %eax, reloc9
 	movl $move_routine_end,%ecx
 	subl %esi,%ecx
 	addl $3,%ecx

@@ -93,20 +106,23 @@
 	rep
 	movsl
 
+	/* Load it's arguments and jump to the move routine */
 	popl %esi	# discard the address
-	popl %ebx	# real mode pointer
 	popl %esi	# low_buffer_start
 	popl %ecx	# lcount
 	popl %edx	# high_buffer_start
 	popl %eax	# hcount
-	movl $0x100000,%edi
+	movl $HIGH_BASE,%edi
 	cli		# make sure we don't get interrupted
-	ljmp $(__KERNEL_CS), $0x1000 # and jump to the move routine
+	jmpl *%ebp
 
 /*
  * Routine (template) for moving the decompressed kernel in place,
- * if we were high loaded. This _must_ PIC-code !
+ * if we were high loaded. This _must_ be PIC-code !
+ * Or it must be anotated with lables so it can be manually relocated.
  */
+	.globl move_routine_start, move_routine_end
+	.balign 4
 move_routine_start:
 	movl %ecx,%ebp
 	shrl $2,%ecx

@@ -122,7 +138,35 @@
 	shrl $2,%ecx
 	rep
 	movsl
-	movl %ebx,%esi	# Restore setup pointer
-	xorl %ebx,%ebx
-	ljmp $(__KERNEL_CS), $0x100000
+out:
+	.byte 0xa1		# movl eax,  %eax
+reloc1:	.long eax
+	.byte 0x8b, 0x1d	# movl ebx,  %ebx
+reloc2:	.long ebx
+	.byte 0x8b, 0x0d	# movl ecx,  %ecx
+reloc3:	.long ecx
+	.byte 0x8b, 0x15	# movl edx, %edx
+reloc4:	.long edx
+	.byte 0x8b, 0x35	# movl esi, %esi
+reloc5:	.long esi
+	.byte 0x8b, 0x3d	# movl edi, %edi
+reloc6:	.long edi
+	.byte 0x8b, 0x25	# movl esp, %esp
+reloc7:	.long esp
+	.byte 0x8b, 0x2d	# movl ebp, %ebp
+reloc8:	.long ebp
+	.byte 0xff, 0x25	# jmpl *(kernel_start)
+reloc9:	.long kernel_start
+	.balign 4
+ENTRY(initial_regs)
+eax:	.long 0x12345678 /* eax */
+ebx:	.long 0x12345678 /* ebx */
+ecx:	.long 0x12345678 /* ecx */
+edx:	.long 0x12345678 /* edx */
+esi:	.long 0x12345678 /* esi */
+edi:	.long 0x12345678 /* edi */
+esp:	.long 0x12345678 /* esp */
+ebp:	.long 0x12345678 /* ebp */
+kernel_start:
+	.long HIGH_BASE
 move_routine_end:

diff -uNr linux-2.5.8.boot.heap/arch/i386/boot/setup.S linux-2.5.8.boot.clean_32bit_entries/arch/i386/boot/setup.S
@@ -64,6 +64,12 @@
 
 #define DELTA_BOOTSECT 512
 
+/* Segments used by setup.S */
+#define __SETUP_CS      0x10
+#define __SETUP_DS      0x18
+#define __SETUP_REAL_CS 0x20
+#define __SETUP_REAL_DS 0x28
+
 INITSEG  = DEF_INITSEG		# 0x9000, we move boot here, out of the way
 SYSSEG   = DEF_SYSSEG		# 0x1000, system loaded at 0x10000 (65536).
 SETUPSEG = DEF_SETUPSEG		# 0x9020, this is the current segment

@@ -784,13 +790,22 @@
 	jmp	flush_instr
 
 flush_instr:
-	xorw	%bx, %bx			# Flag to indicate a boot
 	xorl	%esi, %esi			# Pointer to real-mode code
 	movw	%cs, %si
 	subw	$DELTA_INITSEG, %si
 	shll	$4, %esi			# Convert to 32-bit pointer
+	movl	$ENTRY16, %ebp			# Magic to indicate 16bit entry
+
+# Setup the data segments
+	movw	$(__SETUP_DS), %ax
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+	movw	%ax, %ss
+
 # NOTE: For high loaded big kernels we need a
-#	jmpi    0x100000,__KERNEL_CS
+#	jmpi    0x100000,__SETUP_CS
 #
 #	but we yet haven't reloaded the CS register, so the default size 
 #	of the target offset still is 16 bit.

@@ -801,7 +816,7 @@
 	.byte 0x66, 0xea			# prefix + jmpi-opcode
 code32:	.long	0x1000				# will be set to 0x100000
 						# for big kernels
-	.word	__KERNEL_CS
+	.word	__SETUP_CS
 
 # Here's a bunch of information about your current kernel..
 kernel_version:	.ascii	UTS_RELEASE

268 lines not on this page · raw message

diff -uNr linux-2.5.8.boot.heap/arch/i386/kernel/trampoline.S linux-2.5.8.boot.clean_32bit_entries/arch/i386/kernel/trampoline.S
@@ -12,10 +12,6 @@
  *	In fact we don't actually need a stack so we don't
  *	set one up.
  *
- *	We jump into the boot/compressed/head.S code. So you'd
- *	better be running a compressed kernel image or you
- *	won't get very far.
- *
  *	On entry to trampoline_data, the processor is in real mode
  *	with 16-bit addressing and 16-bit data.  CS has some value
  *	and IP is zero.  Thus, data addresses need to be absolute

@@ -23,12 +19,16 @@
  *
  *	If you work on this file, check the object module with objdump
  *	--full-contents --reloc to make sure there are no relocation
- *	entries except for the gdt one..
+ *	entries except for gdt & secondary_startup_32..
  */
 
 #include <linux/linkage.h>
+#include <linux/threads.h>
 #include <asm/segment.h>
 #include <asm/page.h>
+#include <asm/desc.h>
+
+#define GDT_ENTRIES	(__TSS(NR_CPUS))
 
 .data
 

@@ -42,7 +42,6 @@
 	mov	%cs, %ax	# Code and data in the same place
 	mov	%ax, %ds
 
-	mov	$1, %bx		# Flag an SMP trampoline
 	cli			# We should be safe anyway
 
 	movl	$0xA5A5A5A5, trampoline_data - r_base

@@ -56,16 +55,17 @@
 	lmsw	%ax		# into protected mode
 	jmp	flush_instr
 flush_instr:
-	ljmpl	$__KERNEL_CS, $0x00100000
-			# jump to startup_32 in arch/i386/kernel/head.S
+		# jump to secondary_startup_32 in arch/i386/kernel/head.S
+	ljmpl	$__KERNEL_CS, $(SYMBOL_NAME(secondary_startup_32) - __PAGE_OFFSET)
+	
 
 idt_48:
 	.word	0			# idt limit = 0
 	.word	0, 0			# idt base = 0L
 
 gdt_48:
-	.word	0x0800			# gdt limit = 2048, 256 GDT entries
-	.long	gdt_table-__PAGE_OFFSET	# gdt base = gdt (first SMP CPU)
+	.word	GDT_ENTRIES*8-1		# gdt limit
+	.long	SYMBOL_NAME(gdt_table)-__PAGE_OFFSET	# gdt base = gdt (first SMP CPU)
 
 .globl SYMBOL_NAME(trampoline_end)
 SYMBOL_NAME_LABEL(trampoline_end)