[bios] Add bin-x86_64-pcbios build platform

Move most arch/i386 files to arch/x86, and adjust the contents of the
Makefiles and the include/bits/*.h headers to reflect the new
locations.

This patch makes no substantive code changes, as can be seen using a
rename-aware diff (e.g. "git show -M5").

This patch does not make the pcbios platform functional for x86_64; it
merely allows it to compile without errors.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 671 insertions, 0 deletions

diff --git a/src/arch/x86/transitions/librm.S b/src/arch/x86/transitions/librm.S
new file mode 100644
index 00000000..863e2241
--- /dev/null
+++ b/src/arch/x86/transitions/librm.S
@@ -0,0 +1,671 @@
+/*
+ * librm: a library for interfacing to real-mode code
+ *
+ * Michael Brown <mbrown@fensystems.co.uk>
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
+
+/* Drag in local definitions */
+#include "librm.h"
+
+/* For switches to/from protected mode */
+#define CR0_PE 1
+
+/* Size of various C data structures */
+#define SIZEOF_I386_SEG_REGS	12
+#define SIZEOF_I386_REGS	32
+#define SIZEOF_REAL_MODE_REGS	( SIZEOF_I386_SEG_REGS + SIZEOF_I386_REGS )
+#define SIZEOF_I386_FLAGS	4
+#define SIZEOF_I386_ALL_REGS	( SIZEOF_REAL_MODE_REGS + SIZEOF_I386_FLAGS )
+	
+	.arch i386
+
+/****************************************************************************
+ * Global descriptor table
+ *
+ * Call init_librm to set up the GDT before attempting to use any
+ * protected-mode code.
+ *
+ * NOTE: This must be located before prot_to_real, otherwise gas
+ * throws a "can't handle non absolute segment in `ljmp'" error due to
+ * not knowing the value of REAL_CS when the ljmp is encountered.
+ *
+ * Note also that putting ".word gdt_end - gdt - 1" directly into
+ * gdt_limit, rather than going via gdt_length, will also produce the
+ * "non absolute segment" error.  This is most probably a bug in gas.
+ ****************************************************************************
+ */
+	.section ".data16", "aw", @progbits
+	.align 16
+gdt:
+gdtr:		/* The first GDT entry is unused, the GDTR can fit here. */
+gdt_limit:		.word gdt_length - 1
+gdt_base:		.long 0
+			.word 0 /* padding */
+
+	.org	gdt + VIRTUAL_CS, 0
+virtual_cs:	/* 32 bit protected mode code segment, virtual addresses */
+	.word	0xffff, 0
+	.byte	0, 0x9f, 0xcf, 0
+
+	.org	gdt + VIRTUAL_DS, 0
+virtual_ds:	/* 32 bit protected mode data segment, virtual addresses */
+	.word	0xffff, 0
+	.byte	0, 0x93, 0xcf, 0
+	
+	.org	gdt + PHYSICAL_CS, 0
+physical_cs:	/* 32 bit protected mode code segment, physical addresses */
+	.word	0xffff, 0
+	.byte	0, 0x9f, 0xcf, 0
+
+	.org	gdt + PHYSICAL_DS, 0
+physical_ds:	/* 32 bit protected mode data segment, physical addresses */
+	.word	0xffff, 0
+	.byte	0, 0x93, 0xcf, 0	
+
+	.org	gdt + REAL_CS, 0
+real_cs: 	/* 16 bit real mode code segment */
+	.word	0xffff, 0
+	.byte	0, 0x9b, 0x00, 0
+
+	.org	gdt + REAL_DS	
+real_ds:	/* 16 bit real mode data segment */
+	.word	0xffff, ( REAL_DS << 4 )
+	.byte	0, 0x93, 0x00, 0
+
+gdt_end:
+	.equ	gdt_length, gdt_end - gdt
+
+/****************************************************************************
+ * init_librm (real-mode far call, 16-bit real-mode far return address)
+ *
+ * Initialise the GDT ready for transitions to protected mode.
+ *
+ * Parameters:
+ *   %cs : .text16 segment
+ *   %ds : .data16 segment
+ *   %edi : Physical base of protected-mode code (virt_offset)
+ ****************************************************************************
+ */
+	.section ".text16", "ax", @progbits
+	.code16
+	.globl init_librm
+init_librm:
+	/* Preserve registers */
+	pushl	%eax
+	pushl	%ebx
+
+	/* Store virt_offset and set up virtual_cs and virtual_ds segments */
+	movl	%edi, %eax
+	movw	$virtual_cs, %bx
+	call	set_seg_base
+	movw	$virtual_ds, %bx
+	call	set_seg_base	
+	movl	%edi, rm_virt_offset
+
+	/* Negate virt_offset */
+	negl	%edi
+		
+	/* Store rm_cs and text16, set up real_cs segment */
+	xorl	%eax, %eax
+	movw	%cs, %ax
+	movw	%ax, %cs:rm_cs
+	shll	$4, %eax
+	movw	$real_cs, %bx
+	call	set_seg_base
+	addr32 leal	(%eax, %edi), %ebx
+	movl	%ebx, rm_text16
+
+	/* Store rm_ds and data16 */
+	xorl	%eax, %eax
+	movw	%ds, %ax
+	movw	%ax, %cs:rm_ds
+	shll	$4, %eax
+	addr32 leal	(%eax, %edi), %ebx
+	movl	%ebx, rm_data16
+
+	/* Set GDT base */
+	movl	%eax, gdt_base
+	addl	$gdt, gdt_base
+
+	/* Initialise IDT */
+	pushl	$init_idt
+	pushw	%cs
+	call	prot_call
+	popl	%eax /* discard */
+
+	/* Restore registers */
+	negl	%edi
+	popl	%ebx
+	popl	%eax
+	lret
+
+	.section ".text16", "ax", @progbits
+	.code16
+set_seg_base:
+1:	movw	%ax, 2(%bx)
+	rorl	$16, %eax
+	movb	%al, 4(%bx)
+	movb	%ah, 7(%bx)
+	roll	$16, %eax
+	ret
+
+/****************************************************************************
+ * real_to_prot (real-mode near call, 32-bit virtual return address)
+ *
+ * Switch from 16-bit real-mode to 32-bit protected mode with virtual
+ * addresses.  The real-mode %ss:sp is stored in rm_ss and rm_sp, and
+ * the protected-mode %esp is restored from the saved pm_esp.
+ * Interrupts are disabled.  All other registers may be destroyed.
+ *
+ * The return address for this function should be a 32-bit virtual
+ * address.
+ *
+ * Parameters: 
+ *   %ecx : number of bytes to move from RM stack to PM stack
+ *
+ ****************************************************************************
+ */
+	.section ".text16", "ax", @progbits
+	.code16
+real_to_prot:
+	/* Enable A20 line */
+	call	enable_a20
+	/* A failure at this point is fatal, and there's nothing we
+	 * can do about it other than lock the machine to make the
+	 * problem immediately visible.
+	 */
+1:	jc	1b
+
+	/* Make sure we have our data segment available */
+	movw	%cs:rm_ds, %ax
+	movw	%ax, %ds
+
+	/* Add virt_offset, text16 and data16 to stack to be
+	 * copied, and also copy the return address.
+	 */
+	pushl	rm_virt_offset
+	pushl	rm_text16
+	pushl	rm_data16
+	addw	$16, %cx /* %ecx must be less than 64kB anyway */
+
+	/* Real-mode %ss:%sp => %ebp:%edx and virtual address => %esi */
+	xorl	%ebp, %ebp
+	movw	%ss, %bp
+	movzwl	%sp, %edx
+	movl	%ebp, %eax
+	shll	$4, %eax
+	addr32 leal (%eax,%edx), %esi
+	subl	rm_virt_offset, %esi
+
+	/* Load protected-mode global descriptor table */
+	data32 lgdt gdtr
+
+	/* Zero segment registers.  This wastes around 12 cycles on
+	 * real hardware, but saves a substantial number of emulated
+	 * instructions under KVM.
+	 */
+	xorw	%ax, %ax
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+	movw	%ax, %ss
+
+	/* Switch to protected mode */
+	cli
+	movl	%cr0, %eax
+	orb	$CR0_PE, %al
+	movl	%eax, %cr0
+	data32 ljmp	$VIRTUAL_CS, $r2p_pmode
+	.section ".text", "ax", @progbits
+	.code32
+r2p_pmode:
+	/* Set up protected-mode data segments and stack pointer */
+	movw	$VIRTUAL_DS, %ax
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+	movw	%ax, %ss
+	movl	pm_esp, %esp
+
+	/* Load protected-mode interrupt descriptor table */
+	lidt	idtr
+
+	/* Record real-mode %ss:sp (after removal of data) */
+	movw	%bp, rm_ss
+	addl	%ecx, %edx
+	movw	%dx, rm_sp
+
+	/* Move data from RM stack to PM stack */
+	subl	%ecx, %esp
+	movl	%esp, %edi
+	rep movsb
+
+	/* Publish virt_offset, text16 and data16 for PM code to use */
+	popl	data16
+	popl	text16
+	popl	virt_offset
+
+	/* Return to virtual address */
+	ret
+
+/****************************************************************************
+ * prot_to_real (protected-mode near call, 32-bit real-mode return address)
+ *
+ * Switch from 32-bit protected mode with virtual addresses to 16-bit
+ * real mode.  The protected-mode %esp is stored in pm_esp and the
+ * real-mode %ss:sp is restored from the saved rm_ss and rm_sp.  The
+ * high word of the real-mode %esp is set to zero.  All real-mode data
+ * segment registers are loaded from the saved rm_ds.  Interrupts are
+ * *not* enabled, since we want to be able to use prot_to_real in an
+ * ISR.  All other registers may be destroyed.
+ *
+ * The return address for this function should be a 32-bit (sic)
+ * real-mode offset within .code16.
+ *
+ * Parameters: 
+ *   %ecx : number of bytes to move from PM stack to RM stack
+ *   %esi : real-mode global and interrupt descriptor table registers
+ *
+ ****************************************************************************
+ */
+	.section ".text", "ax", @progbits
+	.code32
+prot_to_real:
+	/* Copy real-mode global descriptor table register to RM code segment */
+	movl	text16, %edi
+	leal	rm_gdtr(%edi), %edi
+	movsw
+	movsl
+
+	/* Load real-mode interrupt descriptor table register */
+	lidt	(%esi)
+
+	/* Add return address to data to be moved to RM stack */
+	addl	$4, %ecx
+	
+	/* Real-mode %ss:sp => %ebp:edx and virtual address => %edi */
+	movzwl	rm_ss, %ebp
+	movzwl	rm_sp, %edx
+	subl	%ecx, %edx
+	movl	%ebp, %eax
+	shll	$4, %eax
+	leal	(%eax,%edx), %edi
+	subl	virt_offset, %edi
+	
+	/* Move data from PM stack to RM stack */
+	movl	%esp, %esi
+	rep movsb
+	
+	/* Record protected-mode %esp (after removal of data) */
+	movl	%esi, pm_esp
+
+	/* Load real-mode segment limits */
+	movw	$REAL_DS, %ax
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+	movw	%ax, %ss
+	ljmp	$REAL_CS, $p2r_rmode
+	.section ".text16", "ax", @progbits
+	.code16
+p2r_rmode:
+	/* Load real-mode GDT */
+	data32 lgdt %cs:rm_gdtr
+	/* Switch to real mode */
+	movl	%cr0, %eax
+	andb	$0!CR0_PE, %al
+	movl	%eax, %cr0
+p2r_ljmp_rm_cs:
+	ljmp	$0, $1f
+1:
+	/* Set up real-mode data segments and stack pointer */
+	movw	%cs:rm_ds, %ax
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+	movw	%bp, %ss
+	movl	%edx, %esp
+
+	/* Return to real-mode address */
+	data32 ret
+
+
+	/* Real-mode code and data segments.  Assigned by the call to
+	 * init_librm.  rm_cs doubles as the segment part of the jump
+	 * instruction used by prot_to_real.  Both are located in
+	 * .text16 rather than .data16: rm_cs since it forms part of
+	 * the jump instruction within the code segment, and rm_ds
+	 * since real-mode code needs to be able to locate the data
+	 * segment with no other reference available.
+	 */
+	.globl rm_cs
+	.equ	rm_cs, ( p2r_ljmp_rm_cs + 3 )
+
+	.section ".text16.data", "aw", @progbits
+	.globl rm_ds
+rm_ds:	.word 0
+
+	/* Real-mode global and interrupt descriptor table registers */
+	.section ".text16.data", "aw", @progbits
+rm_gdtr:
+	.word 0 /* Limit */
+	.long 0 /* Base */
+
+/****************************************************************************
+ * prot_call (real-mode far call, 16-bit real-mode far return address)
+ *
+ * Call a specific C function in the protected-mode code.  The
+ * prototype of the C function must be
+ *   void function ( struct i386_all_regs *ix86 ); 
+ * ix86 will point to a struct containing the real-mode registers
+ * at entry to prot_call.  
+ *
+ * All registers will be preserved across prot_call(), unless the C
+ * function explicitly overwrites values in ix86.  Interrupt status
+ * and GDT will also be preserved.  Gate A20 will be enabled.
+ *
+ * Note that prot_call() does not rely on the real-mode stack
+ * remaining intact in order to return, since everything relevant is
+ * copied to the protected-mode stack for the duration of the call.
+ * In particular, this means that a real-mode prefix can make a call
+ * to main() which will return correctly even if the prefix's stack
+ * gets vapourised during the Etherboot run.  (The prefix cannot rely
+ * on anything else on the stack being preserved, so should move any
+ * critical data to registers before calling main()).
+ *
+ * Parameters:
+ *   function : virtual address of protected-mode function to call
+ *
+ * Example usage:
+ *	pushl	$pxe_api_call
+ *	call	prot_call
+ *	addw	$4, %sp
+ * to call in to the C function
+ *      void pxe_api_call ( struct i386_all_regs *ix86 );
+ ****************************************************************************
+ */
+
+#define PC_OFFSET_GDT ( 0 )
+#define PC_OFFSET_IDT ( PC_OFFSET_GDT + 6 )
+#define PC_OFFSET_IX86 ( PC_OFFSET_IDT + 6 )
+#define PC_OFFSET_RETADDR ( PC_OFFSET_IX86 + SIZEOF_I386_ALL_REGS )
+#define PC_OFFSET_FUNCTION ( PC_OFFSET_RETADDR + 4 )
+#define PC_OFFSET_END ( PC_OFFSET_FUNCTION + 4 )
+
+	.section ".text16", "ax", @progbits
+	.code16
+	.globl prot_call
+prot_call:
+	/* Preserve registers, flags and GDT on external RM stack */
+	pushfl
+	pushal
+	pushw	%gs
+	pushw	%fs
+	pushw	%es
+	pushw	%ds
+	pushw	%ss
+	pushw	%cs
+	subw	$PC_OFFSET_IX86, %sp
+	movw	%sp, %bp
+	sidt	PC_OFFSET_IDT(%bp)
+	sgdt	PC_OFFSET_GDT(%bp)
+
+	/* For sanity's sake, clear the direction flag as soon as possible */
+	cld
+
+	/* Switch to protected mode and move register dump to PM stack */
+	movl	$PC_OFFSET_END, %ecx
+	pushl	$pc_pmode
+	jmp	real_to_prot
+	.section ".text", "ax", @progbits
+	.code32
+pc_pmode:
+	/* Call function */
+	leal	PC_OFFSET_IX86(%esp), %eax
+	pushl	%eax
+	call	*(PC_OFFSET_FUNCTION+4)(%esp)
+	popl	%eax /* discard */
+
+	/* Switch to real mode and move register dump back to RM stack */
+	movl	$PC_OFFSET_END, %ecx
+	movl	%esp, %esi
+	pushl	$pc_rmode
+	jmp	prot_to_real
+	.section ".text16", "ax", @progbits
+	.code16
+pc_rmode:
+	/* Restore registers and flags and return */
+	addw	$( PC_OFFSET_IX86 + 4 /* also skip %cs and %ss */ ), %sp
+	popw	%ds
+	popw	%es
+	popw	%fs
+	popw	%gs
+	popal
+	/* popal skips %esp.  We therefore want to do "movl -20(%sp),
+	 * %esp", but -20(%sp) is not a valid 80386 expression.
+	 * Fortunately, prot_to_real() zeroes the high word of %esp, so
+	 * we can just use -20(%esp) instead.
+	 */
+	addr32 movl -20(%esp), %esp
+	popfl
+	lret
+
+/****************************************************************************
+ * real_call (protected-mode near call, 32-bit virtual return address)
+ *
+ * Call a real-mode function from protected-mode code.
+ *
+ * The non-segment register values will be passed directly to the
+ * real-mode code.  The segment registers will be set as per
+ * prot_to_real.  The non-segment register values set by the real-mode
+ * function will be passed back to the protected-mode caller.  A
+ * result of this is that this routine cannot be called directly from
+ * C code, since it clobbers registers that the C ABI expects the
+ * callee to preserve.
+ *
+ * librm.h defines a convenient macro REAL_CODE() for using real_call.
+ * See librm.h and realmode.h for details and examples.
+ *
+ * Parameters:
+ *   (32-bit) near pointer to real-mode function to call
+ *
+ * Returns: none
+ ****************************************************************************
+ */
+
+#define RC_OFFSET_PRESERVE_REGS ( 0 )
+#define RC_OFFSET_RETADDR ( RC_OFFSET_PRESERVE_REGS + SIZEOF_I386_REGS )
+#define RC_OFFSET_FUNCTION ( RC_OFFSET_RETADDR + 4 )
+#define RC_OFFSET_END ( RC_OFFSET_FUNCTION + 4 )
+
+	.section ".text", "ax", @progbits
+	.code32
+	.globl real_call
+real_call:
+	/* Create register dump and function pointer copy on PM stack */
+	pushal
+	pushl	RC_OFFSET_FUNCTION(%esp)
+
+	/* Switch to real mode and move register dump to RM stack  */
+	movl	$( RC_OFFSET_RETADDR + 4 /* function pointer copy */ ), %ecx
+	pushl	$rc_rmode
+	movl	$rm_default_gdtr_idtr, %esi
+	jmp	prot_to_real
+	.section ".text16", "ax", @progbits
+	.code16
+rc_rmode:
+	/* Call real-mode function */
+	popl	rc_function
+	popal
+	call	*rc_function
+	pushal
+
+	/* For sanity's sake, clear the direction flag as soon as possible */
+	cld
+
+	/* Switch to protected mode and move register dump back to PM stack */
+	movl	$RC_OFFSET_RETADDR, %ecx
+	pushl	$rc_pmode
+	jmp	real_to_prot
+	.section ".text", "ax", @progbits
+	.code32
+rc_pmode:
+	/* Restore registers and return */
+	popal
+	ret
+
+
+	/* Function vector, used because "call xx(%sp)" is not a valid
+	 * 16-bit expression.
+	 */
+	.section ".data16", "aw", @progbits
+rc_function:	.word 0, 0
+
+	/* Default real-mode global and interrupt descriptor table registers */
+	.section ".data", "aw", @progbits
+rm_default_gdtr_idtr:
+	.word 0		/* Global descriptor table limit */
+	.long 0		/* Global descriptor table base */
+	.word 0x03ff	/* Interrupt descriptor table limit */
+	.long 0		/* Interrupt descriptor table base */
+
+/****************************************************************************
+ * flatten_real_mode (real-mode near call)
+ *
+ * Switch to flat real mode
+ *
+ ****************************************************************************
+ */
+	.section ".text16", "ax", @progbits
+	.code16
+	.globl flatten_real_mode
+flatten_real_mode:
+	/* Modify GDT to use flat real mode */
+	movb	$0x8f, real_cs + 6
+	movb	$0x8f, real_ds + 6
+	/* Call dummy protected-mode function */
+	pushl	$flatten_dummy
+	pushw	%cs
+	call	prot_call
+	addw	$4, %sp
+	/* Restore GDT */
+	movb	$0x00, real_cs + 6
+	movb	$0x00, real_ds + 6
+	/* Return */
+	ret
+
+	.section ".text", "ax", @progbits
+	.code32
+flatten_dummy:
+	ret
+
+/****************************************************************************
+ * Interrupt wrapper
+ *
+ * Used by the protected-mode interrupt vectors to call the
+ * interrupt() function.
+ *
+ * May be entered with either physical or virtual stack segment.
+ ****************************************************************************
+ */
+	.globl interrupt_wrapper
+interrupt_wrapper:
+	/* Preserve segment registers and original %esp */
+	pushl	%ds
+	pushl	%es
+	pushl	%fs
+	pushl	%gs
+	pushl	%ss
+	pushl	%esp
+
+	/* Switch to virtual addressing */
+	call	_intr_to_virt
+
+	/* Expand IRQ number to whole %eax register */
+	movzbl	%al, %eax
+
+	/* Call interrupt handler */
+	call	interrupt
+
+	/* Restore original stack and segment registers */
+	lss	(%esp), %esp
+	popl	%ss
+	popl	%gs
+	popl	%fs
+	popl	%es
+	popl	%ds
+
+	/* Restore registers and return */
+	popal
+	iret
+
+/****************************************************************************
+ * Stored real-mode and protected-mode stack pointers
+ *
+ * The real-mode stack pointer is stored here whenever real_to_prot
+ * is called and restored whenever prot_to_real is called.  The
+ * converse happens for the protected-mode stack pointer.
+ *
+ * Despite initial appearances this scheme is, in fact re-entrant,
+ * because program flow dictates that we always return via the point
+ * we left by.  For example:
+ *    PXE API call entry
+ *  1   real => prot
+ *        ...
+ *        Print a text string
+ *	    ...
+ *  2       prot => real
+ *            INT 10
+ *  3       real => prot
+ *	    ...
+ *        ...
+ *  4   prot => real
+ *    PXE API call exit
+ *
+ * At point 1, the RM mode stack value, say RPXE, is stored in
+ * rm_ss,sp.  We want this value to still be present in rm_ss,sp when
+ * we reach point 4.
+ *
+ * At point 2, the RM stack value is restored from RPXE.  At point 3,
+ * the RM stack value is again stored in rm_ss,sp.  This *does*
+ * overwrite the RPXE that we have stored there, but it's the same
+ * value, since the code between points 2 and 3 has managed to return
+ * to us.
+ ****************************************************************************
+ */
+	.section ".data", "aw", @progbits
+	.globl rm_sp
+rm_sp:	.word 0
+	.globl rm_ss
+rm_ss:	.word 0
+pm_esp:	.long _estack
+
+/****************************************************************************
+ * Virtual address offsets
+ *
+ * These are used by the protected-mode code to map between virtual
+ * and physical addresses, and to access variables in the .text16 or
+ * .data16 segments.
+ ****************************************************************************
+ */
+	/* Internal copies, created by init_librm (which runs in real mode) */
+	.section ".data16", "aw", @progbits
+rm_virt_offset:	.long 0
+rm_text16:	.long 0
+rm_data16:	.long 0
+
+	/* Externally-visible copies, created by real_to_prot */
+	.section ".data", "aw", @progbits
+	.globl virt_offset
+virt_offset:	.long 0	
+	.globl text16
+text16:		.long 0
+	.globl data16
+data16:		.long 0