start.s

来自「最新版的u-boot,2008-10-18发布」· S 代码 · 共 662 行 · 第 1/2 页

	ldd	[%g2],%l0
	ldd	[%g2+8],%l2
	std	%l0,[%g4]
	std	%l2,[%g4+8]
	inc	16,%g2
	subcc	%g3,%g2,%g0
	bne	reloc_loop
	inc	16,%g4

	clr	%l0
	clr	%l1
	clr	%l2
	clr	%l3
	clr	%g2

/* register g4 contain address to start
 * This means that BSS must be directly after data and code segments
 *
 * g3 is length of bss = (__bss_end-__bss_start)
 *
 */

clr_bss:
/* clear bss area (the relocated) */
	set	__bss_start,%g2
	set	__bss_end,%g3
	sub	%g3,%g2,%g3
	add	%g3,%g4,%g3
	clr	%g1	/* std %g0 uses g0 and g1 */
/* clearing 16byte a time ==> linker script need to align to 16 byte offset */
clr_bss_16:
	std	%g0,[%g4]
	std	%g0,[%g4+8]
	inc	16,%g4
	cmp	%g3,%g4
	bne	clr_bss_16
	nop

/* add offsets to GOT table */
fixup_got:
	set	__got_start,%g4
	set	__got_end,%g3
/*
 * new got offset = (old GOT-PTR (read with ld) -
 *   CFG_RELOC_MONITOR_BASE(from define) ) +
 *   Destination Address (from define)
 */
	set	CFG_RELOC_MONITOR_BASE,%g2
	set	TEXT_START, %g1
	add	%g4,%g2,%g4
	sub	%g4,%g1,%g4
	add	%g3,%g2,%g3
	sub	%g3,%g1,%g3
	sub	%g2,%g1,%g2	! prepare register with (new base address) -
				!  (old base address)
got_loop:
	ld	[%g4],%l0	! load old GOT-PTR
	add	%l0,%g2,%l0	! increase with (new base address) -
				!  (old base)
	st	%l0,[%g4]
	inc	4,%g4
	cmp	%g3,%g4
	bne	got_loop
	nop

prom_relocate:
	set	__prom_start, %g2
	set	__prom_end, %g3
	set	CFG_PROM_OFFSET, %g4

prom_relocate_loop:
	ldd	[%g2],%l0
	ldd	[%g2+8],%l2
	std	%l0,[%g4]
	std	%l2,[%g4+8]
	inc	16,%g2
	subcc	%g3,%g2,%g0
	bne	prom_relocate_loop
	inc	16,%g4

/* Trap table has been moved, lets tell CPU about
 * the new trap table address
 */

	set	CFG_RELOC_MONITOR_BASE, %g2
	wr	%g0, %g2, %tbr

/*	call	relocate*/
	nop
/* Call relocated init functions */
jump:
	set	cpu_init_f2,%o1
	set	CFG_RELOC_MONITOR_BASE,%o2
	add	%o1,%o2,%o1
	sub	%o1,%g1,%o1
	call	%o1
	clr	%o0

	set	board_init_f,%o1
	set	CFG_RELOC_MONITOR_BASE,%o2
	add	%o1,%o2,%o1
	sub	%o1,%g1,%o1
	call	%o1
	clr	%o0

dead:	ta 0				! if call returns...
	nop

/* Interrupt handler caller,
 * reg L7: interrupt number
 * reg L0: psr after interrupt
 * reg L1: PC
 * reg L2: next PC
 * reg L3: wim
 */
_irq_entry:
	SAVE_ALL

	or	%l0, PSR_PIL, %g2
	wr	%g2, 0x0, %psr
	WRITE_PAUSE
	wr	%g2, PSR_ET, %psr
	WRITE_PAUSE
	mov	%l7, %o0		! irq level
	set	handler_irq, %o1
	set	(CFG_RELOC_MONITOR_BASE-TEXT_BASE), %o2
	add	%o1, %o2, %o1
	call	%o1
	add	%sp, SF_REGS_SZ, %o1	! pt_regs ptr
	or	%l0, PSR_PIL, %g2	! restore PIL after handler_irq
	wr	%g2, PSR_ET, %psr	! keep ET up
	WRITE_PAUSE

	RESTORE_ALL

!Window overflow trap handler.
	.global _window_overflow

_window_overflow:

	mov	%wim, %l3		! Calculate next WIM
	mov	%g1, %l7
	srl	%l3, 1, %g1
	sll	%l3, (CFG_SPARC_NWINDOWS-1) , %l4
	or	%l4, %g1, %g1

	save				! Get into window to be saved.
	mov	%g1, %wim
	nop;
	nop;
	nop
	st	%l0, [%sp + 0];
	st	%l1, [%sp + 4];
	st	%l2, [%sp + 8];
	st	%l3, [%sp + 12];
	st	%l4, [%sp + 16];
	st	%l5, [%sp + 20];
	st	%l6, [%sp + 24];
	st	%l7, [%sp + 28];
	st	%i0, [%sp + 32];
	st	%i1, [%sp + 36];
	st	%i2, [%sp + 40];
	st	%i3, [%sp + 44];
	st	%i4, [%sp + 48];
	st	%i5, [%sp + 52];
	st	%i6, [%sp + 56];
	st	%i7, [%sp + 60];
	restore				! Go back to trap window.
	mov	%l7, %g1
	jmp	%l1			! Re-execute save.
	rett	%l2

/* Window underflow trap handler.  */

	.global  _window_underflow

_window_underflow:

	mov  %wim, %l3			! Calculate next WIM
	sll  %l3, 1, %l4
	srl  %l3, (CFG_SPARC_NWINDOWS-1), %l5
	or   %l5, %l4, %l5
	mov  %l5, %wim
	nop; nop; nop
	restore				! Two restores to get into the
	restore				! window to restore
	ld	[%sp + 0], %l0;		! Restore window from the stack
	ld	[%sp + 4], %l1;
	ld	[%sp + 8], %l2;
	ld	[%sp + 12], %l3;
	ld	[%sp + 16], %l4;
	ld	[%sp + 20], %l5;
	ld	[%sp + 24], %l6;
	ld	[%sp + 28], %l7;
	ld	[%sp + 32], %i0;
	ld	[%sp + 36], %i1;
	ld	[%sp + 40], %i2;
	ld	[%sp + 44], %i3;
	ld	[%sp + 48], %i4;
	ld	[%sp + 52], %i5;
	ld	[%sp + 56], %i6;
	ld	[%sp + 60], %i7;
	save				! Get back to the trap window.
	save
	jmp	%l1			! Re-execute restore.
	rett	%l2

	retl

_nmi_trap:
	nop
	jmp %l1
	rett %l2

_hwerr:
	ta 0
	nop
	nop
	b _hwerr			! loop infinite
	nop

/* Registers to not touch at all. */
#define t_psr      l0 /* Set by caller */
#define t_pc       l1 /* Set by caller */
#define t_npc      l2 /* Set by caller */
#define t_wim      l3 /* Set by caller */
#define t_twinmask l4 /* Set at beginning of this entry routine. */
#define t_kstack   l5 /* Set right before pt_regs frame is built */
#define t_retpc    l6 /* If you change this, change winmacro.h header file */
#define t_systable l7 /* Never touch this, could be the syscall table ptr. */
#define curptr     g6 /* Set after pt_regs frame is built */

trap_setup:
/* build a pt_regs trap frame. */
	sub	%fp, (SF_REGS_SZ + PT_REGS_SZ), %t_kstack
	PT_STORE_ALL(t_kstack, t_psr, t_pc, t_npc, g2)

	/* See if we are in the trap window. */
	mov	1, %t_twinmask
	sll	%t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
	andcc	%t_twinmask, %t_wim, %g0
	beq	1f		! in trap window, clean up
	nop

	/*-------------------------------------------------
	 * Spill , adjust %wim and go.
	 */
	srl	%t_wim, 0x1, %g2		! begin computation of new %wim

	set	(CFG_SPARC_NWINDOWS-1), %g3	!NWINDOWS-1

	sll	%t_wim, %g3, %t_wim	! NWINDOWS-1
	or	%t_wim, %g2, %g2
	and	%g2, 0xff, %g2

	save	%g0, %g0, %g0		! get in window to be saved

	/* Set new %wim value */
	wr	%g2, 0x0, %wim

	/* Save the kernel window onto the corresponding stack. */
	RW_STORE(sp)

	restore	%g0, %g0, %g0
	/*-------------------------------------------------*/

1:
	/* Trap from kernel with a window available.
	 * Just do it...
	 */
	jmpl	%t_retpc + 0x8, %g0	! return to caller
	 mov	%t_kstack, %sp		! jump onto new stack

#define twin_tmp1 l4
#define glob_tmp  g4
#define curptr    g6
ret_trap_entry:
	wr	%t_psr, 0x0, %psr       ! enable nesting again, clear ET

	/* Will the rett land us in the invalid window? */
	mov	2, %g1
	sll	%g1, %t_psr, %g1

	set	CFG_SPARC_NWINDOWS, %g2	!NWINDOWS

	srl	%g1, %g2, %g2
	or	%g1, %g2, %g1
	rd	%wim, %g2
	andcc	%g2, %g1, %g0
	be	1f		! Nope, just return from the trap
	 sll	%g2, 0x1, %g1

	/* We have to grab a window before returning. */
	set	(CFG_SPARC_NWINDOWS-1), %g3	!NWINDOWS-1

	srl	%g2, %g3,  %g2
	or	%g1, %g2, %g1
	and	%g1, 0xff, %g1

	wr	%g1, 0x0, %wim

	/* Grrr, make sure we load from the right %sp... */
	PT_LOAD_ALL(sp, t_psr, t_pc, t_npc, g1)

	restore	%g0, %g0, %g0
	RW_LOAD(sp)
	b	2f
	save	%g0, %g0, %g0

	/* Reload the entire frame in case this is from a
	 * kernel system call or whatever...
	 */
1:
	PT_LOAD_ALL(sp, t_psr, t_pc, t_npc, g1)
2:
	wr	%t_psr, 0x0, %psr
	nop;
	nop;
	nop

	jmp	%t_pc
	rett	%t_npc

/* This is called from relocated C-code.
 * It resets the system by jumping to _start
 */
_reset_reloc:
	set	start, %l0
	call	%l0
	nop