entry.s

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

#define CLONE_VM 0x100	/* Must agree with <linux/sched.h> */

	.export __kernel_thread, code
	.import do_fork
__kernel_thread:
	STREG	%r2, -RP_OFFSET(%r30)

	copy	%r30, %r1
	ldo	PT_SZ_ALGN(%r30),%r30
#ifdef __LP64__
	/* Yo, function pointers in wide mode are little structs... -PB */
	ldd	24(%r26), %r2
	STREG	%r2, PT_GR27(%r1)	/* Store childs %dp */
	ldd	16(%r26), %r26
#endif
	STREG	%r26, PT_GR26(%r1)  /* Store function & argument for child */
	STREG	%r25, PT_GR25(%r1)
	ldo	CLONE_VM(%r0), %r26   /* Force CLONE_VM since only init_mm */
	or	%r26, %r24, %r26      /* will have kernel mappings.	 */
	copy	%r0, %r25
#ifdef __LP64__
	ldo	-16(%r30),%r29		/* Reference param save area */
#endif
	bl	do_fork, %r2
	copy	%r1, %r24

	/* Parent Returns here */

	LDREG	-PT_SZ_ALGN-RP_OFFSET(%r30), %r2
	bv	%r0(%r2)
	ldo	-PT_SZ_ALGN(%r30), %r30

	/*
	 * Child Returns here
	 *
	 * copy_thread moved args from temp save area set up above
	 * into task save area.
	 */

	.export	ret_from_kernel_thread
ret_from_kernel_thread:

	/* Call schedule_tail first though */
	bl	schedule_tail, %r2
	nop

	LDREG	TASK_PT_GR26-TASK_SZ_ALGN(%r30), %r1
	LDREG	TASK_PT_GR25-TASK_SZ_ALGN(%r30), %r26
#ifdef __LP64__
	LDREG	TASK_PT_GR27-TASK_SZ_ALGN(%r30), %r27
#endif
	ble	0(%sr7, %r1)
	copy	%r31, %r2

#ifdef __LP64__
	ldo	-16(%r30),%r29		/* Reference param save area */
	loadgp				/* Thread could have been in a module */
#endif
	b	sys_exit
	ldi	0, %r26

	.import	sys_execve, code
	.export	__execve, code
__execve:
	copy	%r2, %r15
	copy	%r30, %r16
	ldo	PT_SZ_ALGN(%r30), %r30
	STREG	%r26, PT_GR26(%r16)
	STREG	%r25, PT_GR25(%r16)
	STREG	%r24, PT_GR24(%r16)
#ifdef __LP64__
	ldo	-16(%r30),%r29		/* Reference param save area */
#endif
	bl	sys_execve, %r2
	copy	%r16, %r26

	cmpib,=,n 0,%r28,intr_return    /* forward */

	/* yes, this will trap and die. */
	copy	%r15, %r2
	copy	%r16, %r30
	bv	%r0(%r2)
	nop

	.align 4

	/*
	 * struct task_struct *_switch_to(struct task_struct *prev,
	 *	struct task_struct *next)
	 *
	 * switch kernel stacks and return prev */
	.export	_switch_to, code
_switch_to:
	STREG	 %r2, -RP_OFFSET(%r30)

	callee_save

	ldil	L%_switch_to_ret, %r2
	ldo	R%_switch_to_ret(%r2), %r2

	STREG	%r2, TASK_PT_KPC(%r26)
	LDREG	TASK_PT_KPC(%r25), %r2

	STREG	%r30, TASK_PT_KSP(%r26)
	LDREG	TASK_PT_KSP(%r25), %r30
	bv	%r0(%r2)
	mtctl   %r25,%cr30

_switch_to_ret:
	mtctl	%r0, %cr0		/* Needed for single stepping */
	callee_rest

	LDREG	-RP_OFFSET(%r30), %r2
	bv	%r0(%r2)
	copy	%r26, %r28

	/*
	 * Common rfi return path for interruptions, kernel execve, and
	 * sys_rt_sigreturn (sometimes).  The sys_rt_sigreturn syscall will
	 * return via this path if the signal was received when the process
	 * was running; if the process was blocked on a syscall then the
	 * normal syscall_exit path is used.  All syscalls for traced
	 * proceses exit via intr_restore.
	 *
	 * XXX If any syscalls that change a processes space id ever exit
	 * this way, then we will need to copy %sr3 in to PT_SR[3..7], and
	 * adjust IASQ[0..1].
	 *
	 * Note that the following code uses a "relied upon translation".
	 * See the parisc ACD for details. The ssm is necessary due to a
	 * PCXT bug.
	 */

	.align 4096

	.export	syscall_exit_rfi
syscall_exit_rfi:
	mfctl   %cr30,%r16
	ldo	TASK_REGS(%r16),%r16
	/* Force iaoq to userspace, as the user has had access to our current
	 * context via sigcontext. Also Filter the PSW for the same reason.
	 */
	LDREG	PT_IAOQ0(%r16),%r19
	depi	3,31,2,%r19
	STREG	%r19,PT_IAOQ0(%r16)
	LDREG	PT_IAOQ1(%r16),%r19
	depi	3,31,2,%r19
	STREG	%r19,PT_IAOQ1(%r16)
	LDREG   PT_PSW(%r16),%r19
	ldil    L%USER_PSW_MASK,%r1
	ldo     R%USER_PSW_MASK(%r1),%r1
#ifdef __LP64__
	ldil    L%USER_PSW_HI_MASK,%r20
	ldo     R%USER_PSW_HI_MASK(%r20),%r20
	depd    %r20,31,32,%r1
#endif
	and     %r19,%r1,%r19 /* Mask out bits that user shouldn't play with */
	ldil    L%USER_PSW,%r1
	ldo     R%USER_PSW(%r1),%r1
	or      %r19,%r1,%r19 /* Make sure default USER_PSW bits are set */
	STREG   %r19,PT_PSW(%r16)

	/*
	 * If we aren't being traced, we never saved space registers
	 * (we don't store them in the sigcontext), so set them
	 * to "proper" values now (otherwise we'll wind up restoring
	 * whatever was last stored in the task structure, which might
	 * be inconsistant if an interrupt occured while on the gateway
	 * page) Note that we may be "trashing" values the user put in
	 * them, but we don't support the the user changing them.
	 */

	STREG   %r0,PT_SR2(%r16)
	mfsp    %sr3,%r19
	STREG   %r19,PT_SR0(%r16)
	STREG   %r19,PT_SR1(%r16)
	STREG   %r19,PT_SR3(%r16)
	STREG   %r19,PT_SR4(%r16)
	STREG   %r19,PT_SR5(%r16)
	STREG   %r19,PT_SR6(%r16)
	STREG   %r19,PT_SR7(%r16)

intr_return:
	ssm     PSW_SM_I, %r0

	/* Check for software interrupts */

	.import irq_stat,data

	ldil	L%irq_stat,%r19
	ldo	R%irq_stat(%r19),%r19
#ifdef CONFIG_SMP
	mfctl   %cr30,%r1
	ldw	TASK_PROCESSOR(%r1),%r1 /* get cpu # - int */
	/* shift left ____cacheline_aligned (aka L1_CACHE_BYTES) amount
	** irq_stat[] is defined using ____cacheline_aligned.
	*/
#ifdef __LP64__
	shld	%r1, 6, %r20
#else
	shlw	%r1, 5, %r20
#endif
	add     %r19,%r20,%r19	/* now have &irq_stat[smp_processor_id()] */
#endif /* CONFIG_SMP */

	LDREG   IRQSTAT_SIRQ_PEND(%r19),%r20    /* hardirq.h: unsigned long */
	cmpib,<>,n 0,%r20,intr_do_softirq /* forward */

intr_check_resched:

	/* check for reschedule */
	mfctl   %cr30,%r1
	LDREG     TASK_NEED_RESCHED(%r1),%r19	/* sched.h: long need_resched */
	CMPIB<>,n 0,%r19,intr_do_resched /* forward */

intr_check_sig:
	/* As above */
	mfctl   %cr30,%r1
	ldw	TASK_SIGPENDING(%r1),%r19	/* sched.h: int sigpending */
	cmpib,<>,n 0,%r19,intr_do_signal /* forward */

intr_restore:
	copy            %r16,%r29
	ldo             PT_FR31(%r29),%r1
	rest_fp         %r1
	rest_general    %r29
	ssm		0,%r0
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	tophys_r1       %r29
	rsm             (PSW_SM_Q|PSW_SM_P|PSW_SM_D|PSW_SM_I),%r0
	rest_specials	%r29
	rest_stack
	rfi
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop

	.import do_softirq,code
intr_do_softirq:
	bl      do_softirq,%r2
#ifdef __LP64__
	ldo	-16(%r30),%r29		/* Reference param save area */
#else
	nop
#endif
	b       intr_check_resched
	nop

	.import schedule,code
intr_do_resched:
	/* Only do reschedule if we are returning to user space */
	LDREG   PT_IASQ0(%r16), %r20
	CMPIB= 0,%r20,intr_restore /* backward */
	nop
	LDREG   PT_IASQ1(%r16), %r20
	CMPIB= 0,%r20,intr_restore /* backward */
	nop

#ifdef __LP64__
	ldo	-16(%r30),%r29		/* Reference param save area */
#endif

	ldil	L%intr_return, %r2
	b	schedule
	ldo	R%intr_return(%r2), %r2	/* return to intr_return, not here */


	.import do_signal,code
intr_do_signal:
	/* Only do signals if we are returning to user space */
	LDREG   PT_IASQ0(%r16), %r20
	CMPIB= 0,%r20,intr_restore /* backward */
	nop
	LDREG   PT_IASQ1(%r16), %r20
	CMPIB= 0,%r20,intr_restore /* backward */
	nop

	copy	%r0, %r24			/* unsigned long in_syscall */
	copy	%r16, %r25			/* struct pt_regs *regs */
	ssm     PSW_SM_I, %r0
#ifdef __LP64__
	ldo	-16(%r30),%r29			/* Reference param save area */
#endif
	bl	do_signal,%r2
	copy	%r0, %r26			/* sigset_t *oldset = NULL */

	b	intr_restore
	nop

	/*
	 * External interrupts.
	 */

intr_extint:
	CMPIB=,n 0,%r16,1f	/* on User or kernel stack? */
	get_stack_use_cr30
	b,n 3f

1:
#if 0  /* Interrupt Stack support not working yet! */
	mfctl	%cr31,%r1
	copy	%r30,%r17
	/* FIXME! depi below has hardcoded idea of interrupt stack size (32k)*/
#ifdef __LP64__
	depdi	0,63,15,%r17
#else
	depi	0,31,15,%r17
#endif
	CMPB=,n	%r1,%r17,2f
	get_stack_use_cr31
	b,n 3f
#endif
2:
	get_stack_use_r30

3:
	save_specials	%r29
	virt_map
	save_general	%r29

	ldo	PT_FR0(%r29), %r24
	save_fp	%r24
	
	loadgp

	copy	%r29, %r26	/* arg0 is pt_regs */
	copy	%r29, %r16	/* save pt_regs */
	ldil	L%intr_return, %r2
#ifdef __LP64__
	ldo	-16(%r30),%r29	/* Reference param save area */
#endif
	b	do_cpu_irq_mask
	ldo	R%intr_return(%r2), %r2	/* return to intr_return, not here */



	/* Generic interruptions (illegal insn, unaligned, page fault, etc) */

	.export         intr_save, code /* for os_hpmc */

intr_save:
	mfsp    %sr7,%r16
	CMPIB=,n 0,%r16,1f
	get_stack_use_cr30
	b	2f
	copy    %r8,%r26

1:
	get_stack_use_r30
	copy    %r8,%r26

2:
	save_specials	%r29

	/* If this trap is a itlb miss, skip saving/adjusting isr/ior */

	/*
	 * FIXME: 1) Use a #define for the hardwired "6" below (and in
	 *           traps.c.
	 *        2) Once we start executing code above 4 Gb, we need
	 *           to adjust iasq/iaoq here in the same way we
	 *           adjust isr/ior below.
	 */

	CMPIB=,n        6,%r26,skip_save_ior

	/* save_specials left ipsw value in r8 for us to test */

	mfctl           %cr20, %r16 /* isr */
	mfctl           %cr21, %r17 /* ior */

#ifdef __LP64__
	/*
	 * If the interrupted code was running with W bit off (32 bit),
	 * clear the b bits (bits 0 & 1) in the ior.
	 */
	extrd,u,*<>     %r8,PSW_W_BIT,1,%r0
	depdi           0,1,2,%r17

	/*
	 * FIXME: This code has hardwired assumptions about the split
	 *        between space bits and offset bits. This will change
	 *        when we allow alternate page sizes.
	 */

	/* adjust isr/ior. */

	extrd,u         %r16,63,7,%r1    /* get high bits from isr for ior */
	depd            %r1,31,7,%r17    /* deposit them into ior */
	depdi           0,63,7,%r16      /* clear them from isr */
#endif
	STREG           %r16, PT_ISR(%r29)
	STREG           %r17, PT_IOR(%r29)


skip_save_ior:
	virt_map
	save_general	%r29

	ldo		PT_FR0(%r29), %r25
	save_fp		%r25
	
	loadgp

	copy		%r29, %r25	/* arg1 is pt_regs */
#ifdef CONFIG_KWDB
	copy		%r29, %r3	/* KWDB - update frame pointer (gr3) */
#endif

#ifdef __LP64__
	ldo		-16(%r30),%r29	/* Reference param save area */
#endif

	ldil		L%intr_return, %r2
	copy		%r25, %r16	/* save pt_regs */

	b		handle_interruption
	ldo		R%intr_return(%r2), %r2	/* return to intr_return */


	/*
	 * Note for all tlb miss handlers:
	 *
	 * cr24 contains a pointer to the kernel address space
	 * page directory.
	 *
	 * cr25 contains a pointer to the current user address
	 * space page directory.
	 *
	 * sr3 will contain the space id of the user address space
	 * of the current running thread while that thread is
	 * running in the kernel.
	 */

	/*
	 * register number allocations.  Note that these are all
	 * in the shadowed registers
	 */

	t0 = r1		/* temporary register 0 */
	va = r8		/* virtual address for which the trap occured */
	t1 = r9		/* temporary register 1 */
	pte  = r16	/* pte/phys page # */
	prot = r17	/* prot bits */
	spc  = r24	/* space for which the trap occured */
	ptp = r25	/* page directory/page table pointer */

#ifdef __LP64__

dtlb_miss_20w:
	extrd,u         spc,63,7,t1     /* adjust va */
	depd            t1,31,7,va      /* adjust va */
	depdi           0,63,7,spc      /* adjust space */
	mfctl           %cr25,ptp	/* Assume user space miss */
	or,*<>          %r0,spc,%r0     /* If it is user space, nullify */
	mfctl           %cr24,ptp	/* Load kernel pgd instead */
	extrd,u         va,33,9,t1      /* Get pgd index */

	mfsp            %sr7,t0		/* Get current space */
	or,*=           %r0,t0,%r0      /* If kernel, nullify following test */
	cmpb,*<>,n       t0,spc,dtlb_fault /* forward */

	/* First level page table lookup */

	ldd,s           t1(ptp),ptp
	extrd,u         va,42,9,t0     /* get second-level index */
	bb,>=,n         ptp,_PAGE_PRESENT_BIT,dtlb_check_alias_20w
	depdi           0,63,12,ptp     /* clear prot bits */

	/* Second level page table lookup */

	ldd,s           t0(ptp),ptp
	extrd,u         va,51,9,t0     /* get third-level index */
	bb,>=,n         ptp,_PAGE_PRESENT_BIT,dtlb_check_alias_20w
	depdi           0,63,12,ptp     /* clear prot bits */

	/* Third level page table lookup */

	shladd           t0,3,ptp,ptp
	ldi		_PAGE_ACCESSED,t1
	ldd              0(ptp),pte
	bb,>=,n          pte,_PAGE_PRESENT_BIT,dtlb_check_alias_20w

	/* Check whether the "accessed" bit was set, otherwise do so */

	or		t1,pte,t0	/* t0 has R bit set */
	and,*<>         t1,pte,%r0      /* test and nullify if already set */
	std             t0,0(ptp)       /* write back pte */

	space_to_prot   spc prot        /* create prot id from space */
	depd            pte,8,7,prot    /* add in prot bits from pte */

	extrd,u,*=      pte,_PAGE_USER_BIT+32,1,r0
	depdi		7,11,3,prot   /* Set for user space (1 rsvd for read) */
	extrd,u,*= 	pte,_PAGE_GATEWAY_BIT+32,1,r0
	depdi		0,11,2,prot	/* If Gateway, Set PL2 to 0 */

	/* Get rid of prot bits and convert to page addr for idtlbt */

	depdi		0,63,12,pte