head.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

/*
 * Here is where the ball gets rolling as far as the kernel is concerned.
 * When control is transferred to _start, the bootload has already
 * loaded us to the correct address.  All that's left to do here is
 * to set up the kernel's global pointer and jump to the kernel
 * entry point.
 *
 * Copyright (C) 1998-2001 Hewlett-Packard Co
 *	David Mosberger-Tang <[e-mail]>
 *	Stephane Eranian <[e-mail]>
 * Copyright (C) 1999 VA Linux Systems
 * Copyright (C) 1999 Walt Drummond <[e-mail]>
 * Copyright (C) 1999 Intel Corp.
 * Copyright (C) 1999 Asit Mallick <[e-mail]>
 * Copyright (C) 1999 Don Dugger <[e-mail]>
 * Copyright (C) 2002 Fenghua Yu <[e-mail]>
 *   -Optimize __ia64_save_fpu() and __ia64_load_fpu() for Itanium 2.
 */

#include <linux/config.h>

#include <asm/asmmacro.h>
#include <asm/fpu.h>
#include <asm/kregs.h>
#include <asm/mmu_context.h>
#include <asm/offsets.h>
#include <asm/pal.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/system.h>

	.section __special_page_section,"ax"

	.global empty_zero_page
empty_zero_page:
	.skip PAGE_SIZE

	.global swapper_pg_dir
swapper_pg_dir:
	.skip PAGE_SIZE

	.rodata
halt_msg:
	stringz "Halting kernel\n"

	.text

	.global start_ap

	/*
	 * Start the kernel.  When the bootloader passes control to _start(), r28
	 * points to the address of the boot parameter area.  Execution reaches
	 * here in physical mode.
	 */
GLOBAL_ENTRY(_start)
start_ap:
	.prologue
	.save rp, r4		// terminate unwind chain with a NULL rp
	mov r4=r0
	.body

	/*
	 * Initialize the region register for region 7 and install a translation register
	 * that maps the kernel's text and data:
	 */
	rsm psr.i | psr.ic
	mov r16=((ia64_rid(IA64_REGION_ID_KERNEL, PAGE_OFFSET) << 8) | (IA64_GRANULE_SHIFT << 2))
	;;
	srlz.i
	mov r18=KERNEL_TR_PAGE_SHIFT<<2
	movl r17=KERNEL_START
	;;
	mov rr[r17]=r16
	mov cr.itir=r18
	mov cr.ifa=r17
	mov r16=IA64_TR_KERNEL
	movl r18=((1 << KERNEL_TR_PAGE_SHIFT) | PAGE_KERNEL)
	;;
	srlz.i
	;;
	itr.i itr[r16]=r18
	;;
	itr.d dtr[r16]=r18
	;;
	srlz.i

	/*
	 * Switch into virtual mode:
	 */
	movl r16=(IA64_PSR_IT|IA64_PSR_IC|IA64_PSR_DT|IA64_PSR_RT|IA64_PSR_DFH|IA64_PSR_BN \
		  |IA64_PSR_DI)
	;;
	mov cr.ipsr=r16
	movl r17=1f
	;;
	mov cr.iip=r17
	mov cr.ifs=r0
	;;
	rfi
	;;
1:	// now we are in virtual mode

	// set IVT entry point---can't access I/O ports without it
	movl r3=ia64_ivt
	;;
	mov cr.iva=r3
	movl r2=FPSR_DEFAULT
	;;
	srlz.i
	movl gp=__gp

	mov ar.fpsr=r2
	;;

#ifdef CONFIG_IA64_EARLY_PRINTK
	mov r3=(6<<8) | (IA64_GRANULE_SHIFT<<2)
	movl r2=6<<61
	;;
	mov rr[r2]=r3
	;;
	srlz.i
	;;
#endif

#define isAP	p2	// are we an Application Processor?
#define isBP	p3	// are we the Bootstrap Processor?

#ifdef CONFIG_SMP
	/*
	 * Find the init_task for the currently booting CPU.  At poweron, and in
	 * UP mode, cpucount is 0.
	 */
	movl r3=cpucount
 	;;
	ld4 r3=[r3]		// r3 <- smp_processor_id()
	movl r2=init_tasks
	;;
	shladd r2=r3,3,r2
	;;
	ld8 r2=[r2]
#else
	mov r3=0
	movl r2=init_task_union
	;;
#endif
	cmp4.ne isAP,isBP=r3,r0
	;;			// RAW on r2
	extr r3=r2,0,61		// r3 == phys addr of task struct
	mov r16=KERNEL_TR_PAGE_NUM
	;;

	// load the "current" pointer (r13) and ar.k6 with the current task
	mov r13=r2
	mov IA64_KR(CURRENT)=r3		// Physical address

	// initialize k4 to a safe value (64-128MB is mapped by TR_KERNEL)
	mov IA64_KR(CURRENT_STACK)=r16
	/*
	 * Reserve space at the top of the stack for "struct pt_regs".  Kernel threads
	 * don't store interesting values in that structure, but the space still needs
	 * to be there because time-critical stuff such as the context switching can
	 * be implemented more efficiently (for example, __switch_to()
	 * always sets the psr.dfh bit of the task it is switching to).
	 */
	addl r12=IA64_STK_OFFSET-IA64_PT_REGS_SIZE-16,r2
	addl r2=IA64_RBS_OFFSET,r2	// initialize the RSE
	mov ar.rsc=0		// place RSE in enforced lazy mode
	;;
	loadrs			// clear the dirty partition
	;;
	mov ar.bspstore=r2	// establish the new RSE stack
	;;
	mov ar.rsc=0x3		// place RSE in eager mode

(isBP)	dep r28=-1,r28,61,3	// make address virtual
(isBP)	movl r2=ia64_boot_param
	;;
(isBP)	st8 [r2]=r28		// save the address of the boot param area passed by the bootloader

#ifdef CONFIG_IA64_EARLY_PRINTK
	.rodata
alive_msg:
	stringz "I'm alive and well\n"
alive_msg_end:
	.previous

	alloc r2=ar.pfs,0,0,2,0
	movl out0=alive_msg
	movl out1=alive_msg_end-alive_msg-1
	;;
	br.call.sptk.many rp=early_printk
1:	// force new bundle
#endif /* CONFIG_IA64_EARLY_PRINTK */

#ifdef CONFIG_SMP
(isAP)	br.call.sptk.many rp=start_secondary
.ret0:
(isAP)	br.cond.sptk self
#endif

	// This is executed by the bootstrap processor (bsp) only:

#ifdef CONFIG_IA64_FW_EMU
	// initialize PAL & SAL emulator:
	br.call.sptk.many rp=sys_fw_init
.ret1:
#endif
	br.call.sptk.many rp=start_kernel
.ret2:	addl r3=@ltoff(halt_msg),gp
	;;
	alloc r2=ar.pfs,8,0,2,0
	;;
	ld8 out0=[r3]
	br.call.sptk.many b0=console_print
self:	br.sptk.many self		// endless loop
END(_start)

GLOBAL_ENTRY(ia64_save_debug_regs)
	alloc r16=ar.pfs,1,0,0,0
	mov r20=ar.lc			// preserve ar.lc
	mov ar.lc=IA64_NUM_DBG_REGS-1
	mov r18=0
	add r19=IA64_NUM_DBG_REGS*8,in0
	;;
1:	mov r16=dbr[r18]
#ifdef CONFIG_ITANIUM
	;;
	srlz.d
#endif
	mov r17=ibr[r18]
	add r18=1,r18
	;;
	st8.nta [in0]=r16,8
	st8.nta [r19]=r17,8
	br.cloop.sptk.many 1b
	;;
	mov ar.lc=r20			// restore ar.lc
	br.ret.sptk.many rp
END(ia64_save_debug_regs)

GLOBAL_ENTRY(ia64_load_debug_regs)
	alloc r16=ar.pfs,1,0,0,0
	lfetch.nta [in0]
	mov r20=ar.lc			// preserve ar.lc
	add r19=IA64_NUM_DBG_REGS*8,in0
	mov ar.lc=IA64_NUM_DBG_REGS-1
	mov r18=-1
	;;
1:	ld8.nta r16=[in0],8
	ld8.nta r17=[r19],8
	add r18=1,r18
	;;
	mov dbr[r18]=r16
#ifdef CONFIG_ITANIUM
	;;
	srlz.d				// Errata 132 (NoFix status)
#endif
	mov ibr[r18]=r17
	br.cloop.sptk.many 1b
	;;
	mov ar.lc=r20			// restore ar.lc
	br.ret.sptk.many rp
END(ia64_load_debug_regs)

GLOBAL_ENTRY(__ia64_save_fpu)
	alloc r2=ar.pfs,1,4,0,0
	adds loc0=96*16-16,in0
	adds loc1=96*16-16-128,in0
	;;
	stf.spill.nta [loc0]=f127,-256
	stf.spill.nta [loc1]=f119,-256
	;;
	stf.spill.nta [loc0]=f111,-256
	stf.spill.nta [loc1]=f103,-256
	;;
	stf.spill.nta [loc0]=f95,-256
	stf.spill.nta [loc1]=f87,-256
	;;
	stf.spill.nta [loc0]=f79,-256
	stf.spill.nta [loc1]=f71,-256
	;;
	stf.spill.nta [loc0]=f63,-256
	stf.spill.nta [loc1]=f55,-256
	adds loc2=96*16-32,in0
	;;
	stf.spill.nta [loc0]=f47,-256
	stf.spill.nta [loc1]=f39,-256
	adds loc3=96*16-32-128,in0
	;;
	stf.spill.nta [loc2]=f126,-256
	stf.spill.nta [loc3]=f118,-256
	;;
	stf.spill.nta [loc2]=f110,-256
	stf.spill.nta [loc3]=f102,-256
	;;
	stf.spill.nta [loc2]=f94,-256
	stf.spill.nta [loc3]=f86,-256
	;;
	stf.spill.nta [loc2]=f78,-256
	stf.spill.nta [loc3]=f70,-256
	;;
	stf.spill.nta [loc2]=f62,-256
	stf.spill.nta [loc3]=f54,-256
	adds loc0=96*16-48,in0
	;;
	stf.spill.nta [loc2]=f46,-256
	stf.spill.nta [loc3]=f38,-256
	adds loc1=96*16-48-128,in0
	;;
	stf.spill.nta [loc0]=f125,-256
	stf.spill.nta [loc1]=f117,-256
	;;
	stf.spill.nta [loc0]=f109,-256
	stf.spill.nta [loc1]=f101,-256
	;;
	stf.spill.nta [loc0]=f93,-256
	stf.spill.nta [loc1]=f85,-256
	;;
	stf.spill.nta [loc0]=f77,-256
	stf.spill.nta [loc1]=f69,-256
	;;
	stf.spill.nta [loc0]=f61,-256
	stf.spill.nta [loc1]=f53,-256
	adds loc2=96*16-64,in0
	;;
	stf.spill.nta [loc0]=f45,-256
	stf.spill.nta [loc1]=f37,-256
	adds loc3=96*16-64-128,in0
	;;
	stf.spill.nta [loc2]=f124,-256
	stf.spill.nta [loc3]=f116,-256
	;;
	stf.spill.nta [loc2]=f108,-256
	stf.spill.nta [loc3]=f100,-256
	;;
	stf.spill.nta [loc2]=f92,-256
	stf.spill.nta [loc3]=f84,-256
	;;
	stf.spill.nta [loc2]=f76,-256
	stf.spill.nta [loc3]=f68,-256
	;;
	stf.spill.nta [loc2]=f60,-256
	stf.spill.nta [loc3]=f52,-256
	adds loc0=96*16-80,in0
	;;
	stf.spill.nta [loc2]=f44,-256
	stf.spill.nta [loc3]=f36,-256
	adds loc1=96*16-80-128,in0
	;;
	stf.spill.nta [loc0]=f123,-256
	stf.spill.nta [loc1]=f115,-256
	;;
	stf.spill.nta [loc0]=f107,-256
	stf.spill.nta [loc1]=f99,-256
	;;
	stf.spill.nta [loc0]=f91,-256
	stf.spill.nta [loc1]=f83,-256
	;;
	stf.spill.nta [loc0]=f75,-256
	stf.spill.nta [loc1]=f67,-256
	;;
	stf.spill.nta [loc0]=f59,-256
	stf.spill.nta [loc1]=f51,-256
	adds loc2=96*16-96,in0
	;;
	stf.spill.nta [loc0]=f43,-256
	stf.spill.nta [loc1]=f35,-256
	adds loc3=96*16-96-128,in0
	;;
	stf.spill.nta [loc2]=f122,-256
	stf.spill.nta [loc3]=f114,-256
	;;
	stf.spill.nta [loc2]=f106,-256
	stf.spill.nta [loc3]=f98,-256
	;;
	stf.spill.nta [loc2]=f90,-256
	stf.spill.nta [loc3]=f82,-256
	;;
	stf.spill.nta [loc2]=f74,-256
	stf.spill.nta [loc3]=f66,-256
	;;
	stf.spill.nta [loc2]=f58,-256
	stf.spill.nta [loc3]=f50,-256
	adds loc0=96*16-112,in0
	;;
	stf.spill.nta [loc2]=f42,-256
	stf.spill.nta [loc3]=f34,-256
	adds loc1=96*16-112-128,in0
	;;
	stf.spill.nta [loc0]=f121,-256
	stf.spill.nta [loc1]=f113,-256
	;;
	stf.spill.nta [loc0]=f105,-256
	stf.spill.nta [loc1]=f97,-256
	;;
	stf.spill.nta [loc0]=f89,-256
	stf.spill.nta [loc1]=f81,-256
	;;
	stf.spill.nta [loc0]=f73,-256
	stf.spill.nta [loc1]=f65,-256
	;;
	stf.spill.nta [loc0]=f57,-256
	stf.spill.nta [loc1]=f49,-256
	adds loc2=96*16-128,in0
	;;