head.s

优龙2410linux2.6.8内核源代码

	tr    0(64,%r8),.lowcase	
	b     .gotr
.sk8x8:
	mvc   0(240,%r8),0(%r9)		# copy iplparms into buffer
.gotr:
	l     %r10,.tbl			# EBCDIC to ASCII table
	tr    0(240,%r8),0(%r10)
	stidp __LC_CPUID		# Are we running on VM maybe
	cli   __LC_CPUID,0xff
	bnz   .test
	.long 0x83300060		# diag 3,0,x'0060' - storage size
	b     .done
.test:
	mvc   0x68(8),.pgmnw		# set up pgm check handler
	l     %r2,.fourmeg
	lr    %r3,%r2
	bctr  %r3,%r0			# 4M-1
.loop:  iske  %r0,%r3
	ar    %r3,%r2
.pgmx:
	sr    %r3,%r2
	la    %r3,1(%r3)
.done:
        l     %r1,.memsize
	st    %r3,0(%r1)
	slr   %r0,%r0
	st    %r0,INITRD_SIZE-PARMAREA(%r11)
	st    %r0,INITRD_START-PARMAREA(%r11)
	j     startup                   # continue with startup
.tbl:	.long _ebcasc			# translate table
.cmd:	.long COMMAND_LINE		# address of command line buffer
.parm:	.long PARMAREA
.memsize: .long memory_size
.fourmeg: .long 0x00400000      	# 4M
.pgmnw:	.long 0x00080000,.pgmx
.lowcase:
	.byte 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07 
	.byte 0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f
	.byte 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17 
	.byte 0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f
	.byte 0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 
	.byte 0x28,0x29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f
	.byte 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37 
	.byte 0x38,0x39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f
	.byte 0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47 
	.byte 0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f
	.byte 0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57 
	.byte 0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f
	.byte 0x60,0x61,0x62,0x63,0x64,0x65,0x66,0x67 
	.byte 0x68,0x69,0x6a,0x6b,0x6c,0x6d,0x6e,0x6f
	.byte 0x70,0x71,0x72,0x73,0x74,0x75,0x76,0x77 
	.byte 0x78,0x79,0x7a,0x7b,0x7c,0x7d,0x7e,0x7f

	.byte 0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87 
	.byte 0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f
	.byte 0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97 
	.byte 0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f
	.byte 0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7 
	.byte 0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf
	.byte 0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7 
	.byte 0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf
	.byte 0xc0,0x81,0x82,0x83,0x84,0x85,0x86,0x87	# .abcdefg 
	.byte 0x88,0x89,0xca,0xcb,0xcc,0xcd,0xce,0xcf	# hi
	.byte 0xd0,0x91,0x92,0x93,0x94,0x95,0x96,0x97 	# .jklmnop
	.byte 0x98,0x99,0xda,0xdb,0xdc,0xdd,0xde,0xdf	# qr
	.byte 0xe0,0xe1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7	# ..stuvwx
	.byte 0xa8,0xa9,0xea,0xeb,0xec,0xed,0xee,0xef	# yz
	.byte 0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7 
	.byte 0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff

#
# startup-code at 0x10000, running in real mode
# this is called either by the ipl loader or directly by PSW restart
# or linload or SALIPL
#
        .org  0x10000
startup:basr  %r13,0                     # get base
.LPG1:  lctl  %c0,%c15,.Lctl-.LPG1(%r13) # load control registers
	la    %r12,_pstart-.LPG1(%r13)   # pointer to parameter area
					 # move IPL device to lowcore
        mvc   __LC_IPLDEV(4),IPL_DEVICE-PARMAREA(%r12)
	
#
# clear bss memory
#
        l     %r2,.Lbss_bgn-.LPG1(%r13) # start of bss
        l     %r3,.Lbss_end-.LPG1(%r13) # end of bss
        sr    %r3,%r2                   # length of bss
        sr    %r4,%r4                   #
        sr    %r5,%r5                   # set src,length and pad to zero
        sr    %r0,%r0                   #
        mvcle %r2,%r4,0                 # clear mem
        jo    .-4                       # branch back, if not finish

	l     %r2,.Lrcp-.LPG1(%r13)	# Read SCP forced command word
.Lservicecall:
	stosm .Lpmask-.LPG1(%r13),0x01	# authorize ext interrupts

	stctl %r0, %r0,.Lcr-.LPG1(%r13)	# get cr0
	la    %r1,0x200			# set bit 22
	o     %r1,.Lcr-.LPG1(%r13)	# or old cr0 with r1
	st    %r1,.Lcr-.LPG1(%r13)
	lctl  %r0, %r0,.Lcr-.LPG1(%r13)	# load modified cr0

	mvc   __LC_EXT_NEW_PSW(8),.Lpcext-.LPG1(%r13) # set postcall psw
	la    %r1, .Lsclph-.LPG1(%r13)
	a     %r1,__LC_EXT_NEW_PSW+4	# set handler
	st    %r1,__LC_EXT_NEW_PSW+4

	la    %r4,_pstart-.LPG1(%r13)	# %r4 is our index for sccb stuff
	la    %r1, .Lsccb-PARMAREA(%r4)	# our sccb
	.insn rre,0xb2200000,%r2,%r1	# service call
	ipm   %r1
	srl   %r1,28			# get cc code
	xr    %r3, %r3
	chi   %r1,3
	be    .Lfchunk-.LPG1(%r13)	# leave
	chi   %r1,2
	be    .Lservicecall-.LPG1(%r13)
	lpsw  .Lwaitsclp-.LPG1(%r13)
.Lsclph:
	lh    %r1,.Lsccbr-PARMAREA(%r4)
	chi   %r1,0x10			# 0x0010 is the sucess code
	je    .Lprocsccb		# let's process the sccb
	chi   %r1,0x1f0
	bne   .Lfchunk-.LPG1(%r13)	# unhandled error code
	c     %r2, .Lrcp-.LPG1(%r13)	# Did we try Read SCP forced
	bne   .Lfchunk-.LPG1(%r13)	# if no, give up
	l     %r2, .Lrcp2-.LPG1(%r13)	# try with Read SCP
	b     .Lservicecall-.LPG1(%r13)
.Lprocsccb:
	lh    %r1,.Lscpincr1-PARMAREA(%r4) # use this one if != 0
	chi   %r1,0x00
	jne   .Lscnd
	l     %r1,.Lscpincr2-PARMAREA(%r4) # otherwise use this one
.Lscnd:
	xr    %r3,%r3			# same logic
	ic    %r3,.Lscpa1-PARMAREA(%r4)
	chi   %r3,0x00
	jne   .Lcompmem
	l     %r3,.Lscpa2-PARMAREA(%r13)
.Lcompmem:
	mr    %r2,%r1			# mem in MB on 128-bit
	l     %r1,.Lonemb-.LPG1(%r13)
	mr    %r2,%r1			# mem size in bytes in %r3
	b     .Lfchunk-.LPG1(%r13)

.Lpmask:
	.byte 0
.align 8
.Lpcext:.long  0x00080000,0x80000000
.Lcr:
	.long 0x00			# place holder for cr0
.Lwaitsclp:
	.long 0x020A0000
	.long .Lsclph
.Lrcp:
	.int 0x00120001			# Read SCP forced code
.Lrcp2:
	.int 0x00020001			# Read SCP code
.Lonemb:
	.int 0x100000
.Lfchunk:

#
# find memory chunks.
#
	lr    %r9,%r3			 # end of mem
	mvc   __LC_PGM_NEW_PSW(8),.Lpcmem-.LPG1(%r13)
	la    %r1,1                      # test in increments of 128KB
	sll   %r1,17
	l     %r3,.Lmchunk-.LPG1(%r13)   # get pointer to memory_chunk array
	slr   %r4,%r4                    # set start of chunk to zero
	slr   %r5,%r5                    # set end of chunk to zero
	slr   %r6,%r6			 # set access code to zero
	la    %r10, MEMORY_CHUNKS	 # number of chunks
.Lloop:
	tprot 0(%r5),0			 # test protection of first byte
	ipm   %r7
	srl   %r7,28
	clr   %r6,%r7			 # compare cc with last access code
	be    .Lsame-.LPG1(%r13)
	b     .Lchkmem-.LPG1(%r13)
.Lsame:
	ar    %r5,%r1			 # add 128KB to end of chunk
	bno   .Lloop-.LPG1(%r13)	 # r1 < 0x80000000 -> loop
.Lchkmem:				 # > 2GB or tprot got a program check
	clr   %r4,%r5			 # chunk size > 0?
	be    .Lchkloop-.LPG1(%r13)
	st    %r4,0(%r3)		 # store start address of chunk
	lr    %r0,%r5
	slr   %r0,%r4
	st    %r0,4(%r3)		 # store size of chunk
	st    %r6,8(%r3)		 # store type of chunk
	la    %r3,12(%r3)
	l     %r4,.Lmemsize-.LPG1(%r13)	 # address of variable memory_size
	st    %r5,0(%r4)		 # store last end to memory size
	ahi   %r10,-1			 # update chunk number
.Lchkloop:
	lr    %r6,%r7			 # set access code to last cc
	# we got an exception or we're starting a new
	# chunk , we must check if we should
	# still try to find valid memory (if we detected
	# the amount of available storage), and if we
	# have chunks left
	xr    %r0,%r0
	clr   %r0,%r9			 # did we detect memory?
	je    .Ldonemem			 # if not, leave
	chi   %r10,0			 # do we have chunks left?
	je    .Ldonemem
	alr   %r5,%r1			 # add 128KB to end of chunk
	lr    %r4,%r5			 # potential new chunk
	clr    %r5,%r9			 # should we go on?
	jl     .Lloop
.Ldonemem:		
        l      %r12,.Lmflags-.LPG1(%r13) # get address of machine_flags
#
# find out if we are running under VM
#
        stidp  __LC_CPUID               # store cpuid
	tm     __LC_CPUID,0xff          # running under VM ?
	bno    .Lnovm-.LPG1(%r13)
        oi     3(%r12),1                # set VM flag
.Lnovm:
        lh     %r0,__LC_CPUID+4         # get cpu version
        chi    %r0,0x7490               # running on a P/390 ?
        bne    .Lnop390-.LPG1(%r13)
        oi     3(%r12),4                # set P/390 flag
.Lnop390:

#
# find out if we have an IEEE fpu
#
        mvc    __LC_PGM_NEW_PSW(8),.Lpcfpu-.LPG1(%r13)
	efpc   %r0,0                    # test IEEE extract fpc instruction
        oi     3(%r12),2                # set IEEE fpu flag
.Lchkfpu:

#
# find out if we have the CSP instruction
#
       mvc    __LC_PGM_NEW_PSW(8),.Lpccsp-.LPG1(%r13)
       la     %r0,0
       lr     %r1,%r0
       la     %r2,4
       csp    %r0,%r2                   # Test CSP instruction
       oi     3(%r12),8                 # set CSP flag
.Lchkcsp:

#
# find out if we have the MVPG instruction
#
       mvc    __LC_PGM_NEW_PSW(8),.Lpcmvpg-.LPG1(%r13)
       sr     %r0,%r0
       la     %r1,0
       la     %r2,0
       mvpg   %r1,%r2                   # Test CSP instruction
       oi     3(%r12),16                # set MVPG flag
.Lchkmvpg:

#
# find out if we have the IDTE instruction
#
	mvc	__LC_PGM_NEW_PSW(8),.Lpcidte-.LPG1(%r13)
	.long	0xb2b10000		# store facility list
	tm	0xc8,0x08		# check bit for clearing-by-ASCE
	bno	.Lchkidte-.LPG1(%r13)
	lhi	%r1,2094
	lhi	%r2,0
	.long	0xb98e2001
	oi	3(%r12),0x80		# set IDTE flag
.Lchkidte:

        lpsw  .Lentry-.LPG1(13)         # jump to _stext in primary-space,
                                        # virtual and never return ...
        .align 8
.Lentry:.long  0x00080000,0x80000000 + _stext
.Lctl:  .long  0x04b50002               # cr0: various things
        .long  0                        # cr1: primary space segment table
        .long  .Lduct                   # cr2: dispatchable unit control table
        .long  0                        # cr3: instruction authorization
        .long  0                        # cr4: instruction authorization
        .long  0xffffffff               # cr5: primary-aste origin
        .long  0                        # cr6:  I/O interrupts
        .long  0                        # cr7:  secondary space segment table
        .long  0                        # cr8:  access registers translation
        .long  0                        # cr9:  tracing off
        .long  0                        # cr10: tracing off
        .long  0                        # cr11: tracing off
        .long  0                        # cr12: tracing off
        .long  0                        # cr13: home space segment table
        .long  0xc0000000               # cr14: machine check handling off
        .long  0                        # cr15: linkage stack operations
.Lpcmem:.long  0x00080000,0x80000000 + .Lchkmem
.Lpcfpu:.long  0x00080000,0x80000000 + .Lchkfpu
.Lpccsp:.long  0x00080000,0x80000000 + .Lchkcsp
.Lpcmvpg:.long 0x00080000,0x80000000 + .Lchkmvpg
.Lpcidte:.long 0x00080000,0x80000000 + .Lchkidte
.Lmemsize:.long memory_size
.Lmchunk:.long memory_chunk
.Lmflags:.long machine_flags
.Lbss_bgn:  .long  __bss_start
.Lbss_end:  .long  _end

	.org PARMAREA-64
.Lduct:	.long 0,0,0,0,0,0,0,0
	.long 0,0,0,0,0,0,0,0

#
# params at 10400 (setup.h)
#
	.org   PARMAREA
	.global _pstart
_pstart:	
        .long  0,0                      # IPL_DEVICE
        .long  0,RAMDISK_ORIGIN         # INITRD_START
        .long  0,RAMDISK_SIZE           # INITRD_SIZE

        .org   COMMAND_LINE
    	.byte  "root=/dev/ram0 ro"
        .byte  0
	.org   0x11000
.Lsccb:
	.hword 0x1000			# length, one page
	.byte 0x00,0x00,0x00
	.byte 0x80			# variable response bit set
.Lsccbr:
	.hword 0x00			# response code
.Lscpincr1:
	.hword 0x00
.Lscpa1:
	.byte 0x00
	.fill 89,1,0
.Lscpa2:
	.int 0x00
.Lscpincr2:
	.quad 0x00
	.fill 3984,1,0
	.org 0x12000
	.global _pend
_pend:	

#ifdef CONFIG_SHARED_KERNEL
	.org   0x100000
#endif

#
# startup-code, running in virtual mode
#
        .globl _stext
_stext:	basr  %r13,0                    # get base
.LPG2:
#
# Setup stack
#
        l     %r15,.Linittu-.LPG2(%r13)
	mvc   __LC_CURRENT(4),__TI_task(%r15)
        ahi   %r15,8192                 # init_task_union + 8192
        st    %r15,__LC_KERNEL_STACK    # set end of kernel stack
        ahi   %r15,-96
        xc    0(4,%r15),0(%r15)         # set backchain to zero

# check control registers
        stctl  %c0,%c15,0(%r15)
	oi     2(%r15),0x20             # enable sigp external interrupts
	oi     0(%r15),0x10             # switch on low address protection
        lctl   %c0,%c15,0(%r15)

#
        lam    0,15,.Laregs-.LPG2(%r13) # load access regs needed by uaccess
        l      %r14,.Lstart-.LPG2(%r13)
        basr   %r14,%r14                # call start_kernel
#
# We returned from start_kernel ?!? PANIK
#
        basr  %r13,0
	lpsw  .Ldw-.(%r13)           # load disabled wait psw
#
            .align 8
.Ldw:	    .long  0x000a0000,0x00000000
.Linittu:   .long  init_thread_union
.Lstart:    .long  start_kernel
.Laregs:    .long  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0