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kernel/linux-rt-4.4.41/arch/sparc/lib/clear_page.S 2.38 KB
5113f6f70   김현기   kernel add
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  /* clear_page.S: UltraSparc optimized clear page.
   *
   * Copyright (C) 1996, 1998, 1999, 2000, 2004 David S. Miller (davem@redhat.com)
   * Copyright (C) 1997 Jakub Jelinek (jakub@redhat.com)
   */
  
  #include <asm/visasm.h>
  #include <asm/thread_info.h>
  #include <asm/page.h>
  #include <asm/pgtable.h>
  #include <asm/spitfire.h>
  #include <asm/head.h>
  
  	/* What we used to do was lock a TLB entry into a specific
  	 * TLB slot, clear the page with interrupts disabled, then
  	 * restore the original TLB entry.  This was great for
  	 * disturbing the TLB as little as possible, but it meant
  	 * we had to keep interrupts disabled for a long time.
  	 *
  	 * Now, we simply use the normal TLB loading mechanism,
  	 * and this makes the cpu choose a slot all by itself.
  	 * Then we do a normal TLB flush on exit.  We need only
  	 * disable preemption during the clear.
  	 */
  
  	.text
  
  	.globl		_clear_page
  _clear_page:		/* %o0=dest */
  	ba,pt		%xcc, clear_page_common
  	 clr		%o4
  
  	/* This thing is pretty important, it shows up
  	 * on the profiles via do_anonymous_page().
  	 */
  	.align		32
  	.globl		clear_user_page
  clear_user_page:	/* %o0=dest, %o1=vaddr */
  	lduw		[%g6 + TI_PRE_COUNT], %o2
  	sethi		%hi(PAGE_OFFSET), %g2
  	sethi		%hi(PAGE_SIZE), %o4
  
  	ldx		[%g2 + %lo(PAGE_OFFSET)], %g2
  	sethi		%hi(PAGE_KERNEL_LOCKED), %g3
  
  	ldx		[%g3 + %lo(PAGE_KERNEL_LOCKED)], %g3
  	sub		%o0, %g2, %g1		! paddr
  
  	and		%o1, %o4, %o0		! vaddr D-cache alias bit
  
  	or		%g1, %g3, %g1		! TTE data
  	sethi		%hi(TLBTEMP_BASE), %o3
  
  	add		%o2, 1, %o4
  	add		%o0, %o3, %o0		! TTE vaddr
  
  	/* Disable preemption.  */
  	mov		TLB_TAG_ACCESS, %g3
  	stw		%o4, [%g6 + TI_PRE_COUNT]
  
  	/* Load TLB entry.  */
  	rdpr		%pstate, %o4
  	wrpr		%o4, PSTATE_IE, %pstate
  	stxa		%o0, [%g3] ASI_DMMU
  	stxa		%g1, [%g0] ASI_DTLB_DATA_IN
  	sethi		%hi(KERNBASE), %g1
  	flush		%g1
  	wrpr		%o4, 0x0, %pstate
  
  	mov		1, %o4
  
  clear_page_common:
  	VISEntryHalf
  	membar		#StoreLoad | #StoreStore | #LoadStore
  	fzero		%f0
  	sethi		%hi(PAGE_SIZE/64), %o1
  	mov		%o0, %g1		! remember vaddr for tlbflush
  	fzero		%f2
  	or		%o1, %lo(PAGE_SIZE/64), %o1
  	faddd		%f0, %f2, %f4
  	fmuld		%f0, %f2, %f6
  	faddd		%f0, %f2, %f8
  	fmuld		%f0, %f2, %f10
  
  	faddd		%f0, %f2, %f12
  	fmuld		%f0, %f2, %f14
  1:	stda		%f0, [%o0 + %g0] ASI_BLK_P
  	subcc		%o1, 1, %o1
  	bne,pt		%icc, 1b
  	 add		%o0, 0x40, %o0
  	membar		#Sync
  	VISExitHalf
  
  	brz,pn		%o4, out
  	 nop
  
  	stxa		%g0, [%g1] ASI_DMMU_DEMAP
  	membar		#Sync
  	stw		%o2, [%g6 + TI_PRE_COUNT]
  
  out:	retl
  	 nop