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/* $Id: itlb_base.S,v 1.7 1999/03/02 15:42:12 jj Exp $
* itlb_base.S: Front end to ITLB miss replacement strategy.
* This is included directly into the trap table.
*
* Copyright (C) 1996,1998 David S. Miller (davem@dm.cobaltmicro.com)
* Copyright (C) 1997,1998 Jakub Jelinek (jj@ultra.linux.cz)
*/
#define TAG_CONTEXT_BITS 0x3ff
#define VPTE_SHIFT (PAGE_SHIFT - 3)
/* Ways we can get here:
*
* 1) Nucleus instruction misses from module code.
* 2) All user instruction misses.
*
* All real page faults merge their code paths to the
* sparc64_realfault_common label below.
*/
/* ITLB ** ICACHE line 1: Quick user TLB misses */
ldxa [%g1 + %g1] ASI_IMMU, %g4 ! Get TAG_ACCESS
srax %g4, VPTE_SHIFT, %g6 ! Create VPTE offset
ldxa [%g3 + %g6] ASI_P, %g5 ! Load VPTE
1: brgez,pn %g5, 3f ! Not valid, branch out
and %g5, (_PAGE_PRESENT|_PAGE_READ), %g4 ! Mask readable bits
2: stxa %g5, [%g0] ASI_ITLB_DATA_IN ! Load PTE into TLB
retry ! Trap return
3: cmp %g4, (_PAGE_PRESENT|_PAGE_READ) ! Readable page?
/* ITLB ** ICACHE line 2: Quick user ref updates */
bne,pn %xcc, 4f ! Nope, real missing page
sllx %g1, 60, %g4 ! Sliiickkk...
or %g5, _PAGE_ACCESSED, %g5 ! Mark as touched
or %g5, %g4, %g5 ! Allow user to see it
ba,pt %xcc, 2b ! Branch to load TLB
stxa %g5, [%g3 + %g6] ASI_S ! Update PTE table
4: rdpr %pstate, %g4 ! Move into alternate globals
wrpr %g4, PSTATE_AG|PSTATE_MG, %pstate
/* ITLB ** ICACHE line 3: Real faults */
rdpr %tpc, %g5 ! And load faulting VA
clr %g4 ! It was read
sparc64_realfault_common: ! Called by TL0 dtlb_miss too
sethi %hi(1f), %g7 ! Save state
ba,pt %xcc, etrap ! ...
1: or %g7, %lo(1b), %g7 ! ...
mov %l4, %o2 ! Read/Write/No idea
srlx %l5, PAGE_SHIFT, %o1 ! Page align faulting VA
add %sp, STACK_BIAS + REGWIN_SZ, %o0! Compute pt_regs arg
/* ITLB ** ICACHE line 4: Call fault processing code */
call do_sparc64_fault ! Call fault handler
sllx %o1, PAGE_SHIFT, %o1 ! Finish page alignment
ba,a,pt %xcc, rtrap_clr_l6 ! Restore cpu state
nop
winfix_trampoline:
rdpr %tpc, %g3 ! Prepare winfixup TNPC
or %g3, 0x7c, %g3 ! Compute offset to branch
wrpr %g3, %tnpc ! Write it into TNPC
done ! Do it to it
#undef TAG_CONTEXT_BITS
#undef VPTE_SHIFT
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