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/* $Id: itlb_base.S,v 1.9 2000/03/26 09:13:48 davem 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@redhat.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
mov FAULT_CODE_ITLB, %g4 ! It was read from ITLB
sparc64_realfault_common: ! Called by TL0 dtlb_miss too
stb %g4, [%g6 + AOFF_task_thread + AOFF_thread_fault_code]
stx %g5, [%g6 + AOFF_task_thread + AOFF_thread_fault_address]
ba,pt %xcc, etrap ! Save state
1: rd %pc, %g7 ! ...
call do_sparc64_fault ! Call fault handler
add %sp, STACK_BIAS + REGWIN_SZ, %o0! Compute pt_regs arg
/* ITLB ** ICACHE line 4: Finish faults + window fixups */
ba,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
nop
nop
#undef TAG_CONTEXT_BITS
#undef VPTE_SHIFT
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