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/*
* r4k_misc.S: Misc. exception handling code for r4k.
*
* Copyright (C) 1994, 1995, 1996 by Ralf Baechle and Andreas Busse
*
* Multi-cpu abstraction and reworking:
* Copyright (C) 1996 David S. Miller (dm@engr.sgi.com)
*
* $Id: r4k_misc.S,v 1.3 1997/09/07 04:51:07 ralf Exp $
*/
#include <asm/asm.h>
#include <asm/current.h>
#include <asm/offset.h>
#include <asm/bootinfo.h>
#include <asm/cachectl.h>
#include <asm/current.h>
#include <asm/fpregdef.h>
#include <asm/mipsconfig.h>
#include <asm/mipsregs.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#undef NOTLB_OPTIMIZE /* If you are paranoid, define this. */
/* ABUSE of CPP macros 101. */
/* After this macro runs, the pte faulted on is
* in register PTE, a ptr into the table in which
* the pte belongs is in PTR.
*/
#define LOAD_PTE(pte, ptr) \
mfc0 pte, CP0_BADVADDR; \
srl pte, pte, 22; \
_GET_CURRENT(ptr); \
sll pte, pte, 2; \
lw ptr, THREAD_PGDIR(ptr); \
addu ptr, pte, ptr; \
mfc0 pte, CP0_BADVADDR; \
lw ptr, (ptr); \
srl pte, pte, 10; \
and pte, pte, 0xffc; \
addu ptr, ptr, pte; \
lw pte, (ptr);
/* This places the even/odd pte pair in the page
* table at PTR into ENTRYLO0 and ENTRYLO1 using
* TMP as a scratch register.
*/
#define PTE_RELOAD(ptr, tmp) \
ori ptr, ptr, 0x4; \
xori ptr, ptr, 0x4; \
lw tmp, 4(ptr); \
lw ptr, 0(ptr); \
srl tmp, tmp, 6; \
mtc0 tmp, CP0_ENTRYLO1; \
srl ptr, ptr, 6; \
mtc0 ptr, CP0_ENTRYLO0;
#define DO_FAULT(write) \
.set noat; \
.set macro; \
SAVE_ALL; \
mfc0 a2, CP0_BADVADDR; \
STI; \
.set at; \
move a0, sp; \
jal do_page_fault; \
li a1, write; \
j ret_from_sys_call; \
nop; \
.set noat; \
.set nomacro;
/* Check is PTE is present, if not then jump to LABEL.
* PTR points to the page table where this PTE is located,
* when the macro is done executing PTE will be restored
* with it's original value.
*/
#define PTE_PRESENT(pte, ptr, label) \
andi pte, pte, (_PAGE_PRESENT | _PAGE_READ); \
xori pte, pte, (_PAGE_PRESENT | _PAGE_READ); \
bnez pte, label; \
lw pte, (ptr);
/* Make PTE valid, store result in PTR. */
#define PTE_MAKEVALID(pte, ptr) \
ori pte, pte, (_PAGE_VALID | _PAGE_ACCESSED); \
sw pte, (ptr);
/* Check if PTE can be written to, if not branch to LABEL.
* Regardless restore PTE with value from PTR when done.
*/
#define PTE_WRITABLE(pte, ptr, label) \
andi pte, pte, (_PAGE_PRESENT | _PAGE_WRITE); \
xori pte, pte, (_PAGE_PRESENT | _PAGE_WRITE); \
bnez pte, label; \
lw pte, (ptr);
/* Make PTE writable, update software status bits as well,
* then store at PTR.
*/
#define PTE_MAKEWRITE(pte, ptr) \
ori pte, pte, (_PAGE_ACCESSED | _PAGE_MODIFIED | \
_PAGE_VALID | _PAGE_DIRTY); \
sw pte, (ptr);
.set noreorder
.set mips3
/*
* From the IDT errata for the QED RM5230 (Nevada), processor revision 1.0:
* 2. A timing hazard exists for the TLBP instruction.
*
* stalling_instruction
* TLBP
*
* The JTLB is being read for the TLBP throughout the stall generated by the
* previous instruction. This is not really correct as the stalling instruction
* can modify the address used to access the JTLB. The failure symptom is that
* the TLBP instruction will use an address created for the stalling instruction
* and not the address held in C0_ENHI and thus report the wrong results.
*
* The software work-around is to not allow the instruction preceding the TLBP
* to stall - make it an NOP or some other instruction guaranteed not to stall.
*
* Errata 2 will not be fixed. This errata is also on the R5000.
*
* As if we MIPS hackers wouldn't know how to nop pipelines happy ...
*/
#define R5K_HAZARD nop
/*
* Note for many R4k variants tlb probes cannot be executed out
* of the instruction cache else you get bogus results.
*/
.align 5
NESTED(r4k_handle_tlbl, PT_SIZE, sp)
.set noat
.set nomacro
invalid_tlbl:
#ifndef NOTLB_OPTIMIZE
/* Test present bit in entry. */
LOAD_PTE(k0, k1)
R5K_HAZARD
tlbp
PTE_PRESENT(k0, k1, nopage_tlbl)
PTE_MAKEVALID(k0, k1)
PTE_RELOAD(k1, k0)
nop
b 1f
tlbwi
1:
nop
eret
#endif
nopage_tlbl:
DO_FAULT(0)
END(r4k_handle_tlbl)
.align 5
NESTED(r4k_handle_tlbs, PT_SIZE, sp)
.set noat
#ifndef NOTLB_OPTIMIZE
LOAD_PTE(k0, k1)
R5K_HAZARD
tlbp # find faulting entry
PTE_WRITABLE(k0, k1, nopage_tlbs)
PTE_MAKEWRITE(k0, k1)
PTE_RELOAD(k1, k0)
nop
b 1f
tlbwi
1:
nop
eret
#endif
nopage_tlbs:
DO_FAULT(1)
END(r4k_handle_tlbs)
.align 5
NESTED(r4k_handle_mod, PT_SIZE, sp)
.set noat
#ifndef NOTLB_OPTIMIZE
LOAD_PTE(k0, k1)
R5K_HAZARD
tlbp # find faulting entry
andi k0, k0, _PAGE_WRITE
beqz k0, nowrite_mod
lw k0, (k1)
/* Present and writable bits set, set accessed and dirty bits. */
PTE_MAKEWRITE(k0, k1)
#if 0
ori k0, k0, (_PAGE_ACCESSED | _PAGE_DIRTY)
sw k0, (k1)
#endif
/* Now reload the entry into the tlb. */
PTE_RELOAD(k1, k0)
nop
b 1f
tlbwi
1:
nop
eret
#endif
nowrite_mod:
DO_FAULT(1)
END(r4k_handle_mod)
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