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/*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
* Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
* Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
* Adapted for Power Macintosh by Paul Mackerras.
* Low-level exception handlers and MMU support
* rewritten by Paul Mackerras.
* Copyright (C) 1996 Paul Mackerras.
*
* This file contains low-level assembler routines for managing
* the PowerPC MMU hash table. (PPC 8xx processors don't use a
* hash table, so this file is not used on them.)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/ppc_asm.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#ifdef CONFIG_SMP
.section .bss
.align 2
.globl mmu_hash_lock
mmu_hash_lock:
.space 4
#endif /* CONFIG_SMP */
/*
* Load a PTE into the hash table, if possible.
* The address is in r4, and r3 contains an access flag:
* _PAGE_RW (0x400) if a write.
* r9 contains the SRR1 value, from which we use the MSR_PR bit.
* SPRG3 contains the physical address of the current task's thread.
*
* Returns to the caller if the access is illegal or there is no
* mapping for the address. Otherwise it places an appropriate PTE
* in the hash table and returns from the exception.
* Uses r0, r3 - r8, r10, ctr, lr.
*/
.text
_GLOBAL(hash_page)
tophys(r7,0) /* gets -KERNELBASE into r7 */
#ifdef CONFIG_SMP
addis r8,r7,mmu_hash_lock@h
ori r8,r8,mmu_hash_lock@l
lis r0,0x0fff
b 10f
11: lwz r6,0(r8)
cmpwi 0,r6,0
bne 11b
10: lwarx r6,0,r8
cmpwi 0,r6,0
bne- 11b
stwcx. r0,0,r8
bne- 10b
isync
#endif
/* Get PTE (linux-style) and check access */
lis r0,KERNELBASE@h /* check if kernel address */
cmplw 0,r4,r0
mfspr r8,SPRN_SPRG3 /* current task's THREAD (phys) */
ori r3,r3,_PAGE_USER|_PAGE_PRESENT /* test low addresses as user */
lwz r5,PGDIR(r8) /* virt page-table root */
blt+ 112f /* assume user more likely */
lis r5,swapper_pg_dir@ha /* if kernel address, use */
addi r5,r5,swapper_pg_dir@l /* kernel page table */
rlwimi r3,r9,32-12,29,29 /* MSR_PR -> _PAGE_USER */
112: add r5,r5,r7 /* convert to phys addr */
#ifndef CONFIG_PTE_64BIT
rlwimi r5,r4,12,20,29 /* insert top 10 bits of address */
lwz r8,0(r5) /* get pmd entry */
rlwinm. r8,r8,0,0,19 /* extract address of pte page */
#else
rlwinm r8,r4,13,19,29 /* Compute pgdir/pmd offset */
lwzx r8,r8,r5 /* Get L1 entry */
rlwinm. r8,r8,0,0,20 /* extract pt base address */
#endif
#ifdef CONFIG_SMP
beq- hash_page_out /* return if no mapping */
#else
/* XXX it seems like the 601 will give a machine fault on the
rfi if its alignment is wrong (bottom 4 bits of address are
8 or 0xc) and we have had a not-taken conditional branch
to the address following the rfi. */
beqlr-
#endif
#ifndef CONFIG_PTE_64BIT
rlwimi r8,r4,22,20,29 /* insert next 10 bits of address */
#else
rlwimi r8,r4,23,20,28 /* compute pte address */
#endif
rlwinm r0,r3,32-3,24,24 /* _PAGE_RW access -> _PAGE_DIRTY */
ori r0,r0,_PAGE_ACCESSED|_PAGE_HASHPTE
/*
* Update the linux PTE atomically. We do the lwarx up-front
* because almost always, there won't be a permission violation
* and there won't already be an HPTE, and thus we will have
* to update the PTE to set _PAGE_HASHPTE. -- paulus.
*
* If PTE_64BIT is set, the low word is the flags word; use that
* word for locking since it contains all the interesting bits.
*/
#if (PTE_FLAGS_OFFSET != 0)
addi r8,r8,PTE_FLAGS_OFFSET
#endif
retry:
lwarx r6,0,r8 /* get linux-style pte, flag word */
andc. r5,r3,r6 /* check access & ~permission */
#ifdef CONFIG_SMP
bne- hash_page_out /* return if access not permitted */
#else
bnelr-
#endif
or r5,r0,r6 /* set accessed/dirty bits */
#ifdef CONFIG_PTE_64BIT
#ifdef CONFIG_SMP
subf r10,r6,r8 /* create false data dependency */
subi r10,r10,PTE_FLAGS_OFFSET
lwzx r10,r6,r10 /* Get upper PTE word */
#else
lwz r10,-PTE_FLAGS_OFFSET(r8)
#endif /* CONFIG_SMP */
#endif /* CONFIG_PTE_64BIT */
stwcx. r5,0,r8 /* attempt to update PTE */
bne- retry /* retry if someone got there first */
mfsrin r3,r4 /* get segment reg for segment */
mfctr r0
stw r0,_CTR(r11)
bl create_hpte /* add the hash table entry */
#ifdef CONFIG_SMP
eieio
addis r8,r7,mmu_hash_lock@ha
li r0,0
stw r0,mmu_hash_lock@l(r8)
#endif
/* Return from the exception */
lwz r5,_CTR(r11)
mtctr r5
lwz r0,GPR0(r11)
lwz r7,GPR7(r11)
lwz r8,GPR8(r11)
b fast_exception_return
#ifdef CONFIG_SMP
hash_page_out:
eieio
addis r8,r7,mmu_hash_lock@ha
li r0,0
stw r0,mmu_hash_lock@l(r8)
blr
#endif /* CONFIG_SMP */
/*
* Add an entry for a particular page to the hash table.
*
* add_hash_page(unsigned context, unsigned long va, unsigned long pmdval)
*
* We assume any necessary modifications to the pte (e.g. setting
* the accessed bit) have already been done and that there is actually
* a hash table in use (i.e. we're not on a 603).
*/
_GLOBAL(add_hash_page)
mflr r0
stw r0,4(r1)
/* Convert context and va to VSID */
mulli r3,r3,897*16 /* multiply context by context skew */
rlwinm r0,r4,4,28,31 /* get ESID (top 4 bits of va) */
mulli r0,r0,0x111 /* multiply by ESID skew */
add r3,r3,r0 /* note create_hpte trims to 24 bits */
#ifdef CONFIG_SMP
rlwinm r8,r1,0,0,(31-THREAD_SHIFT) /* use cpu number to make tag */
lwz r8,TI_CPU(r8) /* to go in mmu_hash_lock */
oris r8,r8,12
#endif /* CONFIG_SMP */
/*
* We disable interrupts here, even on UP, because we don't
* want to race with hash_page, and because we want the
* _PAGE_HASHPTE bit to be a reliable indication of whether
* the HPTE exists (or at least whether one did once).
* We also turn off the MMU for data accesses so that we
* we can't take a hash table miss (assuming the code is
* covered by a BAT). -- paulus
*/
mfmsr r9
SYNC
rlwinm r0,r9,0,17,15 /* clear bit 16 (MSR_EE) */
rlwinm r0,r0,0,28,26 /* clear MSR_DR */
mtmsr r0
SYNC_601
isync
tophys(r7,0)
#ifdef CONFIG_SMP
addis r6,r7,mmu_hash_lock@ha
addi r6,r6,mmu_hash_lock@l
10: lwarx r0,0,r6 /* take the mmu_hash_lock */
cmpi 0,r0,0
bne- 11f
stwcx. r8,0,r6
beq+ 12f
11: lwz r0,0(r6)
cmpi 0,r0,0
beq 10b
b 11b
12: isync
#endif
/*
* Fetch the linux pte and test and set _PAGE_HASHPTE atomically.
* If _PAGE_HASHPTE was already set, we don't replace the existing
* HPTE, so we just unlock and return.
*/
mr r8,r5
#ifndef CONFIG_PTE_64BIT
rlwimi r8,r4,22,20,29
#else
rlwimi r8,r4,23,20,28
addi r8,r8,PTE_FLAGS_OFFSET
#endif
1: lwarx r6,0,r8
andi. r0,r6,_PAGE_HASHPTE
bne 9f /* if HASHPTE already set, done */
#ifdef CONFIG_PTE_64BIT
#ifdef CONFIG_SMP
subf r10,r6,r8 /* create false data dependency */
subi r10,r10,PTE_FLAGS_OFFSET
lwzx r10,r6,r10 /* Get upper PTE word */
#else
lwz r10,-PTE_FLAGS_OFFSET(r8)
#endif /* CONFIG_SMP */
#endif /* CONFIG_PTE_64BIT */
ori r5,r6,_PAGE_HASHPTE
stwcx. r5,0,r8
bne- 1b
bl create_hpte
9:
#ifdef CONFIG_SMP
addis r6,r7,mmu_hash_lock@ha
addi r6,r6,mmu_hash_lock@l
eieio
|