+++ /dev/null
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * arch/sh64/mm/tlbmiss.c
- *
- * Original code from fault.c
- * Copyright (C) 2000, 2001 Paolo Alberelli
- *
- * Fast PTE->TLB refill path
- * Copyright (C) 2003 Richard.Curnow@superh.com
- *
- * IMPORTANT NOTES :
- * The do_fast_page_fault function is called from a context in entry.S where very few registers
- * have been saved. In particular, the code in this file must be compiled not to use ANY
- * caller-save registers that are not part of the restricted save set. Also, it means that
- * code in this file must not make calls to functions elsewhere in the kernel, or else the
- * excepting context will see corruption in its caller-save registers. Plus, the entry.S save
- * area is non-reentrant, so this code has to run with SR.BL==1, i.e. no interrupts taken inside
- * it and panic on any exception.
- *
- */
-
-#include <linux/signal.h>
-#include <linux/sched.h>
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/string.h>
-#include <linux/types.h>
-#include <linux/ptrace.h>
-#include <linux/mman.h>
-#include <linux/mm.h>
-#include <linux/smp.h>
-#include <linux/interrupt.h>
-
-#include <asm/system.h>
-#include <asm/tlb.h>
-#include <asm/io.h>
-#include <asm/uaccess.h>
-#include <asm/pgalloc.h>
-#include <asm/mmu_context.h>
-#include <asm/registers.h> /* required by inline asm statements */
-
-/* Callable from fault.c, so not static */
-inline void __do_tlb_refill(unsigned long address,
- unsigned long long is_text_not_data, pte_t *pte)
-{
- unsigned long long ptel;
- unsigned long long pteh=0;
- struct tlb_info *tlbp;
- unsigned long long next;
-
- /* Get PTEL first */
- ptel = pte_val(*pte);
-
- /*
- * Set PTEH register
- */
- pteh = address & MMU_VPN_MASK;
-
- /* Sign extend based on neff. */
-#if (NEFF == 32)
- /* Faster sign extension */
- pteh = (unsigned long long)(signed long long)(signed long)pteh;
-#else
- /* General case */
- pteh = (pteh & NEFF_SIGN) ? (pteh | NEFF_MASK) : pteh;
-#endif
-
- /* Set the ASID. */
- pteh |= get_asid() << PTEH_ASID_SHIFT;
- pteh |= PTEH_VALID;
-
- /* Set PTEL register, set_pte has performed the sign extension */
- ptel &= _PAGE_FLAGS_HARDWARE_MASK; /* drop software flags */
-
- tlbp = is_text_not_data ? &(cpu_data->itlb) : &(cpu_data->dtlb);
- next = tlbp->next;
- __flush_tlb_slot(next);
- asm volatile ("putcfg %0,1,%2\n\n\t"
- "putcfg %0,0,%1\n"
- : : "r" (next), "r" (pteh), "r" (ptel) );
-
- next += TLB_STEP;
- if (next > tlbp->last) next = tlbp->first;
- tlbp->next = next;
-
-}
-
-static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long protection_flags,
- unsigned long long textaccess,
- unsigned long address)
-{
- pgd_t *dir;
- pmd_t *pmd;
- static pte_t *pte;
- pte_t entry;
-
- dir = pgd_offset_k(address);
- pmd = pmd_offset(dir, address);
-
- if (pmd_none(*pmd)) {
- return 0;
- }
-
- if (pmd_bad(*pmd)) {
- pmd_clear(pmd);
- return 0;
- }
-
- pte = pte_offset_kernel(pmd, address);
- entry = *pte;
-
- if (pte_none(entry) || !pte_present(entry)) {
- return 0;
- }
-
- if ((pte_val(entry) & protection_flags) != protection_flags) {
- return 0;
- }
-
- __do_tlb_refill(address, textaccess, pte);
-
- return 1;
-}
-
-static int handle_tlbmiss(struct mm_struct *mm, unsigned long long protection_flags,
- unsigned long long textaccess,
- unsigned long address)
-{
- pgd_t *dir;
- pmd_t *pmd;
- pte_t *pte;
- pte_t entry;
-
- /* NB. The PGD currently only contains a single entry - there is no
- page table tree stored for the top half of the address space since
- virtual pages in that region should never be mapped in user mode.
- (In kernel mode, the only things in that region are the 512Mb super
- page (locked in), and vmalloc (modules) + I/O device pages (handled
- by handle_vmalloc_fault), so no PGD for the upper half is required
- by kernel mode either).
-
- See how mm->pgd is allocated and initialised in pgd_alloc to see why
- the next test is necessary. - RPC */
- if (address >= (unsigned long) TASK_SIZE) {
- /* upper half - never has page table entries. */
- return 0;
- }
- dir = pgd_offset(mm, address);
- if (pgd_none(*dir)) {
- return 0;
- }
- if (!pgd_present(*dir)) {
- return 0;
- }
-
- pmd = pmd_offset(dir, address);
- if (pmd_none(*pmd)) {
- return 0;
- }
- if (!pmd_present(*pmd)) {
- return 0;
- }
- pte = pte_offset_kernel(pmd, address);
- entry = *pte;
- if (pte_none(entry)) {
- return 0;
- }
- if (!pte_present(entry)) {
- return 0;
- }
-
- /* If the page doesn't have sufficient protection bits set to service the
- kind of fault being handled, there's not much point doing the TLB refill.
- Punt the fault to the general handler. */
- if ((pte_val(entry) & protection_flags) != protection_flags) {
- return 0;
- }
-
- __do_tlb_refill(address, textaccess, pte);
-
- return 1;
-}
-
-/* Put all this information into one structure so that everything is just arithmetic
- relative to a single base address. This reduces the number of movi/shori pairs needed
- just to load addresses of static data. */
-struct expevt_lookup {
- unsigned short protection_flags[8];
- unsigned char is_text_access[8];
- unsigned char is_write_access[8];
-};
-
-#define PRU (1<<9)
-#define PRW (1<<8)
-#define PRX (1<<7)
-#define PRR (1<<6)
-
-#define DIRTY (_PAGE_DIRTY | _PAGE_ACCESSED)
-#define YOUNG (_PAGE_ACCESSED)
-
-/* Sized as 8 rather than 4 to allow checking the PTE's PRU bit against whether
- the fault happened in user mode or privileged mode. */
-static struct expevt_lookup expevt_lookup_table = {
- .protection_flags = {PRX, PRX, 0, 0, PRR, PRR, PRW, PRW},
- .is_text_access = {1, 1, 0, 0, 0, 0, 0, 0}
-};
-
-/*
- This routine handles page faults that can be serviced just by refilling a
- TLB entry from an existing page table entry. (This case represents a very
- large majority of page faults.) Return 1 if the fault was successfully
- handled. Return 0 if the fault could not be handled. (This leads into the
- general fault handling in fault.c which deals with mapping file-backed
- pages, stack growth, segmentation faults, swapping etc etc)
- */
-asmlinkage int do_fast_page_fault(unsigned long long ssr_md, unsigned long long expevt,
- unsigned long address)
-{
- struct task_struct *tsk;
- struct mm_struct *mm;
- unsigned long long textaccess;
- unsigned long long protection_flags;
- unsigned long long index;
- unsigned long long expevt4;
-
- /* The next few lines implement a way of hashing EXPEVT into a small array index
- which can be used to lookup parameters specific to the type of TLBMISS being
- handled. Note:
- ITLBMISS has EXPEVT==0xa40
- RTLBMISS has EXPEVT==0x040
- WTLBMISS has EXPEVT==0x060
- */
-
- expevt4 = (expevt >> 4);
- /* TODO : xor ssr_md into this expression too. Then we can check that PRU is set
- when it needs to be. */
- index = expevt4 ^ (expevt4 >> 5);
- index &= 7;
- protection_flags = expevt_lookup_table.protection_flags[index];
- textaccess = expevt_lookup_table.is_text_access[index];
-
-#ifdef CONFIG_SH64_PROC_TLB
- ++calls_to_do_fast_page_fault;
-#endif
-
- /* SIM
- * Note this is now called with interrupts still disabled
- * This is to cope with being called for a missing IO port
- * address with interrupts disabled. This should be fixed as
- * soon as we have a better 'fast path' miss handler.
- *
- * Plus take care how you try and debug this stuff.
- * For example, writing debug data to a port which you
- * have just faulted on is not going to work.
- */
-
- tsk = current;
- mm = tsk->mm;
-
- if ((address >= VMALLOC_START && address < VMALLOC_END) ||
- (address >= IOBASE_VADDR && address < IOBASE_END)) {
- if (ssr_md) {
- /* Process-contexts can never have this address range mapped */
- if (handle_vmalloc_fault(mm, protection_flags, textaccess, address)) {
- return 1;
- }
- }
- } else if (!in_interrupt() && mm) {
- if (handle_tlbmiss(mm, protection_flags, textaccess, address)) {
- return 1;
- }
- }
-
- return 0;
-}
-
git.openpandora.org / pandora-kernel.git / blobdiff