page.c

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/*
 * Copyright (C) 2005 Martin Decky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <arch/mm/page.h>
#include <genarch/mm/page_pt.h>
#include <arch/mm/frame.h>
#include <arch/asm.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <mm/as.h>
#include <arch.h>
#include <arch/types.h>
#include <arch/exception.h>
#include <align.h>
#include <config.h>
#include <print.h>
#include <symtab.h>

static phte_t *phte;


static pte_t *find_mapping_and_check(as_t *as, bool lock, __address badvaddr, int access,
                                     istate_t *istate, int *pfrc)
{
        /*
         * Check if the mapping exists in page tables.
         */     
        pte_t *pte = page_mapping_find(as, badvaddr);
        if ((pte) && (pte->p)) {
                /*
                 * Mapping found in page tables.
                 * Immediately succeed.
                 */
                return pte;
        } else {
                int rc;
        
                /*
                 * Mapping not found in page tables.
                 * Resort to higher-level page fault handler.
                 */
                page_table_unlock(as, lock);
                switch (rc = as_page_fault(badvaddr, access, istate)) {
                        case AS_PF_OK:
                                /*
                                 * The higher-level page fault handler succeeded,
                                 * The mapping ought to be in place.
                                 */
                                page_table_lock(as, lock);
                                pte = page_mapping_find(as, badvaddr);
                                ASSERT((pte) && (pte->p));
                                return pte;
                        case AS_PF_DEFER:
                                page_table_lock(as, lock);
                                *pfrc = rc;
                                return NULL;
                        case AS_PF_FAULT:
                                page_table_lock(as, lock);
                                printf("Page fault.\n");
                                *pfrc = rc;
                                return NULL;
                        default:
                                panic("unexpected rc (%d)\n", rc);
                }       
        }
}


static void pht_refill_fail(__address badvaddr, istate_t *istate)
{
        char *symbol = "";
        char *sym2 = "";

        char *s = get_symtab_entry(istate->pc);
        if (s)
                symbol = s;
        s = get_symtab_entry(istate->lr);
        if (s)
                sym2 = s;
        panic("%p: PHT Refill Exception at %p (%s<-%s)\n", badvaddr, istate->pc, symbol, sym2);
}


static void pht_insert(const __address vaddr, const pfn_t pfn)
{
        __u32 page = (vaddr >> 12) & 0xffff;
        __u32 api = (vaddr >> 22) & 0x3f;
        __u32 vsid;
        
        asm volatile (
                "mfsrin %0, %1\n"
                : "=r" (vsid)
                : "r" (vaddr)
        );
        
        /* Primary hash (xor) */
        __u32 h = 0;
        __u32 hash = vsid ^ page;
        __u32 base = (hash & 0x3ff) << 3;
        __u32 i;
        bool found = false;
        
        /* Find unused or colliding
           PTE in PTEG */
        for (i = 0; i < 8; i++) {
                if ((!phte[base + i].v) || ((phte[base + i].vsid == vsid) && (phte[base + i].api == api))) {
                        found = true;
                        break;
                }
        }
        
        if (!found) {
                /* Secondary hash (not) */
                __u32 base2 = (~hash & 0x3ff) << 3;
                
                /* Find unused or colliding
                   PTE in PTEG */
                for (i = 0; i < 8; i++) {
                        if ((!phte[base2 + i].v) || ((phte[base2 + i].vsid == vsid) && (phte[base2 + i].api == api))) {
                                found = true;
                                base = base2;
                                h = 1;
                                break;
                        }
                }
                
                if (!found) {
                        // TODO: A/C precedence groups
                        i = page % 8;
                }
        }
        
        phte[base + i].v = 1;
        phte[base + i].vsid = vsid;
        phte[base + i].h = h;
        phte[base + i].api = api;
        phte[base + i].rpn = pfn;
        phte[base + i].r = 0;
        phte[base + i].c = 0;
        phte[base + i].pp = 2; // FIXME
}


void pht_refill(bool data, istate_t *istate)
{
        __address badvaddr;
        pte_t *pte;
        int pfrc;
        as_t *as;
        bool lock;
        
        if (AS == NULL) {
                as = AS_KERNEL;
                lock = false;
        } else {
                as = AS;
                lock = true;
        }
        
        if (data) {
                asm volatile (
                        "mfdar %0\n"
                        : "=r" (badvaddr)
                );
        } else
                badvaddr = istate->pc;
                
        page_table_lock(as, lock);
        
        pte = find_mapping_and_check(as, lock, badvaddr, PF_ACCESS_READ /* FIXME */, istate, &pfrc);
        if (!pte) {
                switch (pfrc) {
                        case AS_PF_FAULT:
                                goto fail;
                                break;
                        case AS_PF_DEFER:
                                /*
                                 * The page fault came during copy_from_uspace()
                                 * or copy_to_uspace().
                                 */
                                page_table_unlock(as, lock);
                                return;
                        default:
                                panic("Unexpected pfrc (%d)\n", pfrc);
                }
        }
        
        pte->a = 1; /* Record access to PTE */
        pht_insert(badvaddr, pte->pfn);
        
        page_table_unlock(as, lock);
        return;
        
fail:
        page_table_unlock(as, lock);
        pht_refill_fail(badvaddr, istate);
}


void pht_init(void)
{
        memsetb((__address) phte, 1 << PHT_BITS, 0);
}


void page_arch_init(void)
{
        if (config.cpu_active == 1) {
                page_mapping_operations = &pt_mapping_operations;
                
                __address cur;
                int flags;
                
                /* Frames below 128 MB are mapped using BAT,
                   map rest of the physical memory */
                for (cur = 128 << 20; cur < last_frame; cur += FRAME_SIZE) {
                        flags = PAGE_CACHEABLE;
                        if ((PA2KA(cur) >= config.base) && (PA2KA(cur) < config.base + config.kernel_size))
                                flags |= PAGE_GLOBAL;
                        page_mapping_insert(AS_KERNEL, PA2KA(cur), cur, flags);
                }
                
                /* Allocate page hash table */
                phte_t *physical_phte = (phte_t *) PFN2ADDR(frame_alloc(PHT_ORDER, FRAME_KA | FRAME_PANIC));
                phte = (phte_t *) PA2KA((__address) physical_phte);
                
                ASSERT((__address) physical_phte % (1 << PHT_BITS) == 0);
                pht_init();
                
                asm volatile (
                        "mtsdr1 %0\n"
                        :
                        : "r" ((__address) physical_phte)
                );
        }
}


__address hw_map(__address physaddr, size_t size)
{
        if (last_frame + ALIGN_UP(size, PAGE_SIZE) > KA2PA(KERNEL_ADDRESS_SPACE_END_ARCH))
                panic("Unable to map physical memory %p (%d bytes)", physaddr, size)
        
        __address virtaddr = PA2KA(last_frame);
        pfn_t i;
        for (i = 0; i < ADDR2PFN(ALIGN_UP(size, PAGE_SIZE)); i++)
                page_mapping_insert(AS_KERNEL, virtaddr + PFN2ADDR(i), physaddr + PFN2ADDR(i), PAGE_NOT_CACHEABLE);
        
        last_frame = ALIGN_UP(last_frame + size, FRAME_SIZE);
        
        return virtaddr;
}

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