WebSVN – HelenOS – Diff – /branches/tracing/kernel/generic/src/mm/backend_elf.c


/*
 * Copyright (c) 2006 Jakub Jermar
 * 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.
 */
 
/** @addtogroup genericmm
 * @{
 */
 
/**
 * @file
 * @brief   Backend for address space areas backed by an ELF image.
 */
 
#include <lib/elf.h>
#include <debug.h>
#include <arch/types.h>
#include <mm/as.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <mm/page.h>
#include <genarch/mm/page_pt.h>
#include <genarch/mm/page_ht.h>
#include <align.h>
#include <memstr.h>
#include <macros.h>
#include <arch.h>
#include <arch/barrier.h>
 
#ifdef CONFIG_VIRT_IDX_DCACHE
#include <arch/mm/cache.h>
#endif
 
static int elf_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access);
static void elf_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame);
static void elf_share(as_area_t *area);
 
mem_backend_t elf_backend = {
    .page_fault = elf_page_fault,
    .frame_free = elf_frame_free,
    .share = elf_share
};
 
/** Service a page fault in the ELF backend address space area.
 *
 * The address space area and page tables must be already locked.
 *
 * @param area      Pointer to the address space area.
 * @param addr      Faulting virtual address.
 * @param access    Access mode that caused the fault (i.e.
 *          read/write/exec).
 *
 * @return      AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK
 *          on success (i.e. serviced).
 */
int elf_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access)
{
    elf_header_t *elf = area->backend_data.elf;
    elf_segment_header_t *entry = area->backend_data.segment;
    btree_node_t *leaf;
    uintptr_t base, frame, page, start_anon;
    size_t i;
    bool dirty = false;
 
    if (!as_area_check_access(area, access))
        return AS_PF_FAULT;
 
    ASSERT((addr >= ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) &&
        (addr < entry->p_vaddr + entry->p_memsz));
    i = (addr - ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) >> PAGE_WIDTH;
    base = (uintptr_t)
        (((void *) elf) + ALIGN_DOWN(entry->p_offset, PAGE_SIZE));
 
    /* Virtual address of faulting page*/
    page = ALIGN_DOWN(addr, PAGE_SIZE);
 
    /* Virtual address of the end of initialized part of segment */
    start_anon = entry->p_vaddr + entry->p_filesz;
 
    if (area->sh_info) {
        bool found = false;
 
        /*
         * The address space area is shared.
         */
       
        mutex_lock(&area->sh_info->lock);
        frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
            page - area->base, &leaf);
        if (!frame) {
            unsigned int i;
 
            /*
             * Workaround for valid NULL address.
             */
 
            for (i = 0; i < leaf->keys; i++) {
                if (leaf->key[i] == page - area->base) {
                    found = true;
                    break;
                }
            }
        }
        if (frame || found) {
            frame_reference_add(ADDR2PFN(frame));
            page_mapping_insert(AS, addr, frame,
                as_area_get_flags(area));
            if (!used_space_insert(area, page, 1))
                panic("Cannot insert used space.");
            mutex_unlock(&area->sh_info->lock);
            return AS_PF_OK;
        }
    }
 
    /*
     * The area is either not shared or the pagemap does not contain the
     * mapping.
     */
    if (page >= entry->p_vaddr && page + PAGE_SIZE <= start_anon) {
        /*
         * Initialized portion of the segment. The memory is backed
         * directly by the content of the ELF image. Pages are
         * only copied if the segment is writable so that there
         * can be more instantions of the same memory ELF image
         * used at a time. Note that this could be later done
         * as COW.
         */
        if (entry->p_flags & PF_W) {
            frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
            memcpy((void *) PA2KA(frame),
                (void *) (base + i * FRAME_SIZE), FRAME_SIZE);
            if (entry->p_flags & PF_X) {
                smc_coherence_block((void *) PA2KA(frame),
                    FRAME_SIZE);
            }
            dirty = true;
        } else {
            frame = KA2PA(base + i * FRAME_SIZE);
        }  
    } else if (page >= start_anon) {
        /*
         * This is the uninitialized portion of the segment.
         * It is not physically present in the ELF image.
         * To resolve the situation, a frame must be allocated
         * and cleared.
         */
        frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
        memsetb((void *) PA2KA(frame), FRAME_SIZE, 0);
        dirty = true;
    } else {
        size_t pad_lo, pad_hi;
        /*
         * The mixed case.
         *
         * The middle part is backed by the ELF image and
         * the lower and upper parts are anonymous memory.
         * (The segment can be and often is shorter than 1 page).
         */
        if (page < entry->p_vaddr)
            pad_lo = entry->p_vaddr - page;
        else
            pad_lo = 0;
 
        if (start_anon < page + PAGE_SIZE)
            pad_hi = page + PAGE_SIZE - start_anon;
        else
            pad_hi = 0;
 
        frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
        memcpy((void *) (PA2KA(frame) + pad_lo),
            (void *) (base + i * FRAME_SIZE + pad_lo),
            FRAME_SIZE - pad_lo - pad_hi);
        if (entry->p_flags & PF_X) {
            smc_coherence_block((void *) (PA2KA(frame) + pad_lo),
                FRAME_SIZE - pad_lo - pad_hi);
        }
        memsetb((void *) PA2KA(frame), pad_lo, 0);
        memsetb((void *) (PA2KA(frame) + FRAME_SIZE - pad_hi), pad_hi,
            0);
        dirty = true;
    }
 
    if (dirty && area->sh_info) {
        frame_reference_add(ADDR2PFN(frame));
        btree_insert(&area->sh_info->pagemap, page - area->base,
            (void *) frame, leaf);
    }
 
    if (area->sh_info)
        mutex_unlock(&area->sh_info->lock);
 
    page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
    if (!used_space_insert(area, page, 1))
        panic("Cannot insert used space.");
 
    return AS_PF_OK;
}
 
/** Free a frame that is backed by the ELF backend.
 *
 * The address space area and page tables must be already locked.
 *
 * @param area      Pointer to the address space area.
 * @param page      Page that is mapped to frame. Must be aligned to
 *          PAGE_SIZE.
 * @param frame     Frame to be released.
 *
 */
void elf_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
{
    elf_header_t *elf = area->backend_data.elf;
    elf_segment_header_t *entry = area->backend_data.segment;
    uintptr_t base, start_anon;
    size_t i;
 
    ASSERT((page >= ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) &&
        (page < entry->p_vaddr + entry->p_memsz));
    i = (page - ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) >> PAGE_WIDTH;
    base = (uintptr_t) (((void *) elf) +
        ALIGN_DOWN(entry->p_offset, FRAME_SIZE));
    start_anon = entry->p_vaddr + entry->p_filesz;
 
    if (page >= entry->p_vaddr && page + PAGE_SIZE <= start_anon) {
        if (entry->p_flags & PF_W) {
            /*
             * Free the frame with the copy of writable segment
             * data.
             */
            frame_free(frame);
        }
    } else {
        /*
         * The frame is either anonymous memory or the mixed case (i.e.
         * lower part is backed by the ELF image and the upper is
         * anonymous). In any case, a frame needs to be freed.
         */
        frame_free(frame);
    }
}
 
/** Share ELF image backed address space area.
 *
 * If the area is writable, then all mapped pages are duplicated in the pagemap.
 * Otherwise only portions of the area that are not backed by the ELF image
 * are put into the pagemap.
 *
 * The address space and address space area must be locked prior to the call.
 *
 * @param area      Address space area.
 */
void elf_share(as_area_t *area)
{
    elf_segment_header_t *entry = area->backend_data.segment;
    link_t *cur;
    btree_node_t *leaf, *node;
    uintptr_t start_anon = entry->p_vaddr + entry->p_filesz;
 
    /*
     * Find the node in which to start linear search.
     */
    if (area->flags & AS_AREA_WRITE) {
        node = list_get_instance(area->used_space.leaf_head.next,
            btree_node_t, leaf_link);
    } else {
        (void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
        node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap,
            leaf);
        if (!node)
            node = leaf;
    }
 
    /*
     * Copy used anonymous portions of the area to sh_info's page map.
     */
    mutex_lock(&area->sh_info->lock);
    for (cur = &node->leaf_link; cur != &area->used_space.leaf_head;
        cur = cur->next) {
        unsigned int i;
       
        node = list_get_instance(cur, btree_node_t, leaf_link);
       
        for (i = 0; i < node->keys; i++) {
            uintptr_t base = node->key[i];
            size_t count = (size_t) node->value[i];
            unsigned int j;
           
            /*
             * Skip read-only areas of used space that are backed
             * by the ELF image.
             */
            if (!(area->flags & AS_AREA_WRITE))
                if (base >= entry->p_vaddr &&
                    base + count * PAGE_SIZE <= start_anon)
                    continue;
           
            for (j = 0; j < count; j++) {
                pte_t *pte;
           
                /*
                 * Skip read-only pages that are backed by the
                 * ELF image.
                 */
                if (!(area->flags & AS_AREA_WRITE))
                    if (base >= entry->p_vaddr &&
                        base + (j + 1) * PAGE_SIZE <=
                        start_anon)
                        continue;
               
                page_table_lock(area->as, false);
                pte = page_mapping_find(area->as,
                    base + j * PAGE_SIZE);
                ASSERT(pte && PTE_VALID(pte) &&
                    PTE_PRESENT(pte));
                btree_insert(&area->sh_info->pagemap,
                    (base + j * PAGE_SIZE) - area->base,
                    (void *) PTE_GET_FRAME(pte), NULL);
                page_table_unlock(area->as, false);
 
                pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
                frame_reference_add(pfn);
            }
               
        }
    }
    mutex_unlock(&area->sh_info->lock);
}
 
/** @}
 */
 
Subversion Repositories HelenOS

(root)/branches/tracing/kernel/generic/src/mm/backend_elf.c – Rev 4377 → 4692
