Subversion Repositories HelenOS

/** Write directly into a page, bypassing area flags.

 *

 * This allows a debugger to write into a page that is mapped read-only

 * (such as the text segment). Naturally, this is only possible if the

 * correspoinding area is not shared and anonymous.

 *

 * FIXME: doesn't take into account that it isn't a good idea to write

 * into the frame if the area is shared or isn't anonymous

 */

static int debug_write_inside_page(uintptr_t va, void *data, size_t n)

{

    uintptr_t page;

    pte_t *pte;

    as_area_t *area;

    uintptr_t frame;

    ipl_t ipl;

    int rc;

    page = ALIGN_DOWN(va, PAGE_SIZE);

    ASSERT(ALIGN_DOWN(va + n - 1, PAGE_SIZE) == page);

restart:

    mutex_lock(&AS->lock);

    ipl = interrupts_disable();

    area = find_area_and_lock(AS, page);

    pte = page_mapping_find(AS, page);

    if (! (pte && PTE_VALID(pte) && PTE_PRESENT(pte)) ) {

        mutex_unlock(&area->lock);

        mutex_unlock(&AS->lock);

        interrupts_restore(ipl);

        rc = as_page_fault(page, PF_ACCESS_WRITE, NULL);

        if (rc == AS_PF_FAULT) return EINVAL;

        goto restart;

    }

    frame = PTE_GET_FRAME(pte);

    memcpy((void *)(PA2KA(frame) + (va - page)), data, n);

    mutex_unlock(&area->lock);

    mutex_unlock(&AS->lock);

    interrupts_restore(ipl);

    return EOK;

}

/** Write data bypassing area flags.

 *

 * See debug_write_inside_page().

 */

int as_debug_write(uintptr_t va, void *data, size_t n)

{

    size_t now;

    int rc;

    while (n > 0) {

        now = ALIGN_UP(va, PAGE_SIZE) - va;

        if (now > n) now = n;

        rc = debug_write_inside_page(va, data, now);

        if (rc != EOK) return rc;

        va += now;

        data += now;

        n -= now;

    }

    return EOK;

}