source: mainline/kernel/generic/src/mm/km.c

/*
 * Copyright (c) 2011 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 kernel_generic_mm
 * @{
 */

/**
 * @file
 * @brief Kernel virtual memory setup.
 */

#include <mm/km.h>
#include <arch/mm/km.h>
#include <assert.h>
#include <mm/page.h>
#include <mm/frame.h>
#include <mm/asid.h>
#include <config.h>
#include <typedefs.h>
#include <lib/ra.h>
#include <arch.h>
#include <align.h>
#include <macros.h>
#include <bitops.h>
#include <proc/thread.h>

static ra_arena_t *km_ni_arena;

#define DEFERRED_PAGES_MAX      (PAGE_SIZE / sizeof(uintptr_t))

/** Number of freed pages in the deferred buffer. */
static volatile unsigned deferred_pages;
/** Buffer of deferred freed pages. */
static uintptr_t deferred_page[DEFERRED_PAGES_MAX];

/** Flush the buffer of deferred freed pages.
 *
 * @return              Number of freed pages.
 */
static unsigned km_flush_deferred(void)
{
        unsigned i = 0;
        ipl_t ipl;

        ipl = tlb_shootdown_start(TLB_INVL_ASID, ASID_KERNEL, 0, 0);

        for (i = 0; i < deferred_pages; i++) {
                page_mapping_remove(AS_KERNEL, deferred_page[i]);
                km_page_free(deferred_page[i], PAGE_SIZE);
        }

        tlb_invalidate_asid(ASID_KERNEL);

        as_invalidate_translation_cache(AS_KERNEL, 0, -1);
        tlb_shootdown_finalize(ipl);

        return i;
}

/** Architecture dependent setup of identity-mapped kernel memory. */
void km_identity_init(void)
{
        km_identity_arch_init();
        config.identity_configured = true;
}

/** Architecture dependent setup of non-identity-mapped kernel memory. */
void km_non_identity_init(void)
{
        km_ni_arena = ra_arena_create();
        assert(km_ni_arena != NULL);
        km_non_identity_arch_init();
        config.non_identity_configured = true;
}

bool km_is_non_identity(uintptr_t addr)
{
        return km_is_non_identity_arch(addr);
}

void km_non_identity_span_add(uintptr_t base, size_t size)
{
        bool span_added;

        page_mapping_make_global(base, size);

        span_added = ra_span_add(km_ni_arena, base, size);
        assert(span_added);
        (void) span_added;
}

uintptr_t km_page_alloc(size_t size, size_t align)
{
        uintptr_t base;
        if (ra_alloc(km_ni_arena, size, align, &base))
                return base;
        else
                panic("Kernel ran out of virtual address space.");
}

void km_page_free(uintptr_t page, size_t size)
{
        ra_free(km_ni_arena, page, size);
}

static uintptr_t
km_map_aligned(uintptr_t paddr, size_t size, size_t align, unsigned int flags)
{
        uintptr_t vaddr;
        uintptr_t offs;

        if (align == KM_NATURAL_ALIGNMENT)
                align = ispwr2(size) ? size : (1U << (fnzb(size) + 1));

        assert(ALIGN_DOWN(paddr, FRAME_SIZE) == paddr);
        assert(ALIGN_UP(size, FRAME_SIZE) == size);
        assert(ispwr2(align));

        /* Enforce at least PAGE_SIZE alignment. */
        vaddr = km_page_alloc(size, max(PAGE_SIZE, align));

        page_table_lock(AS_KERNEL, true);
        for (offs = 0; offs < size; offs += PAGE_SIZE) {
                page_mapping_insert(AS_KERNEL, vaddr + offs, paddr + offs,
                    flags);
        }
        page_table_unlock(AS_KERNEL, true);

        return vaddr;
}

static void km_unmap_aligned(uintptr_t vaddr, size_t size)
{
        uintptr_t offs;
        ipl_t ipl;

        assert(ALIGN_DOWN(vaddr, PAGE_SIZE) == vaddr);
        assert(ALIGN_UP(size, PAGE_SIZE) == size);

        page_table_lock(AS_KERNEL, true);

        size_t pages = size >> PAGE_WIDTH;
        ipl = tlb_shootdown_start(TLB_INVL_PAGES, ASID_KERNEL, vaddr, pages);

        for (offs = 0; offs < size; offs += PAGE_SIZE)
                page_mapping_remove(AS_KERNEL, vaddr + offs);

        tlb_invalidate_pages(ASID_KERNEL, vaddr, pages);

        as_invalidate_translation_cache(AS_KERNEL, 0, -1);
        tlb_shootdown_finalize(ipl);
        page_table_unlock(AS_KERNEL, true);

        km_page_free(vaddr, size);
}

/** Map a piece of physical address space into the virtual address space.
 *
 * @param paddr         Physical address to be mapped. May be unaligned.
 * @param size          Size of area starting at paddr to be mapped.
 * @param flags         Protection flags to be used for the mapping.
 *
 * @return New virtual address mapped to paddr.
 */
uintptr_t km_map(uintptr_t paddr, size_t size, size_t align, unsigned int flags)
{
        uintptr_t page;
        size_t offs;

        offs = paddr - ALIGN_DOWN(paddr, FRAME_SIZE);
        page = km_map_aligned(ALIGN_DOWN(paddr, FRAME_SIZE),
            ALIGN_UP(size + offs, FRAME_SIZE), align, flags);

        return page + offs;
}

/** Unmap a piece of virtual address space.
 *
 * @param vaddr         Virtual address to be unmapped. May be unaligned, but
 *                      it must be a value previously returned by km_map().
 * @param size          Size of area starting at vaddr to be unmapped.
 */
void km_unmap(uintptr_t vaddr, size_t size)
{
        size_t offs;

        offs = vaddr - ALIGN_DOWN(vaddr, PAGE_SIZE);
        km_unmap_aligned(ALIGN_DOWN(vaddr, PAGE_SIZE),
            ALIGN_UP(size + offs, PAGE_SIZE));
}

/** Unmap kernel non-identity page.
 *
 * @param[in] page      Non-identity page to be unmapped.
 */
static void km_unmap_deferred(uintptr_t page)
{
        page_table_lock(AS_KERNEL, true);

        if (deferred_pages == DEFERRED_PAGES_MAX) {
                (void) km_flush_deferred();
                deferred_pages = 0;
        }

        deferred_page[deferred_pages++] = page;

        page_table_unlock(AS_KERNEL, true);
}

/** Create a temporary page.
 *
 * The page is mapped read/write to a newly allocated frame of physical memory.
 * The page must be returned back to the system by a call to
 * km_temporary_page_put().
 *
 * @param[inout] framep Pointer to a variable which will receive the physical
 *                      address of the allocated frame.
 * @param[in] flags     Frame allocation flags. FRAME_NONE, FRAME_NO_RESERVE
 *                      and FRAME_ATOMIC bits are allowed.
 * @return              Virtual address of the allocated frame.
 */
uintptr_t km_temporary_page_get(uintptr_t *framep, frame_flags_t flags)
{
        assert(THREAD);
        assert(framep);
        assert(!(flags & ~(FRAME_NO_RESERVE | FRAME_ATOMIC)));

        /*
         * Allocate a frame, preferably from high memory.
         */
        uintptr_t page;
        uintptr_t frame;

        frame = frame_alloc(1, FRAME_HIGHMEM | flags, 0);
        if (frame >= config.identity_size) {
                page = km_map(frame, PAGE_SIZE, PAGE_SIZE,
                    PAGE_READ | PAGE_WRITE | PAGE_CACHEABLE);
        } else {
                page = PA2KA(frame);
        }

        *framep = frame;
        return page;
}

/** Destroy a temporary page.
 *
 * This function destroys a temporary page previously created by
 * km_temporary_page_get(). The page destruction may be immediate or deferred.
 * The frame mapped by the destroyed page is not freed.
 *
 * @param[in] page      Temporary page to be destroyed.
 */
void km_temporary_page_put(uintptr_t page)
{
        assert(THREAD);

        if (km_is_non_identity(page))
                km_unmap_deferred(page);
}

/** @}
 */