vfs: check userland buffers before reading them.

[haiku.git] / src / system / boot / arch / m68k / mmu.cpp

/*
 * Copyright 2004-2007, Axel Dörfler, axeld@pinc-software.de.
 * Based on code written by Travis Geiselbrecht for NewOS.
 *
 * Distributed under the terms of the MIT License.
 */


#include "atari_memory_map.h"
#include "toscalls.h"
#include "mmu.h"

#include <boot/platform.h>
#include <boot/stdio.h>
#include <boot/kernel_args.h>
#include <boot/stage2.h>
#include <arch/cpu.h>
#include <arch_kernel.h>
#include <kernel.h>

#include <OS.h>

#include <string.h>


//XXX: x86
/** The (physical) memory layout of the boot loader is currently as follows:
 *        0x0500 - 0x10000      protected mode stack
 *        0x0500 - 0x09000      real mode stack
 *       0x10000 - ?            code (up to ~500 kB)
 *       0x90000                        1st temporary page table (identity maps 0-4 MB)
 *       0x91000                        2nd (4-8 MB)
 *       0x92000 - 0x92000      further page tables
 *       0x9e000 - 0xa0000      SMP trampoline code
 *      [0xa0000 - 0x100000     BIOS/ROM/reserved area]
 *      0x100000                        page directory
 *           ...                        boot loader heap (32 kB)
 *           ...                        free physical memory
 *
 *      The first 8 MB are identity mapped (0x0 - 0x0800000); paging is turned
 *      on. The kernel is mapped at 0x80000000, all other stuff mapped by the
 *      loader (kernel args, modules, driver settings, ...) comes after
 *      0x81000000 which means that there is currently only 1 MB reserved for
 *      the kernel itself (see kMaxKernelSize).
 */

// notes m68k:
/** The (physical) memory layout of the boot loader is currently as follows:
 *        0x0800 - 0x10000      supervisor mode stack (1) XXX: more ? x86 starts at 500
 *       0x10000 - ?            code (up to ~500 kB)
 *  0x100000 or FAST_RAM_BASE if any:
 *           ...                        page root directory
 *           ...                        interrupt vectors (VBR)
 *           ...                        page directory
 *           ...                        boot loader heap (32 kB)
 *           ...                        free physical memory
 *  0xdNNNNN                    video buffer usually there, as per v_bas_ad
 *                                              (=Logbase() but Physbase() is better)
 *
 *      The first 32 MB (2) are identity mapped (0x0 - 0x1000000); paging
 *      is turned on. The kernel is mapped at 0x80000000, all other stuff
 *      mapped by the loader (kernel args, modules, driver settings, ...)
 *      comes after 0x81000000 which means that there is currently only
 *      1 MB reserved for the kernel itself (see kMaxKernelSize).
 *
 *      (1) no need for user stack, we are already in supervisor mode in the
 *      loader.
 *      (2) maps the whole regular ST space; transparent translation registers
 *      have larger granularity anyway.
 */
#warning M68K: check for Physbase() < ST_RAM_TOP

#define TRACE_MMU
#ifdef TRACE_MMU
#       define TRACE(x) dprintf x
#else
#       define TRACE(x) ;
#endif


// since the page root directory doesn't take a full page (1k)
// we stuff some other stuff after it, like the interrupt vectors (1k)
#define VBR_PAGE_OFFSET 1024

static const uint32 kDefaultPageTableFlags = 0x07;      // present, user, R/W
static const size_t kMaxKernelSize = 0x100000;          // 1 MB for the kernel

// working page directory and page table
addr_t gPageRoot = 0;

static addr_t sNextPhysicalAddress = 0x100000;
static addr_t sNextVirtualAddress = KERNEL_LOAD_BASE + kMaxKernelSize;
static addr_t sMaxVirtualAddress = KERNEL_LOAD_BASE /*+ 0x400000*/;

#if 0
static addr_t sNextPageTableAddress = 0x90000;
static const uint32 kPageTableRegionEnd = 0x9e000;
        // we need to reserve 2 pages for the SMP trampoline code XXX:no
#endif

static const struct boot_mmu_ops *gMMUOps;

static addr_t
get_next_virtual_address(size_t size)
{
        addr_t address = sNextVirtualAddress;
        sNextVirtualAddress += size;

        TRACE(("%s(%d): %08x\n", __FUNCTION__, size, address));
        return address;
}


static addr_t
get_next_physical_address(size_t size)
{
        addr_t address = sNextPhysicalAddress;
        sNextPhysicalAddress += size;

        TRACE(("%s(%d): %08x\n", __FUNCTION__, size, address));
        return address;
}


static addr_t
get_next_virtual_page()
{
        TRACE(("%s\n", __FUNCTION__));
        return get_next_virtual_address(B_PAGE_SIZE);
}


static addr_t
get_next_physical_page()
{
        TRACE(("%s\n", __FUNCTION__));
        return get_next_physical_address(B_PAGE_SIZE);
}


// allocate a page worth of page dir or tables
extern "C" addr_t
mmu_get_next_page_tables()
{
#if 0
        TRACE(("mmu_get_next_page_tables, sNextPageTableAddress %p, kPageTableRegionEnd %p\n",
                sNextPageTableAddress, kPageTableRegionEnd));

        addr_t address = sNextPageTableAddress;
        if (address >= kPageTableRegionEnd)
                return (uint32 *)get_next_physical_page();

        sNextPageTableAddress += B_PAGE_SIZE;
        return (uint32 *)address;
#endif
        addr_t tbl = get_next_physical_page();
        if (!tbl)
                return tbl;
        // shouldn't we fill this ?
        //gKernelArgs.arch_args.pgtables[gKernelArgs.arch_args.num_pgtables++] = (uint32)pageTable;

#if 0
        // clear them
        uint32 *p = (uint32 *)tbl;
        for (int32 i = 0; i < 1024; i++)
                p[i] = 0;
#endif
        return tbl;
}

#if 0
/**     Adds a new page table for the specified base address */

static void
add_page_table(addr_t base)
{
        TRACE(("add_page_table(base = %p)\n", (void *)base));
#if 0

        // Get new page table and clear it out
        uint32 *pageTable = mmu_get_next_page_tables();
        if (pageTable > (uint32 *)(8 * 1024 * 1024))
                panic("tried to add page table beyond the indentity mapped 8 MB region\n");

        gKernelArgs.arch_args.pgtables[gKernelArgs.arch_args.num_pgtables++] = (uint32)pageTable;

        for (int32 i = 0; i < 1024; i++)
                pageTable[i] = 0;

        // put the new page table into the page directory
        gPageRoot[base/(4*1024*1024)] = (uint32)pageTable | kDefaultPageTableFlags;
#endif
}
#endif


static void
unmap_page(addr_t virtualAddress)
{
        gMMUOps->unmap_page(virtualAddress);
}


/** Creates an entry to map the specified virtualAddress to the given
 *      physicalAddress.
 *      If the mapping goes beyond the current page table, it will allocate
 *      a new one. If it cannot map the requested page, it panics.
 */

static void
map_page(addr_t virtualAddress, addr_t physicalAddress, uint32 flags)
{
        TRACE(("map_page: vaddr 0x%lx, paddr 0x%lx\n", virtualAddress, physicalAddress));

        if (virtualAddress < KERNEL_LOAD_BASE)
                panic("map_page: asked to map invalid page %p!\n", (void *)virtualAddress);

        // slow but I'm too lazy to fix the code below
        gMMUOps->add_page_table(virtualAddress);
#if 0
        if (virtualAddress >= sMaxVirtualAddress) {
                // we need to add a new page table

                gMMUOps->add_page_table(sMaxVirtualAddress);
                // 64 pages / page table
                sMaxVirtualAddress += B_PAGE_SIZE * 64;

                if (virtualAddress >= sMaxVirtualAddress)
                        panic("map_page: asked to map a page to %p\n", (void *)virtualAddress);
        }
#endif

        physicalAddress &= ~(B_PAGE_SIZE - 1);

        // map the page to the correct page table
        gMMUOps->map_page(virtualAddress, physicalAddress, flags);
}


static void
init_page_directory(void)
{
        TRACE(("init_page_directory\n"));

        // allocate a new pg root dir
        gPageRoot = get_next_physical_page();
        gKernelArgs.arch_args.phys_pgroot = (uint32)gPageRoot;
        gKernelArgs.arch_args.phys_vbr = (uint32)gPageRoot + VBR_PAGE_OFFSET;

        // set the root pointers
        gMMUOps->load_rp(gPageRoot);
        // allocate second level tables for kernel space
        // this will simplify mmu code a lot, and only wastes 32KB
        gMMUOps->allocate_kernel_pgdirs();
        // enable mmu translation
        gMMUOps->enable_paging();
        //XXX: check for errors

        //gKernelArgs.arch_args.num_pgtables = 0;
        gMMUOps->add_page_table(KERNEL_LOAD_BASE);

#if 0


        // clear out the pgdir
        for (int32 i = 0; i < 1024; i++) {
                gPageRoot[i] = 0;
        }

        // Identity map the first 8 MB of memory so that their
        // physical and virtual address are the same.
        // These page tables won't be taken over into the kernel.

        // make the first page table at the first free spot
        uint32 *pageTable = mmu_get_next_page_tables();

        for (int32 i = 0; i < 1024; i++) {
                pageTable[i] = (i * 0x1000) | kDefaultPageFlags;
        }

        gPageRoot[0] = (uint32)pageTable | kDefaultPageFlags;

        // make the second page table
        pageTable = mmu_get_next_page_tables();

        for (int32 i = 0; i < 1024; i++) {
                pageTable[i] = (i * 0x1000 + 0x400000) | kDefaultPageFlags;
        }

        gPageRoot[1] = (uint32)pageTable | kDefaultPageFlags;

        gKernelArgs.arch_args.num_pgtables = 0;
        add_page_table(KERNEL_LOAD_BASE);

        // switch to the new pgdir and enable paging
        asm("movl %0, %%eax;"
                "movl %%eax, %%cr3;" : : "m" (gPageRoot) : "eax");
        // Important.  Make sure supervisor threads can fault on read only pages...
        asm("movl %%eax, %%cr0" : : "a" ((1 << 31) | (1 << 16) | (1 << 5) | 1));
#endif
}


//      #pragma mark -


extern "C" addr_t
mmu_map_physical_memory(addr_t physicalAddress, size_t size, uint32 flags)
{
        addr_t address = sNextVirtualAddress;
        addr_t pageOffset = physicalAddress & (B_PAGE_SIZE - 1);

        physicalAddress -= pageOffset;

        for (addr_t offset = 0; offset < size; offset += B_PAGE_SIZE) {
                map_page(get_next_virtual_page(), physicalAddress + offset, flags);
        }

        return address + pageOffset;
}


extern "C" void *
mmu_allocate(void *virtualAddress, size_t size)
{
        TRACE(("mmu_allocate: requested vaddr: %p, next free vaddr: 0x%lx, size: %ld\n",
                virtualAddress, sNextVirtualAddress, size));

        size = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
                // get number of pages to map

        if (virtualAddress != NULL) {
                // This special path is almost only useful for loading the
                // kernel into memory; it will only allow you to map the
                // 1 MB following the kernel base address.
                // Also, it won't check for already mapped addresses, so
                // you better know why you are here :)
                addr_t address = (addr_t)virtualAddress;

                // is the address within the valid range?
                if (address < KERNEL_LOAD_BASE || address + size * B_PAGE_SIZE
                        >= KERNEL_LOAD_BASE + kMaxKernelSize)
                        return NULL;

                for (uint32 i = 0; i < size; i++) {
                        map_page(address, get_next_physical_page(), kDefaultPageFlags);
                        address += B_PAGE_SIZE;
                }

                TRACE(("mmu_allocate(KERNEL, %d): done\n", size));
                return virtualAddress;
        }

        void *address = (void *)sNextVirtualAddress;

        for (uint32 i = 0; i < size; i++) {
                map_page(get_next_virtual_page(), get_next_physical_page(), kDefaultPageFlags);
        }

        TRACE(("mmu_allocate(NULL, %d): %p\n", size, address));
        return address;
}


/**     This will unmap the allocated chunk of memory from the virtual
 *      address space. It might not actually free memory (as its implementation
 *      is very simple), but it might.
 */

extern "C" void
mmu_free(void *virtualAddress, size_t size)
{
        TRACE(("mmu_free(virtualAddress = %p, size: %ld)\n", virtualAddress, size));

        addr_t address = (addr_t)virtualAddress;
        addr_t pageOffset = address % B_PAGE_SIZE;
        address -= pageOffset;
        size = (size + pageOffset + B_PAGE_SIZE - 1) / B_PAGE_SIZE * B_PAGE_SIZE;

        // is the address within the valid range?
        if (address < KERNEL_LOAD_BASE || address + size > sNextVirtualAddress) {
                panic("mmu_free: asked to unmap out of range region (%p, size %lx)\n",
                        (void *)address, size);
        }

        // unmap all pages within the range
        for (size_t i = 0; i < size; i += B_PAGE_SIZE) {
                unmap_page(address);
                address += B_PAGE_SIZE;
        }

        if (address == sNextVirtualAddress) {
                // we can actually reuse the virtual address space
                sNextVirtualAddress -= size;
        }
}


/** Sets up the final and kernel accessible GDT and IDT tables.
 *      BIOS calls won't work any longer after this function has
 *      been called.
 */

extern "C" void
mmu_init_for_kernel(void)
{
        TRACE(("mmu_init_for_kernel\n"));




        // remove identity mapping of ST space
        // actually done by the kernel when it's done using query_early
        //gMMUOps->set_tt(0, NULL, 0, 0);

#if 0
        // set up a new idt
        {
                struct gdt_idt_descr idtDescriptor;
                uint32 *idt;

                // find a new idt
                idt = (uint32 *)get_next_physical_page();
                gKernelArgs.arch_args.phys_idt = (uint32)idt;

                TRACE(("idt at %p\n", idt));

                // map the idt into virtual space
                gKernelArgs.arch_args.vir_idt = (uint32)get_next_virtual_page();
                map_page(gKernelArgs.arch_args.vir_idt, (uint32)idt, kDefaultPageFlags);

                // clear it out
                uint32* virtualIDT = (uint32*)gKernelArgs.arch_args.vir_idt;
                for (int32 i = 0; i < IDT_LIMIT / 4; i++) {
                        virtualIDT[i] = 0;
                }

                // load the idt
                idtDescriptor.limit = IDT_LIMIT - 1;
                idtDescriptor.base = (uint32 *)gKernelArgs.arch_args.vir_idt;

                asm("lidt       %0;"
                        : : "m" (idtDescriptor));

                TRACE(("idt at virtual address 0x%lx\n", gKernelArgs.arch_args.vir_idt));
        }

        // set up a new gdt
        {
                struct gdt_idt_descr gdtDescriptor;
                segment_descriptor *gdt;

                // find a new gdt
                gdt = (segment_descriptor *)get_next_physical_page();
                gKernelArgs.arch_args.phys_gdt = (uint32)gdt;

                TRACE(("gdt at %p\n", gdt));

                // map the gdt into virtual space
                gKernelArgs.arch_args.vir_gdt = (uint32)get_next_virtual_page();
                map_page(gKernelArgs.arch_args.vir_gdt, (uint32)gdt, kDefaultPageFlags);

                // put standard segment descriptors in it
                segment_descriptor* virtualGDT
                        = (segment_descriptor*)gKernelArgs.arch_args.vir_gdt;
                clear_segment_descriptor(&virtualGDT[0]);

                // seg 0x08 - kernel 4GB code
                set_segment_descriptor(&virtualGDT[1], 0, 0xffffffff, DT_CODE_READABLE,
                        DPL_KERNEL);

                // seg 0x10 - kernel 4GB data
                set_segment_descriptor(&virtualGDT[2], 0, 0xffffffff, DT_DATA_WRITEABLE,
                        DPL_KERNEL);

                // seg 0x1b - ring 3 user 4GB code
                set_segment_descriptor(&virtualGDT[3], 0, 0xffffffff, DT_CODE_READABLE,
                        DPL_USER);

                // seg 0x23 - ring 3 user 4GB data
                set_segment_descriptor(&virtualGDT[4], 0, 0xffffffff, DT_DATA_WRITEABLE,
                        DPL_USER);

                // virtualGDT[5] and above will be filled later by the kernel
                // to contain the TSS descriptors, and for TLS (one for every CPU)

                // load the GDT
                gdtDescriptor.limit = GDT_LIMIT - 1;
                gdtDescriptor.base = (uint32 *)gKernelArgs.arch_args.vir_gdt;

                asm("lgdt       %0;"
                        : : "m" (gdtDescriptor));

                TRACE(("gdt at virtual address %p\n", (void *)gKernelArgs.arch_args.vir_gdt));
        }
#endif

        // save the memory we've physically allocated
        gKernelArgs.physical_allocated_range[0].size = sNextPhysicalAddress - gKernelArgs.physical_allocated_range[0].start;

        // save the memory we've virtually allocated (for the kernel and other stuff)
        gKernelArgs.virtual_allocated_range[0].start = KERNEL_LOAD_BASE;
        gKernelArgs.virtual_allocated_range[0].size = sNextVirtualAddress - KERNEL_LOAD_BASE;
        gKernelArgs.num_virtual_allocated_ranges = 1;

        // sort the address ranges
        sort_address_ranges(gKernelArgs.physical_memory_range,
                gKernelArgs.num_physical_memory_ranges);
        sort_address_ranges(gKernelArgs.physical_allocated_range,
                gKernelArgs.num_physical_allocated_ranges);
        sort_address_ranges(gKernelArgs.virtual_allocated_range,
                gKernelArgs.num_virtual_allocated_ranges);

#ifdef TRACE_MMU
        {
                uint32 i;

                dprintf("phys memory ranges:\n");
                for (i = 0; i < gKernelArgs.num_physical_memory_ranges; i++) {
                        dprintf("    base 0x%08" B_PRIx64 ", length 0x%08" B_PRIx64 "\n",
                                gKernelArgs.physical_memory_range[i].start,
                                gKernelArgs.physical_memory_range[i].size);
                }

                dprintf("allocated phys memory ranges:\n");
                for (i = 0; i < gKernelArgs.num_physical_allocated_ranges; i++) {
                        dprintf("    base 0x%08" B_PRIx64 ", length 0x%08" B_PRIx64 "\n",
                                gKernelArgs.physical_allocated_range[i].start,
                                gKernelArgs.physical_allocated_range[i].size);
                }

                dprintf("allocated virt memory ranges:\n");
                for (i = 0; i < gKernelArgs.num_virtual_allocated_ranges; i++) {
                        dprintf("    base 0x%08" B_PRIx64 ", length 0x%08" B_PRIx64 "\n",
                                gKernelArgs.virtual_allocated_range[i].start,
                                gKernelArgs.virtual_allocated_range[i].size);
                }
        }
#endif
}


extern "C" void
mmu_init(void)
{
        TRACE(("mmu_init\n"));
        switch (gKernelArgs.arch_args.mmu_type) {
#if 0
                case 68851:
                        gMMUOps = &k851MMUOps;
                        break;
#endif
                case 68030:
                        gMMUOps = &k030MMUOps;
                        break;
                case 68040:
                        gMMUOps = &k040MMUOps;
                        break;
#if 0
                case 68060:
                        gMMUOps = &k060MMUOps;
                        break;
#endif
                default:
                        panic("unknown mmu type %d\n", gKernelArgs.arch_args.mmu_type);
        }

        gMMUOps->initialize();

        addr_t fastram_top = 0;
        if (*TOSVARramvalid == TOSVARramvalid_MAGIC)
                fastram_top = *TOSVARramtop;
        if (fastram_top) {
                // we have some fastram, use it first
                sNextPhysicalAddress = ATARI_FASTRAM_BASE;
        }

        gKernelArgs.physical_allocated_range[0].start = sNextPhysicalAddress;
        gKernelArgs.physical_allocated_range[0].size = 0;
        gKernelArgs.num_physical_allocated_ranges = 1;
                // remember the start of the allocated physical pages

        // enable transparent translation of the first 256 MB
        gMMUOps->set_tt(0, ATARI_CHIPRAM_BASE, 0x10000000, 0);
        // enable transparent translation of the 16MB ST shadow range for I/O
        gMMUOps->set_tt(1, ATARI_SHADOW_BASE, 0x01000000, 0);

        init_page_directory();
#if 0//XXX:HOLE

        // Map the page directory into kernel space at 0xffc00000-0xffffffff
        // this enables a mmu trick where the 4 MB region that this pgdir entry
        // represents now maps the 4MB of potential pagetables that the pgdir
        // points to. Thrown away later in VM bringup, but useful for now.
        gPageRoot[1023] = (uint32)gPageRoot | kDefaultPageFlags;
#endif

        // also map it on the next vpage
        gKernelArgs.arch_args.vir_pgroot = get_next_virtual_page();
        map_page(gKernelArgs.arch_args.vir_pgroot, (uint32)gPageRoot, kDefaultPageFlags);

        // set virtual addr for interrupt vector table
        gKernelArgs.arch_args.vir_vbr = gKernelArgs.arch_args.vir_pgroot
                + VBR_PAGE_OFFSET;

        // map in a kernel stack
        gKernelArgs.cpu_kstack[0].start = (addr_t)mmu_allocate(NULL,
                KERNEL_STACK_SIZE + KERNEL_STACK_GUARD_PAGES * B_PAGE_SIZE);
        gKernelArgs.cpu_kstack[0].size = KERNEL_STACK_SIZE
                + KERNEL_STACK_GUARD_PAGES * B_PAGE_SIZE;

        TRACE(("kernel stack at 0x%lx to 0x%lx\n", gKernelArgs.cpu_kstack[0].start,
                gKernelArgs.cpu_kstack[0].start + gKernelArgs.cpu_kstack[0].size));

        // st ram as 1st range
        gKernelArgs.physical_memory_range[0].start = ATARI_CHIPRAM_BASE;
        gKernelArgs.physical_memory_range[0].size = *TOSVARphystop - ATARI_CHIPRAM_BASE;
        gKernelArgs.num_physical_memory_ranges = 1;

        // fast ram as 2nd range
        if (fastram_top) {
                gKernelArgs.physical_memory_range[1].start =
                        ATARI_FASTRAM_BASE;
                gKernelArgs.physical_memory_range[1].size =
                        fastram_top - ATARI_FASTRAM_BASE;
                gKernelArgs.num_physical_memory_ranges++;

        }

        // mark the video area allocated
        addr_t video_base = *TOSVAR_memtop;
        video_base &= ~(B_PAGE_SIZE-1);
        gKernelArgs.physical_allocated_range[gKernelArgs.num_physical_allocated_ranges].start = video_base;
        gKernelArgs.physical_allocated_range[gKernelArgs.num_physical_allocated_ranges].size = *TOSVARphystop - video_base;
        gKernelArgs.num_physical_allocated_ranges++;


        gKernelArgs.arch_args.plat_args.atari.nat_feat.nf_page =
                get_next_physical_page() /*| 0xff000000*/;

}


//      #pragma mark -


extern "C" status_t
platform_allocate_region(void **_address, size_t size, uint8 protection,
        bool /*exactAddress*/)
{
        void *address = mmu_allocate(*_address, size);
        if (address == NULL)
                return B_NO_MEMORY;

        *_address = address;
        return B_OK;
}


extern "C" status_t
platform_free_region(void *address, size_t size)
{
        mmu_free(address, size);
        return B_OK;
}


void
platform_release_heap(struct stage2_args *args, void *base)
{
        // It will be freed automatically, since it is in the
        // identity mapped region, and not stored in the kernel's
        // page tables.
}


status_t
platform_init_heap(struct stage2_args *args, void **_base, void **_top)
{
        void *heap = (void *)get_next_physical_address(args->heap_size);
        if (heap == NULL)
                return B_NO_MEMORY;

        *_base = heap;
        *_top = (void *)((int8 *)heap + args->heap_size);
        return B_OK;
}