Archipelago » qemu

/*

 *  virtual page mapping and translated block handling

 * 

 *  Copyright (c) 2003 Fabrice Bellard

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <stdlib.h>

#include <stdio.h>

#include <stdarg.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <inttypes.h>

#include <sys/mman.h>

#include "cpu-i386.h"

//#define DEBUG_TB_INVALIDATE

#define DEBUG_FLUSH

/* make various TB consistency checks */

//#define DEBUG_TB_CHECK 

/* threshold to flush the translated code buffer */

#define CODE_GEN_BUFFER_MAX_SIZE (CODE_GEN_BUFFER_SIZE - CODE_GEN_MAX_SIZE)

#define CODE_GEN_MAX_BLOCKS    (CODE_GEN_BUFFER_SIZE / 64)

TranslationBlock tbs[CODE_GEN_MAX_BLOCKS];

TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];

int nb_tbs;

/* any access to the tbs or the page table must use this lock */

spinlock_t tb_lock = SPIN_LOCK_UNLOCKED;

uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];

uint8_t *code_gen_ptr;

/* XXX: pack the flags in the low bits of the pointer ? */

typedef struct PageDesc {

    unsigned long flags;

    TranslationBlock *first_tb;

} PageDesc;

#define L2_BITS 10

#define L1_BITS (32 - L2_BITS - TARGET_PAGE_BITS)

#define L1_SIZE (1 << L1_BITS)

#define L2_SIZE (1 << L2_BITS)

static void tb_invalidate_page(unsigned long address);

unsigned long real_host_page_size;

unsigned long host_page_bits;

unsigned long host_page_size;

unsigned long host_page_mask;

static PageDesc *l1_map[L1_SIZE];

void page_init(void)

{

    /* NOTE: we can always suppose that host_page_size >=

       TARGET_PAGE_SIZE */

    real_host_page_size = getpagesize();

    if (host_page_size == 0)

        host_page_size = real_host_page_size;

    if (host_page_size < TARGET_PAGE_SIZE)

        host_page_size = TARGET_PAGE_SIZE;

    host_page_bits = 0;

    while ((1 << host_page_bits) < host_page_size)

        host_page_bits++;

    host_page_mask = ~(host_page_size - 1);

}

/* dump memory mappings */

void page_dump(FILE *f)

{

    unsigned long start, end;

    int i, j, prot, prot1;

    PageDesc *p;

    fprintf(f, "%-8s %-8s %-8s %s\n",

            "start", "end", "size", "prot");

    start = -1;

    end = -1;

    prot = 0;

    for(i = 0; i <= L1_SIZE; i++) {

        if (i < L1_SIZE)

            p = l1_map[i];

        else

            p = NULL;

        for(j = 0;j < L2_SIZE; j++) {

            if (!p)

                prot1 = 0;

            else

                prot1 = p[j].flags;

            if (prot1 != prot) {

                end = (i << (32 - L1_BITS)) | (j << TARGET_PAGE_BITS);

                if (start != -1) {

                    fprintf(f, "%08lx-%08lx %08lx %c%c%c\n",

                            start, end, end - start, 

                            prot & PAGE_READ ? 'r' : '-',

                            prot & PAGE_WRITE ? 'w' : '-',

                            prot & PAGE_EXEC ? 'x' : '-');

                }

                if (prot1 != 0)

                    start = end;

                else

                    start = -1;

                prot = prot1;

            }

            if (!p)

                break;

        }

    }

}

static inline PageDesc *page_find_alloc(unsigned int index)

{

    PageDesc **lp, *p;

    lp = &l1_map[index >> L2_BITS];

    p = *lp;

    if (!p) {

        /* allocate if not found */

        p = malloc(sizeof(PageDesc) * L2_SIZE);

        memset(p, 0, sizeof(PageDesc) * L2_SIZE);

        *lp = p;

    }

    return p + (index & (L2_SIZE - 1));

}

static inline PageDesc *page_find(unsigned int index)

{

    PageDesc *p;

    p = l1_map[index >> L2_BITS];

    if (!p)

        return 0;

    return p + (index & (L2_SIZE - 1));

}

int page_get_flags(unsigned long address)

{

    PageDesc *p;

    p = page_find(address >> TARGET_PAGE_BITS);

    if (!p)

        return 0;

    return p->flags;

}

/* modify the flags of a page and invalidate the code if

   necessary. The flag PAGE_WRITE_ORG is positionned automatically

   depending on PAGE_WRITE */

void page_set_flags(unsigned long start, unsigned long end, int flags)

{

    PageDesc *p;

    unsigned long addr;

    start = start & TARGET_PAGE_MASK;

    end = TARGET_PAGE_ALIGN(end);

    if (flags & PAGE_WRITE)

        flags |= PAGE_WRITE_ORG;

    spin_lock(&tb_lock);

    for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {

        p = page_find_alloc(addr >> TARGET_PAGE_BITS);

        /* if the write protection is set, then we invalidate the code

           inside */

        if (!(p->flags & PAGE_WRITE) && 

            (flags & PAGE_WRITE) &&

            p->first_tb) {

            tb_invalidate_page(addr);

        }

        p->flags = flags;

    }

    spin_unlock(&tb_lock);

}

void cpu_x86_tblocks_init(void)

{

    if (!code_gen_ptr) {

        code_gen_ptr = code_gen_buffer;

    }

}

/* set to NULL all the 'first_tb' fields in all PageDescs */

static void page_flush_tb(void)

{

    int i, j;

    PageDesc *p;

    for(i = 0; i < L1_SIZE; i++) {

        p = l1_map[i];

        if (p) {

            for(j = 0; j < L2_SIZE; j++)

                p[j].first_tb = NULL;

        }

    }

}

/* flush all the translation blocks */

void tb_flush(void)

{

    int i;

#ifdef DEBUG_FLUSH

    printf("qemu: flush code_size=%d nb_tbs=%d avg_tb_size=%d\n", 

           code_gen_ptr - code_gen_buffer, 

           nb_tbs, 

           (code_gen_ptr - code_gen_buffer) / nb_tbs);

#endif

    nb_tbs = 0;

    for(i = 0;i < CODE_GEN_HASH_SIZE; i++)

        tb_hash[i] = NULL;

    page_flush_tb();

    code_gen_ptr = code_gen_buffer;

    /* XXX: flush processor icache at this point */

}

#ifdef DEBUG_TB_CHECK

static void tb_invalidate_check(unsigned long address)

{

    TranslationBlock *tb;

    int i;

    address &= TARGET_PAGE_MASK;

    for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {

        for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {

            if (!(address + TARGET_PAGE_SIZE <= tb->pc ||

                  address >= tb->pc + tb->size)) {

                printf("ERROR invalidate: address=%08lx PC=%08lx size=%04x\n",

                       address, tb->pc, tb->size);

            }

        }

    }

}

/* verify that all the pages have correct rights for code */

static void tb_page_check(void)

{

    TranslationBlock *tb;

    int i, flags1, flags2;

    for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {

        for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {

            flags1 = page_get_flags(tb->pc);

            flags2 = page_get_flags(tb->pc + tb->size - 1);

            if ((flags1 & PAGE_WRITE) || (flags2 & PAGE_WRITE)) {

                printf("ERROR page flags: PC=%08lx size=%04x f1=%x f2=%x\n",

                       tb->pc, tb->size, flags1, flags2);

            }

        }

    }

}

#endif

/* invalidate one TB */

static inline void tb_remove(TranslationBlock **ptb, TranslationBlock *tb,

                             int next_offset)

{

    TranslationBlock *tb1;

    for(;;) {

        tb1 = *ptb;

        if (tb1 == tb) {

            *ptb = *(TranslationBlock **)((char *)tb1 + next_offset);

            break;

        }

        ptb = (TranslationBlock **)((char *)tb1 + next_offset);

    }

}

static inline void tb_invalidate(TranslationBlock *tb, int parity)

{

    PageDesc *p;

    unsigned int page_index1, page_index2;

    unsigned int h;

    /* remove the TB from the hash list */

    h = tb_hash_func(tb->pc);

    tb_remove(&tb_hash[h], tb, 

              offsetof(TranslationBlock, hash_next));

    /* remove the TB from the page list */

    page_index1 = tb->pc >> TARGET_PAGE_BITS;

    if ((page_index1 & 1) == parity) {

        p = page_find(page_index1);

        tb_remove(&p->first_tb, tb, 

                  offsetof(TranslationBlock, page_next[page_index1 & 1]));

    }

    page_index2 = (tb->pc + tb->size - 1) >> TARGET_PAGE_BITS;

    if ((page_index2 & 1) == parity) {

        p = page_find(page_index2);

        tb_remove(&p->first_tb, tb, 

                  offsetof(TranslationBlock, page_next[page_index2 & 1]));

    }

}

/* invalidate all TBs which intersect with the target page starting at addr */

static void tb_invalidate_page(unsigned long address)

{

    TranslationBlock *tb_next, *tb;

    unsigned int page_index;

    int parity1, parity2;

    PageDesc *p;

#ifdef DEBUG_TB_INVALIDATE

    printf("tb_invalidate_page: %lx\n", address);

#endif

    page_index = address >> TARGET_PAGE_BITS;

    p = page_find(page_index);

    if (!p)

        return;

    tb = p->first_tb;

    parity1 = page_index & 1;

    parity2 = parity1 ^ 1;

    while (tb != NULL) {

        tb_next = tb->page_next[parity1];

        tb_invalidate(tb, parity2);

        tb = tb_next;

    }

    p->first_tb = NULL;

}

/* add the tb in the target page and protect it if necessary */

static inline void tb_alloc_page(TranslationBlock *tb, unsigned int page_index)

{

    PageDesc *p;

    unsigned long host_start, host_end, addr, page_addr;

    int prot;

    p = page_find_alloc(page_index);

    tb->page_next[page_index & 1] = p->first_tb;

    p->first_tb = tb;

    if (p->flags & PAGE_WRITE) {

        /* force the host page as non writable (writes will have a

           page fault + mprotect overhead) */

        page_addr = (page_index << TARGET_PAGE_BITS);

        host_start = page_addr & host_page_mask;

        host_end = host_start + host_page_size;

        prot = 0;

        for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)

            prot |= page_get_flags(addr);

        mprotect((void *)host_start, host_page_size, 

                 (prot & PAGE_BITS) & ~PAGE_WRITE);

#ifdef DEBUG_TB_INVALIDATE

        printf("protecting code page: 0x%08lx\n", 

               host_start);

#endif

        p->flags &= ~PAGE_WRITE;

#ifdef DEBUG_TB_CHECK

        tb_page_check();

#endif

    }

}

/* Allocate a new translation block. Flush the translation buffer if

   too many translation blocks or too much generated code. */

TranslationBlock *tb_alloc(unsigned long pc, 

                           unsigned long size)

{

    TranslationBlock *tb;

    unsigned int page_index1, page_index2;

    if (nb_tbs >= CODE_GEN_MAX_BLOCKS || 

        (code_gen_ptr - code_gen_buffer) >= CODE_GEN_BUFFER_MAX_SIZE)

        tb_flush();

    tb = &tbs[nb_tbs++];

    tb->pc = pc;

    tb->size = size;

    /* add in the page list */

    page_index1 = pc >> TARGET_PAGE_BITS;

    tb_alloc_page(tb, page_index1);

    page_index2 = (pc + size - 1) >> TARGET_PAGE_BITS;

    if (page_index2 != page_index1) {

        tb_alloc_page(tb, page_index2);

    }

    return tb;

}

/* called from signal handler: invalidate the code and unprotect the

   page. Return TRUE if the fault was succesfully handled. */

int page_unprotect(unsigned long address)

{

    unsigned int page_index, prot;

    PageDesc *p;

    unsigned long host_start, host_end, addr;

    page_index = address >> TARGET_PAGE_BITS;

    p = page_find(page_index);

    if (!p)

        return 0;

    if ((p->flags & (PAGE_WRITE_ORG | PAGE_WRITE)) == PAGE_WRITE_ORG) {

        /* if the page was really writable, then we change its

           protection back to writable */

        host_start = address & host_page_mask;

        host_end = host_start + host_page_size;

        prot = 0;

        for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)

            prot |= page_get_flags(addr);

        mprotect((void *)host_start, host_page_size, 

                 (prot & PAGE_BITS) | PAGE_WRITE);

        p->flags |= PAGE_WRITE;

        /* and since the content will be modified, we must invalidate

           the corresponding translated code. */

        tb_invalidate_page(address);

#ifdef DEBUG_TB_CHECK

        tb_invalidate_check(address);

#endif

        return 1;

    } else {

        return 0;

    }

}

/* call this function when system calls directly modify a memory area */

void page_unprotect_range(uint8_t *data, unsigned long data_size)

{

    unsigned long start, end, addr;

    start = (unsigned long)data;

    end = start + data_size;

    start &= TARGET_PAGE_MASK;

    end = TARGET_PAGE_ALIGN(end);

    for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {

        page_unprotect(addr);

    }

}