mmap emulation

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@158 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 370 insertions, 0 deletions

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
new file mode 100644
index 0000000000..4c4d9100d8
--- /dev/null
+++ b/linux-user/mmap.c
@@ -0,0 +1,370 @@
+/*
+ *  mmap support for qemu
+ * 
+ *  Copyright (c) 2003 Fabrice Bellard
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/mman.h>
+
+#include "qemu.h"
+
+//#define DEBUG_MMAP
+
+/* NOTE: all the constants are the HOST ones */
+int target_mprotect(unsigned long start, unsigned long len, int prot)
+{
+    unsigned long end, host_start, host_end, addr;
+    int prot1, ret;
+
+#ifdef DEBUG_MMAP
+    printf("mprotect: start=0x%lx len=0x%lx prot=%c%c%c\n", start, len,
+           prot & PROT_READ ? 'r' : '-',
+           prot & PROT_WRITE ? 'w' : '-',
+           prot & PROT_EXEC ? 'x' : '-');
+#endif
+
+    if ((start & ~TARGET_PAGE_MASK) != 0)
+        return -EINVAL;
+    len = TARGET_PAGE_ALIGN(len);
+    end = start + len;
+    if (end < start)
+        return -EINVAL;
+    if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
+        return -EINVAL;
+    if (len == 0)
+        return 0;
+    
+    host_start = start & host_page_mask;
+    host_end = HOST_PAGE_ALIGN(end);
+    if (start > host_start) {
+        /* handle host page containing start */
+        prot1 = prot;
+        for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
+            prot1 |= page_get_flags(addr);
+        }
+        ret = mprotect((void *)host_start, host_page_size, prot1 & PAGE_BITS);
+        if (ret != 0)
+            return ret;
+        host_start += host_page_size;
+    }
+    if (end < host_end) {
+        /* handle host page containing end (can be the same as first page) */
+        prot1 = prot;
+        for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
+            prot1 |= page_get_flags(addr);
+        }
+        ret = mprotect((void *)(host_end - host_page_size), host_page_size, 
+                       prot1 & PAGE_BITS);
+        if (ret != 0)
+            return ret;
+        host_end -= host_page_size;
+    }
+    
+    /* handle the pages in the middle */
+    if (host_start < host_end) {
+        ret = mprotect((void *)host_start, host_end - host_start, prot);
+        if (ret != 0)
+            return ret;
+    }
+
+    page_set_flags(start, start + len, prot | PAGE_VALID);
+    return 0;
+}
+
+/* map an incomplete host page */
+int mmap_frag(unsigned long host_start, 
+               unsigned long start, unsigned long end, 
+               int prot, int flags, int fd, unsigned long offset)
+{
+    unsigned long host_end, ret, addr;
+    int prot1, prot_new;
+
+    host_end = host_start + host_page_size;
+
+    /* get the protection of the target pages outside the mapping */
+    prot1 = 0;
+    for(addr = host_start; addr < host_end; addr++) {
+        if (addr < start || addr >= end)
+            prot1 |= page_get_flags(addr);
+    }
+    
+    if (prot1 == 0) {
+        /* no page was there, so we allocate one */
+        ret = (long)mmap((void *)host_start, host_page_size, prot, 
+                         flags | MAP_ANONYMOUS, -1, 0);
+        if (ret == -1)
+            return ret;
+    }
+    prot1 &= PAGE_BITS;
+
+    prot_new = prot | prot1;
+    if (!(flags & MAP_ANONYMOUS)) {
+        /* msync() won't work here, so we return an error if write is
+           possible while it is a shared mapping */
+        if ((flags & MAP_TYPE) == MAP_SHARED &&
+            (prot & PROT_WRITE))
+            return -EINVAL;
+
+        /* adjust protection to be able to read */
+        if (!(prot1 & PROT_WRITE))
+            mprotect((void *)host_start, host_page_size, prot1 | PROT_WRITE);
+        
+        /* read the corresponding file data */
+        pread(fd, (void *)start, end - start, offset);
+        
+        /* put final protection */
+        if (prot_new != (prot1 | PROT_WRITE))
+            mprotect((void *)host_start, host_page_size, prot_new);
+    } else {
+        /* just update the protection */
+        if (prot_new != prot1) {
+            mprotect((void *)host_start, host_page_size, prot_new);
+        }
+    }
+    return 0;
+}
+
+/* NOTE: all the constants are the HOST ones */
+long target_mmap(unsigned long start, unsigned long len, int prot, 
+                 int flags, int fd, unsigned long offset)
+{
+    unsigned long ret, end, host_start, host_end, retaddr, host_offset, host_len;
+
+#ifdef DEBUG_MMAP
+    {
+        printf("mmap: start=0x%lx len=0x%lx prot=%c%c%c flags=",
+               start, len, 
+               prot & PROT_READ ? 'r' : '-',
+               prot & PROT_WRITE ? 'w' : '-',
+               prot & PROT_EXEC ? 'x' : '-');
+        if (flags & MAP_FIXED)
+            printf("MAP_FIXED ");
+        if (flags & MAP_ANONYMOUS)
+            printf("MAP_ANON ");
+        switch(flags & MAP_TYPE) {
+        case MAP_PRIVATE:
+            printf("MAP_PRIVATE ");
+            break;
+        case MAP_SHARED:
+            printf("MAP_SHARED ");
+            break;
+        default:
+            printf("[MAP_TYPE=0x%x] ", flags & MAP_TYPE);
+            break;
+        }
+        printf("fd=%d offset=%lx\n", fd, offset);
+    }
+#endif
+
+    if (offset & ~TARGET_PAGE_MASK)
+        return -EINVAL;
+
+    len = TARGET_PAGE_ALIGN(len);
+    if (len == 0)
+        return start;
+    host_start = start & host_page_mask;
+
+    if (!(flags & MAP_FIXED)) {
+        if (host_page_size != real_host_page_size) {
+            /* NOTE: this code is only for debugging with '-p' option */
+            /* reserve a memory area */
+            host_len = HOST_PAGE_ALIGN(len) + host_page_size - TARGET_PAGE_SIZE;
+            host_start = (long)mmap((void *)host_start, host_len, PROT_NONE, 
+                                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+            if (host_start == -1)
+                return host_start;
+            host_end = host_start + host_len;
+            start = HOST_PAGE_ALIGN(host_start);
+            end = start + HOST_PAGE_ALIGN(len);
+            if (start > host_start)
+                munmap((void *)host_start, start - host_start);
+            if (end < host_end)
+                munmap((void *)end, host_end - end);
+            /* use it as a fixed mapping */
+            flags |= MAP_FIXED;
+        } else {
+            /* if not fixed, no need to do anything */
+            host_offset = offset & host_page_mask;
+            host_len = len + offset - host_offset;
+            start = (long)mmap((void *)host_start, host_len, 
+                               prot, flags, fd, host_offset);
+            if (start == -1)
+                return start;
+            /* update start so that it points to the file position at 'offset' */
+            if (!(flags & MAP_ANONYMOUS)) 
+                start += offset - host_offset;
+            goto the_end1;
+        }
+    }
+    
+    if (start & ~TARGET_PAGE_MASK)
+        return -EINVAL;
+    end = start + len;
+    host_end = HOST_PAGE_ALIGN(end);
+
+    /* worst case: we cannot map the file because the offset is not
+       aligned, so we read it */
+    if (!(flags & MAP_ANONYMOUS) &&
+        (offset & ~host_page_mask) != (start & ~host_page_mask)) {
+        /* msync() won't work here, so we return an error if write is
+           possible while it is a shared mapping */
+        if ((flags & MAP_TYPE) == MAP_SHARED &&
+            (prot & PROT_WRITE))
+            return -EINVAL;
+        retaddr = target_mmap(start, len, prot | PROT_WRITE, 
+                              MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, 
+                              -1, 0);
+        if (retaddr == -1)
+            return retaddr;
+        pread(fd, (void *)start, len, offset);
+        if (!(prot & PROT_WRITE)) {
+            ret = target_mprotect(start, len, prot);
+            if (ret != 0)
+                return ret;
+        }
+        goto the_end;
+    }
+
+    /* handle the start of the mapping */
+    if (start > host_start) {
+        if (host_end == host_start + host_page_size) {
+            /* one single host page */
+            ret = mmap_frag(host_start, start, end,
+                            prot, flags, fd, offset);
+            if (ret == -1)
+                return ret;
+            goto the_end1;
+        }
+        ret = mmap_frag(host_start, start, host_start + host_page_size,
+                        prot, flags, fd, offset);
+        if (ret == -1)
+            return ret;
+        host_start += host_page_size;
+    }
+    /* handle the end of the mapping */
+    if (end < host_end) {
+        ret = mmap_frag(host_end - host_page_size, 
+                        host_end - host_page_size, host_end,
+                        prot, flags, fd, 
+                        offset + host_end - host_page_size - start);
+        if (ret == -1)
+            return ret;
+        host_end -= host_page_size;
+    }
+    
+    /* map the middle (easier) */
+    if (host_start < host_end) {
+        ret = (long)mmap((void *)host_start, host_end - host_start, 
+                         prot, flags, fd, offset + host_start - start);
+        if (ret == -1)
+            return ret;
+    }
+ the_end1:
+    page_set_flags(start, start + len, prot | PAGE_VALID);
+ the_end:
+#ifdef DEBUG_MMAP
+    page_dump(stdout);
+    printf("\n");
+#endif
+    return start;
+}
+
+int target_munmap(unsigned long start, unsigned long len)
+{
+    unsigned long end, host_start, host_end, addr;
+    int prot, ret;
+
+#ifdef DEBUG_MMAP
+    printf("munmap: start=0x%lx len=0x%lx\n", start, len);
+#endif
+    if (start & ~TARGET_PAGE_MASK)
+        return -EINVAL;
+    len = TARGET_PAGE_ALIGN(len);
+    if (len == 0)
+        return -EINVAL;
+    end = start + len;
+    host_start = start & host_page_mask;
+    host_end = HOST_PAGE_ALIGN(end);
+
+    if (start > host_start) {
+        /* handle host page containing start */
+        prot = 0;
+        for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
+            prot |= page_get_flags(addr);
+        }
+        if (prot != 0)
+            host_start += host_page_size;
+    }
+    if (end < host_end) {
+        /* handle host page containing end (can be the same as first page) */
+        prot = 0;
+        for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
+            prot |= page_get_flags(addr);
+        }
+        if (prot != 0)
+            host_end -= host_page_size;
+    }
+    
+    /* unmap what we can */
+    if (host_start < host_end) {
+        ret = munmap((void *)host_start, host_end - host_start);
+        if (ret != 0)
+            return ret;
+    }
+
+    page_set_flags(start, start + len, 0);
+    return 0;
+}
+
+/* XXX: currently, we only handle MAP_ANONYMOUS and not MAP_FIXED
+   blocks which have been allocated starting on a host page */
+long target_mremap(unsigned long old_addr, unsigned long old_size, 
+                   unsigned long new_size, unsigned long flags,
+                   unsigned long new_addr)
+{
+    int prot;
+
+    /* XXX: use 5 args syscall */
+    new_addr = (long)mremap((void *)old_addr, old_size, new_size, flags);
+    if (new_addr == -1)
+        return new_addr;
+    prot = page_get_flags(old_addr);
+    page_set_flags(old_addr, old_addr + old_size, 0);
+    page_set_flags(new_addr, new_addr + new_size, prot | PAGE_VALID);
+    return new_addr;
+}
+
+int target_msync(unsigned long start, unsigned long len, int flags)
+{
+    unsigned long end;
+
+    if (start & ~TARGET_PAGE_MASK)
+        return -EINVAL;
+    len = TARGET_PAGE_ALIGN(len);
+    if (len == 0)
+        return 0;
+    end = start + len;
+    
+    start &= host_page_mask;
+    return msync((void *)start, len, flags);
+}
+