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Partialy fix mmap at EOF for large pagesize targets in user-mode.

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Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6510 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
edgar_igl 2009-02-03 23:06:34 +00:00
parent d6755878db
commit 54c5a2ae54
1 changed files with 37 additions and 2 deletions
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39
linux-user/mmap.c
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@ -24,6 +24,8 @@
#include <string.h> #include <string.h>
#include <unistd.h> #include <unistd.h>
#include <errno.h> #include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h> #include <sys/mman.h>
#include <linux/mman.h> #include <linux/mman.h>
#include <linux/unistd.h> #include <linux/unistd.h>
@ -366,6 +368,36 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
goto the_end; goto the_end;
real_start = start & qemu_host_page_mask; real_start = start & qemu_host_page_mask;
/* When mapping files into a memory area larger than the file, accesses
to pages beyond the file size will cause a SIGBUS.
For example, if mmaping a file of 100 bytes on a host with 4K pages
emulating a target with 8K pages, the target expects to be able to
access the first 8K. But the host will trap us on any access beyond
4K.
When emulating a target with a larger page-size than the hosts, we
may need to truncate file maps at EOF and add extra anonymous pages
up to the targets page boundary. */
if ((qemu_real_host_page_size < TARGET_PAGE_SIZE)
&& !(flags & MAP_ANONYMOUS)) {
struct stat sb;
if (fstat (fd, &sb) == -1)
goto fail;
/* Are we trying to create a map beyond EOF?. */
if (offset + len > sb.st_size) {
/* If so, truncate the file map at eof aligned with
the hosts real pagesize. Additional anonymous maps
will be created beyond EOF. */
len = (sb.st_size - offset);
len += qemu_real_host_page_size - 1;
len &= ~(qemu_real_host_page_size - 1);
}
}
if (!(flags & MAP_FIXED)) { if (!(flags & MAP_FIXED)) {
abi_ulong mmap_start; abi_ulong mmap_start;
void *p; void *p;
@ -381,13 +413,16 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
especially important if qemu_host_page_size > especially important if qemu_host_page_size >
qemu_real_host_page_size */ qemu_real_host_page_size */
p = mmap(g2h(mmap_start), p = mmap(g2h(mmap_start),
host_len, prot, flags | MAP_FIXED, fd, host_offset); host_len, prot, flags | MAP_FIXED | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) if (p == MAP_FAILED)
goto fail; goto fail;
/* update start so that it points to the file position at 'offset' */ /* update start so that it points to the file position at 'offset' */
host_start = (unsigned long)p; host_start = (unsigned long)p;
if (!(flags & MAP_ANONYMOUS)) if (!(flags & MAP_ANONYMOUS)) {
p = mmap(g2h(mmap_start), len, prot,
flags | MAP_FIXED, fd, host_offset);
host_start += offset - host_offset; host_start += offset - host_offset;
}
start = h2g(host_start); start = h2g(host_start);
} else { } else {
int flg; int flg;