When the host page size is greater than the target page size and
MAP_FIXED or MAP_FIXED_NOREPLACE is requested, mmap will be done for
three parts: start, middle, and end. If a later part of mmap fail,
mmap done in the earlier parts must be reverted.
Fixes: 54936004fd ("mmap emulation")
Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
---
Based-on: <20230804014517.6361-1-richard.hender...@linaro.org>
("[PATCH for-8.1 v8 00/17] linux-user: brk fixes")
linux-user/mmap.c | 65 +++++++++++++++++++++++++++++------------------
1 file changed, 40 insertions(+), 25 deletions(-)
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 949c4090f3..0a4ce79ce5 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -224,13 +224,15 @@ int target_mprotect(abi_ulong start, abi_ulong len, int
target_prot)
/* map an incomplete host page */
static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last,
- int prot, int flags, int fd, off_t offset)
+ int prot, int flags, int fd, off_t offset, bool *mapped)
{
abi_ulong real_last;
void *host_start;
int prot_old, prot_new;
int host_prot_old, host_prot_new;
+ *mapped = false;
+
if (!(flags & MAP_ANONYMOUS)
&& (flags & MAP_TYPE) == MAP_SHARED
&& (prot & PROT_WRITE)) {
@@ -271,6 +273,7 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong
start, abi_ulong last,
return false;
}
prot_old = prot;
+ *mapped = true;
}
prot_new = prot | prot_old;
@@ -448,7 +451,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size,
abi_ulong align)
abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
int flags, int fd, off_t offset)
{
- abi_ulong ret, last, real_start, real_last, retaddr, host_len;
+ abi_ulong ret, last, real_start, retaddr, host_len;
abi_ulong passthrough_start = -1, passthrough_last = 0;
int page_flags;
off_t host_offset;
@@ -577,12 +580,16 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
target_prot,
passthrough_start = start;
passthrough_last = last;
} else {
+ abi_ulong middle_start = HOST_PAGE_ALIGN(start);
+ abi_ulong middle_last = ((start + len) & qemu_host_page_mask) - 1;
+ abi_ulong mapped_len = 0;
+ bool mapped;
+
if (start & ~TARGET_PAGE_MASK) {
errno = EINVAL;
goto fail;
}
last = start + len - 1;
- real_last = HOST_PAGE_ALIGN(last) - 1;
/*
* Test if requested memory area fits target address space
@@ -649,35 +656,26 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
target_prot,
}
/* handle the start of the mapping */
- if (start > real_start) {
- if (real_last == real_start + qemu_host_page_size - 1) {
+ if (start < middle_start) {
+ if (last < middle_start) {
/* one single host page */
if (!mmap_frag(real_start, start, last,
- target_prot, flags, fd, offset)) {
+ target_prot, flags, fd, offset, &mapped)) {
goto fail;
}
goto the_end1;
}
- if (!mmap_frag(real_start, start,
- real_start + qemu_host_page_size - 1,
- target_prot, flags, fd, offset)) {
+ if (!mmap_frag(real_start, start, middle_start - 1,
+ target_prot, flags, fd, offset, &mapped)) {
goto fail;
}
- real_start += qemu_host_page_size;
- }
- /* handle the end of the mapping */
- if (last < real_last) {
- abi_ulong real_page = real_last - qemu_host_page_size + 1;
- if (!mmap_frag(real_page, real_page, last,
- target_prot, flags, fd,
- offset + real_page - start)) {
- goto fail;
+ if (mapped) {
+ mapped_len = qemu_host_page_size;
}
- real_last -= qemu_host_page_size;
}
/* map the middle (easier) */
- if (real_start < real_last) {
+ if (middle_start < middle_last) {
void *p, *want_p;
off_t offset1;
size_t len1;
@@ -685,10 +683,10 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
target_prot,
if (flags & MAP_ANONYMOUS) {
offset1 = 0;
} else {
- offset1 = offset + real_start - start;
+ offset1 = offset + middle_start - start;
}
- len1 = real_last - real_start + 1;
- want_p = g2h_untagged(real_start);
+ len1 = middle_last - middle_start + 1;
+ want_p = g2h_untagged(middle_start);
p = mmap(want_p, len1, target_to_host_prot(target_prot),
flags, fd, offset1);
@@ -697,10 +695,27 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
target_prot,
munmap(p, len1);
errno = EEXIST;
}
+ if (mapped_len) {
+ munmap(g2h_untagged(middle_start - mapped_len),
mapped_len);
+ }
+ goto fail;
+ }
+ mapped_len += len1;
+ passthrough_start = middle_start;
+ passthrough_last = middle_last;
+ }
+
+ /* handle the end of the mapping */
+ if (last > middle_last) {
+ abi_ulong real_page = middle_last + 1;
+ if (!mmap_frag(real_page, real_page, last,
+ target_prot, flags, fd,
+ offset + real_page - start, &mapped)) {
+ if (mapped_len) {
+ munmap(g2h_untagged(real_page - mapped_len), mapped_len);
+ }
goto fail;
}
- passthrough_start = real_start;
- passthrough_last = real_last;
}
}
the_end1:
--
2.41.0
