From: Guy Yur <guy...@gmail.com>
Switch checks for !(flags & MAP_ANONYMOUS) with checks for fd != -1.
MAP_STACK and MAP_GUARD both require fd == -1 and don't require mapping
the fd either. Add analysis from Guy Yur detailing the different cases
for MAP_GUARD and MAP_STACK.
Signed-off-by: Guy Yur <guy...@gmail.com>
[ partially merged before, finishing the job and documenting origin]
Signed-off-by: Warner Losh <i...@bsdimp.com>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Reviewed-by: Kyle Evans <kev...@freebsd.org>
---
bsd-user/mmap.c | 30 +++++++++++++++++++++++++-----
roms/seabios-hppa | 2 +-
2 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index face98573f..4ecd949a10 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -127,7 +127,27 @@ error:
return ret;
}
-/* map an incomplete host page */
+/*
+ * map an incomplete host page
+ *
+ * mmap_frag can be called with a valid fd, if flags doesn't contain one of
+ * MAP_ANON, MAP_STACK, MAP_GUARD. If we need to map a page in those cases, we
+ * pass fd == -1. However, if flags contains MAP_GUARD then MAP_ANON cannot be
+ * added.
+ *
+ * * If fd is valid (not -1) we want to map the pages with MAP_ANON.
+ * * If flags contains MAP_GUARD we don't want to add MAP_ANON because it
+ * will be rejected. See kern_mmap's enforcing of constraints for MAP_GUARD
+ * in sys/vm/vm_mmap.c.
+ * * If flags contains MAP_ANON it doesn't matter if we add it or not.
+ * * If flags contains MAP_STACK, mmap adds MAP_ANON when called so doesn't
+ * matter if we add it or not either. See enforcing of constraints for
+ * MAP_STACK in kern_mmap.
+ *
+ * Don't add MAP_ANON for the flags that use fd == -1 without specifying the
+ * flags directly, with the assumption that future flags that require fd == -1
+ * will also not require MAP_ANON.
+ */
static int mmap_frag(abi_ulong real_start,
abi_ulong start, abi_ulong end,
int prot, int flags, int fd, abi_ulong offset)
@@ -147,9 +167,9 @@ static int mmap_frag(abi_ulong real_start,
}
if (prot1 == 0) {
- /* no page was there, so we allocate one */
+ /* no page was there, so we allocate one. See also above. */
void *p = mmap(host_start, qemu_host_page_size, prot,
- flags | MAP_ANON, -1, 0);
+ flags | ((fd != -1) ? MAP_ANON : 0), -1, 0);
if (p == MAP_FAILED)
return -1;
prot1 = prot;
@@ -157,7 +177,7 @@ static int mmap_frag(abi_ulong real_start,
prot1 &= PAGE_BITS;
prot_new = prot | prot1;
- if (!(flags & MAP_ANON)) {
+ if (fd != -1) {
/* msync() won't work here, so we return an error if write is
possible while it is a shared mapping */
if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
@@ -565,7 +585,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
prot,
* worst case: we cannot map the file because the offset is not
* aligned, so we read it
*/
- if (!(flags & MAP_ANON) &&
+ if (fd != -1 &&
(offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask))
{
/*
* msync() won't work here, so we return an error if write is
diff --git a/roms/seabios-hppa b/roms/seabios-hppa
index b12acac4be..73b740f771 160000
--- a/roms/seabios-hppa
+++ b/roms/seabios-hppa
@@ -1 +1 @@
-Subproject commit b12acac4be27b6d5d9fbe48c4be1286dcc245fbb
+Subproject commit 73b740f77190643b2ada5ee97a9a108c6ef2a37b
--
2.32.0
