[PATCH v2 8/9] bsd-user/mmap.c: Implement MAP_EXCL, required by jemalloc in head

[Warner Losh]

From: Kyle Evans <kevans@FreeBSD.org>

jemalloc requires a working MAP_EXCL. Ensure that no page is double
mapped when specified.

Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>
---
 bsd-user/mmap.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index 347d314aa9..792ff00548 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -387,7 +387,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
                      int flags, int fd, off_t offset)
 {
-    abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
+    abi_ulong addr, ret, end, real_start, real_end, retaddr, host_offset, 
host_len;
 
     mmap_lock();
 #ifdef DEBUG_MMAP
@@ -599,6 +599,14 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int 
prot,
             goto the_end;
         }
 
+        /* Reject the mapping if any page within the range is mapped */
+        if (flags & MAP_EXCL) {
+            for (addr = start; addr < end; addr++) {
+                if (page_get_flags(addr) != 0)
+                    goto fail;
+            }
+        }
+
         /* handle the start of the mapping */
         if (start > real_start) {
             if (real_end == real_start + qemu_host_page_size) {
-- 
2.32.0