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Index: lib/libvmmapi/vmmapi.c
===================================================================
--- lib/libvmmapi/vmmapi.c
+++ lib/libvmmapi/vmmapi.c
@@ -362,7 +362,7 @@
size_t objsize, len;
vm_paddr_t gpa;
char *baseaddr, *ptr;
- int error, flags;
+ int error;
assert(vms == VM_MMAP_ALL);
@@ -389,12 +389,21 @@
* and the adjoining guard regions.
*/
len = VM_MMAP_GUARD_SIZE + objsize + VM_MMAP_GUARD_SIZE;
- flags = MAP_PRIVATE | MAP_ANON | MAP_NOCORE | MAP_ALIGNED_SUPER;
- ptr = mmap(NULL, len, PROT_NONE, flags, -1, 0);
+ ptr = mmap(NULL, len, PROT_NONE, MAP_GUARD | MAP_ALIGNED_SUPER,
+ -1, 0);
if (ptr == MAP_FAILED)
return (-1);
- baseaddr = ptr + VM_MMAP_GUARD_SIZE;
+ baseaddr = mmap(ptr + VM_MMAP_GUARD_SIZE, objsize, PROT_NONE,
+ MAP_PRIVATE | MAP_ANON | MAP_NOCORE | MAP_ALIGNED_SUPER |
+ MAP_FIXED, -1, 0);
+ if (baseaddr == MAP_FAILED) {
+ error = errno;
+ munmap(ptr, len);
+ errno = error;
+ return (-1);
+ }
+
if (ctx->highmem > 0) {
gpa = 4*GB;
len = ctx->highmem;
@@ -463,7 +472,6 @@
vm_create_devmem(struct vmctx *ctx, int segid, const char *name, size_t len)
{
char pathname[MAXPATHLEN];
- size_t len2;
char *base, *ptr;
int fd, error, flags;
@@ -488,12 +496,11 @@
goto done;
/*
- * Stake out a contiguous region covering the device memory and the
- * adjoining guard regions.
+ * Map the entire region with MAP_GUARD first. Remap the
+ * device memory post-guard.
*/
- len2 = VM_MMAP_GUARD_SIZE + len + VM_MMAP_GUARD_SIZE;
- flags = MAP_PRIVATE | MAP_ANON | MAP_NOCORE | MAP_ALIGNED_SUPER;
- base = mmap(NULL, len2, PROT_NONE, flags, -1, 0);
+ base = mmap(NULL, len + VM_MMAP_GUARD_SIZE * 2, PROT_NONE,
+ MAP_GUARD | MAP_ALIGNED_SUPER, -1, 0);
if (base == MAP_FAILED)
goto done;

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