Make mincore lie. The nature of shared memory means it can spy on what

another process is doing. We don't want that, so instead have it
always return that memory is in core.
ok deraadt kettenis

1 files changed, 6 insertions, 98 deletions

diff --git a/sys/uvm/uvm_mmap.c b/sys/uvm/uvm_mmap.c
index e4bf3647f2c..80d32dbb668 100644
--- a/sys/uvm/uvm_mmap.c
+++ b/sys/uvm/uvm_mmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_mmap.c,v 1.151 2018/08/15 20:22:13 kettenis Exp $	*/
+/*	$OpenBSD: uvm_mmap.c,v 1.152 2019/01/10 21:55:26 tedu Exp $	*/
 /*	$NetBSD: uvm_mmap.c,v 1.49 2001/02/18 21:19:08 chs Exp $	*/
 
 /*
@@ -180,22 +180,13 @@ sys_mincore(struct proc *p, void *v, register_t *retval)
 		syscallarg(size_t) len;
 		syscallarg(char *) vec;
 	} */ *uap = v;
-	vm_page_t m;
-	char *vec, *pgi, *pgs;
-	struct uvm_object *uobj;
-	struct vm_amap *amap;
-	struct vm_anon *anon;
-	vm_map_entry_t entry, next;
-	vaddr_t start, end, lim;
-	vm_map_t map;
+	char *pgs;
+	vaddr_t start, end;
 	vsize_t len, npgs;
 	int error = 0; 
 
-	map = &p->p_vmspace->vm_map;
-
 	start = (vaddr_t)SCARG(uap, addr);
 	len = SCARG(uap, len);
-	vec = SCARG(uap, vec);
 
 	if (start & PAGE_MASK)
 		return (EINVAL);
@@ -215,94 +206,11 @@ sys_mincore(struct proc *p, void *v, register_t *retval)
 	pgs = mallocarray(npgs, sizeof(*pgs), M_TEMP, M_WAITOK | M_CANFAIL);
 	if (pgs == NULL)
 		return (ENOMEM);
-	pgi = pgs;
-
 	/*
-	 * Lock down vec, so our returned status isn't outdated by
-	 * storing the status byte for a page.
+	 * Lie. After all, the answer may change at anytime.
 	 */
-	if ((error = uvm_vslock(p, vec, npgs, PROT_WRITE)) != 0) {
-		free(pgs, M_TEMP, npgs * sizeof(*pgs));
-		return (error);
-	}
-
-	vm_map_lock_read(map);
-
-	if (uvm_map_lookup_entry(map, start, &entry) == FALSE) {
-		error = ENOMEM;
-		goto out;
-	}
-
-	for (/* nothing */;
-	     entry != NULL && entry->start < end;
-	     entry = RBT_NEXT(uvm_map_addr, entry)) {
-		KASSERT(!UVM_ET_ISSUBMAP(entry));
-		KASSERT(start >= entry->start);
-
-		/* Make sure there are no holes. */
-		next = RBT_NEXT(uvm_map_addr, entry);
-		if (entry->end < end &&
-		     (next == NULL ||
-		      next->start > entry->end)) {
-			error = ENOMEM;
-			goto out;
-		}
-
-		lim = end < entry->end ? end : entry->end;
-
-		/*
-		 * Special case for objects with no "real" pages.  Those
-		 * are always considered resident (mapped devices).
-		 */
-		if (UVM_ET_ISOBJ(entry)) {
-			KASSERT(!UVM_OBJ_IS_KERN_OBJECT(entry->object.uvm_obj));
-			if (entry->object.uvm_obj->pgops->pgo_fault != NULL) {
-				for (/* nothing */; start < lim;
-				     start += PAGE_SIZE, pgi++)
-					*pgi = 1;
-				continue;
-			}
-		}
-
-		amap = entry->aref.ar_amap;	/* top layer */
-		uobj = entry->object.uvm_obj;	/* bottom layer */
-
-		for (/* nothing */; start < lim; start += PAGE_SIZE, pgi++) {
-			*pgi = 0;
-			if (amap != NULL) {
-				/* Check the top layer first. */
-				anon = amap_lookup(&entry->aref,
-				    start - entry->start);
-				if (anon != NULL && anon->an_page != NULL) {
-					/*
-					 * Anon has the page for this entry
-					 * offset.
-					 */
-					*pgi = 1;
-				}
-			}
-
-			if (uobj != NULL && *pgi == 0) {
-				/* Check the bottom layer. */
-				m = uvm_pagelookup(uobj,
-				    entry->offset + (start - entry->start));
-				if (m != NULL) {
-					/*
-					 * Object has the page for this entry
-					 * offset.
-					 */
-					*pgi = 1;
-				}
-			}
-		}
-	}
-
- out:
-	vm_map_unlock_read(map);
-	uvm_vsunlock(p, SCARG(uap, vec), npgs);
-	/* now the map is unlocked we can copyout without fear. */
-	if (error == 0)
-		copyout(pgs, vec, npgs * sizeof(char));
+	memset(pgs, 1, npgs * sizeof(*pgs));
+	error = copyout(pgs, SCARG(uap, vec), npgs * sizeof(char));
 	free(pgs, M_TEMP, npgs * sizeof(*pgs));
 	return (error);
 }