Use the fields in the sysentvec and in the vm map header in place of the

constants VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS, USRSTACK and PS_STRINGS.
This is mainly so that they can be variable even for the native abi, based
on different machine types.  Get stack protections from the sysentvec too.
This makes it trivial to map the stack non-executable for certain abis, on
machines that support it.

1 files changed, 46 insertions, 20 deletions

diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 3bad18a..784ed5c 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -74,6 +74,9 @@ MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
 
 static MALLOC_DEFINE(M_ATEXEC, "atexec", "atexec callback");
 
+static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
+static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
+
 /*
  * callout list for things to do at exec time
  */
@@ -86,13 +89,12 @@ TAILQ_HEAD(exec_list_head, execlist);
 static struct exec_list_head exec_list = TAILQ_HEAD_INITIALIZER(exec_list);
 
 /* XXX This should be vm_size_t. */
-static u_long ps_strings = PS_STRINGS;
-SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings,
-    0, "");
+SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
+    NULL, 0, sysctl_kern_ps_strings, "LU", "");
 
 /* XXX This should be vm_size_t. */
-static u_long usrstack = USRSTACK;
-SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, "");
+SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD,
+    NULL, 0, sysctl_kern_usrstack, "LU", "");
 
 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
@@ -107,6 +109,26 @@ static int regstkpages = 256;
 SYSCTL_INT(_machdep, OID_AUTO, regstkpages, CTLFLAG_RW, &regstkpages, 0, "");
 #endif
 
+static int
+sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
+{
+	struct proc *p;
+
+	p = curproc;
+	return (SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
+	   sizeof(p->p_sysent->sv_psstrings)));
+}
+
+static int
+sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
+{
+	struct proc *p;
+
+	p = curproc;
+	return (SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
+	    sizeof(p->p_sysent->sv_usrstack)));
+}
+
 /*
  * Each of the items is a pointer to a `const struct execsw', hence the
  * double pointer here.
@@ -688,18 +710,20 @@ exec_unmap_first_page(imgp)
  *	automatically in trap.c.
  */
 int
-exec_new_vmspace(imgp, minuser, maxuser, stack_addr)
+exec_new_vmspace(imgp, sv)
 	struct image_params *imgp;
-	vm_offset_t minuser, maxuser, stack_addr;
+	struct sysentvec *sv;
 {
 	int error;
 	struct execlist *ep;
 	struct proc *p = imgp->proc;
 	struct vmspace *vmspace = p->p_vmspace;
+	vm_offset_t stack_addr;
+	vm_map_t map;
 
 	GIANT_REQUIRED;
 
-	stack_addr = stack_addr - maxssiz;
+	stack_addr = sv->sv_usrstack - maxssiz;
 
 	imgp->vmspace_destroyed = 1;
 
@@ -714,21 +738,23 @@ exec_new_vmspace(imgp, minuser, maxuser, stack_addr)
 	 * otherwise, create a new VM space so that other threads are
 	 * not disrupted
 	 */
-	if (vmspace->vm_refcnt == 1 &&
-	    vm_map_min(&vmspace->vm_map) == minuser &&
-	    vm_map_max(&vmspace->vm_map) == maxuser) {
+	map = &vmspace->vm_map;
+	if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser &&
+	    vm_map_max(map) == sv->sv_maxuser) {
 		if (vmspace->vm_shm)
 			shmexit(p);
-		pmap_remove_pages(vmspace_pmap(vmspace), minuser, maxuser);
-		vm_map_remove(&vmspace->vm_map, minuser, maxuser);
+		pmap_remove_pages(vmspace_pmap(vmspace), vm_map_min(map),
+		    vm_map_max(map));
+		vm_map_remove(map, vm_map_min(map), vm_map_max(map));
 	} else {
-		vmspace_exec(p, minuser, maxuser);
+		vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
 		vmspace = p->p_vmspace;
+		map = &vmspace->vm_map;
 	}
 
 	/* Allocate a new stack */
-	error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz,
-	    VM_PROT_ALL, VM_PROT_ALL, 0);
+	error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz,
+	    sv->sv_stackprot, VM_PROT_ALL, 0);
 	if (error)
 		return (error);
 
@@ -740,8 +766,8 @@ exec_new_vmspace(imgp, minuser, maxuser, stack_addr)
 		 * store to grow upwards. This will do for now.
 		 */
 		vm_offset_t bsaddr;
-		bsaddr = USRSTACK - 2 * maxssiz;
-		error = vm_map_find(&vmspace->vm_map, 0, 0, &bsaddr,
+		bsaddr = p->p_sysent->sv_usrstack - 2 * maxssiz;
+		error = vm_map_find(map, 0, 0, &bsaddr,
 		    regstkpages * PAGE_SIZE, 0, VM_PROT_ALL, VM_PROT_ALL, 0);
 		FIRST_THREAD_IN_PROC(p)->td_md.md_bspstore = bsaddr;
 	}
@@ -752,7 +778,7 @@ exec_new_vmspace(imgp, minuser, maxuser, stack_addr)
 	 * process stack so we can check the stack rlimit.
 	 */
 	vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
-	vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz;
+	vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - maxssiz;
 
 	return (0);
 }
@@ -851,7 +877,7 @@ exec_copyout_strings(imgp)
 	 */
 	p = imgp->proc;
 	szsigcode = 0;
-	arginfo = (struct ps_strings *)PS_STRINGS;
+	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
 	if (p->p_sysent->sv_szsigcode != NULL)
 		szsigcode = *(p->p_sysent->sv_szsigcode);
 	destp =	(caddr_t)arginfo - szsigcode - SPARE_USRSPACE -