[Sbcl-commits] CVS: sbcl/src/runtime interrupt.c,1.62,1.63 validate.c,1.21,1.22 validate.h,1.11,1.12

[Nikodemus S. <de...@us...>]

Update of /cvsroot/sbcl/sbcl/src/runtime
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv15373/src/runtime

Modified Files:
	interrupt.c validate.c validate.h 
Log Message:
0.8.14.24: En Garde!
            * Robuster control stack exhaustion handling:
               automagically reprotect the guard-page after enough
               stack has unwound.
            * Simple stress tests for this.


Index: interrupt.c
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/runtime/interrupt.c,v
retrieving revision 1.62
retrieving revision 1.63
diff -u -d -r1.62 -r1.63
--- interrupt.c	16 Aug 2004 18:19:15 -0000	1.62
+++ interrupt.c	14 Sep 2004 18:11:25 -0000	1.63
@@ -701,17 +701,31 @@
 
 boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr){
     struct thread *th=arch_os_get_current_thread();
+    
     /* note the os_context hackery here.  When the signal handler returns, 
      * it won't go back to what it was doing ... */
-    if(addr>=(void *)CONTROL_STACK_GUARD_PAGE(th) && 
-       addr<(void *)(CONTROL_STACK_GUARD_PAGE(th)+os_vm_page_size)) {
-	/* we hit the end of the control stack.  disable protection
-	 * temporarily so the error handler has some headroom */
-	protect_control_stack_guard_page(th->pid,0L);
-	
-	arrange_return_to_lisp_function
-	    (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
-	return 1;
+    if(addr >= CONTROL_STACK_GUARD_PAGE(th) && 
+       addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
+        /* We hit the end of the control stack: disable guard page
+         * protection so the error handler has some headroom, protect the
+         * previous page so that we can catch returns from the guard page
+         * and restore it. */
+        protect_control_stack_guard_page(th->pid,0);
+        protect_control_stack_return_guard_page(th->pid,1);
+        
+        arrange_return_to_lisp_function
+            (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
+        return 1;
+    }
+    else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
+            addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
+        /* We're returning from the guard page: reprotect it, and
+         * unprotect this one. This works even if we somehow missed
+         * the return-guard-page, and hit it on our way to new
+         * exhaustion instead. */
+        protect_control_stack_guard_page(th->pid,1);
+        protect_control_stack_return_guard_page(th->pid,0);
+        return 1;
     }
     else return 0;
 }

Index: validate.c
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/runtime/validate.c,v
retrieving revision 1.21
retrieving revision 1.22
diff -u -d -r1.21 -r1.22
--- validate.c	9 Sep 2004 12:10:15 -0000	1.21
+++ validate.c	14 Sep 2004 18:11:25 -0000	1.22
@@ -69,3 +69,9 @@
 	       (OS_VM_PROT_READ|OS_VM_PROT_EXECUTE) : OS_VM_PROT_ALL);
 }
 
+void protect_control_stack_return_guard_page(pid_t t_id, int protect_p) {
+    struct thread *th = find_thread_by_pid(t_id);
+    os_protect(CONTROL_STACK_RETURN_GUARD_PAGE(th),
+	       os_vm_page_size,protect_p ?
+	       (OS_VM_PROT_READ|OS_VM_PROT_EXECUTE) : OS_VM_PROT_ALL);
+}

Index: validate.h
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/runtime/validate.h,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -d -r1.11 -r1.12
--- validate.h	9 Sep 2004 12:10:15 -0000	1.11
+++ validate.h	14 Sep 2004 18:11:25 -0000	1.12
@@ -27,13 +27,15 @@
 #include <thread.h>
 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD 
 #define CONTROL_STACK_GUARD_PAGE(th) ((void *)(th->control_stack_start))
+#define CONTROL_STACK_RETURN_GUARD_PAGE(th) (CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size)
 #else
-#define CONTROL_STACK_GUARD_PAGE(th) \
-     (((void *)(th->control_stack_end)) - os_vm_page_size)
+#define CONTROL_STACK_GUARD_PAGE(th) (((void *)(th->control_stack_end)) - os_vm_page_size)
+#define CONTROL_STACK_RETURN_GUARD_PAGE(th) (CONTROL_STACK_GUARD_PAGE(th) - os_vm_page_size)
 #endif
 
 extern void validate(void);
 extern void protect_control_stack_guard_page(pid_t t_id, int protect_p);
+extern void protect_control_stack_return_guard_page(pid_t t_id, int protect_p);
 #endif
 
 /* note for anyone trying to port an architecture's support files