[src/trunk]: src/lib/libpthread Further refine stack allocation. If the stack...

[joerg <joerg%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/985c9ec7e6ab
branches:  trunk
changeset: 778013:985c9ec7e6ab
user:      joerg <joerg%NetBSD.org@localhost>
date:      Mon Mar 12 16:37:15 2012 +0000

description:
Further refine stack allocation. If the stack was provided by the user,
don't bother with setting up a guard page. Otherwise, round up the size
to page size. Point stack inside the guarded area, without the guard
page. Fix size when mprotect failed.

diffstat:

 lib/libpthread/pthread.c |  24 +++++++++++++-----------
 1 files changed, 13 insertions(+), 11 deletions(-)

diffs (61 lines):

diff -r 86ff058005a4 -r 985c9ec7e6ab lib/libpthread/pthread.c
--- a/lib/libpthread/pthread.c  Mon Mar 12 15:32:02 2012 +0000
+++ b/lib/libpthread/pthread.c  Mon Mar 12 16:37:15 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pthread.c,v 1.130 2012/03/10 18:01:10 joerg Exp $      */
+/*     $NetBSD: pthread.c,v 1.131 2012/03/12 16:37:15 joerg Exp $      */
 
 /*-
  * Copyright (c) 2001, 2002, 2003, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: pthread.c,v 1.130 2012/03/10 18:01:10 joerg Exp $");
+__RCSID("$NetBSD: pthread.c,v 1.131 2012/03/12 16:37:15 joerg Exp $");
 
 #define        __EXPOSE_STACK  1
 
@@ -320,8 +320,7 @@
 pthread__newstack(pthread_t newthread, const pthread_attr_t *attr)
 {
        void *stackbase, *redzone;
-       size_t stacksize;
-       bool mapped_stack = false;
+       size_t stacksize, guardsize;
 
        if (attr != NULL) {
                pthread_attr_getstack(attr, &stackbase, &stacksize);
@@ -333,22 +332,25 @@
                stacksize = pthread__stacksize;
 
        if (stackbase == NULL) {
-               stackbase = mmap(NULL, stacksize,
+               stacksize = (stacksize | (pthread__pagesize - 1)) + 1;
+               guardsize = pthread__pagesize;
+               stackbase = mmap(NULL, stacksize + guardsize,
                    PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, (off_t)0);
                if (stackbase == MAP_FAILED)
                        return ENOMEM;
-               mapped_stack = true;
+       } else {
+               guardsize = 0;
        }
-       newthread->pt_stack.ss_size = stacksize - pthread__pagesize;
-       newthread->pt_stack.ss_sp = stackbase;
+       newthread->pt_stack.ss_size = stacksize;
 #ifdef __MACHINE_STACK_GROWS_UP
        redzone = (char *)stackbase + newthread->pt_stack.ss_size;
+       newthread->pt_stack.ss_sp = (char *)stackbase + guardsize;
 #else
        redzone = (char *)stackbase;
+       newthread->pt_stack.ss_sp = (char *)stackbase + guardsize;
 #endif
-       if (mprotect(redzone, pthread__pagesize, PROT_NONE) == -1) {
-               if (mapped_stack)
-                       munmap(stackbase, pthread__stacksize);
+       if (guardsize && mprotect(redzone, guardsize, PROT_NONE) == -1) {
+               munmap(stackbase, stacksize + guardsize);
                return EPERM;
        }
        return 0;