Update.

* internals.h: Declare __pthread_max_stacksize.
	* pthread.c (__pthread_max_stacksize): New variable.
	(__pthread_initialize_manager): Determine __pthread_initialize_manager
	value.
	* manager.c (thread_segment): Return always NULL if FLOATING_STACKS.
	(pthread_allocate_stack): Allow kernel to choose stack address if
	FLOATING_STACKS.  This also handles variable-sized stacks.
	Always allocate stack and guardoage together.  Use mprotect to
	change guardpage access.
	* sysdeps/i386/useldt.h: Define FLOATING_STACKS and
	ARCH_STACK_MAX_SIZE.

	* attr.c (__pthread_attr_setstacksize): Also test value against
	upper limit.

linuxthreads/ChangeLog

@@ -1,5 +1,20 @@
 2000-08-04  Ulrich Drepper  <drepper@redhat.com>
 
+	* internals.h: Declare __pthread_max_stacksize.
+	* pthread.c (__pthread_max_stacksize): New variable.
+	(__pthread_initialize_manager): Determine __pthread_initialize_manager
+	value.
+	* manager.c (thread_segment): Return always NULL if FLOATING_STACKS.
+	(pthread_allocate_stack): Allow kernel to choose stack address if
+	FLOATING_STACKS.  This also handles variable-sized stacks.
+	Always allocate stack and guardoage together.  Use mprotect to
+	change guardpage access.
+	* sysdeps/i386/useldt.h: Define FLOATING_STACKS and
+	ARCH_STACK_MAX_SIZE.
+
+	* attr.c (__pthread_attr_setstacksize): Also test value against
+	upper limit.
+
 	* manager.c (__pthread_nonstandard_stacks): Define only if
 	THREAD_SELF is not defined.
 	(pthread_allocate_stack): Always initialize gardaddr to a correct

linuxthreads/attr.c

@@ -18,6 +18,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/param.h>
+#include <sys/resource.h>
 #include "pthread.h"
 #include "internals.h"
 #include <shlib-compat.h>
@@ -184,6 +185,30 @@ weak_alias (__pthread_attr_getstackaddr, pthread_attr_getstackaddr)
 
 int __pthread_attr_setstacksize(pthread_attr_t *attr, size_t stacksize)
 {
+#ifdef FLOATING_STACKS
+  /* We have to check against the maximum allowed stack size.  This is no
+     problem if the manager is already started and we determined it.  If
+     this hasn't happened, we have to find the limit outself.  */
+  if (__pthread_max_stacksize == 0)
+    {
+      struct rlimit limit;
+
+      getrlimit(RLIMIT_STACK, &limit);
+# ifdef NEED_SEPARATE_REGISTER_STACK
+      __pthread_max_stacksize = limit.rlim_max / 2;
+# else
+      __pthread_max_stacksize = limit.rlim_max;
+# endif
+    }
+
+  if (stacksize > __pthread_max_stacksize)
+    return EINVAL;
+#else
+  /* We have a fixed size limit.  */
+  if (stacksize > STACK_SIZE)
+    return EINVAL;
+#endif
+
   /* We don't accept value smaller than PTHREAD_STACK_MIN.  */
   if (stacksize < PTHREAD_STACK_MIN)
     return EINVAL;

linuxthreads/internals.h

@@ -272,6 +272,11 @@ extern int __pthread_manager_reader;
 extern char *__pthread_manager_thread_bos;
 extern char *__pthread_manager_thread_tos;
 
+#ifdef FLOATING_STACKS
+/* Maximum stack size.  */
+extern size_t __pthread_max_stacksize;
+#endif
+
 /* Pending request for a process-wide exit */
 
 extern int __pthread_exit_requested, __pthread_exit_code;

linuxthreads/manager.c

@@ -64,25 +64,29 @@ volatile pthread_descr __pthread_last_event;
 /* Stack segment numbers are also indices into the __pthread_handles array. */
 /* Stack segment number 0 is reserved for the initial thread. */
 
+#if FLOATING_STACKS
+# define thread_segment(seq) NULL
+#else
 static inline pthread_descr thread_segment(int seg)
 {
   return (pthread_descr)(THREAD_STACK_START_ADDRESS - (seg - 1) * STACK_SIZE)
          - 1;
 }
+#endif
 
 /* Flag set in signal handler to record child termination */
 
-static volatile int terminated_children = 0;
+static volatile int terminated_children;
 
 /* Flag set when the initial thread is blocked on pthread_exit waiting
    for all other threads to terminate */
 
-static int main_thread_exiting = 0;
+static int main_thread_exiting;
 
 /* Counter used to generate unique thread identifier.
    Thread identifier is pthread_threads_counter + segment. */
 
-static pthread_t pthread_threads_counter = 0;
+static pthread_t pthread_threads_counter;
 
 #ifdef NEED_SEPARATE_REGISTER_STACK
 /* Signal masks for the manager.  These have to be global only when clone2
@@ -338,6 +342,7 @@ static int pthread_allocate_stack(const pthread_attr_t *attr,
       void *map_addr;
 
       /* Allocate space for stack and thread descriptor at default address */
+#ifdef NEED_SEPARATE_REGISTER_STACK
       if (attr != NULL)
 	{
 	  guardsize = page_roundup (attr->__guardsize, granularity);
@@ -350,7 +355,7 @@ static int pthread_allocate_stack(const pthread_attr_t *attr,
 	  guardsize = granularity;
 	  stacksize = STACK_SIZE - granularity;
 	}
-#ifdef NEED_SEPARATE_REGISTER_STACK
+
       new_thread = default_new_thread;
       new_thread_bottom = (char *) (new_thread + 1) - stacksize - guardsize;
       /* Includes guard area, unlike the normal case.  Use the bottom
@@ -361,6 +366,8 @@ static int pthread_allocate_stack(const pthread_attr_t *attr,
        in the same region.  The cost is that we might be able to map
        slightly fewer stacks.  */
 
+      /* XXX Fix for floating stacks with variable sizes.  */
+
       /* First the main stack: */
       if (mmap((caddr_t)((char *)(new_thread + 1) - stacksize / 2),
 	       stacksize / 2, PROT_READ | PROT_WRITE | PROT_EXEC,
@@ -382,37 +389,63 @@ static int pthread_allocate_stack(const pthread_attr_t *attr,
       guardaddr = new_thread_bottom + stacksize/2;
       /* We leave the guard area in the middle unmapped.	*/
 #else  /* !NEED_SEPARATE_REGISTER_STACK */
+# if FLOATING_STACKS
+      if (attr != NULL)
+	{
+	  guardsize = page_roundup (attr->__guardsize, granularity);
+	  stacksize = __pthread_max_stacksize - guardsize;
+	  stacksize = MIN (stacksize,
+			   page_roundup (attr->__stacksize, granularity));
+	}
+      else
+	{
+	  guardsize = granularity;
+	  stacksize = __pthread_max_stacksize - guardsize;
+	}
+
+      map_addr = mmap(NULL, stacksize + guardsize,
+		      PROT_READ | PROT_WRITE | PROT_EXEC,
+		      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+      if (map_addr == MAP_FAILED)
+        /* No more memory available.  */
+        return -1;
+
+      guardaddr = map_addr;
+      if (guardsize > 0)
+	mprotect (guardaddr, guardsize, PROT_NONE);
+
+      new_thread_bottom = (char *) map_addr + guardsize;
+      new_thread = ((pthread_descr) (new_thread_bottom + stacksize)) - 1;
+# else
+      if (attr != NULL)
+	{
+	  guardsize = page_roundup (attr->__guardsize, granularity);
+	  stacksize = STACK_SIZE - guardsize;
+	  stacksize = MIN (stacksize,
+			   page_roundup (attr->__stacksize, granularity));
+	}
+      else
+	{
+	  guardsize = granularity;
+	  stacksize = STACK_SIZE - granularity;
+	}
+
       new_thread = default_new_thread;
       new_thread_bottom = (char *) (new_thread + 1) - stacksize;
-      map_addr = mmap((caddr_t)((char *)(new_thread + 1) - stacksize),
+      map_addr = mmap((caddr_t)((char *)(new_thread + 1) - stacksize - guardsize),
-		      stacksize, PROT_READ | PROT_WRITE | PROT_EXEC,
+		      stacksize + guardsize,
+		      PROT_READ | PROT_WRITE | PROT_EXEC,
 		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
       if (map_addr == MAP_FAILED)
         /* Bad luck, this segment is already mapped. */
         return -1;
-      /* We manage to get a stack.  Now see whether we need a guard
+
-	 and allocate it if necessary.  Notice that the default
+      /* We manage to get a stack.  Protect the guard area pages if
-	 attributes (stack_size = STACK_SIZE - pagesize and guardsize
+	 necessary.  */
-	 = pagesize) do not need a guard page, since the RLIMIT_STACK
+      guardaddr = map_addr;
-	 soft limit prevents stacks from running into one another. */
+      if (guardsize > 0)
-      if (stacksize == STACK_SIZE - pagesize)
+	mprotect (guardaddr, guardsize, PROT_NONE);
-        {
+# endif
-          /* We don't need a guard page. */
-          guardaddr = new_thread_bottom;
-          guardsize = 0;
-        }
-      else
-        {
-          /* Put a bad page at the bottom of the stack */
-	  guardaddr = (void *)new_thread_bottom - guardsize;
-          if (mmap ((caddr_t) guardaddr, guardsize, 0, MAP_FIXED, -1, 0)
-              == MAP_FAILED)
-            {
-              /* We don't make this an error.  */
-              guardaddr = new_thread_bottom;
-              guardsize = 0;
-            }
-        }
 #endif /* !NEED_SEPARATE_REGISTER_STACK */
     }
   /* Clear the thread data structure.  */

linuxthreads/pthread.c

@@ -182,6 +182,9 @@ char *__pthread_manager_thread_tos;
 int __pthread_exit_requested;
 int __pthread_exit_code;
 
+/* Maximum stack size.  */
+size_t __pthread_max_stacksize;
+
 /* Nozero if the machine has more than one processor.  */
 int __pthread_smp_kernel;
 
@@ -455,20 +458,32 @@ int __pthread_initialize_manager(void)
   struct rlimit limit;
   int max_stack;
 
+  getrlimit(RLIMIT_STACK, &limit);
+#ifdef FLOATING_STACKS
+  if (limit.rlim_cur == RLIM_INFINITY)
+    limit.rlim_cur = ARCH_STACK_MAX_SIZE;
+# ifdef NEED_SEPARATE_REGISTER_STACK
+  max_stack = limit.rlim_cur / 2;
+# else
+  max_stack = limit.rlim_cur;
+#endif
+
+  __pthread_max_stacksize = max_stack;
+#else
   /* Play with the stack size limit to make sure that no stack ever grows
      beyond STACK_SIZE minus one page (to act as a guard page). */
-  getrlimit(RLIMIT_STACK, &limit);
+# ifdef NEED_SEPARATE_REGISTER_STACK
-#ifdef NEED_SEPARATE_REGISTER_STACK
   /* STACK_SIZE bytes hold both the main stack and register backing
      store. The rlimit value applies to each individually.  */
-  max_stack = STACK_SIZE/2 - __getpagesize();
+  max_stack = STACK_SIZE/2 - __getpagesize ();
-#else
+# else
   max_stack = STACK_SIZE - __getpagesize();
-#endif
+# endif
   if (limit.rlim_cur > max_stack) {
     limit.rlim_cur = max_stack;
     setrlimit(RLIMIT_STACK, &limit);
   }
+#endif
   /* If basic initialization not done yet (e.g. we're called from a
      constructor run before our constructor), do it now */
   if (__pthread_initial_thread_bos == NULL) pthread_initialize();

linuxthreads/sysdeps/i386/useldt.h

@@ -169,3 +169,9 @@ extern int __modify_ldt (int, struct modify_ldt_ldt_s *, size_t);
 					     member)));			      \
     }									      \
 })
+
+/* We want the OS to assign stack addresses.  */
+#define FLOATING_STACKS	1
+
+/* Maximum size o fthe stack if the rlimit is unlimited.  */
+#define ARCH_STACK_MAX_SIZE	8*1024*1024