Make libc_r check the kern.usrstack sysctl instead of using internal

kernel #defines to figure out where the stack is located.  This stops
libc_r from exploding when the kernel is compiled with a different
KVM size.  IMHO this is all kinda bogus, it would be better to just
check %esp and work from that.

3 files changed, 20 insertions, 6 deletions

diff --git a/lib/libpthread/thread/thr_init.c b/lib/libpthread/thread/thr_init.c
index 7bf09e5..30ec765 100644
--- a/lib/libpthread/thread/thr_init.c
+++ b/lib/libpthread/thread/thr_init.c
@@ -266,6 +266,12 @@ _thread_init(void)
 		memcpy((void *) &_thread_initial->attr, &pthread_attr_default,
 		    sizeof(struct pthread_attr));
 
+		/* Find the stack top */
+		mib[0] = CTL_KERN;
+		mib[1] = KERN_USRSTACK;
+		len = sizeof (int);
+		if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1)
+			_usrstack = USRSTACK;
 		/*
 		 * Create a red zone below the main stack.  All other stacks are
 		 * constrained to a maximum size by the paramters passed to
@@ -273,14 +279,13 @@ _thread_init(void)
 		 * this stack needs an explicitly mapped red zone to protect the
 		 * thread stack that is just beyond.
 		 */
-		if (mmap((void *) USRSTACK - PTHREAD_STACK_INITIAL -
+		if (mmap(_usrstack - PTHREAD_STACK_INITIAL -
 		    PTHREAD_GUARD_DEFAULT, PTHREAD_GUARD_DEFAULT, 0, MAP_ANON,
 		    -1, 0) == MAP_FAILED)
 			PANIC("Cannot allocate red zone for initial thread");
 
 		/* Set the main thread stack pointer. */
-		_thread_initial->stack = (void *) USRSTACK -
-		    PTHREAD_STACK_INITIAL;
+		_thread_initial->stack = _usrstack - PTHREAD_STACK_INITIAL;
 
 		/* Set the stack attributes: */
 		_thread_initial->attr.stackaddr_attr = _thread_initial->stack;
diff --git a/lib/libpthread/thread/thr_private.h b/lib/libpthread/thread/thr_private.h
index 9af2090..151fd03 100644
--- a/lib/libpthread/thread/thr_private.h
+++ b/lib/libpthread/thread/thr_private.h
@@ -881,6 +881,13 @@ struct pthread {
  * Global variables for the uthread kernel.
  */
 
+SCLASS void *_usrstack
+#ifdef GLOBAL_PTHREAD_PRIVATE
+= (void *) USRSTACK;
+#else
+;
+#endif
+
 /* Kernel thread structure used when there are no running threads: */
 SCLASS struct pthread   _thread_kern_thread;
 
diff --git a/lib/libpthread/thread/thr_stack.c b/lib/libpthread/thread/thr_stack.c
index 055af07..86f0a2d 100644
--- a/lib/libpthread/thread/thr_stack.c
+++ b/lib/libpthread/thread/thr_stack.c
@@ -112,8 +112,7 @@ static LIST_HEAD(, stack)	_mstackq = LIST_HEAD_INITIALIZER(_mstackq);
  * high memory
  *
  */
-static void *	last_stack = (void *) USRSTACK - PTHREAD_STACK_INITIAL
-		    - PTHREAD_GUARD_DEFAULT;
+static void *	last_stack;
 
 void *
 _thread_stack_alloc(size_t stacksize, size_t guardsize)
@@ -186,8 +185,11 @@ _thread_stack_alloc(size_t stacksize, size_t guardsize)
 	/* Check if a stack was not allocated from a stack cache: */
 	if (stack == NULL) {
 
-		/* Allocate a new stack. */
+		if (last_stack == NULL)
+			last_stack = _usrstack - PTHREAD_STACK_INITIAL -
+			    PTHREAD_GUARD_DEFAULT;
 
+		/* Allocate a new stack. */
 		stack = last_stack - stack_size;
 
 		/*