[PATCH] uml: eliminate use of libc PAGE_SIZE

On some systems, libc PAGE_SIZE calls getpagesize, which can't happen from a
stub.  So, I use UM_KERN_PAGE_SIZE, which is less variable in its definition,
instead.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/kernel/skas/clone.c

@@ -9,9 +9,13 @@
 #include "stub-data.h"
 #include "uml-config.h"
 #include "sysdep/stub.h"
+#include "kern_constants.h"
 
 /* This is in a separate file because it needs to be compiled with any
  * extraneous gcc flags (-pg, -fprofile-arcs, -ftest-coverage) disabled
+ *
+ * Use UM_KERN_PAGE_SIZE instead of PAGE_SIZE because that calls getpagesize
+ * on some systems.
  */
 
 #define STUB_DATA(field) (((struct stub_data *) UML_CONFIG_STUB_DATA)->field)
@@ -22,7 +26,7 @@ stub_clone_handler(void)
 	long err;
 
 	err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
-			    UML_CONFIG_STUB_DATA + PAGE_SIZE / 2 -
+			    UML_CONFIG_STUB_DATA + UM_KERN_PAGE_SIZE / 2 -
 			    sizeof(void *));
 	if(err != 0)
 		goto out;
@@ -36,9 +40,10 @@ stub_clone_handler(void)
 	if(err)
 		goto out;
 
-	err = stub_syscall6(STUB_MMAP_NR, UML_CONFIG_STUB_DATA, PAGE_SIZE,
-			    PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED,
-			    STUB_DATA(fd), STUB_DATA(offset));
+	err = stub_syscall6(STUB_MMAP_NR, UML_CONFIG_STUB_DATA,
+			    UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
+			    MAP_FIXED | MAP_SHARED, STUB_DATA(fd),
+			    STUB_DATA(offset));
  out:
 	/* save current result. Parent: pid; child: retcode of mmap */
 	STUB_DATA(err) = err;