uml: clean up TASK_SIZE usage
Clean up the calculation and use of the usable address space size on the host.
task_size is gone, replaced with TASK_SIZE, which is calculated from
CONFIG_TOP_ADDR. get_kmem_end and set_task_sizes_skas are also gone.
host_task_size, which refers to the entire address space usable by the UML
kernel and which may be larger than the address space usable by a UML process,
since that has to end on a pgdir boundary, is replaced by CONFIG_TOP_ADDR.
STACK_TOP is now TASK_SIZE minus the two stub pages.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/include/as-layout.h b/arch/um/include/as-layout.h
index 2b859e0..a2008f5 100644
--- a/arch/um/include/as-layout.h
+++ b/arch/um/include/as-layout.h
@@ -29,9 +29,20 @@
#define _AC(X, Y) __AC(X, Y)
#endif
+/*
+ * The "- 1"'s are to avoid gcc complaining about integer overflows
+ * and unrepresentable decimal constants. With 3-level page tables,
+ * TASK_SIZE is 0x80000000, which gets turned into its signed decimal
+ * equivalent in asm-offsets.s. gcc then complains about that being
+ * unsigned only in C90. To avoid that, UM_TASK_SIZE is defined as
+ * TASK_SIZE - 1. To compensate, we need to add the 1 back here.
+ * However, adding it back to UM_TASK_SIZE produces more gcc
+ * complaints. So, I adjust the thing being subtracted from
+ * UM_TASK_SIZE instead. Bah.
+ */
#define STUB_CODE _AC((unsigned long), \
- UML_CONFIG_TOP_ADDR - 2 * UM_KERN_PAGE_SIZE)
-#define STUB_DATA _AC((unsigned long), UML_CONFIG_TOP_ADDR - UM_KERN_PAGE_SIZE)
+ UM_TASK_SIZE - (2 * UM_KERN_PAGE_SIZE - 1))
+#define STUB_DATA _AC((unsigned long), UM_TASK_SIZE - (UM_KERN_PAGE_SIZE - 1))
#define STUB_START _AC(, STUB_CODE)
#ifndef __ASSEMBLY__