[S390] dynamic page tables.
Add support for different number of page table levels dependent
on the highest address used for a process. This will cause a 31 bit
process to use a two level page table instead of the four level page
table that is the default after the pud has been introduced. Likewise
a normal 64 bit process will use three levels instead of four. Only
if a process runs out of the 4 tera bytes which can be addressed with
a three level page table the fourth level is dynamically added. Then
the process can use up to 8 peta byte.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 356257c..5932a82 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -27,6 +27,7 @@
#include <linux/personality.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <asm/pgalloc.h>
/*
* Top of mmap area (just below the process stack).
@@ -62,6 +63,8 @@
current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;
}
+#ifndef CONFIG_64BIT
+
/*
* This function, called very early during the creation of a new
* process VM image, sets up which VM layout function to use:
@@ -84,3 +87,65 @@
}
EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
+#else
+
+static unsigned long
+s390_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ int rc;
+
+ addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
+ if (addr & ~PAGE_MASK)
+ return addr;
+ if (unlikely(mm->context.asce_limit < addr + len)) {
+ rc = crst_table_upgrade(mm, addr + len);
+ if (rc)
+ return (unsigned long) rc;
+ }
+ return addr;
+}
+
+static unsigned long
+s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long addr = addr0;
+ int rc;
+
+ addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
+ if (addr & ~PAGE_MASK)
+ return addr;
+ if (unlikely(mm->context.asce_limit < addr + len)) {
+ rc = crst_table_upgrade(mm, addr + len);
+ if (rc)
+ return (unsigned long) rc;
+ }
+ return addr;
+}
+/*
+ * This function, called very early during the creation of a new
+ * process VM image, sets up which VM layout function to use:
+ */
+void arch_pick_mmap_layout(struct mm_struct *mm)
+{
+ /*
+ * Fall back to the standard layout if the personality
+ * bit is set, or if the expected stack growth is unlimited:
+ */
+ if (mmap_is_legacy()) {
+ mm->mmap_base = TASK_UNMAPPED_BASE;
+ mm->get_unmapped_area = s390_get_unmapped_area;
+ mm->unmap_area = arch_unmap_area;
+ } else {
+ mm->mmap_base = mmap_base();
+ mm->get_unmapped_area = s390_get_unmapped_area_topdown;
+ mm->unmap_area = arch_unmap_area_topdown;
+ }
+}
+EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
+
+#endif