Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / powerpc / mm / mmap.c

diff --git a/kernel/arch/powerpc/mm/mmap.c b/kernel/arch/powerpc/mm/mmap.c
new file mode 100644 (file)
index 0000000..0f0502e
--- /dev/null
+++ b/kernel/arch/powerpc/mm/mmap.c
@@ -0,0 +1,103 @@
+/*
+ *  flexible mmap layout support
+ *
+ * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *
+ * Started by Ingo Molnar <mingo@elte.hu>
+ */
+
+#include <linux/personality.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/sched.h>
+
+/*
+ * Top of mmap area (just below the process stack).
+ *
+ * Leave at least a ~128 MB hole on 32bit applications.
+ *
+ * On 64bit applications we randomise the stack by 1GB so we need to
+ * space our mmap start address by a further 1GB, otherwise there is a
+ * chance the mmap area will end up closer to the stack than our ulimit
+ * requires.
+ */
+#define MIN_GAP32 (128*1024*1024)
+#define MIN_GAP64 ((128 + 1024)*1024*1024UL)
+#define MIN_GAP ((is_32bit_task()) ? MIN_GAP32 : MIN_GAP64)
+#define MAX_GAP (TASK_SIZE/6*5)
+
+static inline int mmap_is_legacy(void)
+{
+       if (current->personality & ADDR_COMPAT_LAYOUT)
+               return 1;
+
+       if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
+               return 1;
+
+       return sysctl_legacy_va_layout;
+}
+
+unsigned long arch_mmap_rnd(void)
+{
+       unsigned long rnd;
+
+       /* 8MB for 32bit, 1GB for 64bit */
+       if (is_32bit_task())
+               rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT));
+       else
+               rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT));
+
+       return rnd << PAGE_SHIFT;
+}
+
+static inline unsigned long mmap_base(unsigned long rnd)
+{
+       unsigned long gap = rlimit(RLIMIT_STACK);
+
+       if (gap < MIN_GAP)
+               gap = MIN_GAP;
+       else if (gap > MAX_GAP)
+               gap = MAX_GAP;
+
+       return PAGE_ALIGN(TASK_SIZE - gap - rnd);
+}
+
+/*
+ * 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)
+{
+       unsigned long random_factor = 0UL;
+
+       if (current->flags & PF_RANDOMIZE)
+               random_factor = arch_mmap_rnd();
+
+       /*
+        * 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 = arch_get_unmapped_area;
+       } else {
+               mm->mmap_base = mmap_base(random_factor);
+               mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+       }
+}