v4.19.13 snapshot.
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
new file mode 100644
index 0000000..b24ce40
--- /dev/null
+++ b/arch/powerpc/mm/mmap.c
@@ -0,0 +1,242 @@
+/*
+ * 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/signal.h>
+#include <linux/sched/mm.h>
+#include <linux/elf-randomize.h>
+#include <linux/security.h>
+#include <linux/mman.h>
+
+/*
+ * Top of mmap area (just below the process stack).
+ *
+ * Leave at least a ~128 MB hole.
+ */
+#define MIN_GAP (128*1024*1024)
+#define MAX_GAP (TASK_SIZE/6*5)
+
+static inline int mmap_is_legacy(struct rlimit *rlim_stack)
+{
+ if (current->personality & ADDR_COMPAT_LAYOUT)
+ return 1;
+
+ if (rlim_stack->rlim_cur == RLIM_INFINITY)
+ return 1;
+
+ return sysctl_legacy_va_layout;
+}
+
+unsigned long arch_mmap_rnd(void)
+{
+ unsigned long shift, rnd;
+
+ shift = mmap_rnd_bits;
+#ifdef CONFIG_COMPAT
+ if (is_32bit_task())
+ shift = mmap_rnd_compat_bits;
+#endif
+ rnd = get_random_long() % (1ul << shift);
+
+ return rnd << PAGE_SHIFT;
+}
+
+static inline unsigned long stack_maxrandom_size(void)
+{
+ if (!(current->flags & PF_RANDOMIZE))
+ return 0;
+
+ /* 8MB for 32bit, 1GB for 64bit */
+ if (is_32bit_task())
+ return (1<<23);
+ else
+ return (1<<30);
+}
+
+static inline unsigned long mmap_base(unsigned long rnd,
+ struct rlimit *rlim_stack)
+{
+ unsigned long gap = rlim_stack->rlim_cur;
+ unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
+
+ /* Values close to RLIM_INFINITY can overflow. */
+ if (gap + pad > gap)
+ gap += pad;
+
+ if (gap < MIN_GAP)
+ gap = MIN_GAP;
+ else if (gap > MAX_GAP)
+ gap = MAX_GAP;
+
+ return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);
+}
+
+#ifdef CONFIG_PPC_RADIX_MMU
+/*
+ * Same function as generic code used only for radix, because we don't need to overload
+ * the generic one. But we will have to duplicate, because hash select
+ * HAVE_ARCH_UNMAPPED_AREA
+ */
+static unsigned long
+radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ int fixed = (flags & MAP_FIXED);
+ unsigned long high_limit;
+ struct vm_unmapped_area_info info;
+
+ high_limit = DEFAULT_MAP_WINDOW;
+ if (addr >= high_limit || (fixed && (addr + len > high_limit)))
+ high_limit = TASK_SIZE;
+
+ if (len > high_limit)
+ return -ENOMEM;
+
+ if (fixed) {
+ if (addr > high_limit - len)
+ return -ENOMEM;
+ return addr;
+ }
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (high_limit - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+ info.flags = 0;
+ info.length = len;
+ info.low_limit = mm->mmap_base;
+ info.high_limit = high_limit;
+ info.align_mask = 0;
+
+ return vm_unmapped_area(&info);
+}
+
+static unsigned long
+radix__arch_get_unmapped_area_topdown(struct file *filp,
+ const unsigned long addr0,
+ const unsigned long len,
+ const unsigned long pgoff,
+ const unsigned long flags)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm = current->mm;
+ unsigned long addr = addr0;
+ int fixed = (flags & MAP_FIXED);
+ unsigned long high_limit;
+ struct vm_unmapped_area_info info;
+
+ high_limit = DEFAULT_MAP_WINDOW;
+ if (addr >= high_limit || (fixed && (addr + len > high_limit)))
+ high_limit = TASK_SIZE;
+
+ if (len > high_limit)
+ return -ENOMEM;
+
+ if (fixed) {
+ if (addr > high_limit - len)
+ return -ENOMEM;
+ return addr;
+ }
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (high_limit - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ info.length = len;
+ info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+ info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
+ info.align_mask = 0;
+
+ addr = vm_unmapped_area(&info);
+ if (!(addr & ~PAGE_MASK))
+ return addr;
+ VM_BUG_ON(addr != -ENOMEM);
+
+ /*
+ * A failed mmap() very likely causes application failure,
+ * so fall back to the bottom-up function here. This scenario
+ * can happen with large stack limits and large mmap()
+ * allocations.
+ */
+ return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
+}
+
+static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
+ unsigned long random_factor,
+ struct rlimit *rlim_stack)
+{
+ if (mmap_is_legacy(rlim_stack)) {
+ mm->mmap_base = TASK_UNMAPPED_BASE;
+ mm->get_unmapped_area = radix__arch_get_unmapped_area;
+ } else {
+ mm->mmap_base = mmap_base(random_factor, rlim_stack);
+ mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
+ }
+}
+#else
+/* dummy */
+extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
+ unsigned long random_factor,
+ struct rlimit *rlim_stack);
+#endif
+/*
+ * 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, struct rlimit *rlim_stack)
+{
+ unsigned long random_factor = 0UL;
+
+ if (current->flags & PF_RANDOMIZE)
+ random_factor = arch_mmap_rnd();
+
+ if (radix_enabled())
+ return radix__arch_pick_mmap_layout(mm, random_factor,
+ rlim_stack);
+ /*
+ * Fall back to the standard layout if the personality
+ * bit is set, or if the expected stack growth is unlimited:
+ */
+ if (mmap_is_legacy(rlim_stack)) {
+ mm->mmap_base = TASK_UNMAPPED_BASE;
+ mm->get_unmapped_area = arch_get_unmapped_area;
+ } else {
+ mm->mmap_base = mmap_base(random_factor, rlim_stack);
+ mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+ }
+}