--- /dev/null
+/*
+ * 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/mman.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/compat.h>
+#include <linux/security.h>
+#include <asm/pgalloc.h>
+
+unsigned long mmap_rnd_mask;
+static unsigned long mmap_align_mask;
+
+static unsigned long stack_maxrandom_size(void)
+{
+ if (!(current->flags & PF_RANDOMIZE))
+ return 0;
+ if (current->personality & ADDR_NO_RANDOMIZE)
+ return 0;
+ return STACK_RND_MASK << PAGE_SHIFT;
+}
+
+/*
+ * Top of mmap area (just below the process stack).
+ *
+ * Leave at least a ~32 MB hole.
+ */
+#define MIN_GAP (32*1024*1024)
+#define MAX_GAP (STACK_TOP/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)
+{
+ if (is_32bit_task())
+ return (get_random_int() & 0x7ff) << PAGE_SHIFT;
+ else
+ return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
+}
+
+static unsigned long mmap_base_legacy(unsigned long rnd)
+{
+ return TASK_UNMAPPED_BASE + rnd;
+}
+
+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;
+ gap &= PAGE_MASK;
+ return STACK_TOP - stack_maxrandom_size() - rnd - gap;
+}
+
+unsigned long
+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;
+ struct vm_unmapped_area_info info;
+ int do_color_align;
+
+ if (len > TASK_SIZE - mmap_min_addr)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vma->vm_start))
+ return addr;
+ }
+
+ do_color_align = 0;
+ if (filp || (flags & MAP_SHARED))
+ do_color_align = !is_32bit_task();
+
+ info.flags = 0;
+ info.length = len;
+ info.low_limit = mm->mmap_base;
+ info.high_limit = TASK_SIZE;
+ info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
+ info.align_offset = pgoff << PAGE_SHIFT;
+ return vm_unmapped_area(&info);
+}
+
+unsigned long
+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;
+ struct vm_unmapped_area_info info;
+ int do_color_align;
+
+ /* requested length too big for entire address space */
+ if (len > TASK_SIZE - mmap_min_addr)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ /* requesting a specific address */
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vma->vm_start))
+ return addr;
+ }
+
+ do_color_align = 0;
+ if (filp || (flags & MAP_SHARED))
+ do_color_align = !is_32bit_task();
+
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ info.length = len;
+ info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+ info.high_limit = mm->mmap_base;
+ info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
+ info.align_offset = pgoff << PAGE_SHIFT;
+ addr = vm_unmapped_area(&info);
+
+ /*
+ * 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.
+ */
+ if (addr & ~PAGE_MASK) {
+ VM_BUG_ON(addr != -ENOMEM);
+ info.flags = 0;
+ info.low_limit = TASK_UNMAPPED_BASE;
+ info.high_limit = TASK_SIZE;
+ addr = vm_unmapped_area(&info);
+ }
+
+ return addr;
+}
+
+int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
+{
+ if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
+ return 0;
+ if (!(flags & MAP_FIXED))
+ addr = 0;
+ if ((addr + len) >= TASK_SIZE)
+ return crst_table_upgrade(current->mm, 1UL << 53);
+ return 0;
+}
+
+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;
+ unsigned long area;
+ int rc;
+
+ area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
+ if (!(area & ~PAGE_MASK))
+ return area;
+ if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
+ /* Upgrade the page table to 4 levels and retry. */
+ rc = crst_table_upgrade(mm, 1UL << 53);
+ if (rc)
+ return (unsigned long) rc;
+ area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
+ }
+ return area;
+}
+
+static unsigned long
+s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long area;
+ int rc;
+
+ area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
+ if (!(area & ~PAGE_MASK))
+ return area;
+ if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
+ /* Upgrade the page table to 4 levels and retry. */
+ rc = crst_table_upgrade(mm, 1UL << 53);
+ if (rc)
+ return (unsigned long) rc;
+ area = arch_get_unmapped_area_topdown(filp, addr, len,
+ pgoff, flags);
+ }
+ return area;
+}
+/*
+ * 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 = mmap_base_legacy(random_factor);
+ mm->get_unmapped_area = s390_get_unmapped_area;
+ } else {
+ mm->mmap_base = mmap_base(random_factor);
+ mm->get_unmapped_area = s390_get_unmapped_area_topdown;
+ }
+}
+
+static int __init setup_mmap_rnd(void)
+{
+ struct cpuid cpu_id;
+
+ get_cpu_id(&cpu_id);
+ switch (cpu_id.machine) {
+ case 0x9672:
+ case 0x2064:
+ case 0x2066:
+ case 0x2084:
+ case 0x2086:
+ case 0x2094:
+ case 0x2096:
+ case 0x2097:
+ case 0x2098:
+ case 0x2817:
+ case 0x2818:
+ case 0x2827:
+ case 0x2828:
+ mmap_rnd_mask = 0x7ffUL;
+ mmap_align_mask = 0UL;
+ break;
+ case 0x2964: /* z13 */
+ default:
+ mmap_rnd_mask = 0x3ff80UL;
+ mmap_align_mask = 0x7fUL;
+ break;
+ }
+ return 0;
+}
+early_initcall(setup_mmap_rnd);
Code Review / kvmfornfv.git / blobdiff