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author | Catalin Marinas <catalin.marinas@arm.com> | 2012-03-05 11:49:27 (GMT) |
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committer | Catalin Marinas <catalin.marinas@arm.com> | 2012-09-17 12:41:57 (GMT) |
commit | 1d18c47c735e8adfe531fc41fae31e98f86b68fe (patch) | |
tree | b63f253304e2d955e1a17d12e4f0dc94312f58ea /arch/arm64/mm/mmap.c | |
parent | c1cc1552616d0f354d040823151e61634e7ad01f (diff) | |
download | linux-1d18c47c735e8adfe531fc41fae31e98f86b68fe.tar.xz |
arm64: MMU fault handling and page table management
This patch adds support for the handling of the MMU faults (exception
entry code introduced by a previous patch) and page table management.
The user translation table is pointed to by TTBR0 and the kernel one
(swapper_pg_dir) by TTBR1. There is no translation information shared or
address space overlapping between user and kernel page tables.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/arm64/mm/mmap.c')
-rw-r--r-- | arch/arm64/mm/mmap.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c new file mode 100644 index 0000000..7c7be78 --- /dev/null +++ b/arch/arm64/mm/mmap.c @@ -0,0 +1,144 @@ +/* + * Based on arch/arm/mm/mmap.c + * + * Copyright (C) 2012 ARM Ltd. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/elf.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/export.h> +#include <linux/shm.h> +#include <linux/sched.h> +#include <linux/io.h> +#include <linux/personality.h> +#include <linux/random.h> + +#include <asm/cputype.h> + +/* + * Leave enough space between the mmap area and the stack to honour ulimit in + * the face of randomisation. + */ +#define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1)) +#define MAX_GAP (STACK_TOP/6*5) + +static 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; +} + +/* + * Since get_random_int() returns the same value within a 1 jiffy window, we + * will almost always get the same randomisation for the stack and mmap + * region. This will mean the relative distance between stack and mmap will be + * the same. + * + * To avoid this we can shift the randomness by 1 bit. + */ +static unsigned long mmap_rnd(void) +{ + unsigned long rnd = 0; + + if (current->flags & PF_RANDOMIZE) + rnd = (long)get_random_int() & (STACK_RND_MASK >> 1); + + return rnd << (PAGE_SHIFT + 1); +} + +static unsigned long mmap_base(void) +{ + unsigned long gap = rlimit(RLIMIT_STACK); + + if (gap < MIN_GAP) + gap = MIN_GAP; + else if (gap > MAX_GAP) + gap = MAX_GAP; + + return PAGE_ALIGN(STACK_TOP - gap - mmap_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) +{ + /* + * 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; + mm->unmap_area = arch_unmap_area; + } else { + mm->mmap_base = mmap_base(); + mm->get_unmapped_area = arch_get_unmapped_area_topdown; + mm->unmap_area = arch_unmap_area_topdown; + } +} +EXPORT_SYMBOL_GPL(arch_pick_mmap_layout); + + +/* + * You really shouldn't be using read() or write() on /dev/mem. This might go + * away in the future. + */ +int valid_phys_addr_range(unsigned long addr, size_t size) +{ + if (addr < PHYS_OFFSET) + return 0; + if (addr + size > __pa(high_memory - 1) + 1) + return 0; + + return 1; +} + +/* + * Do not allow /dev/mem mappings beyond the supported physical range. + */ +int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) +{ + return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK); +} + +#ifdef CONFIG_STRICT_DEVMEM + +#include <linux/ioport.h> + +/* + * devmem_is_allowed() checks to see if /dev/mem access to a certain address + * is valid. The argument is a physical page number. We mimic x86 here by + * disallowing access to system RAM as well as device-exclusive MMIO regions. + * This effectively disable read()/write() on /dev/mem. + */ +int devmem_is_allowed(unsigned long pfn) +{ + if (iomem_is_exclusive(pfn << PAGE_SHIFT)) + return 0; + if (!page_is_ram(pfn)) + return 1; + return 0; +} + +#endif |