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67f3977f80
arm64 handles top-down mmap layout in a way that can be easily reused by other architectures, so make it available in mm. It then introduces a new config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT that can be set by other architectures to benefit from those functions. Note that this new config depends on MMU being enabled, if selected without MMU support, a warning will be thrown. Link: http://lkml.kernel.org/r/20190730055113.23635-5-alex@ghiti.fr Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Suggested-by: Christoph Hellwig <hch@infradead.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: James Hogan <jhogan@kernel.org> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
71 lines
1.8 KiB
C
71 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Based on arch/arm/mm/mmap.c
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*
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* Copyright (C) 2012 ARM Ltd.
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*/
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#include <linux/elf.h>
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#include <linux/fs.h>
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#include <linux/memblock.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/export.h>
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#include <linux/shm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/mm.h>
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#include <linux/io.h>
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#include <linux/personality.h>
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#include <linux/random.h>
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#include <asm/cputype.h>
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/*
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* You really shouldn't be using read() or write() on /dev/mem. This might go
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* away in the future.
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*/
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int valid_phys_addr_range(phys_addr_t addr, size_t size)
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{
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/*
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* Check whether addr is covered by a memory region without the
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* MEMBLOCK_NOMAP attribute, and whether that region covers the
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* entire range. In theory, this could lead to false negatives
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* if the range is covered by distinct but adjacent memory regions
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* that only differ in other attributes. However, few of such
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* attributes have been defined, and it is debatable whether it
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* follows that /dev/mem read() calls should be able traverse
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* such boundaries.
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*/
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return memblock_is_region_memory(addr, size) &&
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memblock_is_map_memory(addr);
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}
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/*
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* Do not allow /dev/mem mappings beyond the supported physical range.
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*/
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int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
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{
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return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
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}
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#ifdef CONFIG_STRICT_DEVMEM
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#include <linux/ioport.h>
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/*
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* devmem_is_allowed() checks to see if /dev/mem access to a certain address
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* is valid. The argument is a physical page number. We mimic x86 here by
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* disallowing access to system RAM as well as device-exclusive MMIO regions.
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* This effectively disable read()/write() on /dev/mem.
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*/
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int devmem_is_allowed(unsigned long pfn)
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{
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if (iomem_is_exclusive(pfn << PAGE_SHIFT))
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return 0;
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if (!page_is_ram(pfn))
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return 1;
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return 0;
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}
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#endif
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