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Matthew noticed that hugetlb mappings don't participate in ASLR on x86-64: % for i in `seq 3`; do > tools/testing/selftests/vm/map_hugetlb | grep address > done Returned address is 0x2aaaaac00000 Returned address is 0x2aaaaac00000 Returned address is 0x2aaaaac00000 /proc/PID/maps entries for the mapping are always the same (except inode number): 2aaaaac00000-2aaabac00000 rw-p 00000000 00:0c 8200 /anon_hugepage (deleted) 2aaaaac00000-2aaabac00000 rw-p 00000000 00:0c 256 /anon_hugepage (deleted) 2aaaaac00000-2aaabac00000 rw-p 00000000 00:0c 7180 /anon_hugepage (deleted) The reason is the generic hugetlb_get_unmapped_area() function which is used on x86-64. It doesn't support randomization and use bottom-up unmapped area lookup, instead of usual top-down on x86-64. x86 has arch-specific hugetlb_get_unmapped_area(), but it's used only on x86-32. Let's use arch-specific hugetlb_get_unmapped_area() on x86-64 too. That adds ASLR and switches hugetlb mappings to use top-down unmapped area lookup: % for i in `seq 3`; do > tools/testing/selftests/vm/map_hugetlb | grep address > done Returned address is 0x7f4f08a00000 Returned address is 0x7fdda4200000 Returned address is 0x7febe0000000 /proc/PID/maps entries: 7f4f08a00000-7f4f18a00000 rw-p 00000000 00:0c 1168 /anon_hugepage (deleted) 7fdda4200000-7fddb4200000 rw-p 00000000 00:0c 7092 /anon_hugepage (deleted) 7febe0000000-7febf0000000 rw-p 00000000 00:0c 7183 /anon_hugepage (deleted) Unmapped area lookup policy for hugetlb mappings is consistent with normal mappings now -- the only difference is alignment requirements for huge pages. libhugetlbfs test-suite didn't detect any regressions with the patch applied (although it shows few failures on my machine regardless the patch). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mel Gorman <mgorman@suse.de> Link: http://lkml.kernel.org/r/20131119131750.EA45CE0090@blue.fi.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
78 lines
2.1 KiB
C
78 lines
2.1 KiB
C
#ifndef _ASM_X86_PAGE_H
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#define _ASM_X86_PAGE_H
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#include <linux/types.h>
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#ifdef __KERNEL__
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#include <asm/page_types.h>
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#ifdef CONFIG_X86_64
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#include <asm/page_64.h>
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#else
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#include <asm/page_32.h>
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#endif /* CONFIG_X86_64 */
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#ifndef __ASSEMBLY__
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struct page;
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#include <linux/range.h>
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extern struct range pfn_mapped[];
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extern int nr_pfn_mapped;
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static inline void clear_user_page(void *page, unsigned long vaddr,
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struct page *pg)
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{
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clear_page(page);
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}
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static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
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struct page *topage)
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{
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copy_page(to, from);
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}
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#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
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alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
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#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
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#define __pa(x) __phys_addr((unsigned long)(x))
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#define __pa_nodebug(x) __phys_addr_nodebug((unsigned long)(x))
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/* __pa_symbol should be used for C visible symbols.
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This seems to be the official gcc blessed way to do such arithmetic. */
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/*
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* We need __phys_reloc_hide() here because gcc may assume that there is no
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* overflow during __pa() calculation and can optimize it unexpectedly.
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* Newer versions of gcc provide -fno-strict-overflow switch to handle this
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* case properly. Once all supported versions of gcc understand it, we can
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* remove this Voodoo magic stuff. (i.e. once gcc3.x is deprecated)
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*/
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#define __pa_symbol(x) \
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__phys_addr_symbol(__phys_reloc_hide((unsigned long)(x)))
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#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
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#define __boot_va(x) __va(x)
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#define __boot_pa(x) __pa(x)
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/*
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* virt_to_page(kaddr) returns a valid pointer if and only if
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* virt_addr_valid(kaddr) returns true.
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*/
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#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
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#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
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extern bool __virt_addr_valid(unsigned long kaddr);
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#define virt_addr_valid(kaddr) __virt_addr_valid((unsigned long) (kaddr))
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#endif /* __ASSEMBLY__ */
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#include <asm-generic/memory_model.h>
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#include <asm-generic/getorder.h>
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#define __HAVE_ARCH_GATE_AREA 1
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#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
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#endif /* __KERNEL__ */
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#endif /* _ASM_X86_PAGE_H */
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