mirror of
https://github.com/torvalds/linux
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e6e5494cb2
Move the i386 VDSO down into a vma and thus randomize it. Besides the security implications, this feature also helps debuggers, which can COW a vma-backed VDSO just like a normal DSO and can thus do single-stepping and other debugging features. It's good for hypervisors (Xen, VMWare) too, which typically live in the same high-mapped address space as the VDSO, hence whenever the VDSO is used, they get lots of guest pagefaults and have to fix such guest accesses up - which slows things down instead of speeding things up (the primary purpose of the VDSO). There's a new CONFIG_COMPAT_VDSO (default=y) option, which provides support for older glibcs that still rely on a prelinked high-mapped VDSO. Newer distributions (using glibc 2.3.3 or later) can turn this option off. Turning it off is also recommended for security reasons: attackers cannot use the predictable high-mapped VDSO page as syscall trampoline anymore. There is a new vdso=[0|1] boot option as well, and a runtime /proc/sys/vm/vdso_enabled sysctl switch, that allows the VDSO to be turned on/off. (This version of the VDSO-randomization patch also has working ELF coredumping, the previous patch crashed in the coredumping code.) This code is a combined work of the exec-shield VDSO randomization code and Gerd Hoffmann's hypervisor-centric VDSO patch. Rusty Russell started this patch and i completed it. [akpm@osdl.org: cleanups] [akpm@osdl.org: compile fix] [akpm@osdl.org: compile fix 2] [akpm@osdl.org: compile fix 3] [akpm@osdl.org: revernt MAXMEM change] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Cc: Gerd Hoffmann <kraxel@suse.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Zachary Amsden <zach@vmware.com> Cc: Andi Kleen <ak@muc.de> Cc: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
147 lines
4.2 KiB
C
147 lines
4.2 KiB
C
#ifndef _I386_PAGE_H
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#define _I386_PAGE_H
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/* PAGE_SHIFT determines the page size */
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#define PAGE_SHIFT 12
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#define PAGE_SIZE (1UL << PAGE_SHIFT)
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#define PAGE_MASK (~(PAGE_SIZE-1))
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#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
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#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
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#ifdef __KERNEL__
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_X86_USE_3DNOW
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#include <asm/mmx.h>
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#define clear_page(page) mmx_clear_page((void *)(page))
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#define copy_page(to,from) mmx_copy_page(to,from)
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#else
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/*
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* On older X86 processors it's not a win to use MMX here it seems.
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* Maybe the K6-III ?
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*/
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#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
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#define copy_page(to,from) memcpy((void *)(to), (void *)(from), PAGE_SIZE)
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#endif
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#define clear_user_page(page, vaddr, pg) clear_page(page)
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#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)
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#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr)
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#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
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/*
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* These are used to make use of C type-checking..
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*/
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extern int nx_enabled;
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#ifdef CONFIG_X86_PAE
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extern unsigned long long __supported_pte_mask;
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typedef struct { unsigned long pte_low, pte_high; } pte_t;
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typedef struct { unsigned long long pmd; } pmd_t;
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typedef struct { unsigned long long pgd; } pgd_t;
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typedef struct { unsigned long long pgprot; } pgprot_t;
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#define pmd_val(x) ((x).pmd)
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#define pte_val(x) ((x).pte_low | ((unsigned long long)(x).pte_high << 32))
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#define __pmd(x) ((pmd_t) { (x) } )
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#define HPAGE_SHIFT 21
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#else
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typedef struct { unsigned long pte_low; } pte_t;
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typedef struct { unsigned long pgd; } pgd_t;
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typedef struct { unsigned long pgprot; } pgprot_t;
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#define boot_pte_t pte_t /* or would you rather have a typedef */
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#define pte_val(x) ((x).pte_low)
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#define HPAGE_SHIFT 22
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#endif
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#define PTE_MASK PAGE_MASK
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#ifdef CONFIG_HUGETLB_PAGE
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#define HPAGE_SIZE ((1UL) << HPAGE_SHIFT)
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#define HPAGE_MASK (~(HPAGE_SIZE - 1))
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#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
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#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
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#endif
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#define pgd_val(x) ((x).pgd)
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#define pgprot_val(x) ((x).pgprot)
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#define __pte(x) ((pte_t) { (x) } )
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#define __pgd(x) ((pgd_t) { (x) } )
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#define __pgprot(x) ((pgprot_t) { (x) } )
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#endif /* !__ASSEMBLY__ */
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/* to align the pointer to the (next) page boundary */
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#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
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/*
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* This handles the memory map.. We could make this a config
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* option, but too many people screw it up, and too few need
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* it.
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*
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* A __PAGE_OFFSET of 0xC0000000 means that the kernel has
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* a virtual address space of one gigabyte, which limits the
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* amount of physical memory you can use to about 950MB.
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*
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* If you want more physical memory than this then see the CONFIG_HIGHMEM4G
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* and CONFIG_HIGHMEM64G options in the kernel configuration.
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*/
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#ifndef __ASSEMBLY__
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struct vm_area_struct;
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/*
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* This much address space is reserved for vmalloc() and iomap()
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* as well as fixmap mappings.
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*/
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extern unsigned int __VMALLOC_RESERVE;
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extern int sysctl_legacy_va_layout;
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extern int page_is_ram(unsigned long pagenr);
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#endif /* __ASSEMBLY__ */
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#ifdef __ASSEMBLY__
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#define __PAGE_OFFSET CONFIG_PAGE_OFFSET
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#define __PHYSICAL_START CONFIG_PHYSICAL_START
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#else
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#define __PAGE_OFFSET ((unsigned long)CONFIG_PAGE_OFFSET)
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#define __PHYSICAL_START ((unsigned long)CONFIG_PHYSICAL_START)
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#endif
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#define __KERNEL_START (__PAGE_OFFSET + __PHYSICAL_START)
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#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
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#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
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#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE)
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#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
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#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
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#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
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#ifdef CONFIG_FLATMEM
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#define pfn_valid(pfn) ((pfn) < max_mapnr)
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#endif /* CONFIG_FLATMEM */
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#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
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#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
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#define VM_DATA_DEFAULT_FLAGS \
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(VM_READ | VM_WRITE | \
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((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \
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VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
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#include <asm-generic/memory_model.h>
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#include <asm-generic/page.h>
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#define __HAVE_ARCH_GATE_AREA 1
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#endif /* __KERNEL__ */
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#endif /* _I386_PAGE_H */
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