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    arm: mm: support ARCH_MMAP_RND_BITS · e0c25d95
    Daniel Cashman authored
    
    
    arm: arch_mmap_rnd() uses a hard-code value of 8 to generate the random
    offset for the mmap base address.  This value represents a compromise
    between increased ASLR effectiveness and avoiding address-space
    fragmentation.  Replace it with a Kconfig option, which is sensibly
    bounded, so that platform developers may choose where to place this
    compromise.  Keep 8 as the minimum acceptable value.
    
    [arnd@arndb.de: ARM: avoid ARCH_MMAP_RND_BITS for NOMMU]
    Signed-off-by: default avatarDaniel Cashman <dcashman@google.com>
    Cc: Russell King <linux@arm.linux.org.uk>
    Acked-by: default avatarKees Cook <keescook@chromium.org>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Jonathan Corbet <corbet@lwn.net>
    Cc: Don Zickus <dzickus@redhat.com>
    Cc: Eric W. Biederman <ebiederm@xmission.com>
    Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Mark Salyzyn <salyzyn@android.com>
    Cc: Jeff Vander Stoep <jeffv@google.com>
    Cc: Nick Kralevich <nnk@google.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Hector Marco-Gisbert <hecmargi@upv.es>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    e0c25d95