+ arm64-mm-support-arch_mmap_rnd_bits-v4.patch added to -mm tree

+ arm64-mm-support-arch_mmap_rnd_bits-v4.patch added to -mm tree

[akpm]

The patch titled
     Subject: arm64-mm-support-arch_mmap_rnd_bits-v4
has been added to the -mm tree.  Its filename is
     arm64-mm-support-arch_mmap_rnd_bits-v4.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/arm64-mm-support-arch_mmap_rnd_bits-v4.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/arm64-mm-support-arch_mmap_rnd_bits-v4.patch

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------------------------------------------------------
From: Daniel Cashman <dcashman@android.com>
Subject: arm64-mm-support-arch_mmap_rnd_bits-v4

arm64: arch_mmap_rnd() uses STACK_RND_MASK 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 default values as new minimums.

Signed-off-by: Daniel Cashman <dcashman@android.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/Kconfig   |   20 ++++++++++++++------
 arch/arm64/mm/mmap.c |    2 ++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff -puN arch/arm64/Kconfig~arm64-mm-support-arch_mmap_rnd_bits-v4 arch/arm64/Kconfig
--- a/arch/arm64/Kconfig~arm64-mm-support-arch_mmap_rnd_bits-v4
+++ a/arch/arm64/Kconfig
@@ -108,20 +108,28 @@ config MMU
 
 config ARCH_MMAP_RND_BITS_MIN
        default 15 if ARM64_64K_PAGES
+       default 17 if ARM64_16K_PAGES
        default 19
 
 config ARCH_MMAP_RND_BITS_MAX
-       default 20 if ARM64_64K_PAGES && ARCH_VA_BITS=39
-       default 24 if ARCH_VA_BITS=39
-       default 23 if ARM64_64K_PAGES && ARCH_VA_BITS=42
-       default 27 if ARCH_VA_BITS=42
-       default 29 if ARM64_64K_PAGES && ARCH_VA_BITS=48
-       default 33 if ARCH_VA_BITS=48
+       default 19 if ARM64_VA_BITS=36
+       default 20 if ARM64_64K_PAGES && ARM64_VA_BITS=39
+       default 22 if ARM64_16K_PAGES && ARM64_VA_BITS=39
+       default 24 if ARM64_VA_BITS=39
+       default 23 if ARM64_64K_PAGES && ARM64_VA_BITS=42
+       default 25 if ARM64_16K_PAGES && ARM64_VA_BITS=42
+       default 27 if ARM64_VA_BITS=42
+       default 30 if ARM64_VA_BITS=47
+       default 29 if ARM64_64K_PAGES && ARM64_VA_BITS=48
+       default 31 if ARM64_16K_PAGES && ARM64_VA_BITS=48
+       default 33 if ARM64_VA_BITS=48
        default 15 if ARM64_64K_PAGES
+       default 17 if ARM64_16K_PAGES
        default 19
 
 config ARCH_MMAP_RND_COMPAT_BITS_MIN
        default 7 if ARM64_64K_PAGES
+       default 9 if ARM64_16K_PAGES
        default 11
 
 config ARCH_MMAP_RND_COMPAT_BITS_MAX
diff -puN arch/arm64/mm/mmap.c~arm64-mm-support-arch_mmap_rnd_bits-v4 arch/arm64/mm/mmap.c
--- a/arch/arm64/mm/mmap.c~arm64-mm-support-arch_mmap_rnd_bits-v4
+++ a/arch/arm64/mm/mmap.c
@@ -51,9 +51,11 @@ unsigned long arch_mmap_rnd(void)
 {
 	unsigned long rnd;
 
+ifdef CONFIG_COMPAT
 	if (test_thread_flag(TIF_32BIT))
 		rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits);
 	else
+#endif
 		rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits);
 	return rnd << PAGE_SHIFT;
 }
_

Patches currently in -mm which might be from dcashman@android.com are

mm-mmap-add-new-proc-tunable-for-mmap_base-aslr-v4.patch
arm64-mm-support-arch_mmap_rnd_bits-v4.patch