On x86_32 casting the unsigned int result of get_random_int() to
long may result in a negative value. On x86_32 the range of
mmap_rnd() therefore was -255 to 255. The 32bit mode on x86_64
used 0 to 255 as intended.
The bug was introduced by 675a081 ("x86: unify mmap_{32|64}.c")
in January 2008.
Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: harvey.harrison@gmail.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/201111152246.pAFMklOB028527@wpaz5.hot.corp.google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
hpa reported that dfb09f9b7a breaks 32-bit
builds with the following error message:
/home/hpa/kernel/linux-tip.cpu/arch/x86/kernel/cpu/amd.c:437: undefined
reference to `va_align'
/home/hpa/kernel/linux-tip.cpu/arch/x86/kernel/cpu/amd.c:436: undefined
reference to `va_align'
This is due to the fact that va_align is a global in a 64-bit only
compilation unit. Move it to mmap.c where it is visible to both
subarches.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1312633899-1131-1-git-send-email-bp@amd64.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This patch provides performance tuning for the "Bulldozer" CPU. With its
shared instruction cache there is a chance of generating an excessive
number of cache cross-invalidates when running specific workloads on the
cores of a compute module.
This excessive amount of cross-invalidations can be observed if cache
lines backed by shared physical memory alias in bits [14:12] of their
virtual addresses, as those bits are used for the index generation.
This patch addresses the issue by clearing all the bits in the [14:12]
slice of the file mapping's virtual address at generation time, thus
forcing those bits the same for all mappings of a single shared library
across processes and, in doing so, avoids instruction cache aliases.
It also adds the command line option "align_va_addr=(32|64|on|off)" with
which virtual address alignment can be enabled for 32-bit or 64-bit x86
individually, or both, or be completely disabled.
This change leaves virtual region address allocation on other families
and/or vendors unaffected.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1312550110-24160-2-git-send-email-bp@amd64.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Make sure compiler won't do weird things with limits. Fetching them
twice may return 2 different values after writable limits are
implemented.
We can either use rlimit helpers added in
3e10e716ab or ACCESS_ONCE if not
applicable; this patch uses the helpers.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
LKML-Reference: <1264609942-24621-1-git-send-email-jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Currently we are not including randomized stack size when calculating
mmap_base address in arch_pick_mmap_layout for topdown case. This might
cause that mmap_base starts in the stack reserved area because stack is
randomized by 1GB for 64b (8MB for 32b) and the minimum gap is 128MB.
If the stack really grows down to mmap_base then we can get silent mmap
region overwrite by the stack values.
Let's include maximum stack randomization size into MIN_GAP which is
used as the low bound for the gap in mmap.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
LKML-Reference: <1252400515-6866-1-git-send-email-mhocko@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Stable Team <stable@kernel.org>
mmap_is_ia32 always true for X86_32, or while emulating IA32 on X86_64
Randomization not supported on X86_32 in legacy layout. Both layouts allow
randomization on X86_64.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
