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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2015-11-10 12:30:28 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2015-11-16 12:04:18 +0100
commitc7e8b2c21c6a6fd88022ae64f997ebc574036067 (patch)
tree4e625e806cfb7c30e8053a7e88ad04f4aa83b7a4 /arch/s390/include/asm/elf.h
parentf07f21b3e20c11017cea17ec841f0150a62aac53 (diff)
downloadlinux-linaro-stable-c7e8b2c21c6a6fd88022ae64f997ebc574036067.tar.gz
s390: avoid cache aliasing under z/VM and KVM
commit 1f6b83e5e4d3 ("s390: avoid z13 cache aliasing") checks for the machine type to optimize address space randomization and zero page allocation to avoid cache aliases. This check might fail under a hypervisor with migration support. z/VMs "Single System Image and Live Guest Relocation" facility will "fake" the machine type of the oldest system in the group. For example in a group of zEC12 and Z13 the guest appears to run on a zEC12 (architecture fencing within the relocation domain) Remove the machine type detection and always use cache aliasing rules that are known to work for all machines. These are the z13 aliasing rules. Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/elf.h')
-rw-r--r--arch/s390/include/asm/elf.h13
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 3ad48f22de78..bab6739a1154 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -206,9 +206,16 @@ do { \
} while (0)
#endif /* CONFIG_COMPAT */
-extern unsigned long mmap_rnd_mask;
-
-#define STACK_RND_MASK (test_thread_flag(TIF_31BIT) ? 0x7ff : mmap_rnd_mask)
+/*
+ * Cache aliasing on the latest machines calls for a mapping granularity
+ * of 512KB. For 64-bit processes use a 512KB alignment and a randomization
+ * of up to 1GB. For 31-bit processes the virtual address space is limited,
+ * use no alignment and limit the randomization to 8MB.
+ */
+#define BRK_RND_MASK (is_32bit_task() ? 0x7ffUL : 0x3ffffUL)
+#define MMAP_RND_MASK (is_32bit_task() ? 0x7ffUL : 0x3ff80UL)
+#define MMAP_ALIGN_MASK (is_32bit_task() ? 0 : 0x7fUL)
+#define STACK_RND_MASK MMAP_RND_MASK
#define ARCH_DLINFO \
do { \