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authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-01-12 09:55:30 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2011-01-12 09:55:25 +0100
commit3351918282fd664e918a3175ddfae9b15656122e (patch)
treefcfcf8d8ab1ad7380d802276e0dc4a0026b70d84 /arch/s390/kernel
parenta05c90f1948baacedd0c3e7e3250225be4cae727 (diff)
downloadlinux-linaro-stable-3351918282fd664e918a3175ddfae9b15656122e.tar.gz
[S390] Randomise the brk region
Randomize heap address like other architectures do already. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel')
-rw-r--r--arch/s390/kernel/process.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 38ff69e562c8..26d48fe72999 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -341,3 +341,21 @@ unsigned long arch_align_stack(unsigned long sp)
sp -= get_random_int() & ~PAGE_MASK;
return sp & ~0xf;
}
+
+static inline unsigned long brk_rnd(void)
+{
+ /* 8MB for 32bit, 1GB for 64bit */
+ if (is_32bit_task())
+ return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
+ else
+ return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
+}
+
+unsigned long arch_randomize_brk(struct mm_struct *mm)
+{
+ unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
+
+ if (ret < mm->brk)
+ return mm->brk;
+ return ret;
+}