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-rw-r--r--arch/powerpc/kernel/process.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 0a3216433051..1168c5f440ab 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1165,7 +1165,22 @@ static inline unsigned long brk_rnd(void)
1165 1165
1166unsigned long arch_randomize_brk(struct mm_struct *mm) 1166unsigned long arch_randomize_brk(struct mm_struct *mm)
1167{ 1167{
1168 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd()); 1168 unsigned long base = mm->brk;
1169 unsigned long ret;
1170
1171#ifdef CONFIG_PPC64
1172 /*
1173 * If we are using 1TB segments and we are allowed to randomise
1174 * the heap, we can put it above 1TB so it is backed by a 1TB
1175 * segment. Otherwise the heap will be in the bottom 1TB
1176 * which always uses 256MB segments and this may result in a
1177 * performance penalty.
1178 */
1179 if (!is_32bit_task() && (mmu_highuser_ssize == MMU_SEGSIZE_1T))
1180 base = max_t(unsigned long, mm->brk, 1UL << SID_SHIFT_1T);
1181#endif
1182
1183 ret = PAGE_ALIGN(base + brk_rnd());
1169 1184
1170 if (ret < mm->brk) 1185 if (ret < mm->brk)
1171 return mm->brk; 1186 return mm->brk;