diff options
| -rw-r--r-- | arch/powerpc/kernel/process.c | 17 |
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) unsigned long arch_randomize_brk(struct mm_struct *mm) { - unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd()); + unsigned long base = mm->brk; + unsigned long ret; + +#ifdef CONFIG_PPC64 + /* + * If we are using 1TB segments and we are allowed to randomise + * the heap, we can put it above 1TB so it is backed by a 1TB + * segment. Otherwise the heap will be in the bottom 1TB + * which always uses 256MB segments and this may result in a + * performance penalty. + */ + if (!is_32bit_task() && (mmu_highuser_ssize == MMU_SEGSIZE_1T)) + base = max_t(unsigned long, mm->brk, 1UL << SID_SHIFT_1T); +#endif + + ret = PAGE_ALIGN(base + brk_rnd()); if (ret < mm->brk) return mm->brk; |