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s390/mm: optimize randomize_et_dyn for !PF_RANDOMIZE

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Skip the call to brk_rnd() if the PF_RANDOMIZE flag is not set for
the process. This avoids the costly get_random_int() call. Modify
arch_randomize_brk() as well to make it look like randomize_et_dyn().

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2013-12-17 13:41:31 +01:00
parent 61aa4884b7
commit 9efe4f2992
1 changed files with 6 additions and 8 deletions
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14
arch/s390/kernel/process.c
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@ -261,20 +261,18 @@ 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 ret;
if (ret < mm->brk)
return mm->brk;
return ret;
ret = PAGE_ALIGN(mm->brk + brk_rnd());
return (ret > mm->brk) ? ret : mm->brk;
}
unsigned long randomize_et_dyn(unsigned long base)
{
unsigned long ret = PAGE_ALIGN(base + brk_rnd());
unsigned long ret;
if (!(current->flags & PF_RANDOMIZE))
return base;
if (ret < base)
return base;
return ret;
ret = PAGE_ALIGN(base + brk_rnd());
return (ret > base) ? ret : base;
}