2017-02-10 23:10 GMT+03:00 Thomas Gleixner <tglx@xxxxxxxxxxxxx>:
> On Thu, 9 Feb 2017, Borislav Petkov wrote:
>> I can't say that I'm thrilled about the ifdeffery this is adding.
>>
>> But I can't think of a cleaner approach at a quick glance, though -
>> that's generic and arch-specific code intertwined muck. Sad face.
>
> It's trivial enough to do ....
>
> Thanks,
>
> tglx
>
> ---
> arch/x86/mm/mmap.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
> #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
> #define MAX_GAP (TASK_SIZE/6*5)
>
> +#ifndef CONFIG_COMPAT
> +# define mmap_rnd_compat_bits mmap_rnd_bits
> +#endif
> +
>From my POV, I can't say that it's clearer to shadow mmap_compat_bits
like that then to have two functions with native/compat names.
But if you insist, I'll resend patches set with your version.
> static int mmap_is_legacy(void)
> {
> if (current->personality & ADDR_COMPAT_LAYOUT)
> @@ -66,20 +70,14 @@ static int mmap_is_legacy(void)
> return sysctl_legacy_va_layout;
> }
>
> -unsigned long arch_mmap_rnd(void)
> +static unsigned long arch_rnd(unsigned int rndbits)
> {
> - unsigned long rnd;
> -
> - if (mmap_is_ia32())
> -#ifdef CONFIG_COMPAT
> - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
> -#else
> - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> -#endif
> - else
> - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> + return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
> +}
>
> - return rnd << PAGE_SHIFT;
> +unsigned long arch_mmap_rnd(void)
> +{
> + return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits);
> }
>
> static unsigned long mmap_base(unsigned long rnd)
--
Dmitry
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