[PATCH] powerpc/64s: Fix possible corruption on big endian due to pgd/pud_present()
Michael Ellerman
mpe at ellerman.id.au
Sun Feb 17 19:34:36 AEDT 2019
Segher Boessenkool <segher at kernel.crashing.org> writes:
> Hi all,
>
> On Sat, Feb 16, 2019 at 09:55:11PM +1100, Balbir Singh wrote:
>> On Thu, Feb 14, 2019 at 05:23:39PM +1100, Michael Ellerman wrote:
>> > In v4.20 we changed our pgd/pud_present() to check for _PAGE_PRESENT
>> > rather than just checking that the value is non-zero, e.g.:
>> >
>> > static inline int pgd_present(pgd_t pgd)
>> > {
>> > - return !pgd_none(pgd);
>> > + return (pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
>> > }
>> >
>> > Unfortunately this is broken on big endian, as the result of the
>> > bitwise && is truncated to int, which is always zero because
>
> (Bitwise "&" of course).
Thanks, I fixed that up.
cheers
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