Messages in this thread | | | Subject | Re: [PATCH 6/6] x86: Fix stray A/D bit setting into non-present PTEs | From | Dave Hansen <> | Date | Fri, 1 Jul 2016 08:51:36 -0700 |
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On 07/01/2016 07:25 AM, Eric W. Biederman wrote: > Linus Torvalds <torvalds@linux-foundation.org> writes: >> > On Thu, Jun 30, 2016 at 9:39 PM, Dave Hansen <dave@sr71.net> wrote: >>> >> >>> >> I think what you suggest will work if we don't consider A/D in >>> >> pte_none(). I think there are a bunch of code path where assume that >>> >> !pte_present() && !pte_none() means swap. >> > >> > Yeah, we would need to change pte_none() to mask off D/A, but I think >> > that might be the only real change needed (other than making sure that >> > we don't use the bits in the swap entries, I didn't look at that part >> > at all) > It looks like __pte_to_swp_entry also needs to be changed to mask out > those bits when the swap code reads pte entries. For all of the same > reasons as pte_none.
I guess that would be nice, but isn't it redundant?
static inline swp_entry_t pte_to_swp_entry(pte_t pte) { ... arch_entry = __pte_to_swp_entry(pte); return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); }
As long as __swp_type() and __swp_offset() don't let A/D through, then we should be OK. This site is the only call to __pte_to_swp_entry() that I can find in the entire codebase.
Or am I missing something?
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