This version looks really clean. Thank for keeping working on
this through 9 versions!
A couple of small issues.
1) In arch/ia64/mm/init.c: __ia64_sync_icache_dcache()
- if (!pte_exec(pte))
- return; /* not an executable page... */
+ BUG_ON(!pte_exec(pte));
In this latest version the only route to this routine is from set_pte()
inside the test :
if (pte_exec(pteval) && ....) {
}
So this BUG_ON is now redundant.
2) In include/asm-ia64/pgtable.h
+ if (pte_exec(pteval) && // flush only new executable page.
+ pte_present(pteval) && // swap out ?
+ pte_user(pteval) && // ignore kernel page
+ (!pte_present(*ptep) ||// do_no_page or swap in, migration,
+ pte_pfn(*ptep) != pte_pfn(pteval))) // do_wp_page(), page copy
+ /* load_module() calles flush_icache_range() explicitly*/
+ __ia64_sync_icache_dcache(pteval);
Just above this there is a comment saying that pte_exec() only works
when pte_present() is true. So we must re-order the conditions so that
we check that the pteval satisfies pte_present() before using either of
pte_exec() or pte_user() on it like this:
if (pte_present(pteval) &&
pte_exec(pteval) &&
pte_user(pteval) &&
I put in some crude counters to see whether we should check pte_exec() or
pte_user() next ... and it was very clear that the pte_exec() check gets
us out of the if() faster (at least during a kernel build).
I also compared how often the old code called lazy_mmu_prot_update()
with how often the new code calls __ia64_sync_icache_dcache() (again
using kernel build as my workload) ... and the answer is about the
same (less than 0.2% change ... probably less than run-to-run variation).
So now the only remaining task is to convince myself that this
new version covers all the cases.
-Tony
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