On Thu, Sep 04, 2014 at 06:23:42PM +0100, Kees Cook wrote: > On Thu, Sep 4, 2014 at 10:03 AM, Will Deacon <[email protected]> wrote: > > Hi Kees, > > > > On Wed, Sep 03, 2014 at 10:57:04PM +0100, Kees Cook wrote: > >> This is used from set_fixmap() and clear_fixmap() via asm-generic/fixmap.h. > >> Also makes sure that the fixmap allocation fits into the expected range. > >> > >> Based on patch by Rabin Vincent. > > > > [...] > > > >> +void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t > >> prot) > >> +{ > >> + unsigned long vaddr = __fix_to_virt(idx); > >> + pte_t *pte = pte_offset_kernel(pmd_off_k(vaddr), vaddr); > >> + > >> + /* Make sure fixmap region does not exceed available allocation. */ > >> + BUILD_BUG_ON(FIXADDR_START + (__end_of_fixed_addresses * PAGE_SIZE) > > >> + FIXADDR_END); > >> + BUG_ON(idx >= __end_of_fixed_addresses); > >> + > >> + if (pgprot_val(prot)) > >> + set_pte_at(NULL, vaddr, pte, > >> + pfn_pte(phys >> PAGE_SHIFT, prot)); > >> + else > >> + pte_clear(NULL, vaddr, pte); > >> + > >> + /* > >> + * Given the potential a15 tlbi errata, we can only do tlb flushes > >> + * with interrupts disabled. Callers must have taken care of this. > >> + */ > >> + WARN_ON_ONCE(!irqs_disabled()); > >> + flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); > > > > Aha, this explains why we were confusing each other! The issue is that > > interrupts must be *enabled*, so this code does the exact opposite of > > what we need. > > > > I think this got lost in a sea of double negatives during the last round > > of review. > > Ah! If this is the case, perhaps we can get away with > local_flush_tlb_kernel_range() then?
That's a bit tricky, since you need to ensure that preemption is disabled until the mapping is put back like it was. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
