On Fri, 6 Nov 2015 12:43:08 +0100 Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > The open coded tests for checking whether a PTE maps a page as > uncached use a flawed 'pte_val(xxx) & CONST != CONST' pattern, > which is not guaranteed to work since the type of a mapping is an > index into the MAIR table, not a set of mutually exclusive bits. > > Considering that, on arm64, the S2 type definitions use the following > MAIR indexes > > #define MT_S2_NORMAL 0xf > #define MT_S2_DEVICE_nGnRE 0x1 > > we have been getting lucky merely because the S2 device mappings also > have the PTE_UXN bit set, which means that a device PTE still does not > equal a normal PTE after masking with the former type. > > Instead, implement proper checking against the MAIR indexes that are > known to define uncached memory attributes. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Very well spotted, thanks Ard! Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx> M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
