On Thu, 3 Dec 2015, Dave Hansen wrote: > > From: Dave Hansen <[email protected]> > > Today, mprotect() takes 4 bits of data: PROT_READ/WRITE/EXEC/NONE. > Three of those bits: READ/WRITE/EXEC get translated directly in to > vma->vm_flags by calc_vm_prot_bits(). If a bit is unset in > mprotect()'s 'prot' argument then it must be cleared in vma->vm_flags > during the mprotect() call. > > We do the by first calculating the VMA flags we want set, then > clearing the ones we do not want to inherit from the original VMA: > > vm_flags = calc_vm_prot_bits(prot, key); > ... > newflags = vm_flags; > newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); > > However, we *also* want to mask off the original VMA's vm_flags in > which we store the protection key. > > To do that, this patch adds a new macro: > > ARCH_VM_FLAGS_AFFECTED_BY_MPROTECT
-ENOSUCHMACRO > which allows the architecture to specify additional bits that it would > like cleared. We use that to ensure that the VM_PKEY_BIT* bits get > cleared. Other than that: Reviewed-by: Thomas Gleixner <[email protected]> -- 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/
