On 11/22/2017 01:15 PM, Florian Weimer wrote: > On 11/22/2017 09:18 AM, Vlastimil Babka wrote: >> And, was the pkey == -1 internal wiring supposed to be exposed to the >> pkey_mprotect() signal, or should there have been a pre-check returning >> EINVAL in SYSCALL_DEFINE4(pkey_mprotect), before calling >> do_mprotect_pkey())? I assume it's too late to change it now anyway (or >> not?), so should we also document it? > > I think the -1 case to the set the default key is useful because it > allows you to use a key value of -1 to mean “MPK is not supported”, and > still call pkey_mprotect. Hmm the current manpage says then when MPK is not supported, pkey has to be specified 0. Which is a value that doesn't work when MPK *is* supported. So -1 is more universal indeed. > I plan to document this behavior on the glibc side, and glibc will call > mprotect (not pkey_mprotect) for key -1, so that you won't get ENOSYS > with kernels which do not support pkey_mprotect. Fair enough. What will you do about pkey_alloc() in that case, emulate ENOSPC? Oh, the manpage already suggests so. And the return value in that case is... -1. Makes sense :) > Thanks, > Florian > -- > To unsubscribe from this list: send the line "unsubscribe linux-api" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html >
