On Tue, Nov 17, 2020 at 10:17 AM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > Peter Collingbourne <pcc@xxxxxxxxxx> writes: > > > The kernel currently clears the tag bits (i.e. bits 56-63) in the fault > > address exposed via siginfo.si_addr and sigcontext.fault_address. However, > > the tag bits may be needed by tools in order to accurately diagnose > > memory errors, such as HWASan [1] or future tools based on the Memory > > Tagging Extension (MTE). > > > > We should not stop clearing these bits in the existing fault address > > fields, because there may be existing userspace applications that are > > expecting the tag bits to be cleared. Instead, introduce a flag in > > sigaction.sa_flags, SA_EXPOSE_TAGBITS, and only expose the tag bits > > there if the signal handler has this flag set. > > > > In order to allow userspace to determine whether SA_EXPOSE_TAGBITS > > is supported, we first introduce a mechanism for userspace to detect > > kernel support for SA_* flags. > > > > These patches need to be applied on top of: > > https://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git signal-for-v5.11 > > The first two patches look good and I have applied them. > > While I was at it I added Link tags to the LKML postings to the entire > series. I don't think anyone has merged my branch into another so it > should still be safe. Thanks! Peter
