[PATCH v21 1/2] signal: define the SA_EXPOSE_TAGBITS bit in sa_flags

[Catalin Marinas]

On Fri, Nov 20, 2020 at 05:22:58PM -0600, Eric W. Biederman wrote:
> Peter Collingbourne <pcc at google.com> writes:
> 
> > Architectures that support address tagging, such as arm64, may want to
> > expose fault address tag bits to the signal handler to help diagnose
> > memory errors. However, these bits have not been previously set,
> > and their presence may confuse unaware user applications. Therefore,
> > introduce a SA_EXPOSE_TAGBITS flag bit in sa_flags that a signal
> > handler may use to explicitly request that the bits are set.
> >
> > The generic signal handler APIs expect to receive tagged addresses.
> > Architectures may specify how to untag addresses in the case where
> > SA_EXPOSE_TAGBITS is clear by defining the arch_untagged_si_addr
> > function.
> >
> > Signed-off-by: Peter Collingbourne <pcc at google.com>
> > Acked-by: "Eric W. Biederman" <ebiederm at xmission.com>
> > Link: https://linux-review.googlesource.com/id/I16dd0ed2081f091fce97be0190cb8caa874c26cb
> > ---
> > To be applied on top of:
> > https://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git signal-for-v5.11
> 
> I have merged this first patch into signal-for-v5.11 and pushed
> everything out to linux-next.

Thank you Eric. Assuming this branch won't be rebased, I'll apply the
arm64 changes on top (well, if you rebase it, just let me know so that
we don't end up with duplicate commits in mainline).

-- 
Catalin