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

[Eric W. Biederman]

Catalin Marinas <catalin.marinas at arm.com> writes:

> 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).

No.  I won't be rebasing it.  Not unless something serious problem shows
up, and at that point I will be more likely to apply a corrective change
on top that you can also grab.

Eric