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

Catalin Marinas [off-list ref] writes:

On Fri, Nov 20, 2020 at 05:22:58PM -0600, Eric W. Biederman wrote:

quoted

Peter Collingbourne [off-list ref] writes:

quoted

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 <redacted>
Acked-by: "Eric W. Biederman" <redacted>
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