svn commit: r307971 - head/sys/mips/include

[John Baldwin]

On Wednesday, October 26, 2016 05:37:08 PM John Baldwin wrote:
> Author: jhb
> Date: Wed Oct 26 17:37:08 2016
> New Revision: 307971
> URL: https://svnweb.freebsd.org/changeset/base/307971
> 
> Log:
>   Correct definition of 'struct sigcontext' on MIPS.
>   
>   Add missing fields ('sr' and 'mc_tls') to 'struct sigcontext'.
>   
>   The kernel doesn't use 'struct sigcontext' but instead uses 'ucontext_t'
>   which includes 'mcontext_t' in 'struct sigframe' to build the signal frame.
>   As a result, this change is not an ABI change but simply making
>   'struct sigcontext' correct.  Note that 'struct sigcontext' is only used
>   for "Traditional BSD style" signal handlers.
>   
>   While here, rename the 'xxx' field to '__spare__' to match 'mcontext_t'.
>   
>   Sponsored by:	DARPA, AFRL

We should perhaps a static assertion somewhere that
sizeof(sigset_t) + sizeof(ucontext_t) == sizeof(struct sigcontext) if
that is really true of all of our architectures.

Alternatively, we might consider retiring 'struct sigcontext' altogether.
It's purpose has been superseded by SA_SIGINFO (which is more portable)
which has been around for quite a while now.  As a first step I guess
we could try an exp-run with 'struct sigcontext' removed.  (We should
have ditched this in 5.0 since we have a separate sendsig/sigreturn path
for FreeBSD 4.x already.  Oh well.)

-- 
John Baldwin