Date: Fri, 28 Oct 2016 09:59:26 -0700 From: John Baldwin <jhb@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r307971 - head/sys/mips/include Message-ID: <4639059.6gemL8B1hY@ralph.baldwin.cx> In-Reply-To: <20161028153158.GD54029@kib.kiev.ua> References: <201610261737.u9QHb8Ps036831@repo.freebsd.org> <11698910.Akp5I7OyZ5@ralph.baldwin.cx> <20161028153158.GD54029@kib.kiev.ua>
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On Friday, October 28, 2016 06:31:58 PM Konstantin Belousov wrote: > On Thu, Oct 27, 2016 at 03:08:01PM -0700, John Baldwin wrote: > > 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. > This should be mcontext_t instead of ucontext_t. Yes. I will try adding that static assert to sys/kern/kern_sig.c and seeing if it survives a universe build. > > 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 It's purpose has been superseded by SA_SIGINFO (which is more portable) 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.) > > I do not think that this is a practical option. I know that struct > sigcontext is used by nongnu libunwind. Quick search identifies mono and > go as consumers as well. Well, we could perhaps patch those to use SA_SIGINFO instead, but if it's a non-trivial amount of effort I'm not going to bother. I'm surprised that some of those would use sigcontext. Both mono and go post-date SA_SIGINFO being standardized and supported on FreeBSD AFAIK. Supporting sigcontext just means extra BSD-specific code in those applications compared to using SA_SIGINFO. :-/ -- John Baldwin
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