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Date: Wed, 8 Feb 2023 16:45:31 -0500
From: Rich Felker <dalias@...c.org>
To: enh <enh@...gle.com>
Cc: Khem Raj <raj.khem@...il.com>, musl@...ts.openwall.com
Subject: Re: SA_RESTORER for rv64?

On Mon, Feb 06, 2023 at 12:49:53PM -0500, Rich Felker wrote:
> On Mon, Feb 06, 2023 at 08:51:13AM -0800, enh wrote:
> > On Sun, Feb 5, 2023 at 3:54 PM Rich Felker <dalias@...c.org> wrote:
> > >
> > > On Fri, Feb 03, 2023 at 10:44:56AM -0800, enh wrote:
> > > > oops, never actually sent the patch. attached...
> > > >
> > > > On Thu, Nov 10, 2022 at 9:31 AM Khem Raj <raj.khem@...il.com> wrote:
> > > > >
> > > > > On Thu, Nov 10, 2022 at 9:19 AM Rich Felker <dalias@...c.org> wrote:
> > > > > >
> > > > > > On Thu, Nov 10, 2022 at 07:44:23AM -0800, enh wrote:
> > > > > > > arch/riscv64/bits/signal.h has contained a definition for SA_RESTORER since
> > > > > > > the initial commit, but i think that's just copy & paste from whichever
> > > > > > > architecture the rv64 headers were based on? the linux kernel itself
> > > > > > > doesn't have SA_RESTORER for rv64, unless i'm missing something?
> > > > > >
> > > > > > I suspect this is just a mistake. Have you seen any ill effects from
> > > > > > it? If riscv folks can confirm it's wrong, I'll remove it.
> > > > >
> > > > > Yeah I think it should be removed. Perhaps mips is in same boat.
> > > > >
> > > > > >
> > > > > > Rich
> > >
> > > > From 6413de6d9f785c98e5bc0cf40be947f1169d2fd7 Mon Sep 17 00:00:00 2001
> > > > From: Elliott Hughes <enh@...gle.com>
> > > > Date: Fri, 3 Feb 2023 10:42:55 -0800
> > > > Subject: [PATCH] risc-v does not have SA_RESTORER.
> > > >
> > > > The kernel's include/uapi/asm-generic/signal-defs.h explicitly calls
> > > > this out as obsolete. New architectures like risc-v do not define it.
> > > > ---
> > > >  arch/riscv64/bits/signal.h | 1 -
> > > >  1 file changed, 1 deletion(-)
> > > >
> > > > diff --git a/arch/riscv64/bits/signal.h b/arch/riscv64/bits/signal.h
> > > > index 287367db..fd6157a3 100644
> > > > --- a/arch/riscv64/bits/signal.h
> > > > +++ b/arch/riscv64/bits/signal.h
> > > > @@ -76,7 +76,6 @@ typedef struct __ucontext
> > > >  #define SA_RESTART   0x10000000
> > > >  #define SA_NODEFER   0x40000000
> > > >  #define SA_RESETHAND 0x80000000
> > > > -#define SA_RESTORER  0x04000000
> > > >
> > > >  #endif
> > > >
> > > > --
> > > > 2.39.1.519.gcb327c4b5f-goog
> > > >
> > >
> > > I don't think this patch works as-is, since musl unconditionally uses
> > > SA_RESTORER. We probably need to make that conditional on its
> > > presence, and it looks like there's also a wrong-struct-layout issue
> > > on archs where it's absent...
> > 
> > yeah, bionic just uses the kernel uapi headers directly, and they look
> > like this:
> > 
> > struct sigaction {
> >   __sighandler_t sa_handler;
> >   unsigned long sa_flags;
> > #ifdef SA_RESTORER
> >   __sigrestore_t sa_restorer;
> > #endif
> >   sigset_t sa_mask;
> > };
> 
> OK. It looks like we need to remove the wrong SA_RESTORER for archs
> that aren't supposed to have it *and* add such an #ifdef. Right now,
> we're passing bogus sa_mask on these archs... :(

How does the attached look?

Rich

View attachment "SA_RESTORER.diff" of type "text/plain" (4370 bytes)

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