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Message-ID: <20170803001944.GC5455@dora.lan>
Date: Wed, 2 Aug 2017 19:19:44 -0500
From: Bobby Bingham <koorogi@...rogi.info>
To: musl@...ts.openwall.com
Subject: Re: possible bug in setjmp implementation for ppc64
On Wed, Aug 02, 2017 at 10:46:12AM -0400, Rich Felker wrote:
> On Wed, Aug 02, 2017 at 08:38:25AM -0500, Bobby Bingham wrote:
> Whether the call to longjmp/siglongjmp was local or not is irrelevant.
> It's only whether the original call to setjmp/sigsetjmp was local or
> not that's relevant. And in either case I'm pretty sure it suffices to
I think I was treating whether longjmp is called locally as a proxy for
whether setjmp was called locally. But of course that doesn't work.
I think we're on the same page now.
> restore the saved value to both *(r1+24) and r2. Per the ABI, *(r1+24)
> can't be used for any purpose except saving the TOC, so upon return
> from setjmp, the caller's only options are to treat the value at
> *(r1+24) as indeterminate or assume it contains the TOC pointer.
> Likewise for r2, if the call was non-local, r2 is call-clobbered so it
> doesn't matter what it contains after return, and if the call was
> local, r2 is expected to contain the caller's TOC pointer.
>
> Rich
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