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Re: [PATCH] Tests for minimal signal handler functionality in MINSIGSTKSZ space.
- From: Florian Weimer <fweimer at redhat dot com>
- To: Zack Weinberg <zackw at panix dot com>
- Cc: "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>, Siddhesh Poyarekar <siddhesh at gotplt dot org>
- Date: Wed, 16 Jan 2019 15:16:22 +0100
- Subject: Re: [PATCH] Tests for minimal signal handler functionality in MINSIGSTKSZ space.
- References: <20190115200526.4677-1-zackw@panix.com> <1d45c6cb-192c-5ade-513e-a40c65d9fb7e@redhat.com> <CAKCAbMhSxEznwJDjSscq_whWk8j8TV409HAgGJ4AGOrHhV=8bw@mail.gmail.com> <dfefe1c3-7952-9878-757d-48a15c880332@redhat.com> <CAKCAbMiaUYOLkRD36MEVJRuzbAyjC7DEYNz68ZuJdWDrq=YPRQ@mail.gmail.com>
* Zack Weinberg:
> It also occurs to me that on some architectures MINSIGSTKSZ is less
> than a page; on those architectures, the rounding done in xsigstack.c
> means we aren't _really_ testing this stuff in MINSIGSTKSZ space.
> Since overflow is much more of a concern than underflow, what do
> people think of adjusting the code in xsigstack.c so that the area
> actually passed to sigaltstack will not be rounded and will be right
> up against the guard in the direction of overflow? This would mean
> xsigstack.c has to know which direction the stack grows, but I think
> we already have internal macros for that,
_STACK_GROWS_DOWN, _STACK_GROWS_UP, and NEED_SEPARATE_REGISTER_STACK on
ia64. But ia64 uses stack sizes which are a multiple of the page size,
so you are lucky. 8-)
Thanks,
Florian