From: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
To: Carlos O'Donell <carlos@redhat.com>,
GNU C Library <libc-alpha@sourceware.org>
Cc: nd <nd@arm.com>
Subject: Re: What can a signal handler do with SIGSTKSZ?
Date: Fri, 11 Jan 2019 19:02:00 -0000 [thread overview]
Message-ID: <efbcfeb5-c3bc-77e9-baa7-46547da86bfa@arm.com> (raw)
In-Reply-To: <e4215c6e-e8a4-a9b6-d88f-3c54e262711a@redhat.com>
On 11/01/2019 17:44, Carlos O'Donell wrote:
> In the continuing series of "What can X do with Y?" [1]
>
> I would like to get consensus on what a signal handler can do with
> SIGSTKSZ amount of space.
>
> I propose the following:
> ~~~
> The implementation only guarantees that a signal handler can
> manipulate a reasonable amount of local variables (no more than
> 2 KiB worth), and can read and write to memory, carry out atomic
> operations, and call simple C library functions that do similar
> memory and simple string operations e.g. memcpy, memset, strcmp,
> strcpy. The amount of signal stack allocated for SIGSTKSZ is not
> sufficient to call complex signal-safe functions e.g. fork, _exit,
> abort, nor any that can be canceled (requires enough stack for
> cancellation). Any other operations or function calls in the
> signal handler should be evaluated for runtime stack usage and
> additional stack beyond SIGSTKSZ should be allocated.
> ~~~
>
> Thoughts?
instead of "local variables" i'd say: user
code may use X bytes stack space and the
rest is for the runtime (which is guaranteed
to be enough for simple libc calls,...).
X can be 2048.
runtime stack usage vs user stack usage can
be accounted based on stack usage of libc code
vs user code.
next prev parent reply other threads:[~2019-01-11 19:02 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-11 17:44 Carlos O'Donell
2019-01-11 19:02 ` Szabolcs Nagy [this message]
2019-01-11 19:11 ` Carlos O'Donell
2019-01-11 20:23 ` Szabolcs Nagy
[not found] ` <CAKCAbMiCaBst_ofjKkH3Ck1CoOV86wPKv3QSkC89XW_zu=1BLA@mail.gmail.com>
2019-01-11 19:34 ` Fwd: " Zack Weinberg
2019-01-11 20:00 ` Florian Weimer
2019-01-11 20:06 ` Christian Brauner
2019-01-11 20:14 ` Florian Weimer
2019-01-11 20:26 ` Christian Brauner
2019-01-14 16:15 ` Florian Weimer
2019-01-11 20:09 ` Zack Weinberg
2019-01-11 20:29 ` Florian Weimer
2019-01-11 23:59 ` Zack Weinberg
2019-01-14 11:18 ` Szabolcs Nagy
2019-01-14 11:29 ` Adhemerval Zanella
2019-01-14 16:34 ` Zack Weinberg
2019-01-14 20:29 ` Carlos O'Donell
2019-01-14 16:18 ` Florian Weimer
2019-01-14 16:23 ` Carlos O'Donell
2019-01-14 16:31 ` Florian Weimer
2019-01-14 16:34 ` Szabolcs Nagy
2019-01-14 18:19 ` Joseph Myers
2019-01-14 20:30 ` Carlos O'Donell
2019-01-16 22:51 ` Christian Brauner
2019-01-11 19:40 ` Florian Weimer
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