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Re: Saving errno around signal handlers
- From: Florian Weimer <fweimer at redhat dot com>
- To: Richard Henderson <rth at twiddle dot net>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 28 Feb 2014 17:58:54 +0100
- Subject: Re: Saving errno around signal handlers
- Authentication-results: sourceware.org; auth=none
- References: <531077D9 dot 2000308 at redhat dot com> <5310BE05 dot 7090606 at twiddle dot net>
On 02/28/2014 05:49 PM, Richard Henderson wrote:
On 02/28/2014 03:49 AM, Florian Weimer wrote:
In all cases (kernel and glibc implementation), we can use a tail call to make
sure that the stack layout looks like it is at present (at least on
architectures with an available callee-saved register), and we would not have
to adjust GDB and other tools.
How's that? A tail call would not be able to "restore" anything afterward.
We already have the restorer that calls sigreturn, and could add
movq errno@gottpoff(%rip), %rdi
movl %r12d, %fs:(%rdi)
right before that.
--
Florian Weimer / Red Hat Product Security Team