From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Subject: Re: [PATCH] replace 'hlt' by 'ud2' in i386/x32/x86_64 a_crash implementations
Date: Fri, 17 Apr 2015 21:48:38 +0300 (MSK) [thread overview]
Message-ID: <alpine.LNX.2.11.1504172128260.11963@monopod.intra.ispras.ru> (raw)
In-Reply-To: <20150417164401.GY6817@brightrain.aerifal.cx>
> > An argument in favor of plain hlt/ud2 is that registers and memory are
> > preserved, in case someone will be analyzing the coredump.
>
> That's a good point. The above could be fixed to preserve registers
> with some minor added push/pop (simple pusha/popa on 32-bit)
> before/after the syscall, but then it gets bigger.
Hm, no, I wouldn't like to see that. By the time a_crash executes, "the
impossible happened", so stack pointer might be pointing somewhere you
wouldn't want modified.
A good reason for compilers to generate ud2 is that it also works for kernel
code, unlike hlt -- but then OSv carries a copy of musl to run it in the
context of, as I understand, virtualized kernel -- what happens when they
execute a_crash?
Alexander.
next prev parent reply other threads:[~2015-04-17 18:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-16 17:58 Alexander Monakov
2015-04-17 5:55 ` Rich Felker
2015-04-17 8:12 ` Alexander Monakov
2015-04-17 16:44 ` Rich Felker
2015-04-17 18:48 ` Alexander Monakov [this message]
2015-04-17 20:23 ` Rich Felker
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