From: "Dmitry V. Levin" <ldv@altlinux.org>
To: sparclinux@vger.kernel.org
Subject: Re: using ptrace to cancel a syscall on sparc
Date: Sun, 20 Dec 2015 23:31:44 +0000 [thread overview]
Message-ID: <20151220233144.GA23664@altlinux.org> (raw)
In-Reply-To: <20151220054754.GZ11489@vapier.lan>
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On Sun, Dec 20, 2015 at 12:47:54AM -0500, Mike Frysinger wrote:
> i've been playing with ptrace on sparc and trying to use it to watch and
> cancel specific syscalls. i have this working for other arches already.
[...]
> i'm having trouble with canceling of the syscall itself. seems like
> no matter what i stuff into o0, the kernel executes the unlink. i've
> tried tracing arch/sparc/kernel/syscalls.S and kernel/head_64.S, the
> the entry is linux_sparc_syscall32 which calls linux_syscall_trace32,
> but it seems like the o0 stuff doesn't seem to work for me. my sparc
> asm foo isn't strong enough to figure out what's going wrong :/.
Yes, sparc is odd in this respect: whatever you write to u_regs[] on
entering syscall, it doesn't affect syscall number or syscall arguments.
--
ldv
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next prev parent reply other threads:[~2015-12-20 23:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-20 5:47 using ptrace to cancel a syscall on sparc Mike Frysinger
2015-12-20 23:31 ` Dmitry V. Levin [this message]
2016-01-18 11:32 ` Mike Frysinger
2016-01-19 19:39 ` David Miller
2016-01-19 20:10 ` David Miller
2016-01-19 20:56 ` Mike Frysinger
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