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Date: Fri, 16 Jan 2015 15:59:23 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Roman Peniaev <r.peniaev@gmail.com>
Cc: Kees Cook <keescook@chromium.org>, Will Deacon <will.deacon@arm.com>,
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Subject: Re: [PATCH 1/2] ARM: entry-common: fix forgotten set of
 thread_info->syscall
Message-ID: <20150116155923.GK12302@n2100.arm.linux.org.uk>
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On Sat, Jan 17, 2015 at 12:57:02AM +0900, Roman Peniaev wrote:
> On Fri, Jan 16, 2015 at 7:54 AM, Kees Cook <keescook@chromium.org> wrote:
> > One interesting thing I noticed (which is unchanged by this series),
> > but pulling ARM_r7 during the seccomp ptrace event shows __NR_poll,
> > not __NR_restart_syscall, even though it was a __NR_restart_syscall
> > trap from seccomp. Is there a better place to see the actual syscall?
> 
> As I understand we do not push new r7 to the stack, and ptrace uses the
> old value.

And why should we push r7 to the stack?  ptrace should be using the
recorded system call number, rather than poking about on the stack
itself.

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