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Date:   Thu, 9 Nov 2017 15:04:16 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Yonghong Song <yhs@fb.com>
Cc:     mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        netdev@vger.kernel.org, ast@fb.com, kernel-team@fb.com
Subject: Re: [PATCH] uprobes/x86: emulate push insns for uprobe on x86
Message-ID: <20171109140416.GA11186@redhat.com>
References: <20171109080155.359718-1-yhs@fb.com>
 <20171109134423.GA8746@redhat.com>
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On 11/09, Oleg Nesterov wrote:
>
> And. Do you really need ->post_xol() method to emulate "push"? Why we can't
> simply execute it out-of-line if copy_to_user() fails?
>
> branch_post_xol_op() is needed because we can't execute "call" out-of-line,
> we need to restart and try again if copy_to_user() fails, but I don not
> understand why it is needed to emulate "push".

If I wasn't clear, please see the comment in branch_clear_offset().

Oleg.


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