From: Richard Henderson <richard.henderson@linaro.org>
To: Emilio Cota <cota@braap.org>, qemu-devel@nongnu.org
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
"Aaron Lindsay" <aaron@os.amperecomputing.com>,
"Eli G. Boling" <eboling@draper.com>
Subject: Re: [PATCH] plugin: fix clearing of plugin_mem_cbs before TB exit
Date: Tue, 28 Feb 2023 10:50:26 -1000 [thread overview]
Message-ID: <e1fc5734-2548-eba1-cc14-5f2a6482fba0@linaro.org> (raw)
In-Reply-To: <20230222043204.941336-1-cota@braap.org>
On 2/21/23 18:32, Emilio Cota wrote:
> Currently we are wrongly accessing plugin_tb->mem_helper at
> translation time from plugin_gen_disable_mem_helpers, which is
> called before generating a TB exit, e.g. with exit_tb.
>
> Recall that it is only during TB finalisation, i.e. when we go over
> the TB post-translation to inject or remove plugin instrumentation,
> when plugin_tb->mem_helper is set. This means that we never clear
> plugin_mem_cbs when calling plugin_gen_disable_mem_helpers since
> mem_helper is always false. Therefore a guest instruction that uses
> helpers and emits an explicit TB exit results in plugin_mem_cbs being
> set upon exiting, which is caught by an assertion as reported in
> the reopening of issue #1381 and replicated below.
>
> Fix this by (1) adding an insertion point before exiting a TB
> ("before_exit"), and (2) deciding whether or not to emit the
> clearing of plugin_mem_cbs at this newly-added insertion point
> during TB finalisation.
This is an improvement, but incomplete, because it does not handle the exception exit
case, via cpu_loop_exit.
r~
next prev parent reply other threads:[~2023-02-28 20:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-22 4:32 [PATCH] plugin: fix clearing of plugin_mem_cbs before TB exit Emilio Cota
2023-02-28 17:33 ` Frédéric Pétrot
2023-02-28 20:50 ` Richard Henderson [this message]
2023-03-01 11:41 ` Emilio Cota
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