From: Aaron Lindsay <aaron@os.amperecomputing.com>
To: Emilio Cota <cota@braap.org>
Cc: qemu-devel@nongnu.org, "Alex Bennée" <alex.bennee@linaro.org>,
"Richard Henderson" <richard.henderson@linaro.org>
Subject: Re: [PATCH 1/4] plugins: fix optimization in plugin_gen_disable_mem_helpers
Date: Tue, 10 Jan 2023 10:29:40 -0500 [thread overview]
Message-ID: <Y72EZGiDBQsvTyUs@strawberry.localdomain> (raw)
In-Reply-To: <20230108164731.61469-2-cota@braap.org>
On Jan 08 11:47, Emilio Cota wrote:
> We were mistakenly checking tcg_ctx->plugin_insn as a canary to know
> whether the TB had emitted helpers that might have accessed memory.
>
> The problem is that tcg_ctx->plugin_insn gets updated on every
> instruction in the TB, which results in us wrongly performing the
> optimization (i.e. not clearing cpu->plugin_mem_cbs) way too often,
> since it's not rare that the last instruction in the TB doesn't
> use helpers.
>
> Fix it by tracking a per-TB canary.
>
> While at it, expand documentation.
>
> Related: #1381
>
> Signed-off-by: Emilio Cota <cota@braap.org>
> ---
> accel/tcg/plugin-gen.c | 26 ++++++++++++++++++--------
> include/qemu/plugin.h | 7 +++++++
> 2 files changed, 25 insertions(+), 8 deletions(-)
Tested-by: Aaron Lindsay <aaron@os.amperecomputing.com>
next prev parent reply other threads:[~2023-01-10 15:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-08 16:47 [PATCH 0/4] plugin patches to fix #1381 Emilio Cota
2023-01-08 16:47 ` [PATCH 1/4] plugins: fix optimization in plugin_gen_disable_mem_helpers Emilio Cota
2023-01-10 15:29 ` Aaron Lindsay [this message]
2023-01-08 16:47 ` [PATCH 2/4] translator: always pair plugin_gen_insn_{start, end} calls Emilio Cota
2023-01-08 19:56 ` Philippe Mathieu-Daudé
2023-01-10 15:26 ` [PATCH 2/4] translator: always pair plugin_gen_insn_{start,end} calls Aaron Lindsay
2023-01-08 16:47 ` [PATCH 3/4] tcg: exclude lookup_tb_ptr from helper instrumentation Emilio Cota
2023-01-08 16:51 ` [PATCH 4/4] cpu-exec: assert that plugin_mem_cbs is NULL after execution Emilio Cota
2023-01-09 13:52 ` Alex Bennée
2023-01-10 2:16 ` Emilio Cota
2023-01-10 13:02 ` Alex Bennée
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