From: "Alex Bennée" <alex.bennee@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: ysato@users.sourceforge.jp, qemu-devel@nongnu.org,
Ahmed Karaman <ahmedkhaledkaraman@gmail.com>,
aleksandar.qemu.devel@gmail.com, stefanha@redhat.com,
rth@twiddle.net
Subject: Re: [PATCH 0/2] Update use_goto_tb() in hppa and rx targets
Date: Tue, 19 May 2020 19:38:28 +0100 [thread overview]
Message-ID: <87r1vfhisb.fsf@linaro.org> (raw)
In-Reply-To: <a0f3967f-e125-d888-bc6d-44414edbfd5b@linaro.org>
Richard Henderson <richard.henderson@linaro.org> writes:
> On 5/19/20 9:21 AM, Ahmed Karaman wrote:
>> The issue arose because the page crossings check in use_goto_tb()
>> function is required only in the system mode. Checking it in both modes
>> causes an unnecessary overhead in the user mode.
>
> It is not only required in system mode.
>
> You can see failures in user-mode if you modify executable pages, or change
> their permissions with mmap. Such as if the guest program contains a
> JIT.
If we kept better track couldn't we just tb_flush() if a new +x region
gets mmaped? I guess that would be sub-optimal compared to having a
translation cache per mmap region.
--
Alex Bennée
next prev parent reply other threads:[~2020-05-19 18:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 16:21 [PATCH 0/2] Update use_goto_tb() in hppa and rx targets Ahmed Karaman
2020-05-19 16:21 ` [PATCH 1/2] target/hppa: Check page crossings in use_goto_tb() only in system mode Ahmed Karaman
2020-05-19 16:21 ` [PATCH 2/2] target/rx: Check for page crossings in use_goto_tb() Ahmed Karaman
2020-05-19 18:01 ` [PATCH 0/2] Update use_goto_tb() in hppa and rx targets Richard Henderson
2020-05-19 18:38 ` Alex Bennée [this message]
2020-05-19 18:51 ` Richard Henderson
2020-05-21 11:32 ` Ahmed Karaman
2020-05-22 3:12 ` Richard Henderson
2020-05-25 18:39 ` Aleksandar Markovic
2020-05-26 14:14 ` Aleksandar Markovic
2020-05-26 16:08 ` Ahmed Karaman
2020-05-26 16:29 ` Aleksandar Markovic
2020-05-26 16:45 ` Aleksandar Markovic
2020-05-26 17:38 ` Aleksandar Markovic
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