Date: Mon, 21 Mar 2016 21:43:12 +0300
From: Yury Norov <ynorov@caviumnetworks.com>
To: "Zhangjian (Bamvor)" <bamvor.zhangjian@huawei.com>
CC: Alexander Graf <agraf@suse.de>, Andreas Schwab <schwab@suse.de>,
        <arnd@arndb.de>, <catalin.marinas@arm.com>,
        <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <pinskia@gmail.com>, <Prasun.Kapoor@caviumnetworks.com>,
        <broonie@kernel.org>, <heiko.carstens@de.ibm.com>,
        <klimov.linux@gmail.com>, <jan.dakinevich@gmail.com>,
        <schwidefsky@de.ibm.com>, <Nathan_Lynch@mentor.com>,
        <joseph@codesourcery.com>, <christoph.muellner@theobroma-systems.com>,
        Bamvor Zhang Jian <bamvor.zhangjian@linaro.org>,
        "dingtianhong@huawei.com" <dingtianhong@huawei.com>
Subject: Re: [RFC5 PATCH v6 00/21] ILP32 for ARM64
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On Mon, Mar 21, 2016 at 07:23:28PM +0800, Zhangjian (Bamvor) wrote:
> >>So this most probably means that ilp32 code doesn't handle one of cloned
> >>item properly. I have already discovered a bug where child processes
> >>used parent TLS,
> >It is a kernel bug or glibc bug? Could you please explain it or show the patch?
> >The current ILP32 patches looks good to me. Recently, I backport these patches
> >to our 4.1 kernel. And I saw crash frequently even if I only do a single print
> >or infinite loop. There is some small changes about tls register after 4.1. I
> >am not sure if it is a similar issue. It is great if you have some suggestions/
> >ideas.
> My issue is because I forget to change is_compat_task to
> is_a32_compat_task in arch/arm64/kernel/process.c such piece of code
> is delete after commit d00a3810c162 ("arm64: context-switch user tls
> register tpidr_el0 for compat tasks). It is not exist in upstream
> kernel, never mind.
> 
> Meanwhile, I found that it seem that there is another is_compat_task
> in tls_thread_flush. Is it relative the issue you mentioned?
> 
> ```
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 432b094..9ab968c 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -209,7 +209,7 @@ static void tls_thread_flush(void)
>  {
>         asm ("msr tpidr_el0, xzr");
> 
> -       if (is_compat_task()) {
> +       if (is_a32_compat_task()) {
>                 current->thread.tp_value = 0;
> 
>                 /*
> ```
> 
> Regards
> 
> Bamvor

Hi,

This fix looks correct, though doesn't fix issue.
Thank you.

Yury.