Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2] MIPS/bpf: Enable bpf_probe_read{, str}() on MIPS again
To:     "Maciej W. Rozycki" <macro@orcam.me.uk>
References: <1616034557-5844-1-git-send-email-yangtiezhu@loongson.cn>
 <alpine.DEB.2.21.2103220540591.21463@angie.orcam.me.uk>
Cc:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Christoph Hellwig <hch@lst.de>
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <f36f4ca6-a3bb-8db9-01e6-65fec0916b58@loongson.cn>
Date:   Mon, 22 Mar 2021 15:12:59 +0800
User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <alpine.DEB.2.21.2103220540591.21463@angie.orcam.me.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 03/22/2021 12:46 PM, Maciej W. Rozycki wrote:
> On Thu, 18 Mar 2021, Tiezhu Yang wrote:
>
>> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
>> index 160b3a8..4b94ec7 100644
>> --- a/arch/mips/Kconfig
>> +++ b/arch/mips/Kconfig
>> @@ -6,6 +6,7 @@ config MIPS
>>   	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
>>   	select ARCH_HAS_FORTIFY_SOURCE
>>   	select ARCH_HAS_KCOV
>> +	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
>   Hmm, documentation on ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE seems rather
> scarce, but based on my guess shouldn't this be "if !EVA"?
>
>    Maciej

I do not quite know what the effect if MIPS EVA (Enhanced Virtual 
Addressing)
is set, I saw that ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE should be 
restricted
to archs with non-overlapping address ranges.

I wonder whether MIPS EVA will generate overlapping address ranges?
If yes, it is better to make ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE depend
on !EVA on MIPS.

Thanks,
Tiezhu