linux-kernel - Re: [PATCH v2] MIPS/bpf: Enable bpf_probe

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Message-ID: <f36f4ca6-a3bb-8db9-01e6-65fec0916b58@loongson.cn>
Date:   Mon, 22 Mar 2021 15:12:59 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     "Maciej W. Rozycki" <macro@...am.me.uk>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-mips@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v2] MIPS/bpf: Enable bpf_probe_read{, str}() on MIPS again

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