linux-kernel - Re: [PATCH 1/2] perf tools riscv: Allow get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <IA1PR20MB49532515E0DD00227B7CE5F3BB799@IA1PR20MB4953.namprd20.prod.outlook.com>
Date:   Tue, 16 May 2023 17:43:54 +0800
From:   Inochi Amaoto <inochiama@...look.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Nikita Shubin <n.shubin@...ro.com>,
        Inochi Amaoto <inochiama@...look.com>
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 1/2] perf tools riscv: Allow get_cpuid return empty MARCH and MIMP

> > The T-HEAD C9xx series CPU only has MVENDOR defined, and left MARCH
> > and MIMP unimplemented.
>
> According to the docs you can still read them, but it's hardwired to
> 64h0.
>
> How it's supposed to distinguish c906 and c910 for example ?

It is unnecessary to distinguish c9xx, their event index is compatible.
The dtb and opensbi will final decide which event can be used.

> What does /proc/cpuinfo shows on c9xx ? Why can't we use zeroes ?

The content is as follows.

processor     : 0
hart          : 0
isa           : rv64imafdc
mmu           : sv39
uarch         : thead,c910
mvendorid     : 0x5b7
marchid       : 0x0
mimpid        : 0x0

The `mvendorid`, `marchid`, `mimpid` are the same across allwinner D1 (C906),
T-HEAD th1520 (C910) and the sophgo mango (C920). It seems T-HEAD use MCPUID
CSR to store CPU info. But this is not standard and not shown in cpuinfo.