linux-kernel - Re: [PATCH v9] kallsyms: Add self-test facility

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Message-ID: <f21eb27b-4c7f-5136-85ab-61a8ca762496@huawei.com>
Date:   Tue, 15 Nov 2022 16:43:57 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        <live-patching@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Luis Chamberlain" <mcgrof@...nel.org>,
        <linux-modules@...r.kernel.org>,
        "Steven Rostedt" <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>
CC:     David Laight <David.Laight@...LAB.COM>
Subject: Re: [PATCH v9] kallsyms: Add self-test facility



On 2022/11/15 16:33, Zhen Lei wrote:
> Added test cases for basic functions and performance of functions
> kallsyms_lookup_name(), kallsyms_on_each_symbol() and
> kallsyms_on_each_match_symbol(). It also calculates the compression rate
> of the kallsyms compression algorithm for the current symbol set.
> 
> The basic functions test begins by testing a set of symbols whose address
> values are known. Then, traverse all symbol addresses and find the
> corresponding symbol name based on the address. It's impossible to
> determine whether these addresses are correct, but we can use the above
> three functions along with the addresses to test each other. Due to the
> traversal operation of kallsyms_on_each_symbol() is too slow, only 60
> symbols can be tested in one second, so let it test on average once
> every 128 symbols. The other two functions validate all symbols.
> 
> If the basic functions test is passed, print only performance test
> results. If the test fails, print error information, but do not perform
> subsequent performance tests.
> 
> Start self-test automatically after system startup if
> CONFIG_KALLSYMS_SELFTEST=y.
> 
> Example of output content: (prefix 'kallsyms_selftest:' is omitted
>  start
>   ---------------------------------------------------------
>  | nr_symbols | compressed size | original size | ratio(%) |
>  |---------------------------------------------------------|
>  |     107543 |       1357912   |      2407433  |  56.40   |
>   ---------------------------------------------------------
>  kallsyms_lookup_name() looked up 107543 symbols
>  The time spent on each symbol is (ns): min=630, max=35295, avg=7353
>  kallsyms_on_each_symbol() traverse all: 11782628 ns
>  kallsyms_on_each_match_symbol() traverse all: 9261 ns
>  finish
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
>  include/linux/kallsyms.h   |   1 +
>  init/Kconfig               |  13 +
>  kernel/Makefile            |   1 +
>  kernel/kallsyms.c          |   2 +-
>  kernel/kallsyms_selftest.c | 485 +++++++++++++++++++++++++++++++++++++
>  kernel/kallsyms_selftest.h |  13 +
>  6 files changed, 514 insertions(+), 1 deletion(-)
>  create mode 100644 kernel/kallsyms_selftest.c
>  create mode 100644 kernel/kallsyms_selftest.h

v8 --> v9:
[v8] https://lkml.org/lkml/2022/11/2/225

Adjust the prototype of some callback functions. Because 7/9 and 8/9
in v8 are dropped.

-- 
Regards,
  Zhen Lei