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Subject: Re: [PATCH v9] kallsyms: Add self-test facility
To:     Geert Uytterhoeven <geert@linux-m68k.org>
CC:     Josh Poimboeuf <jpoimboe@kernel.org>,
        Jiri Kosina <jikos@kernel.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        <live-patching@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        <linux-modules@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        David Laight <David.Laight@aculab.com>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>
References: <20221115083349.1662-1-thunder.leizhen@huawei.com>
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 <e81710a9-2c45-0724-ec5f-727977202858@huawei.com>
 <CAMuHMdWAAQNJd21fhodDONb40LFMae3V_517iT22FykCqG90Og@mail.gmail.com>
From:   "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Message-ID: <4aaede14-8bd3-6071-f17b-7efcb5f0de42@huawei.com>
Date:   Fri, 16 Dec 2022 15:42:55 +0800
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On 2022/12/15 22:51, Geert Uytterhoeven wrote:
> Hi Zhen,
> 
> On Thu, Dec 15, 2022 at 3:40 PM Leizhen (ThunderTown)
> <thunder.leizhen@huawei.com> wrote:
>> On 2022/12/15 21:58, Leizhen (ThunderTown) wrote:
>>> On 2022/12/15 21:24, Geert Uytterhoeven wrote:
>>>> On Thu, Dec 15, 2022 at 1:34 PM Leizhen (ThunderTown)
>>>> <thunder.leizhen@huawei.com> wrote:
>>>>> On 2022/12/15 17:39, Geert Uytterhoeven wrote:
>>>>>> On Thu, Dec 15, 2022 at 10:16 AM Leizhen (ThunderTown)
>>>>>> <thunder.leizhen@huawei.com> wrote:
>>>>>>> On 2022/12/15 16:50, Geert Uytterhoeven wrote:
>>>>>>>> On Tue, Nov 15, 2022 at 9:41 AM Zhen Lei <thunder.leizhen@huawei.com> 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@huawei.com>
>>>>>>>>
>>>>>>>> Thanks for your patch, which is now commit 30f3bb09778de64e ("kallsyms:
>>>>>>>> Add self-test facility") in linus/master.
>>>>>>>>
>>>>>>>> I gave this a try on m68k (atari_defconfig + CONFIG_KALLSYMS_SELFTEST=y),
>>>>>>>> but it failed:
>>>>>>>>
>>>>>>>>     start
>>>>>>>>     kallsyms_lookup_name() for kallsyms_test_func_static failed:
>>>>>>>> addr=0, expect 60ab0
>>>>>>>>     kallsyms_lookup_name() for kallsyms_test_func failed: addr=0, expect 60ac0
>>>>>>>>     kallsyms_lookup_name() for kallsyms_test_func_weak failed: addr=0,
>>>>>>>> expect 60ac2
>>>>>>>>     kallsyms_lookup_name() for vmalloc failed: addr=0, expect c272a
>>>>>>>>     kallsyms_lookup_name() for vfree failed: addr=0, expect c2142
>>>>>>>>     kallsyms_on_each_match_symbol() for kallsyms_test_func_static
>>>>>>>> failed: count=0, addr=0, expect 60ab0
>>>>>>>>     kallsyms_on_each_match_symbol() for kallsyms_test_func failed:
>>>>>>>> count=0, addr=0, expect 60ac0
>>>>>>>>     kallsyms_on_each_match_symbol() for kallsyms_test_func_weak
>>>>>>>> failed: count=0, addr=0, expect 60ac2
>>>>>>>>     kallsyms_on_each_match_symbol() for vmalloc failed: count=0,
>>>>>>>> addr=0, expect c272a
>>>>>>>>     kallsyms_on_each_match_symbol() for vfree failed: count=0, addr=0,
>>>>>>>> expect c2142
>>>>>>>>     abort
>>>>>>>>
>>>>>>>> Given all addresses are zero, it looks like some required functionality
>>>>>>>> or config option is missing.
>>>>>>>>
>>>>>>>> $ grep SYM .config
>>>>>>>> CONFIG_KALLSYMS=y
>>>>>>>> CONFIG_KALLSYMS_SELFTEST=y
>>>>>>>> CONFIG_KALLSYMS_BASE_RELATIVE=y
>>>>>>>> # CONFIG_ASYMMETRIC_KEY_TYPE is not set
>>>>>>>> CONFIG_SYMBOLIC_ERRNAME=y
>>>>>>>> # CONFIG_STRIP_ASM_SYMS is not set
>>>>>>>> CONFIG_KALLSYMS_SELFTEST
>>>>>>>>
>>>>>>>> Do you have a clue?
>>>>>>>
>>>>>>> cat /proc/kallsyms | grep kallsyms_test_func
>>>>>>> Let's see if the compiler-generated symbols have some special suffixes.
>>>>>>
>>>>>> Thanks, looks normal to me:
>>>>>>
>>>>>>     atari:~# cat /proc/kallsyms | grep kallsyms_test_func
>>>>>>     00060ab0 t kallsyms_test_func_static
>>>>>>     00060ac0 T kallsyms_test_func
>>>>>>     00060ac2 W kallsyms_test_func_weak
>>>>>>     atari:~#
>>>>>
>>>>> It's incredible. I don't have a m68k environment and I'm trying to build a qemu
>>>>> environment. If you're in a hurry and willing, you can apply the debugging patch
>>>>> in the attachment. I'd like to see what's wrong. Use "dmesg | grep tst" to collect
>>>>> the output information.
>>>>
>>>> Still fails:
>>>>
>>>>     tst: found kallsyms_test_func at index=12845
>>>>     tst: [12533] = kallsyms_test_func, seq=17370, offset=191223
>>>>     tst: [18800] = kallsyms_test_func, seq=23193, offset=259263
>>>>     tst: [21934] = kallsyms_test_func, seq=2527, offset=22331
>>>>     tst: [23501] = kallsyms_test_func, seq=11792, offset=126366
>>>>     tst: [24284] = kallsyms_test_func, seq=8427, offset=87395
>>>>     tst: [24676] = kallsyms_test_func, seq=21896, offset=243536
>>>>     tst: [24872] = kallsyms_test_func, seq=22571, offset=251856
>>>>     tst: [24970] = kallsyms_test_func, seq=23264, offset=260074
>>>>     tst: [25019] = kallsyms_test_func, seq=9003, offset=93752
>>>>     tst: [25043] = kallsyms_test_func, seq=14324, offset=155117
>>>>     tst: [25055] = kallsyms_test_func, seq=5942, offset=62266
>>>>     tst: [25061] = kallsyms_test_func, seq=14347, offset=155467
>>>>     tst: [25064] = kallsyms_test_func, seq=14350, offset=155512
>>>>     tst: [25066] = kallsyms_test_func, seq=14346, offset=155457
>>>>     tst: [25067] = kallsyms_test_func, seq=14354, offset=155565
>>>
>>> -               pr_warn("tst: [%d] = %s, seq=%d, offset=%d\n", mid, name, seq, off);
>>> +               pr_warn("tst: [%d] = %s, seq=%d, offset=%d\n", mid, namebuf, seq, off);
>>>
>>> Sorry, a variable in the debugging code is incorrectly written. 'name' should
>>> be replaced with 'namebuf', then we can see which function the comparison is wrong.
>>
>> I attached debug patch v2.
> 
> On 30f3bb09778de64 with your debug patch v2:

I've set up the qemu environment, and I'll try to solve it by tomorrow at the latest.

> 
> kallsyms_selftest: start
> tst: kallsyms_lookup_names() is OK, name=kallsyms_test_func, i=0
> kallsyms_selftest: kallsyms_lookup_name() for
> kallsyms_test_func_static failed: addr=8dbc, expect 60498
> kallsyms_selftest: kallsyms_lookup_name() for kallsyms_test_func
> failed: addr=8dbc, expect 604a8
> kallsyms_selftest: kallsyms_lookup_name() for kallsyms_test_func_weak
> failed: addr=8dbc, expect 604aa
> kallsyms_selftest: kallsyms_lookup_name() for vmalloc failed:
> addr=8dbc, expect bde18
> kallsyms_selftest: kallsyms_lookup_name() for vfree failed: addr=8dbc,
> expect bd86e
> kallsyms_selftest: kallsyms_on_each_match_symbol() for
> kallsyms_test_func_static failed: count=24891, addr=1eea00, expect
> 60498
> kallsyms_selftest: kallsyms_on_each_match_symbol() for
> kallsyms_test_func failed: count=24891, addr=1eea00, expect 604a8
> kallsyms_selftest: kallsyms_on_each_match_symbol() for
> kallsyms_test_func_weak failed: count=24891, addr=1eea00, expect 604aa
> kallsyms_selftest: kallsyms_on_each_match_symbol() for vmalloc failed:
> count=24891, addr=1eea00, expect bde18
> kallsyms_selftest: kallsyms_on_each_match_symbol() for vfree failed:
> count=24891, addr=1eea00, expect bd86e
> kallsyms_selftest: abort
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> 
> .
> 

-- 
Regards,
  Zhen Lei