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

Leizhen (ThunderTown)
2022-12-16T07:43:04Z

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