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[209.85.219.173]) by smtp.gmail.com with ESMTPSA id s1-20020a05620a0bc100b006cfc01b4461sm12136578qki.118.2022.12.15.06.52.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Dec 2022 06:52:04 -0800 (PST) Received: by mail-yb1-f173.google.com with SMTP id g4so3751932ybg.7; Thu, 15 Dec 2022 06:52:04 -0800 (PST) X-Received: by 2002:a25:7a02:0:b0:6f7:952d:b145 with SMTP id v2-20020a257a02000000b006f7952db145mr44315072ybc.604.1671115923915; Thu, 15 Dec 2022 06:52:03 -0800 (PST) MIME-Version: 1.0 References: <20221115083349.1662-1-thunder.leizhen@huawei.com> <49070ac3-02bb-a3b3-b929-ede07e3b2c95@huawei.com> In-Reply-To: From: Geert Uytterhoeven Date: Thu, 15 Dec 2022 15:51:52 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v9] kallsyms: Add self-test facility To: "Leizhen (ThunderTown)" Cc: Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Masahiro Yamada , Alexei Starovoitov , Jiri Olsa , Kees Cook , Andrew Morton , Luis Chamberlain , linux-modules@vger.kernel.org, Steven Rostedt , Ingo Molnar , David Laight , linux-m68k , "Jason A. Donenfeld" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: Hi Zhen, On Thu, Dec 15, 2022 at 3:40 PM Leizhen (ThunderTown) 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) > >> wrote: > >>> On 2022/12/15 17:39, Geert Uytterhoeven wrote: > >>>> On Thu, Dec 15, 2022 at 10:16 AM Leizhen (ThunderTown) > >>>> wrote: > >>>>> On 2022/12/15 16:50, Geert Uytterhoeven wrote: > >>>>>> On Tue, Nov 15, 2022 at 9:41 AM 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 > >>>>>> > >>>>>> 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: 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