From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>,
Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
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>
Subject: Re: [PATCH v4 2/8] scripts/kallsyms: ensure that all possible combinations are compressed
Date: Wed, 21 Sep 2022 16:31:04 +0800 [thread overview]
Message-ID: <f1eaedb1-fc3e-cd0e-e63a-6e3caa9e015e@huawei.com> (raw)
In-Reply-To: <YyrEh+fbhYh6ltLp@alley>
On 2022/9/21 16:00, Petr Mladek wrote:
> On Tue 2022-09-20 15:13:11, Zhen Lei wrote:
>> For a symbol, there may be more than one place that can be merged. For
>> example: nfs_fs_proc_net_init, there are two "f"+"s_" combinations.
>> And we're only compressing the first combination at the moment.
>
> Really?
Yes, there are about 200 such functions.
>
>> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
>> index 8caccc8f4a23703..3319d9f38d7a5f2 100644
>> --- a/scripts/kallsyms.c
>> +++ b/scripts/kallsyms.c
>> @@ -553,7 +553,7 @@ static void compress_symbols(const unsigned char *str, int idx)
>> unsigned char *p1, *p2;
>>
>> for (i = 0; i < table_cnt; i++) {
>> -
>> +retry:
>> len = table[i]->len;
>> p1 = table[i]->sym;
>>
>> @@ -585,6 +585,9 @@ static void compress_symbols(const unsigned char *str, int idx)
>>
>> /* increase the counts for this symbol's new tokens */
>> learn_symbol(table[i]->sym, len);
>> +
>> + /* May be more than one place that can be merged, try again */
>> + goto retry;
>> }
>> }
>
> My understanding is that the code already tries to find the same
> token several times. Here are the important parts of the existing
> code:
>
> static void compress_symbols(const unsigned char *str, int idx)
> {
>
> p2 = find_token(p1, len, str);
>
> do {
> /* replace the found token with idx */
> *p2 = idx;
> [...]
>
> /* find the token on the symbol */
> p2 = find_token(p1, size, str);
Oh, yes, it retries. Let me reanalyze it. However, the problem is
real, and there may be a problem somewhere in the loop.
>
> } while (p2);
>
> Best Regards,
> Petr
> .
>
--
Regards,
Zhen Lei
next prev parent reply other threads:[~2022-09-21 8:31 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 7:13 [PATCH v4 0/8] kallsyms: Optimizes the performance of lookup symbols Zhen Lei
2022-09-20 7:13 ` [PATCH v4 1/8] scripts/kallsyms: rename build_initial_tok_table() Zhen Lei
2022-09-21 7:47 ` Petr Mladek
2022-09-20 7:13 ` [PATCH v4 2/8] scripts/kallsyms: ensure that all possible combinations are compressed Zhen Lei
2022-09-21 8:00 ` Petr Mladek
2022-09-21 8:31 ` Leizhen (ThunderTown) [this message]
2022-09-21 12:46 ` Leizhen (ThunderTown)
2022-09-20 7:13 ` [PATCH v4 3/8] scripts/kallsyms: don't compress symbol types Zhen Lei
2022-09-21 9:00 ` Petr Mladek
2022-09-21 13:13 ` Leizhen (ThunderTown)
2022-09-20 7:13 ` [PATCH v4 4/8] kallsyms: Improve the performance of kallsyms_lookup_name() Zhen Lei
2022-09-21 15:25 ` Petr Mladek
2022-09-22 2:15 ` Leizhen (ThunderTown)
2022-09-22 7:02 ` Petr Mladek
2022-09-22 7:21 ` Leizhen (ThunderTown)
2022-09-22 13:17 ` Petr Mladek
2022-09-28 1:35 ` Leizhen (ThunderTown)
2022-09-30 11:37 ` Leizhen (ThunderTown)
2022-09-22 7:14 ` Leizhen (ThunderTown)
2022-09-20 7:13 ` [PATCH v4 5/8] kallsyms: Add helper kallsyms_on_each_match_symbol() Zhen Lei
2022-09-21 15:30 ` Petr Mladek
2022-09-22 2:16 ` Leizhen (ThunderTown)
2022-09-20 7:13 ` [PATCH v4 6/8] livepatch: Use kallsyms_on_each_match_symbol() to improve performance Zhen Lei
2022-09-20 7:13 ` [PATCH v4 7/8] livepatch: Improve the search performance of module_kallsyms_on_each_symbol() Zhen Lei
2022-09-20 7:13 ` [PATCH v4 8/8] kallsyms: Add self-test facility Zhen Lei
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