From: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Julien Grall <julien.grall.oss@gmail.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Michal Orzel <michal.orzel@amd.com>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v2 3/4] xen: arm: enable stack protector feature
Date: Mon, 9 Dec 2024 12:45:44 +0000 [thread overview]
Message-ID: <87v7vt2few.fsf@epam.com> (raw)
In-Reply-To: <0de3796a-b2b4-4661-b6d7-eee32be66014@suse.com> (Jan Beulich's message of "Mon, 9 Dec 2024 10:36:00 +0100")
Hi Jan,
Jan Beulich <jbeulich@suse.com> writes:
[...]
>
>> #else
>> const unsigned long a = 2862933555777941757;
>> #endif
>> const unsigned c = 1;
>
> I'm having a hard time seeing why this need to be a static variable. Its
> sole use is ...
It's a constant in a hope that compiler is smart enough to optimize it out.
>> unsigned long cycles = get_cycles();
>>
>> if ( !cycles )
>> return;
>>
>> __stack_chk_guard = cycles * a + c;
>
> ... here, where you can as well write a literal 1.
For readability. Formula for LCG is X_n+1 = (X_n * a + c) mod m.
--
WBR, Volodymyr
prev parent reply other threads:[~2024-12-09 12:46 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-30 1:10 [PATCH v2 0/4] Add stack protector Volodymyr Babchuk
2024-11-30 1:10 ` [PATCH v2 1/4] common: remove -fno-stack-protector from EMBEDDED_EXTRA_CFLAGS Volodymyr Babchuk
2024-12-02 8:06 ` Jan Beulich
2024-12-02 10:32 ` Andrew Cooper
2024-12-02 11:31 ` Jan Beulich
2024-11-30 1:10 ` [PATCH v2 2/4] xen: common: add ability to enable stack protector Volodymyr Babchuk
2024-12-02 8:29 ` Jan Beulich
2024-12-03 20:33 ` Andrew Cooper
2024-12-05 3:34 ` Volodymyr Babchuk
2024-12-05 12:52 ` Andrew Cooper
2024-11-30 1:10 ` [PATCH v2 4/4] xen: riscv: enable stack protector feature Volodymyr Babchuk
2024-12-02 8:12 ` Jan Beulich
2024-12-02 8:54 ` oleksii.kurochko
2024-12-02 9:56 ` oleksii.kurochko
2024-12-03 19:30 ` Volodymyr Babchuk
2024-11-30 1:10 ` [PATCH v2 3/4] xen: arm: " Volodymyr Babchuk
2024-11-30 17:06 ` Julien Grall
2024-12-03 22:00 ` Andrew Cooper
2024-12-03 23:16 ` Julien Grall
2024-12-05 19:23 ` Andrew Cooper
2024-12-06 4:46 ` Volodymyr Babchuk
2024-12-09 9:36 ` Jan Beulich
2024-12-09 12:45 ` Volodymyr Babchuk [this message]
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