From: Borislav Petkov <bp@alien8.de>
To: Marco Elver <elver@google.com>
Cc: Tony Luck <tony.luck@intel.com>, Jakub Kicinski <kuba@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/3] x86/mce: Fix more noinstr fun
Date: Fri, 4 Feb 2022 15:48:40 +0100 [thread overview]
Message-ID: <Yf08yMZZDCtYMBVX@zn.tnic> (raw)
In-Reply-To: <CANpmjNOvf7z4BdPqrJH2iF0KnZmP58uUzSH0fFoc4VNg+2S=hw@mail.gmail.com>
On Fri, Feb 04, 2022 at 12:24:00PM +0100, Marco Elver wrote:
> I guess to solve noinstr "calling" something else the only solution is
> to make the other function noinstr as well, or __always_inline.
>
> Have you considered making some of these other functions 'noinstr' as
> well? I guess __always_inline works, esp. if there's just 1 caller.
> And by the looks of it you're getting a net .text reduction, so
Yeah, I started doing that and the savings were the persuasive
argument.
Even more so if the function has one caller only and gets inlined,
normally. I guess it doesn't get inlined when there's KASAN
instrumentation or so but I haven't verified it fully why.
Because even for oneliners like v8086_mode() which should get inlined
trivially, the compiler ends up doing this constprop thing - I guess
some constants folding optimization thing... it probably doesn't even
matter so much whether oneliners get inlined in KASAN-enabled builds so
I guess we might just as well force-inline them for the other configs.
> Acked-by: Marco Elver <elver@google.com>
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
prev parent reply other threads:[~2022-02-04 14:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 8:30 [PATCH 0/3] x86/mce: Fix more noinstr fun Borislav Petkov
2022-02-04 8:30 ` [PATCH 1/3] cpumask: Add a x86-specific cpumask_clear_cpu() helper Borislav Petkov
2022-02-04 16:46 ` Luck, Tony
2022-02-04 18:04 ` Borislav Petkov
2022-02-13 10:59 ` [tip: locking/core] " tip-bot2 for Borislav Petkov
2022-02-04 8:30 ` [PATCH 2/3] x86/ptrace: Always inline v8086_mode() for instrumentation Borislav Petkov
2022-02-13 10:59 ` [tip: locking/core] " tip-bot2 for Borislav Petkov
2022-02-04 8:30 ` [PATCH 3/3] x86/mce: Use arch atomic and bit helpers Borislav Petkov
2022-02-14 10:03 ` [tip: ras/core] " tip-bot2 for Borislav Petkov
2022-02-04 11:24 ` [PATCH 0/3] x86/mce: Fix more noinstr fun Marco Elver
2022-02-04 14:48 ` Borislav Petkov [this message]
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