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From: Kees Cook <keescook@chromium.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Masahiro Yamada" <masahiroy@kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Michal Marek" <michal.lkml@markovi.net>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Tony Luck" <tony.luck@intel.com>,
	"Dmitry Vyukov" <dvyukov@google.com>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Joe Perches" <joe@perches.com>,
	"Joel Fernandes" <joel@joelfernandes.org>,
	"Daniel Axtens" <dja@axtens.net>,
	"Arvind Sankar" <nivedita@alum.mit.edu>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Alexandru Ardelean" <alexandru.ardelean@analog.com>,
	"Yury Norov" <yury.norov@gmail.com>,
	x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	"Daniel Kiper" <daniel.kiper@oracle.com>,
	"Bruce Ashfield" <bruce.ashfield@gmail.com>,
	"Marco Elver" <elver@google.com>,
	"Vamshi K Sthambamkadi" <vamshi.k.sthambamkadi@gmail.com>,
	"Andi Kleen" <ak@suse.de>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Dávid Bolvanský" <david.bolvansky@gmail.com>,
	"Eli Friedman" <efriedma@quicinc.com>
Subject: Re: [PATCH 3/4] x86/boot: use -fno-builtin-bcmp
Date: Tue, 18 Aug 2020 12:24:40 -0700	[thread overview]
Message-ID: <202008181224.4C682B38@keescook> (raw)
In-Reply-To: <20200817220212.338670-4-ndesaulniers@google.com>

On Mon, Aug 17, 2020 at 03:02:11PM -0700, Nick Desaulniers wrote:
> We're reverting
> commit 5f074f3e192f ("lib/string.c: implement a basic bcmp")
> in favor of -fno-builtin-bcmp. Remove the additional definition here,
> too.
> 
> arch/x86/purgatory/Makefile uses -ffreestanding, so there's no risk of
> this libcall optimization occurring for arch/x86/boot/purgatory.ro.
> 
> arch/x86/boot/Makefile resets KBUILD_CFLAGS, so make sure to reset this
> flag that was set for the top level Makefile.
> 
> Fixes: 4ce97317f41d ("x86/purgatory: Do not use __builtin_memcpy and __builtin_memset")
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

  reply	other threads:[~2020-08-18 19:24 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-17 22:02 [PATCH 0/4] -ffreestanding/-fno-builtin-* patches Nick Desaulniers
2020-08-17 22:02 ` [PATCH 1/4] Makefile: add -fno-builtin-stpcpy Nick Desaulniers
2020-08-17 22:31   ` H. Peter Anvin
2020-08-17 23:36     ` Nick Desaulniers
2020-08-18 19:21     ` Kees Cook
2020-08-18  7:10   ` Ard Biesheuvel
2020-08-18  7:25     ` Greg KH
2020-08-18  7:29       ` Ard Biesheuvel
2020-08-18  7:34         ` Greg KH
2020-08-18 19:23   ` Kees Cook
2020-08-17 22:02 ` [PATCH 2/4] Revert "lib/string.c: implement a basic bcmp" Nick Desaulniers
2020-08-18  5:44   ` Nathan Chancellor
2020-08-18 18:00     ` Nick Desaulniers
2020-08-18 19:24       ` Kees Cook
2020-08-17 22:02 ` [PATCH 3/4] x86/boot: use -fno-builtin-bcmp Nick Desaulniers
2020-08-18 19:24   ` Kees Cook [this message]
2020-08-17 22:02 ` [PATCH 4/4] x86: don't build CONFIG_X86_32 as -ffreestanding Nick Desaulniers
2020-08-18 19:24   ` Kees Cook
2021-01-07  0:27   ` Fangrui Song
2022-04-07 15:34   ` [tip: x86/build] x86/build: Don't " tip-bot2 for Nick Desaulniers
2022-04-07 17:01     ` Nick Desaulniers
2022-04-07 22:28       ` Borislav Petkov
2020-08-17 22:44 ` [PATCH 0/4] -ffreestanding/-fno-builtin-* patches H. Peter Anvin
2020-08-18 17:56   ` Nick Desaulniers
2020-08-18 19:02     ` H. Peter Anvin
2020-08-18 19:13       ` Linus Torvalds
2020-08-18 19:25         ` Nick Desaulniers
2020-08-18 19:58           ` Nick Desaulniers
2020-08-19 12:19             ` Clement Courbet
2020-08-18 20:24         ` Arvind Sankar
2020-08-18 20:27           ` Nick Desaulniers
2020-08-18 20:58             ` Nick Desaulniers
2020-08-18 21:41               ` Arvind Sankar
2020-08-18 21:51                 ` Dávid Bolvanský
2020-08-18 21:59                 ` Nick Desaulniers
2020-08-18 22:05                   ` Dávid Bolvanský
2020-08-18 23:22                     ` Nick Desaulniers
2020-08-20 14:56                 ` Rasmus Villemoes
2020-08-20 17:56                   ` Arvind Sankar
2020-08-20 18:05                     ` Dávid Bolvanský
2020-08-20 23:33                     ` Linus Torvalds
2020-08-21 17:29                       ` Arvind Sankar
2020-08-21 17:54                         ` Linus Torvalds
2020-08-21 18:02                           ` Linus Torvalds
2020-08-21 19:14                             ` Arvind Sankar
2020-08-21 19:23                               ` Linus Torvalds
2020-08-21 19:57                           ` Arvind Sankar
2020-08-21 20:03                             ` Peter Zijlstra
2020-08-21 21:39                             ` Linus Torvalds
2020-08-22  0:12                               ` Nick Desaulniers
2020-08-22 12:20                                 ` David Laight
2020-08-21  6:45                     ` Rasmus Villemoes
2020-08-24 15:57                 ` Masahiro Yamada
2020-08-24 17:34                   ` Arvind Sankar
2020-08-25  7:10                     ` Nick Desaulniers
2020-08-25  7:31                       ` Nick Desaulniers
2020-08-25 12:28                       ` Masahiro Yamada
2020-08-25 14:02                         ` Nick Desaulniers
2020-08-26 13:28                           ` Masahiro Yamada
2020-08-18 21:53               ` David Laight
2020-08-20 22:41               ` H. Peter Anvin
2020-08-20 23:17                 ` Arvind Sankar
2020-08-18 19:35       ` Nick Desaulniers
2020-08-18 22:25 ` Arvind Sankar
2020-08-18 22:59   ` Nick Desaulniers
2020-08-18 23:51     ` Arvind Sankar
2020-08-19  0:20     ` Arvind Sankar
2020-08-19  8:26   ` David Laight

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