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From: Arvind Sankar <nivedita@alum.mit.edu>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Sami Tolvanen" <samitolvanen@google.com>,
	"Arvind Sankar" <nivedita@alum.mit.edu>,
	"Kees Cook" <keescook@chromium.org>,
	"Sedat Dilek" <sedat.dilek@gmail.com>,
	"Fangrui Song" <maskray@google.com>,
	"Joe Perches" <joe@perches.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Dávid Bolvanský" <david.bolvansky@gmail.com>,
	"Eli Friedman" <efriedma@quicinc.com>,
	"# 3.4.x" <stable@vger.kernel.org>,
	"Vishal Verma" <vishal.l.verma@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	"Daniel Axtens" <dja@axtens.net>,
	"Ingo Molnar" <mingo@kernel.org>,
	"Yury Norov" <yury.norov@gmail.com>,
	"Alexandru Ardelean" <alexandru.ardelean@analog.com>,
	LKML <linux-kernel@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
	"Nathan Chancellor" <natechancellor@gmail.com>
Subject: Re: [PATCH v2] lib/string.c: implement stpcpy
Date: Mon, 17 Aug 2020 16:13:51 -0400	[thread overview]
Message-ID: <20200817201351.GA2246446@rani.riverdale.lan> (raw)
In-Reply-To: <CAKwvOd=Ns4_+amT8P-7yQ56xUdDmL=1zDUThF-OmFKhexhJPdg@mail.gmail.com>

On Mon, Aug 17, 2020 at 11:36:49AM -0700, Nick Desaulniers wrote:
> > > Though I don't understand the original issue, with -ffreestanding,
> > > sprintf shouldn't have been turned into strcpy in the first place.
> 
> Huh? The original issue for this thread is because `-ffreestanding`
> *isn't* being used for most targets (oh boy, actually mixed usage by
> ARCH. Looks like MIPS, m68k, superH, xtensa, and 32b x86 use it?); and
> I'm not suggesting it be used.
> 

Sorry, I meant the issue mentioned in the commit that removed
-ffreestanding, not the stpcpy one you're solving now. It says that
sprintf got converted into strcpy, which caused failures because back
then, strcpy was #define'd to __builtin_strcpy, and the default
implementation was actually of a function called __builtin_strcpy o_O,
not strcpy.

Anyway, that's water under the bridge now.

6edfba1b33c7 ("x86_64: Don't define string functions to builtin")
  gcc should handle this anyways, and it causes problems when
  sprintf is turned into strcpy by gcc behind our backs and
  the C fallback version of strcpy is actually defining __builtin_strcpy

  parent reply	other threads:[~2020-08-17 20:14 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-15  0:24 [PATCH] lib/string.c: implement stpcpy Nick Desaulniers
2020-08-15  0:52 ` Joe Perches
2020-08-15  2:00   ` Nick Desaulniers
2020-08-15  0:53 ` Sami Tolvanen
2020-08-15  1:33 ` Arvind Sankar
2020-08-15  1:40   ` Arvind Sankar
2020-08-15  2:09     ` [PATCH v2] " Nick Desaulniers
2020-08-15  2:58       ` Arvind Sankar
2020-08-15  3:42       ` Joe Perches
2020-08-15 16:34       ` Kees Cook
2020-08-15 17:38         ` Dávid Bolvanský
2020-08-15 20:47         ` Nick Desaulniers
2020-08-15 21:23           ` Joe Perches
2020-08-15 21:27             ` Dávid Bolvanský
2020-08-15 21:28             ` Nick Desaulniers
2020-08-15 21:31               ` Joe Perches
2020-08-15 22:17                 ` Nick Desaulniers
2020-08-16  0:19                   ` Fangrui Song
2020-08-16  5:22                     ` Sedat Dilek
2020-08-16 15:02                       ` Arvind Sankar
2020-08-17 17:14                         ` Sami Tolvanen
2020-08-17 18:36                           ` Nick Desaulniers
2020-08-17 19:15                             ` Kees Cook
2020-08-17 20:13                             ` Arvind Sankar [this message]
2020-08-17 21:45                               ` Nick Desaulniers
     [not found]                             ` <77557c29286140dea726cc334b4f59fc@AcuMS.aculab.com>
2020-08-18  8:32                               ` Joe Perches
2020-08-17 19:16                           ` Kees Cook
2020-08-16  7:44       ` kernel test robot
2020-08-16  7:44         ` kernel test robot
2020-08-15  2:00   ` [PATCH] " Nick Desaulniers
2020-08-15 22:17 ` David Laight

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