From: Gabriel Paubert <paubert@iram.es>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-arch@vger.kernel.org, linux-toolchains@vger.kernel.org,
Masahiro Yamada <masahiroy@kernel.org>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] kbuild: treat char as always signed
Date: Sun, 23 Oct 2022 22:23:56 +0200 [thread overview]
Message-ID: <Y1Wi29MuYlCRTKfH@lt-gp.iram.es> (raw)
In-Reply-To: <CAHk-=wgaeTa9nAeJ8DP1cBWrs8fZvJ7k1-L8-kjxEOxpLf+XNA@mail.gmail.com>
On Sat, Oct 22, 2022 at 11:16:33AM -0700, Linus Torvalds wrote:
> On Fri, Oct 21, 2022 at 11:06 PM Gabriel Paubert <paubert@iram.es> wrote:
> >
> > Ok, I´ve just tried it, except that I had something slightly different in
> > mind, but perhaps should have been clearer in my first post.
> >
> > I have change your code to the following:
>
> I actually tested that, but using a slightly different version, and my
> non-union test case ended up like
>
> size_t strlen(const char *p)
> {
> return __builtin_strlen(p);
> }
>
> and then gcc actually complains about
>
> warning: infinite recursion detected
>
> and I (incorrectly) thought this was unworkable. But your version
> seems to work fine.
Incidentally, it also gives exactly the same code with -ffreestanding.
>
> So yeah, for the kernel I think we could do something like this. It's
> ugly, but it gets rid of the crazy warning.
Not as ugly as casts IMO, and it's localized in a few header files.
However, it does not solve the problem of assigning a constant string to
an u8 *; I've no idea on how to fix that.
>
> Practically speaking this might be a bit painful, because we've got
> several different variations of this all due to all the things like
> our debugging versions (see <linux/fortify-string.h> for example), so
> some of our code is this crazy jungle of "with this config, use this
> wrapper".
I've just had a look at that code, and I don't want to touch it with a
10 foot pole. If someone else to get his hands dirty...
Gabriel
>
> But if somebody wants to deal with the '-Wpointer-sign' warnings,
> there does seem to be a way out. Maybe with another set of helper
> macros, creating those odd __transparent_union__ wrappers might even
> end up reasonable.
>
> It's not like we don't have crazy macros for function wrappers
> elsewhere (the SYSCALL macros come to mind - shudder). The macros
> themselves may be a nasty horror, but when done right the _use_ point
> of said macros can be nice and clean.
>
> Linus
next prev parent reply other threads:[~2022-10-23 20:25 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-19 16:26 [PATCH] kbuild: treat char as always signed Jason A. Donenfeld
2022-10-19 16:54 ` Segher Boessenkool
2022-10-19 17:14 ` Linus Torvalds
2022-10-19 17:26 ` Linus Torvalds
2022-10-19 18:10 ` Nick Desaulniers
2022-10-19 18:35 ` Linus Torvalds
2022-10-19 19:23 ` Andy Shevchenko
2022-10-19 19:36 ` Linus Torvalds
2022-10-19 17:43 ` Segher Boessenkool
2022-10-19 18:11 ` Linus Torvalds
2022-10-19 18:20 ` Nick Desaulniers
2022-10-19 18:56 ` Linus Torvalds
2022-10-19 19:11 ` Kees Cook
2022-10-19 19:30 ` Linus Torvalds
2022-10-19 20:35 ` Jason A. Donenfeld
2022-10-20 0:10 ` Linus Torvalds
2022-10-20 3:11 ` Jason A. Donenfeld
2022-10-19 20:15 ` Segher Boessenkool
2022-10-19 21:07 ` David Laight
2022-10-19 21:26 ` Segher Boessenkool
2022-10-20 10:41 ` Gabriel Paubert
2022-10-21 22:46 ` Linus Torvalds
2022-10-22 6:06 ` Gabriel Paubert
2022-10-22 18:16 ` Linus Torvalds
2022-10-23 20:23 ` Gabriel Paubert [this message]
2022-10-25 23:00 ` Kees Cook
2022-10-26 0:04 ` Jason A. Donenfeld
2022-10-26 15:41 ` Kees Cook
2022-10-19 19:54 ` Linus Torvalds
2022-10-19 20:23 ` Jason A. Donenfeld
2022-10-19 20:30 ` [PATCH v2] kbuild: treat char as always unsigned Jason A. Donenfeld
2022-10-19 23:56 ` Linus Torvalds
2022-10-20 0:02 ` Jason A. Donenfeld
2022-10-20 0:38 ` Linus Torvalds
2022-10-20 2:59 ` Jason A. Donenfeld
2022-10-20 18:41 ` Kees Cook
2022-10-21 1:01 ` Jason A. Donenfeld
2022-10-20 20:24 ` Segher Boessenkool
2022-10-24 9:24 ` Dan Carpenter
2022-10-24 9:30 ` Dan Carpenter
2022-10-24 16:33 ` Jason A. Donenfeld
2022-10-24 17:10 ` Linus Torvalds
2022-10-24 17:17 ` Jason A. Donenfeld
2022-10-25 19:22 ` Kalle Valo
2022-10-25 10:16 ` David Laight
2022-10-24 15:17 ` Jason A. Donenfeld
2022-12-21 14:53 ` Guenter Roeck
2022-12-21 15:05 ` Geert Uytterhoeven
2022-12-21 15:23 ` Guenter Roeck
2022-12-21 15:29 ` Rasmus Villemoes
2022-12-21 15:56 ` Guenter Roeck
2022-12-21 17:06 ` Linus Torvalds
2022-12-21 17:19 ` Guenter Roeck
2022-12-21 18:46 ` Linus Torvalds
2022-12-21 19:08 ` Linus Torvalds
2022-12-21 21:01 ` Guenter Roeck
2022-12-22 13:05 ` Geert Uytterhoeven
2022-12-22 10:41 ` David Laight
[not found] ` <f02e0ac7f2d805020a7ba66803aaff3e31b5eeff.camel@t-online.de>
2022-12-24 9:47 ` Geert Uytterhoeven
2022-12-30 11:39 ` David Laight
2022-12-30 13:13 ` David Laight
2023-01-02 8:29 ` Geert Uytterhoeven
2022-12-21 17:49 ` Andreas Schwab
2022-12-21 16:57 ` Geert Uytterhoeven
2022-10-19 20:58 ` [PATCH] kbuild: treat char as always signed David Laight
2022-10-26 0:10 ` make ctype ascii only? (was [PATCH] kbuild: treat char as always signed) Rasmus Villemoes
2022-10-26 18:10 ` Linus Torvalds
2022-10-27 7:59 ` Rasmus Villemoes
2022-10-27 18:28 ` Linus Torvalds
[not found] ` <202210201618.8XhEGsLd-lkp@intel.com>
2022-10-20 16:33 ` [PATCH] kbuild: treat char as always signed Jason A. Donenfeld
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