From: Arvind Sankar <nivedita@alum.mit.edu>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Nathan Chancellor <natechancellor@gmail.com>,
linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com
Subject: Re: [PATCH] compiler.h: avoid escaped section names
Date: Tue, 29 Sep 2020 16:13:24 -0400 [thread overview]
Message-ID: <20200929201324.GB2668747@rani.riverdale.lan> (raw)
In-Reply-To: <20200929200801.GA2668747@rani.riverdale.lan>
On Tue, Sep 29, 2020 at 04:08:01PM -0400, Arvind Sankar wrote:
> On Tue, Sep 29, 2020 at 12:43:18PM -0700, Nick Desaulniers wrote:
> > The stringification operator, `#`, in the preprocessor escapes strings.
> > For example, `# "foo"` becomes `"\"foo\""`. GCC and Clang differ in how
> > they treat section names that contain \".
> >
> > The portable solution is to not use a string literal with the
> > preprocessor stringification operator.
> >
> > In this case, since __section unconditionally uses the stringification
> > operator, we actually want the more verbose
> > __attribute__((__section__())).
> >
> > Link: https://bugs.llvm.org/show_bug.cgi?id=42950
> > Fixes: commit e04462fb82f8 ("Compiler Attributes: remove uses of __attribute__ from compiler.h")
> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> > ---
> > include/linux/compiler.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> > index 92ef163a7479..ac45f6d40d39 100644
> > --- a/include/linux/compiler.h
> > +++ b/include/linux/compiler.h
> > @@ -155,7 +155,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
> > extern typeof(sym) sym; \
> > static const unsigned long __kentry_##sym \
> > __used \
> > - __section("___kentry" "+" #sym ) \
> > + __attribute__((__section__("___kentry+" #sym))) \
> > = (unsigned long)&sym;
> > #endif
> >
> > --
> > 2.28.0.709.gb0816b6eb0-goog
> >
>
> There was this previous mini-thread:
> https://lore.kernel.org/lkml/20200629205448.GA1474367@rani.riverdale.lan/
> and this older one:
> https://lore.kernel.org/lkml/20190904181740.GA19688@gmail.com/
>
> Just for my own curiosity: how does KENTRY actually get used? grep
> doesn't show any hits, and the thread from 2019 was actually going to
> drop it if I read it right, and also just remove stringification from
> the __section macro.
>
> There are still other instances that need to be fixed, right?
>
> Thanks.
Ignore the last question, I see you have separate patches for the rest.
next prev parent reply other threads:[~2020-09-29 20:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 19:43 [PATCH] compiler.h: avoid escaped section names Nick Desaulniers
2020-09-29 20:08 ` Arvind Sankar
2020-09-29 20:13 ` Arvind Sankar [this message]
2020-09-29 20:25 ` Nick Desaulniers
2020-09-29 20:30 ` Nick Desaulniers
2020-09-29 20:47 ` Arvind Sankar
2020-09-29 20:59 ` Nick Desaulniers
2020-09-30 15:40 ` Joe Perches
2020-09-30 18:33 ` Joe Perches
2020-09-30 23:10 ` convert_section.pl attached Joe Perches
2020-09-29 21:33 ` [PATCH] compiler.h: avoid escaped section names Miguel Ojeda
2020-09-30 8:33 ` David Laight
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