From: Arvind Sankar <nivedita@alum.mit.edu>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Kees Cook <keescook@chromium.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Peter Collingbourne <pcc@google.com>,
James Morse <james.morse@arm.com>, Borislav Petkov <bp@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Russell King <linux@armlinux.org.uk>,
Masahiro Yamada <masahiroy@kernel.org>,
Nathan Chancellor <natechancellor@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
linux-arch <linux-arch@vger.kernel.org>,
linux-efi <linux-efi@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Joe Perches <joe@perches.com>
Subject: Re: [PATCH v4 08/17] arm64/mm: Remove needless section quotes
Date: Mon, 29 Jun 2020 17:06:19 -0400 [thread overview]
Message-ID: <20200629210619.GA1603907@rani.riverdale.lan> (raw)
In-Reply-To: <20200629205448.GA1474367@rani.riverdale.lan>
On Mon, Jun 29, 2020 at 04:54:48PM -0400, Arvind Sankar wrote:
> On Mon, Jun 29, 2020 at 01:04:31PM -0700, Kees Cook wrote:
> > On Mon, Jun 29, 2020 at 12:53:47PM -0700, Nick Desaulniers wrote:
> > > On Sun, Jun 28, 2020 at 11:18 PM Kees Cook <keescook@chromium.org> wrote:
> > > >
> > > > Fix a case of needless quotes in __section(), which Clang doesn't like.
> > > >
> > > > Acked-by: Will Deacon <will@kernel.org>
> > > > Signed-off-by: Kees Cook <keescook@chromium.org>
> > >
> > > Yep, I remember bugs from this. Probably should scan the kernel for
> > > other instances of this. +Joe for checkpatch.pl validation.
> >
> > I think the others are safe because they're in macros:
>
> Why does that make it safe -- the commit msg is a bit sparse, but I
> assume the problem is that it generates
> __attribute__((__section__("\".foo\"")))
> from
> __section(".foo")
> after preprocessing, and clang keeps the quotes in the section name when
> generating assembly, while gcc appears to strip them off.
>
> It does that even if nested in another macro, no?
Yep, I can see things like:
[25] ".discard.ksym" PROGBITS 0000000000000000 0000217c
0000000000000000 0000000000000000 WA 0 0 4
Doesn't seem to cause a build error, but that can't be good.
>
> >
> > $ git grep -4 '__section("'
> > include/linux/compiler.h-# define KENTRY(sym) \
>
> Am I missing something, or is KENTRY unused in the tree?
>
> > include/linux/compiler.h- extern typeof(sym) sym; \
> > include/linux/compiler.h- static const unsigned long __kentry_##sym \
> > include/linux/compiler.h- __used \
> > include/linux/compiler.h: __section("___kentry" "+" #sym ) \
> > include/linux/compiler.h- = (unsigned long)&sym;
> > --
> > include/linux/export.h-#define __ksym_marker(sym) \
> > include/linux/export.h: static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
> > --
> > include/linux/srcutree.h-# define __DEFINE_SRCU(name, is_static) \
> > include/linux/srcutree.h- is_static struct srcu_struct name; \
> > include/linux/srcutree.h- struct srcu_struct * const __srcu_struct_##name \
> > include/linux/srcutree.h: __section("___srcu_struct_ptrs") = &name
> >
> >
> > > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> >
> > Thanks!
> >
> > --
> > Kees Cook
next prev parent reply other threads:[~2020-06-29 21:06 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-29 6:18 [PATCH v4 00/17] Warn on orphan section placement Kees Cook
2020-06-29 6:18 ` [PATCH v4 01/17] vmlinux.lds.h: Add .gnu.version* to DISCARDS Kees Cook
2020-06-29 6:18 ` [PATCH v4 02/17] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections Kees Cook
2020-06-29 6:18 ` [PATCH v4 03/17] vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG Kees Cook
2020-06-29 6:18 ` [PATCH v4 04/17] vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS Kees Cook
2020-06-29 6:18 ` [PATCH v4 05/17] ctype: Work around Clang -mbranch-protection=none bug Kees Cook
2020-06-29 8:15 ` Ard Biesheuvel
2020-06-29 14:43 ` Kees Cook
2020-06-29 15:06 ` Kees Cook
2020-06-29 15:08 ` Ard Biesheuvel
2020-06-29 15:16 ` Kees Cook
2020-06-29 18:02 ` Nick Desaulniers
2020-06-29 18:37 ` Kees Cook
2020-06-29 6:18 ` [PATCH v4 06/17] efi/libstub: Disable -mbranch-protection Kees Cook
2020-06-29 6:18 ` [PATCH v4 07/17] arm64/build: Use common DISCARDS in linker script Kees Cook
2020-06-29 6:18 ` [PATCH v4 08/17] arm64/mm: Remove needless section quotes Kees Cook
2020-06-29 19:53 ` Nick Desaulniers
2020-06-29 20:03 ` Joe Perches
2020-06-29 20:29 ` Nick Desaulniers
2020-06-29 20:04 ` Kees Cook
2020-06-29 20:54 ` Arvind Sankar
2020-06-29 21:06 ` Arvind Sankar [this message]
2020-06-29 6:18 ` [PATCH v4 09/17] arm64/build: Remove .eh_frame* sections due to unwind tables Kees Cook
2020-06-29 6:18 ` [PATCH v4 10/17] arm64/kernel: Remove needless Call Frame Information annotations Kees Cook
2020-06-29 6:18 ` [PATCH v4 11/17] arm64/build: Warn on orphan section placement Kees Cook
2020-06-29 6:18 ` [PATCH v4 12/17] arm/build: Refactor linker script headers Kees Cook
2020-06-29 6:18 ` [PATCH v4 13/17] arm/build: Explicitly keep .ARM.attributes sections Kees Cook
2020-06-29 6:18 ` [PATCH v4 14/17] arm/build: Warn on orphan section placement Kees Cook
2020-06-29 15:54 ` Arvind Sankar
2020-06-29 18:07 ` Russell King - ARM Linux admin
2020-06-29 18:15 ` Arvind Sankar
2020-06-29 19:03 ` Russell King - ARM Linux admin
2020-06-29 19:47 ` Nick Desaulniers
2020-06-29 6:18 ` [PATCH v4 15/17] arm/boot: " Kees Cook
2020-06-29 6:18 ` [PATCH v4 16/17] x86/build: " Kees Cook
2020-06-29 6:18 ` [PATCH v4 17/17] x86/boot: " Kees Cook
2020-08-21 16:02 ` [PATCH v4 00/17] " Will Deacon
2020-08-21 17:36 ` Kees Cook
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