From: Nathan Chancellor <natechancellor@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Andrew Murray <andrew.murray@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg
Date: Tue, 17 Sep 2019 13:34:25 -0700 [thread overview]
Message-ID: <20190917203425.GA31423@archlinux-threadripper> (raw)
In-Reply-To: <20190910115643.391995-1-arnd@arndb.de>
On Tue, Sep 10, 2019 at 01:56:22PM +0200, Arnd Bergmann wrote:
> On arm64 build with clang, sometimes the __cmpxchg_mb is not inlined
> when CONFIG_OPTIMIZE_INLINING is set.
> Clang then fails a compile-time assertion, because it cannot tell at
> compile time what the size of the argument is:
>
> mm/memcontrol.o: In function `__cmpxchg_mb':
> memcontrol.c:(.text+0x1a4c): undefined reference to `__compiletime_assert_175'
> memcontrol.c:(.text+0x1a4c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `__compiletime_assert_175'
>
> Mark all of the cmpxchg() style functions as __always_inline to
> ensure that the compiler can see the result.
>
> Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/648
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> Tested-by: Nathan Chancellor <natechancellor@gmail.com>
> Reviewed-by: Andrew Murray <andrew.murray@arm.com>
> Tested-by: Andrew Murray <andrew.murray@arm.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: skip unneeded changes, as suggested by Andrew Murray
> ---
> arch/arm64/include/asm/cmpxchg.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
> index a1398f2f9994..f9bef42c1411 100644
> --- a/arch/arm64/include/asm/cmpxchg.h
> +++ b/arch/arm64/include/asm/cmpxchg.h
> @@ -62,7 +62,7 @@ __XCHG_CASE( , , mb_, 64, dmb ish, nop, , a, l, "memory")
> #undef __XCHG_CASE
>
> #define __XCHG_GEN(sfx) \
> -static inline unsigned long __xchg##sfx(unsigned long x, \
> +static __always_inline unsigned long __xchg##sfx(unsigned long x, \
> volatile void *ptr, \
> int size) \
> { \
> @@ -148,7 +148,7 @@ __CMPXCHG_DBL(_mb)
> #undef __CMPXCHG_DBL
>
> #define __CMPXCHG_GEN(sfx) \
> -static inline unsigned long __cmpxchg##sfx(volatile void *ptr, \
> +static __always_inline unsigned long __cmpxchg##sfx(volatile void *ptr, \
> unsigned long old, \
> unsigned long new, \
> int size) \
> @@ -255,7 +255,7 @@ __CMPWAIT_CASE( , , 64);
> #undef __CMPWAIT_CASE
>
> #define __CMPWAIT_GEN(sfx) \
> -static inline void __cmpwait##sfx(volatile void *ptr, \
> +static __always_inline void __cmpwait##sfx(volatile void *ptr, \
> unsigned long val, \
> int size) \
> { \
> --
> 2.20.0
>
Looks like the arm64 pull request happened without this patch so clang
all{mod,yes}config builds are broken. Did the maintainers have any
further comments on it or could this make it in with the next one?
Cheers,
Nathan
next prev parent reply other threads:[~2019-09-17 20:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-10 11:56 [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg Arnd Bergmann
2019-09-17 20:34 ` Nathan Chancellor [this message]
2019-09-18 9:02 ` Will Deacon
2019-09-18 16:02 ` Nathan Chancellor
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190917203425.GA31423@archlinux-threadripper \
--to=natechancellor@gmail.com \
--cc=andrew.murray@arm.com \
--cc=arnd@arndb.de \
--cc=catalin.marinas@arm.com \
--cc=clang-built-linux@googlegroups.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=ndesaulniers@google.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).