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From: Will Deacon <will@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arch@vger.kernel.org, Arnd Bergmann <arnd@kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Arnd Bergmann <arnd@arndb.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Nathan Chancellor <natechancellor@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: make atomic helpers __always_inline
Date: Wed, 13 Jan 2021 13:44:12 +0000	[thread overview]
Message-ID: <20210113134412.GA11757@willie-the-truck> (raw)
In-Reply-To: <20210112102312.GC34326@C02TD0UTHF1T.local>

On Tue, Jan 12, 2021 at 10:23:12AM +0000, Mark Rutland wrote:
> On Fri, Jan 08, 2021 at 09:39:53PM +0100, Peter Zijlstra wrote:
> > On Fri, Jan 08, 2021 at 09:32:58AM +0000, Will Deacon wrote:
> > > Hi Arnd,
> > > 
> > > On Fri, Jan 08, 2021 at 10:19:56AM +0100, Arnd Bergmann wrote:
> > > > From: Arnd Bergmann <arnd@arndb.de>
> > > > 
> > > > With UBSAN enabled and building with clang, there are occasionally
> > > > warnings like
> > > > 
> > > > WARNING: modpost: vmlinux.o(.text+0xc533ec): Section mismatch in reference from the function arch_atomic64_or() to the variable .init.data:numa_nodes_parsed
> > > > The function arch_atomic64_or() references
> > > > the variable __initdata numa_nodes_parsed.
> > > > This is often because arch_atomic64_or lacks a __initdata
> > > > annotation or the annotation of numa_nodes_parsed is wrong.
> > > > 
> > > > for functions that end up not being inlined as intended but operating
> > > > on __initdata variables. Mark these as __always_inline, along with
> > > > the corresponding asm-generic wrappers.
> > > 
> > > Hmm, I don't fully grok this. Why does it matter if a non '__init' function
> > > is called with a pointer to some '__initdata'? Or is the reference coming
> > > from somewhere else? (where?).
> > 
> > FWIW the x86 atomics are __always_inline in part due to the noinstr
> > crud, which I imagine resulted in much the same 'fun'.
> 
> FWIW, I was planning on doing the same here as part of making arm64
> noinstr safe, so I reckon we should probably do this regardless of
> whether it's a complete fix for the section mismatch issue.

Fair enough:

Acked-by: Will Deacon <will@kernel.org>

Will

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  reply	other threads:[~2021-01-13 13:45 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08  9:19 [PATCH] arm64: make atomic helpers __always_inline Arnd Bergmann
2021-01-08  9:32 ` Will Deacon
2021-01-08 10:26   ` Arnd Bergmann
2021-01-08 18:50     ` Will Deacon
2021-01-08 20:04       ` Arnd Bergmann
2021-01-08 21:23     ` Nick Desaulniers
2021-01-08 20:39   ` Peter Zijlstra
2021-01-12 10:23     ` Mark Rutland
2021-01-13 13:44       ` Will Deacon [this message]
2021-01-13 16:06 ` Catalin Marinas

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