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Message-ID: <20180709135409.GQ2476@hirez.programming.kicks-ass.net>
Date: Mon, 9 Jul 2018 15:54:09 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Alexey Brodkin <Alexey.Brodkin@...opsys.com>
Cc: linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
linux-arch@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
David Laight <David.Laight@...LAB.COM>,
Thomas Gleixner <tglx@...utronix.de>,
Will Deacon <will.deacon@....com>, Greg KH <greg@...ah.com>,
stable@...r.kernel.org
Subject: Re: [PATCH v3] devres: Explicitly align datai[] to 64-bit
On Mon, Jul 09, 2018 at 04:45:50PM +0300, Alexey Brodkin wrote:
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index f98a097e73f2..d65327cb83c9 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -24,8 +24,12 @@ struct devres_node {
>
> struct devres {
> struct devres_node node;
> - /* -- 3 pointers */
> - unsigned long long data[]; /* guarantee ull alignment */
> + /*
> + * data[] must be 64 bit aligned even on 32 bit architectures
> + * because it might be accessed by instructions that require
> + * aligned memory arguments such as atomic64_t.
> + */
> + u8 __aligned(8) data[];
> };
>From a quick reading in Documentation/driver-model/devres.txt this
devres muck is supposed to be device memory, right?
atomics (as in atomic*_t) are not defined for use on mmio.
wth kind of code is relying on this?
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