linux-kernel - Re: [PATCH v1 3/3] spi: xilinx: Make num_chipselect 8-bit in the struct xspi_platform

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZesYvnwiSMPMq98s@smile.fi.intel.com>
Date: Fri, 8 Mar 2024 15:55:10 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Michal Simek <michal.simek@....com>
Cc: linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v1 3/3] spi: xilinx: Make num_chipselect 8-bit in the
 struct xspi_platform_data

On Fri, Mar 08, 2024 at 02:48:04PM +0100, Michal Simek wrote:
> On 3/8/24 14:31, Andy Shevchenko wrote:
> > On Fri, Mar 08, 2024 at 09:20:23AM +0100, Michal Simek wrote:
> > > On 3/7/24 16:43, Andy Shevchenko wrote:

..

> > > >    struct xspi_platform_data {
> > > > -	u16 num_chipselect;
> > > > -	u8 bits_per_word;
> > > > -	struct spi_board_info *devices;
> > > > -	u8 num_devices;
> > > >    	bool force_irq;
> > > > +	u8 num_chipselect;
> > > > +	u8 bits_per_word;
> > > > +	u8 num_devices;
> > > 
> > > all above have 32bits. It means on 64bit cpu you have 32bit gap here.
> > 
> > > > +	struct spi_board_info *devices;
> > 
> > On all architectures? I mean do all 64-bit architecture ABIs _require_
> > the pointer to be aligned at 8-byte boundary? Even if so, the struct
> > itself can be aligned on 4-byte boundary.
> 
> I am not able to tell if toolchain enforce 8byte alignment by default/by
> setup on all 64bit systems.
> I am using pahole to check this which was recommended by Greg in past which
> reports gap in the middle.

I see, thanks for explanation.

Yes, it's likely that in some cases it will be a gap on 64-bit platforms, but
after this patch no gap on 32-bit. Do you still want me to reshuffle that as
you suggested?

-- 
With Best Regards,
Andy Shevchenko