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From: David Laight <David.Laight@ACULAB.COM>
To: 'Guenter Roeck' <linux@roeck-us.net>,
	Charlie Jenkins <charlie@rivosinc.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Helge Deller <deller@gmx.de>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Parisc List <linux-parisc@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v8 2/2] lib: checksum: Use aligned accesses for ip_fast_csum and csum_ipv6_magic tests
Date: Thu, 15 Feb 2024 10:27:13 +0000	[thread overview]
Message-ID: <a7e9691432374000b9566a0201d004e6@AcuMS.aculab.com> (raw)
In-Reply-To: <2ec91b11-23c7-4beb-8cef-c68367c8f029@roeck-us.net>

...
> It would be worthwhile tracking this down since there are
> lots of unaligned data accesses (8-byte accesses on 4-byte aligned addresses)
> when running the kernel in 64-bit mode.

Hmmm....
For performance reasons you really don't want any of them.
The misaligned 64bit fields need an __attribute((aligned(4)) marker.

If the checksum code can do them it really needs to detect
and handle the misalignment.

The misaligned trap handler probably ought to contain a
warn_on_once() to dump stack on the first such error.
They can then be fixed one at a time.

	David

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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  parent reply	other threads:[~2024-02-15 10:27 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-14 21:41 [PATCH v8 0/2] lib: checksum: Fix issues with checksum tests Charlie Jenkins
2024-02-14 21:41 ` [PATCH v8 1/2] lib: checksum: Fix type casting in checksum kunits Charlie Jenkins
2024-02-14 21:41 ` [PATCH v8 2/2] lib: checksum: Use aligned accesses for ip_fast_csum and csum_ipv6_magic tests Charlie Jenkins
2024-02-14 23:03   ` Guenter Roeck
2024-02-15  1:30     ` Charlie Jenkins
2024-02-15  1:58       ` Guenter Roeck
2024-02-15  3:00         ` John David Anglin
2024-02-15  3:35           ` Charlie Jenkins
2024-02-15  4:11             ` Charlie Jenkins
2024-02-15  8:56             ` Guenter Roeck
2024-02-15 15:36               ` Charlie Jenkins
2024-02-15 16:30                 ` Guenter Roeck
2024-02-15 16:51                   ` Charlie Jenkins
2024-02-15 17:13                     ` John David Anglin
2024-02-15 17:29                     ` Guenter Roeck
2024-02-15 15:22           ` Guenter Roeck
2024-02-16  5:54         ` Helge Deller
2024-02-16  5:25           ` Guenter Roeck
2024-02-16  7:31             ` Helge Deller
2024-02-16  6:58               ` Guenter Roeck
2024-02-16  6:09           ` Guenter Roeck
2024-02-16  6:13             ` Charlie Jenkins
2024-02-16 12:05               ` Helge Deller
2024-02-16 18:22           ` John David Anglin
2024-02-15 10:27     ` David Laight [this message]
2024-02-15 15:44       ` Guenter Roeck
2024-02-15 16:51         ` John David Anglin
2024-02-15 17:06           ` Guenter Roeck
2024-02-15 17:25             ` John David Anglin
2024-02-15 18:17               ` Guenter Roeck
2024-02-15 18:56                 ` John David Anglin
2024-02-15 21:00                   ` Guenter Roeck
2024-02-15 21:08                     ` John David Anglin
2024-02-15 18:42               ` Guenter Roeck
2024-02-15 19:41                 ` David Laight
2024-02-15 19:42                 ` Charlie Jenkins
2024-02-16  5:00                   ` Guenter Roeck
2024-02-15  1:24   ` Guenter Roeck

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