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From: David Laight <David.Laight@ACULAB.COM>
To: 'Guenter Roeck' <linux@roeck-us.net>,
	John David Anglin <dave.anglin@bell.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 19:41:33 +0000	[thread overview]
Message-ID: <ef2785806bb34b4688888063edab0588@AcuMS.aculab.com> (raw)
In-Reply-To: <a7b70196-2387-4532-94ac-81220fd07088@roeck-us.net>

...
> > Descriptors need 8-byte alignment for efficiency on 64-bit parisc. The pc and gp are accessed
> > using ldd instructions.
> >
> 
> How about the patch below ?

I think you still need something to avoid the misalignment trap
in the 'false' case.

If they only need to be aligned 'for efficiency' then I'd assume
the cpu (or whatever normally processes them) is ok with 4-byte
alignment even though 'ldd' (8 byte load?) faults.

Which would mean you need to read them with two 4-byte loads.

Especially if 'fn' isn't just one of a couple of specific values
that can be forced to be aligned.

But the code might just be completely broken.
(as suggested elsewhere).

	David

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

  reply	other threads:[~2024-02-15 19:41 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
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 [this message]
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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