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From: David Laight <David.Laight@ACULAB.COM>
To: 'Borislav Petkov' <bp@alien8.de>,
	Dave Hansen <dave.hansen@intel.com>,
	Richard Weinberger <richard@nod.at>
Cc: Sebastian Sumpf <Sebastian.Sumpf@genode-labs.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [Bug report] __arch_hweight32/64 x86
Date: Thu, 29 Jun 2023 09:10:11 +0000	[thread overview]
Message-ID: <fc6f668458fc4cad8ed009f0a796f5f9@AcuMS.aculab.com> (raw)
In-Reply-To: <20230627042538.GAZJpkwldpkqTKeeDL@fat_crate.local>

From: Borislav Petkov
> Sent: 27 June 2023 05:26
> 
> On Mon, Jun 26, 2023 at 03:41:27PM -0700, Dave Hansen wrote:
> > I'm not even sure that UML needs GENERIC_HWEIGHT.  From a quick glance,
> > it looks like x86 used to use GENERIC_HWEIGHT, but got arch-specific
> > versions later.  UML just never moved over to the arch-specific versions.
> 
> Thanks - that could very well be the explanation.
> 
> That bug report made me blink a couple of times since I did take extra
> precaution to not clobber regs in arch/x86/lib/hweight.S as this was
> part of the whole pain back then with calling a function from asm where
> gcc doesn't even know we're calling a function, see:

Perhaps the asm called function should use a different global
label than the one in the C file.

Then it wouldn't be as fragile.

	David

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

      parent reply	other threads:[~2023-06-29  9:13 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-26 20:49 Sebastian Sumpf
2023-06-26 21:06 ` Borislav Petkov
2023-06-26 21:42   ` Sebastian Sumpf
2023-06-26 22:41     ` Dave Hansen
2023-06-27  4:25       ` Borislav Petkov
2023-06-27 16:57         ` Sebastian Sumpf
2023-06-29  9:10         ` David Laight [this message]

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