LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: hans.rosenfeld@amd.com, torvalds@linux-foundation.org,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Arjan van de Ven <arjan@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: bisected boot regression post 2.6.25-rc3.. please revert
Date: Mon, 3 Mar 2008 23:33:52 +0100	[thread overview]
Message-ID: <a9af8424f96a9118c6b097d9b2df79b2@kernel.crashing.org> (raw)
In-Reply-To: <4ffd9be7b13d6300b888c146d6d040d5@kernel.crashing.org>

>> so (on 32-bit) ~_PAGE_PSE is ~0x80L is 0xffffff7f, which when cast to
>> 64-bit is 0x00000000ffffff7f,
>
> Actually, it is signed, so this isn't true.  Comments about unsafeness
> still apply.

It turns out that PAGE_SIZE is unsigned.  So this gives us for

	(~PAGE_MASK & ~_PAGE_USER & ~_PAGE_PSE & ~_PAGE_NX)

the types UL, L, L, ULL resp.

The associativity of & is left-to-right, so this in turn becomes

	UL, L, ULL

	UL, ULL

	ULL

and that cast from UL to ULL doesn't sign-extend.


Segher


  reply	other threads:[~2008-03-03 22:35 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-01 18:56 Arjan van de Ven
2008-03-03  7:46 ` Ingo Molnar
2008-03-03  9:13   ` Ingo Molnar
2008-03-03 16:41     ` Arjan van de Ven
2008-03-03 17:40       ` Ingo Molnar
2008-03-03 17:51         ` Nish Aravamudan
2008-03-03 17:55           ` Ingo Molnar
2008-03-03 17:58             ` H. Peter Anvin
2008-03-03 18:36         ` Arjan van de Ven
2008-03-03 18:44           ` Linus Torvalds
2008-03-03 22:00             ` Arjan van de Ven
2008-03-04  1:05               ` Arjan van de Ven
2008-03-04  6:53                 ` Ingo Molnar
2008-03-05 15:35                   ` Arjan van de Ven
2008-03-09 11:56             ` Ingo Molnar
2008-03-09 17:27               ` Linus Torvalds
2008-03-09 18:57                 ` Ingo Molnar
2008-03-10  2:45                 ` Jeremy Fitzhardinge
2008-03-10  4:35                 ` Paul Mackerras
2008-03-03 21:13           ` Segher Boessenkool
2008-03-03 21:22             ` Segher Boessenkool
2008-03-03 22:33               ` Segher Boessenkool [this message]
2008-03-03 22:55                 ` H. Peter Anvin
2008-03-03 22:56                 ` Jeremy Fitzhardinge
2008-03-03 23:04                   ` H. Peter Anvin
2008-03-04  6:58             ` Ingo Molnar
2008-03-03 17:15 ` Nish Aravamudan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=a9af8424f96a9118c6b097d9b2df79b2@kernel.crashing.org \
    --to=segher@kernel.crashing.org \
    --cc=arjan@linux.intel.com \
    --cc=hans.rosenfeld@amd.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: bisected boot regression post 2.6.25-rc3.. please revert' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).