All of lore.kernel.org
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/2] arm64: Use simpler arithmetics for the linear map macros
Date: Mon, 1 Feb 2021 15:17:04 -0800	[thread overview]
Message-ID: <CAHk-=wgDgseQFpmVB2rw6h4De1Z70xwDgoaOMp9=WXVE4g0pPQ@mail.gmail.com> (raw)
In-Reply-To: <CAMj1kXHBJt2nN1vBu9rmvN2mVcNiiocT4NtpMf8Y4NozpONzPA@mail.gmail.com>

On Mon, Feb 1, 2021 at 3:05 PM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> Why still subtract PAGE_OFFSET on both sides of the comparison here?

Because otherwise you'd have to use 'addr' twice in a macro, and write
it something like

   #define __is_lm_address(addr) \
        (((u64)(addr) >= PAGE_OFFSET) &&  < ((u64)(addr) < PAGE_END))

which then would require you to do a local variable in a statement
expression to avoid the double evaluation..

              Linus

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-02-01 23:18 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01 19:06 [PATCH 0/2] arm64: Further fixes to the linear address checking Catalin Marinas
2021-02-01 19:06 ` [PATCH 1/2] arm64: Do not pass tagged addresses to __is_lm_address() Catalin Marinas
2021-02-01 19:06   ` Catalin Marinas
2021-02-01 19:06 ` [PATCH 2/2] arm64: Use simpler arithmetics for the linear map macros Catalin Marinas
2021-02-01 23:05   ` Ard Biesheuvel
2021-02-01 23:17     ` Linus Torvalds [this message]
2021-02-02 11:36     ` Catalin Marinas
2021-02-02 11:40       ` Ard Biesheuvel
2021-02-01 19:33 ` [PATCH 0/2] arm64: Further fixes to the linear address checking Linus Torvalds
2021-02-02 17:46 ` Catalin Marinas

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='CAHk-=wgDgseQFpmVB2rw6h4De1Z70xwDgoaOMp9=WXVE4g0pPQ@mail.gmail.com' \
    --to=torvalds@linux-foundation.org \
    --cc=ardb@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=mark.rutland@arm.com \
    --cc=vincenzo.frascino@arm.com \
    --cc=will@kernel.org \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.