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From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFT/RFC PATCH 6/6] ARM: keep .text and .fixup regions together
Date: Thu, 12 Mar 2015 21:10:52 +0000	[thread overview]
Message-ID: <20150312211051.GZ8656@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1426181892-15440-7-git-send-email-ard.biesheuvel@linaro.org>

On Thu, Mar 12, 2015 at 06:38:12PM +0100, Ard Biesheuvel wrote:
> Fixup snippets are put into a dedicated section so that they don't
> bloat cache lines with instructions that are usually not executed.
> But there is no reason to put all these snippets together at the far
> end of the .text output region, where the branch instruction they
> contain could go out of range if the kernel grows in size.
> 
> Instead, emit .text and .fixup regions together for each input object.
> They should still be out of the way, but not so far that they go out
> of range.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> 
> Note that the TEXT_TEXT macro will emit *(.text) again but this should be
> harmless.

However, I wonder if by doing this, we're weakening the ability for
kallsyms final link to succeed:

/* .text section. Map to function alignment to avoid address changes
 * during second ld run in second ld pass when generating System.map */

Can we not just move .fixup before TEXT_TEXT?  The only thing between it
and .text would be .text.hot.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

  parent reply	other threads:[~2015-03-12 21:10 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-12 17:38 [RFT/RFC PATCH 0/6] ARM kernel size fixes Ard Biesheuvel
2015-03-12 17:38 ` [RFT/RFC PATCH 1/6] ARM: replace PROCINFO embedded branch with relative offset Ard Biesheuvel
2015-03-12 20:24   ` Nicolas Pitre
2015-03-12 20:50   ` Russell King - ARM Linux
2015-03-12 21:00     ` Ard Biesheuvel
2015-03-12 17:38 ` [RFT/RFC PATCH 2/6] ARM: move HYP text to end of .text section Ard Biesheuvel
2015-03-12 17:38 ` [RFT/RFC PATCH 3/6] ARM: add macro to perform far branches (b/bl) Ard Biesheuvel
2015-03-12 20:32   ` Nicolas Pitre
2015-03-12 20:36     ` Ard Biesheuvel
2015-03-12 21:03       ` Nicolas Pitre
2015-03-12 21:15         ` Ard Biesheuvel
2015-03-12 21:37           ` Ard Biesheuvel
2015-03-12 22:26             ` Nicolas Pitre
2015-03-12 20:56   ` Russell King - ARM Linux
2015-03-12 17:38 ` [RFT/RFC PATCH 4/6] ARM: use bl_far to call __hyp_stub_install_secondary from the .data section Ard Biesheuvel
2015-03-12 17:38 ` [RFT/RFC PATCH 5/6] ARM: move the .idmap.text section closer to .head.text Ard Biesheuvel
2015-03-12 20:33   ` Nicolas Pitre
2015-03-12 17:38 ` [RFT/RFC PATCH 6/6] ARM: keep .text and .fixup regions together Ard Biesheuvel
2015-03-12 20:34   ` Nicolas Pitre
2015-03-12 21:10   ` Russell King - ARM Linux [this message]
2015-03-12 21:18     ` Ard Biesheuvel
2015-03-12 21:22       ` Russell King - ARM Linux
2015-03-13 11:18         ` Arnd Bergmann
2015-03-13 11:26           ` Ard Biesheuvel
2015-03-13 11:52             ` Arnd Bergmann

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