From: Paul Mackerras <paulus@samba.org>
To: Tom <tommusta@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [V2 PATCH 1/3] powerpc: Enable emulate_step In Little Endian Mode
Date: Mon, 4 Nov 2013 13:28:35 +1100 [thread overview]
Message-ID: <20131104022835.GA32010@drongo> (raw)
In-Reply-To: <1383244738-5986-2-git-send-email-tommusta@gmail.com>
On Thu, Oct 31, 2013 at 01:38:56PM -0500, Tom wrote:
> From: Tom Musta <tommusta@gmail.com>
>
> This patch modifies the endian chicken switch in the single step
"Chicken switch" is IBM jargon, perhaps best avoided where possible in
commit messages.
> emulation code (emulate_step()). The old (big endian) code bailed
> early if a load or store instruction was to be emulated in little
> endian mode.
>
> The new code modifies the check and only bails in a cross-endian
> situation (LE mode in a kernel compiled for BE and vice verse).
The patch adds #ifdefs inside code, which is generally frowned upon
in kernel code as it can make the code flow harder to see. Perhaps
you could do something like
if ((regs->msr & MSR_LE) != (MSR_KERNEL & MSR_LE))
as an alternative that wouldn't require an #ifdef. Or, define a
symbol that is 0 in a BE kernel and MSR_LE in a LE kernel, and compare
to that.
Paul.
next prev parent reply other threads:[~2013-11-04 2:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-31 18:38 [V2 PATCH 0/3] powerpc: Fix Little Endian Bugs in Single Step Code Tom
2013-10-31 18:38 ` [V2 PATCH 1/3] powerpc: Enable emulate_step In Little Endian Mode Tom
2013-11-04 2:28 ` Paul Mackerras [this message]
2013-10-31 18:38 ` [V2 PATCH 2/3] powerpc: Fix Unaligned Fixed Point Loads and Stores Tom
2013-11-04 2:34 ` Benjamin Herrenschmidt
2013-11-04 2:43 ` Paul Mackerras
2013-10-31 18:38 ` [V2 PATCH 3/3] powerpc: Fix Unaligned LE Floating " Tom
2013-11-04 2:34 ` Benjamin Herrenschmidt
2013-11-04 13:29 ` Tom Musta
2013-12-11 3:54 ` Paul Mackerras
2013-12-11 4:57 ` Paul Mackerras
2013-12-12 15:08 ` Tom Musta
2013-12-12 20:33 ` Tom Musta
2013-12-12 21:19 ` Paul Mackerras
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