[PATCH] ARM: cache-v7: Disable preemption when reading CCSIDR
rabin at rab.in
Tue Feb 14 09:15:24 EST 2012
On Mon, Feb 13, 2012 at 11:29:01PM +0000, Russell King - ARM Linux wrote:
> On Mon, Feb 13, 2012 at 02:23:29PM -0800, Stephen Boyd wrote:
> > On 02/13/12 10:15, Russell King - ARM Linux wrote:
> > > On Mon, Feb 13, 2012 at 10:13:27AM -0800, Stephen Boyd wrote:
> > >> Thanks. Russell has already merged the original patch to the fixes
> > >> branch. Hopefully he can fold this one in.
> > > Nope, I've asked Linus to pull it.
> > >
> > > So do we conclude that the original patch wasn't properly tested? :P
> > Sigh. Lockdep strikes again! I promise I tested it with lockdep disabled.
> > It looks like Linus' hasn't pulled yet but maybe he just hasn't
> > published it.
> It's not nice to change something after you've sent a pull request -
> there's no way of knowing when Linus actually pulls it before he's
> published it, and if he gets something different then it can raise
> So, it's gone in as-is, and, as I'm now intending asking for another
> pull request soo soon after my previous one, this is something that
> we will have to live with probably for the remainder of the week.
OK, since it can't be folded in, here is a proper patch:
>From 26f02624a20a61ed1997a4e8648e4c766a54d91d Mon Sep 17 00:00:00 2001
From: Rabin Vincent <rabin at rab.in>
Date: Tue, 14 Feb 2012 19:22:07 +0530
Subject: [PATCH] ARM: fix v7 boot with lockdep enabled
Bootup with lockdep enabled has been broken on v7 since b46c0f74657d
("ARM: 7321/1: cache-v7: Disable preemption when reading CCSIDR").
This is because v7_setup (which is called very early during boot) calls
v7_flush_dcache_all, and the save_and_disable_irqs added by that patch
ends up attempting to call into lockdep C code (trace_hardirqs_off())
when we are in no position to execute it (no stack, MMU off).
Fix this by using a notrace variant of save_and_disable_irqs. The code
already uses the notrace variant of restore_irqs.
Cc: Stephen Boyd <sboyd at codeaurora.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Nicolas Pitre <nico at linaro.org>
Cc: stable at vger.kernel.org
Signed-off-by: Rabin Vincent <rabin at rab.in>
arch/arm/include/asm/assembler.h | 5 +++++
arch/arm/mm/cache-v7.S | 2 +-
2 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 62f8095..23371b1 100644
@@ -137,6 +137,11 @@
+ .macro save_and_disable_irqs_notrace, oldcpsr
+ mrs \oldcpsr, cpsr
* Restore interrupt state previously stored in a register. We don't
* guarantee that this will preserve the flags.
diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
index 7a24d396..a655d3d 100644
@@ -55,7 +55,7 @@ loop1:
cmp r1, #2 @ see what cache we have at this level
blt skip @ skip if no cache, or just i-cache
- save_and_disable_irqs r9 @ make cssr&csidr read atomic
+ save_and_disable_irqs_notrace r9 @ make cssr&csidr read atomic
mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
isb @ isb to sych the new cssr&csidr
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