From: Jon Hunter <jon-hunter@ti.com>
To: Tony Lindgren <tony@atomide.com>
Cc: Paul Walmsley <paul@pwsan.com>,
Dave Martin <dave.martin@linaro.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-omap@vger.kernel.org,
Mans Rullgard <mans.rullgard@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3] ARM: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set
Date: Tue, 16 Oct 2012 12:13:22 -0500 [thread overview]
Message-ID: <507D95B2.3020506@ti.com> (raw)
In-Reply-To: <20121015175317.GE15569@atomide.com>
On 10/15/2012 12:53 PM, Tony Lindgren wrote:
> * Paul Walmsley <paul@pwsan.com> [121014 22:26]:
>>
>> After commit 846a136881b8f73c1f74250bf6acfaa309cab1f2 ("ARM: vfp: fix
>> saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP board
>> started crashing during boot with omap2plus_defconfig:
>>
>> [ 3.875122] mmcblk0: mmc0:e624 SD04G 3.69 GiB
>> [ 3.915954] mmcblk0: p1
>> [ 4.086639] Internal error: Oops - undefined instruction: 0 [#1] SMP ARM
>> [ 4.093719] Modules linked in:
>> [ 4.096954] CPU: 0 Not tainted (3.6.0-02232-g759e00b #570)
>> [ 4.103149] PC is at vfp_reload_hw+0x1c/0x44
>> [ 4.107666] LR is at __und_usr_fault_32+0x0/0x8
>>
>> It turns out that the context save/restore fix unmasked a latent bug
>> in commit 5aaf254409f8d58229107b59507a8235b715a960 ("ARM: 6203/1: Make
>> VFPv3 usable on ARMv6"). When CONFIG_VFPv3 is set, but the kernel is
>> booted on a pre-VFPv3 core, the code attempts to save and restore the
>> d16-d31 VFP registers. These are only present on non-D16 VFPv3+, so
>> this results in an undefined instruction exception. The code didn't
>> crash before commit 846a136 because the save and restore code was
>> only touching d0-d15, present on all VFP.
>>
>> Fix by implementing a request from Russell King to add a new HWCAP
>> flag that affirmatively indicates the presence of the d16-d31
>> registers:
>>
>> http://marc.info/?l=linux-arm-kernel&m=135013547905283&w=2
>>
>> and some feedback from Måns to clarify the name of the HWCAP flag.
>>
>> Signed-off-by: Paul Walmsley <paul@pwsan.com>
>> Cc: Tony Lindgren <tony@atomide.com>
>> Cc: Russell King <rmk+kernel@arm.linux.org.uk>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Dave Martin <dave.martin@linaro.org>
>> Cc: Måns Rullgård <mans.rullgard@linaro.org>
>
> This fixes the error above on my 2430sdp:
>
> Tested-by: Tony Lindgren <tony@atomide.com>
Fixes same error on 2420 H4.
Tested-by: Jon Hunter <jon-hunter@ti.com>
Cheers
Jon
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prev parent reply other threads:[~2012-10-16 17:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-13 4:46 [PATCH] ARM: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set Paul Walmsley
2012-10-13 9:02 ` Russell King - ARM Linux
2012-10-13 10:50 ` Måns Rullgård
2012-10-13 13:36 ` Russell King - ARM Linux
2012-10-15 1:58 ` Paul Walmsley
2012-10-15 2:39 ` Mans Rullgard
2012-10-15 5:24 ` [PATCH v3] " Paul Walmsley
2012-10-15 17:53 ` Tony Lindgren
2012-10-16 17:13 ` Jon Hunter [this message]
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