ARM: 7417/1: vfp: ensure preemption is disabled when enabling VFP access
authorWill Deacon <will.deacon@arm.com>
Fri, 11 May 2012 16:42:37 +0000 (17:42 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Sat, 12 May 2012 13:37:59 +0000 (14:37 +0100)
commit998de4acb2ba188d20768d1065658377a2e7d29b
treeb1c21f8cd96a6eb7cbce7e810eac65febf17982d
parentfde165b2a29673aabf18ceff14dea1f1cfb0daad
ARM: 7417/1: vfp: ensure preemption is disabled when enabling VFP access

The vfp_enable function enables access to the VFP co-processor register
space (cp10 and cp11) on the current CPU and must be called with
preemption disabled. Unfortunately, the vfp_init late initcall does not
disable preemption and can lead to an oops during boot if thread
migration occurs at the wrong time and we end up attempting to access
the FPSID on a CPU with VFP access disabled.

This patch fixes the initcall to call vfp_enable from a non-preemptible
context on each CPU and adds a BUG_ON(preemptible) to ensure that any
similar problems are easily spotted in the future.

Cc: stable@vger.kernel.org
Reported-by: Hyungwoo Yang <hwoo.yang@gmail.com>
Signed-off-by: Hyungwoo Yang <hyungwooy@nvidia.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arch/arm/vfp/vfpmodule.c