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authorGeorge G. Davis <gdavis@mvista.com>2009-04-01 20:27:18 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-04-01 22:17:50 +0100
commitf2255be8126e86142901c61dd482c1c2a5ffdda7 (patch)
treea59ff8fecbbf30a7a1e33f97b59e1ed3cd38c018 /arch/arm/vfp/vfpmodule.c
parentfe68e68f6a379d317a87ae24de050a65b11ea1fb (diff)
[ARM] 5440/1: Fix VFP state corruption due to preemption during VFP exceptions
We've observed that ARM VFP state can be corrupted during VFP exception handling when PREEMPT is enabled. The exact conditions are difficult to reproduce but appear to occur during VFP exception handling when a task causes a VFP exception which is handled via VFP_bounce and is then preempted by yet another task which in turn causes yet another VFP exception. Since the VFP_bounce code is not preempt safe, VFP state then becomes corrupt. In order to prevent preemption from occuring while handling a VFP exception, this patch disables preemption while handling VFP exceptions. Signed-off-by: George G. Davis <gdavis@mvista.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/vfp/vfpmodule.c')
-rw-r--r--arch/arm/vfp/vfpmodule.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 75457b30d81..01599c4ef72 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -266,7 +266,7 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
* on VFP subarch 1.
*/
vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs);
- return;
+ goto exit;
}
/*
@@ -297,7 +297,7 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
* the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.
*/
if (fpexc ^ (FPEXC_EX | FPEXC_FP2V))
- return;
+ goto exit;
/*
* The barrier() here prevents fpinst2 being read
@@ -310,6 +310,8 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs);
if (exceptions)
vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
+ exit:
+ preempt_enable();
}
static void vfp_enable(void *unused)