[PATCH v2 3/3] arm: vfp: Bounce undefined instructions in vectored mode

From: Stephen Boyd
Date: Tue Oct 14 2014 - 09:49:13 EST

From: Stepan Moskovchenko <stepanm@xxxxxxxxxxxxxx>

Certain ARM CPU implementations (e.g. Cortex-A15) may not raise a
floating- point exception whenever deprecated short-vector VFP
instructions are executed. Instead these instructions are treated
as UNALLOCATED. Change the VFP exception handling code to emulate
short-vector instructions even if FPEXC exception bits are not

Signed-off-by: Stepan Moskovchenko <stepanm@xxxxxxxxxxxxxx>
Tested-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
arch/arm/vfp/vfphw.S | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index cda654cbf2c2..f74a8f7e5f84 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -197,6 +197,12 @@ look_for_VFP_exceptions:
tst r5, #FPSCR_IXE
bne process_exception

+ beq skip
+ orr r1, r1, #FPEXC_DEX
+ b process_exception
@ Fall into hand on to next handler - appropriate coproc instr
@ not recognised by VFP

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