Enforce that for M-profile various FPSCR bits which are RES0 there
but have defined meanings on A-profile are never settable. This
ensures that M-profile code can't enable the A-profile behaviour
(notably vector length/stride handling) by accident.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
target/arm/vfp_helper.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/target/arm/vfp_helper.c b/target/arm/vfp_helper.c
index 2468fc16294..7a46d991486 100644
--- a/target/arm/vfp_helper.c
+++ b/target/arm/vfp_helper.c
@@ -105,6 +105,14 @@ void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val)
val &= ~FPCR_FZ16;
}
+ if (arm_feature(env, ARM_FEATURE_M)) {
+ /*
+ * M profile FPSCR is RES0 for the QC, STRIDE, FZ16, LEN bits
+ * and also for the trapped-exception-handling bits IxE.
+ */
+ val &= 0xf7c0009f;
+ }
+
/*
* We don't implement trapped exception handling, so the
* trap enable bits, IDE|IXE|UFE|OFE|DZE|IOE are all RAZ/WI (not RES0!)
--
2.20.1
