From ec930dfbab3b9d4ab3f9978f0f87ff02fa8a2ec6 Mon Sep 17 00:00:00 2001 From: Christophe Lyon Date: Fri, 25 Oct 2019 11:57:11 +0200 Subject: target/arm: Allow reading flags from FPSCR for M-profile rt==15 is a special case when reading the flags: it means the destination is APSR. This patch avoids rejecting vmrs apsr_nzcv, fpscr as illegal instruction. Cc: qemu-stable@nongnu.org Signed-off-by: Christophe Lyon Message-id: 20191025095711.10853-1-christophe.lyon@linaro.org [PMM: updated the comment] Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- target/arm/translate-vfp.inc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c index 9ae980bef6..85c5ef897b 100644 --- a/target/arm/translate-vfp.inc.c +++ b/target/arm/translate-vfp.inc.c @@ -703,9 +703,10 @@ static bool trans_VMSR_VMRS(DisasContext *s, arg_VMSR_VMRS *a) if (arm_dc_feature(s, ARM_FEATURE_M)) { /* * The only M-profile VFP vmrs/vmsr sysreg is FPSCR. - * Writes to R15 are UNPREDICTABLE; we choose to undef. + * Accesses to R15 are UNPREDICTABLE; we choose to undef. + * (FPSCR -> r15 is a special case which writes to the PSR flags.) */ - if (a->rt == 15 || a->reg != ARM_VFP_FPSCR) { + if (a->rt == 15 && (!a->l || a->reg != ARM_VFP_FPSCR)) { return false; } } -- cgit v1.2.3