42 lines
1.6 KiB
Diff
42 lines
1.6 KiB
Diff
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From cdc6896659b85f7ed8f7552850312e55170de0c5 Mon Sep 17 00:00:00 2001
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From: Christophe Lyon <christophe.lyon@linaro.org>
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Date: Fri, 25 Oct 2019 11:57:11 +0200
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Subject: [PATCH] target/arm: Allow reading flags from FPSCR for M-profile
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rt==15 is a special case when reading the flags: it means the
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destination is APSR. This patch avoids rejecting
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vmrs apsr_nzcv, fpscr
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as illegal instruction.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Christophe Lyon <christophe.lyon@linaro.org>
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Message-id: 20191025095711.10853-1-christophe.lyon@linaro.org
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[PMM: updated the comment]
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Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
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Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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(cherry picked from commit 2529ab43b8a05534494704e803e0332d111d8b91)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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target/arm/translate-vfp.inc.c | 5 +++--
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1 file changed, 3 insertions(+), 2 deletions(-)
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diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c
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index ef45cecbea..75406fd9db 100644
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--- a/target/arm/translate-vfp.inc.c
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+++ b/target/arm/translate-vfp.inc.c
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@@ -704,9 +704,10 @@ static bool trans_VMSR_VMRS(DisasContext *s, arg_VMSR_VMRS *a)
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if (arm_dc_feature(s, ARM_FEATURE_M)) {
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/*
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* The only M-profile VFP vmrs/vmsr sysreg is FPSCR.
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- * Writes to R15 are UNPREDICTABLE; we choose to undef.
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+ * Accesses to R15 are UNPREDICTABLE; we choose to undef.
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+ * (FPSCR -> r15 is a special case which writes to the PSR flags.)
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*/
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- if (a->rt == 15 || a->reg != ARM_VFP_FPSCR) {
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+ if (a->rt == 15 && (!a->l || a->reg != ARM_VFP_FPSCR)) {
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return false;
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}
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}
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--
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2.23.0
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