From 362379a9e10b1e512cf2574e117ad175ff576b19 Mon Sep 17 00:00:00 2001
From: Peter Maydell <peter.maydell@linaro.org>
Date: Wed, 3 Mar 2021 18:48:46 -0500
Subject: [PATCH] target/arm: Factor out preserve-fp-state from
 full_vfp_access_check()

Factor out the code which handles M-profile lazy FP state preservation
from full_vfp_access_check(); accesses to the FPCXT_NS register are
a special case which need to do just this part (corresponding in the
pseudocode to the PreserveFPState() function), and not the full
set of actions matching the pseudocode ExecuteFPCheck() which
normal FP instructions need to do.

Backports 96dfae686628fc14ba4f993824322b93395e221b
---
 qemu/target/arm/translate-vfp.inc.c | 47 ++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/qemu/target/arm/translate-vfp.inc.c b/qemu/target/arm/translate-vfp.inc.c
index c9a36c2e..4c25d172 100644
--- a/qemu/target/arm/translate-vfp.inc.c
+++ b/qemu/target/arm/translate-vfp.inc.c
@@ -83,6 +83,34 @@ static inline long vfp_f16_offset(unsigned reg, bool top)
     return offs;
 }
 
+/*
+ * Generate code for M-profile lazy FP state preservation if needed;
+ * this corresponds to the pseudocode PreserveFPState() function.
+ */
+static void gen_preserve_fp_state(DisasContext *s)
+{
+    TCGContext *tcg_ctx = s->uc->tcg_ctx;
+
+    if (s->v7m_lspact) {
+        /*
+         * Lazy state saving affects external memory and also the NVIC,
+         * so we must mark it as an IO operation for icount (and cause
+         * this to be the last insn in the TB).
+         */
+        if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+            s->base.is_jmp = DISAS_UPDATE_EXIT;
+            gen_io_start(tcg_ctx);
+        }
+        gen_helper_v7m_preserve_fp_state(tcg_ctx, tcg_ctx->cpu_env);
+        /*
+         * If the preserve_fp_state helper doesn't throw an exception
+         * then it will clear LSPACT; we don't need to repeat this for
+         * any further FP insns in this TB.
+         */
+        s->v7m_lspact = false;
+    }
+}
+
 /*
  * Check that VFP access is enabled. If it is, do the necessary
  * M-profile lazy-FP handling and then return true.
@@ -115,24 +143,7 @@ static bool full_vfp_access_check(DisasContext *s, bool ignore_vfp_enabled)
         /* Handle M-profile lazy FP state mechanics */
 
         /* Trigger lazy-state preservation if necessary */
-        if (s->v7m_lspact) {
-            /*
-             * Lazy state saving affects external memory and also the NVIC,
-             * so we must mark it as an IO operation for icount (and cause
-             * this to be the last insn in the TB).
-             */
-            if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
-                s->base.is_jmp = DISAS_UPDATE_EXIT;
-                gen_io_start(tcg_ctx);
-            }
-            gen_helper_v7m_preserve_fp_state(tcg_ctx, tcg_ctx->cpu_env);
-            /*
-             * If the preserve_fp_state helper doesn't throw an exception
-             * then it will clear LSPACT; we don't need to repeat this for
-             * any further FP insns in this TB.
-             */
-            s->v7m_lspact = false;
-        }
+        gen_preserve_fp_state(s);
 
         /* Update ownership of FP context: set FPCCR.S to match current state */
         if (s->v8m_fpccr_s_wrong) {