[Qemu-devel] [PATCH v1 1/9] target/arm: handle M-profile semihosting at translate time

["Alex Bennée" <alex.bennee@linaro.org>]

We do this for other semihosting calls so we might as well do it for
M-profile as well.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/m_helper.c  | 18 ++++++------------
 target/arm/translate.c | 20 +++++++++++++++++++-
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/target/arm/m_helper.c b/target/arm/m_helper.c
index 884d35d2b02..27cd2f3f964 100644
--- a/target/arm/m_helper.c
+++ b/target/arm/m_helper.c
@@ -2114,19 +2114,13 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
             break;
         }
         break;
+    case EXCP_SEMIHOST:
+        qemu_log_mask(CPU_LOG_INT,
+                      "...handling as semihosting call 0x%x\n",
+                      env->regs[0]);
+        env->regs[0] = do_arm_semihosting(env);
+        return;
     case EXCP_BKPT:
-        if (semihosting_enabled()) {
-            int nr;
-            nr = arm_lduw_code(env, env->regs[15], arm_sctlr_b(env)) & 0xff;
-            if (nr == 0xab) {
-                env->regs[15] += 2;
-                qemu_log_mask(CPU_LOG_INT,
-                              "...handling as semihosting call 0x%x\n",
-                              env->regs[0]);
-                env->regs[0] = do_arm_semihosting(env);
-                return;
-            }
-        }
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_DEBUG, false);
         break;
     case EXCP_IRQ:
diff --git a/target/arm/translate.c b/target/arm/translate.c
index cbe19b7a625..259c4669b4c 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10889,6 +10889,24 @@ illegal_op:
     unallocated_encoding(s);
 }
 
+/*
+ * Thumb BKPT. On M-profile CPUs this may be a semihosting call which
+ * we can process much the same way as gen_hlt() above.
+ */
+static inline void gen_thumb_bkpt(DisasContext *s, int imm8)
+{
+    if (arm_dc_feature(s, ARM_FEATURE_M) &&
+        semihosting_enabled() &&
+#ifndef CONFIG_USER_ONLY
+        s->current_el != 0 &&
+#endif
+        (imm8 == 0xab)) {
+        gen_exception_internal_insn(s, 0, EXCP_SEMIHOST);
+        return;
+    }
+    gen_exception_bkpt_insn(s, syn_aa32_bkpt(imm8, true));
+}
+
 static void disas_thumb_insn(DisasContext *s, uint32_t insn)
 {
     uint32_t val, op, rm, rn, rd, shift, cond;
@@ -11511,7 +11529,7 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
         {
             int imm8 = extract32(insn, 0, 8);
             ARCH(5);
-            gen_exception_bkpt_insn(s, syn_aa32_bkpt(imm8, true));
+            gen_thumb_bkpt(s, imm8);
             break;
         }
 
-- 
2.20.1