[Qemu-devel] [PATCH v6 2/6] 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>

---
v2
  - update for change to gen_exception_internal_insn API
v3
  - update for decode tree
v4
  - use !IS_USER
v5
  - return #ifndef CONFIG_USER
---
 target/arm/m_helper.c  | 18 ++++++------------
 target/arm/translate.c | 11 ++++++++++-
 2 files changed, 16 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 34bb280e3da..b5272119330 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8424,7 +8424,16 @@ static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
     if (!ENABLE_ARCH_5) {
         return false;
     }
-    gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
+    if (arm_dc_feature(s, ARM_FEATURE_M) &&
+        semihosting_enabled() &&
+#ifndef CONFIG_USER_ONLY
+        !IS_USER(s) &&
+#endif
+        (a->imm == 0xab)) {
+        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
+    } else {
+        gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
+    }
     return true;
 }
 
-- 
2.20.1