[Qemu-arm] [PATCH v4 2/4] target/arm: handle A-profile semihosting at translate time

[Alex Bennée]

As for the other semihosting calls we can resolve this at translate
time.

Signed-off-by: Alex Bennée <address@hidden>

---
v2
  - update for change to gen_exception_internal_insn API
v3
  - update for decode tree, merge T32 & A32 commits
  - dropped r-b due to changes
v4
  - !IS_USER and !arm_dc_feature(s, ARM_FEATURE_M)
---
 target/arm/translate.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/target/arm/translate.c b/target/arm/translate.c
index 6689acc911e..d7ee4f88ace 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10219,14 +10219,22 @@ static bool trans_CBZ(DisasContext *s, arg_CBZ *a)
 }
 
 /*
- * Supervisor call
+ * Supervisor call - both T32 & A32 come here so we need to check
+ * which mode we are in when checking for semihosting.
  */
 
 static bool trans_SVC(DisasContext *s, arg_SVC *a)
 {
-    gen_set_pc_im(s, s->base.pc_next);
-    s->svc_imm = a->imm;
-    s->base.is_jmp = DISAS_SWI;
+    const uint32_t semihost_imm = s->thumb ? 0xab : 0x123456;
+
+    if (!arm_dc_feature(s, ARM_FEATURE_M) && semihosting_enabled()
+        && !IS_USER(s) && (a->imm == semihost_imm)) {
+        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
+    } else {
+        gen_set_pc_im(s, s->base.pc_next);
+        s->svc_imm = a->imm;
+        s->base.is_jmp = DISAS_SWI;
+    }
     return true;
 }
 
-- 
2.20.1