target/arm: Don't allow Thumb Neon insns without FEATURE_NEON

We were accidentally permitting decode of Thumb Neon insns even if
the CPU didn't have the FEATURE_NEON bit set, because the feature
check was being done before the call to disas_neon_data_insn() and
disas_neon_ls_insn() in the Arm decoder but was omitted from the
Thumb decoder.  Push the feature bit check down into the called
functions so it is done for both Arm and Thumb encodings.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20200430181003.21682-3-peter.maydell@linaro.org

diff --git a/target/arm/translate.c b/target/arm/translate.c
index e3fc7924428035a00333a485c3110a111f707365..4cf5267be00484d814d911a7a325c3bdf4a31d78 100644 (file)
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -3258,6 +3258,10 @@ static int disas_neon_ls_insn(DisasContext *s, uint32_t insn)
     TCGv_i32 tmp2;
     TCGv_i64 tmp64;
 
+    if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
+        return 1;
+    }
+
     /* FIXME: this access check should not take precedence over UNDEF
      * for invalid encodings; we will generate incorrect syndrome information
      * for attempts to execute invalid vfp/neon encodings with FP disabled.
@@ -5002,6 +5006,10 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
     TCGv_ptr ptr1, ptr2, ptr3;
     TCGv_i64 tmp64;
 
+    if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
+        return 1;
+    }
+
     /* FIXME: this access check should not take precedence over UNDEF
      * for invalid encodings; we will generate incorrect syndrome information
      * for attempts to execute invalid vfp/neon encodings with FP disabled.
@@ -10948,10 +10956,6 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
 
         if (((insn >> 25) & 7) == 1) {
             /* NEON Data processing.  */
-            if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
-                goto illegal_op;
-            }
-
             if (disas_neon_data_insn(s, insn)) {
                 goto illegal_op;
             }
@@ -10959,10 +10963,6 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
         }
         if ((insn & 0x0f100000) == 0x04000000) {
             /* NEON load/store.  */
-            if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
-                goto illegal_op;
-            }
-
             if (disas_neon_ls_insn(s, insn)) {
                 goto illegal_op;
             }