[PATCH 04/11] target/hexagon: guard writes to unimplemented guest registers

[Brian Cain <brian.cain@oss.qualcomm.com>]

Gate guest-register writes on greg_writable() in the generated code so
writes to gregs above G3 are dropped instead of dereferencing an
unallocated TCG temp.

Signed-off-by: Brian Cain <brian.cain@oss.qualcomm.com>
---
 target/hexagon/translate.h   |  7 ++++---
 target/hexagon/hex_common.py | 18 +++++++++++++++++-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/target/hexagon/translate.h b/target/hexagon/translate.h
index 00de2b0d2ec..05425d92b29 100644
--- a/target/hexagon/translate.h
+++ b/target/hexagon/translate.h
@@ -97,9 +97,10 @@ bool is_gather_store_insn(DisasContext *ctx);
 #ifndef CONFIG_USER_ONLY
 static inline void ctx_log_greg_write(DisasContext *ctx, int rnum)
 {
-    assert(rnum <= HEX_GREG_G3);
-    ctx->greg_log[ctx->greg_log_idx] = rnum;
-    ctx->greg_log_idx++;
+    if (rnum <= HEX_GREG_G3) {
+        ctx->greg_log[ctx->greg_log_idx] = rnum;
+        ctx->greg_log_idx++;
+    }
 }
 
 static inline void ctx_log_greg_write_pair(DisasContext *ctx, int rnum)
diff --git a/target/hexagon/hex_common.py b/target/hexagon/hex_common.py
index e33d43e3ce0..c180c19b092 100755
--- a/target/hexagon/hex_common.py
+++ b/target/hexagon/hex_common.py
@@ -1097,11 +1097,24 @@ def analyze_write(self, f, tag, regno):
         """))
 
 class GuestRegister(Register):
-    pass
+    def gen_check_impl(self, f, regno):
+        if self.is_written():
+            f.write(code_fmt(f"""\
+                if (!greg_writable(insn->regno[{regno}],
+                    {str(self.is_pair()).lower()})) {{
+                    return;
+                }}
+            """))
+        else:
+            f.write(code_fmt(f"""\
+                check_greg_impl(insn->regno[{regno}],
+                                {str(self.is_pair()).lower()});
+            """))
 
 class GuestDest(GuestRegister, Single, Dest):
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
+        self.gen_check_impl(f, regno)
         f.write(code_fmt(f"""\
             TCGv_i32 {self.reg_tcg()} = tcg_temp_new_i32();
         """))
@@ -1121,6 +1134,7 @@ def decl_reg_num(self, f, regno):
         """))
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
+        self.gen_check_impl(f, regno)
         f.write(code_fmt(f"""\
             TCGv_i32 {self.reg_tcg()} = tcg_temp_new_i32();
             gen_read_greg({self.reg_tcg()}, {self.reg_num});
@@ -1131,6 +1145,7 @@ def analyze_read(self, f, regno):
 class GuestPairDest(GuestRegister, Pair, Dest):
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
+        self.gen_check_impl(f, regno)
         f.write(code_fmt(f"""\
             TCGv_i64 {self.reg_tcg()} = tcg_temp_new_i64();
         """))
@@ -1150,6 +1165,7 @@ def decl_reg_num(self, f, regno):
         """))
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
+        self.gen_check_impl(f, regno)
         f.write(code_fmt(f"""\
             TCGv_i64 {self.reg_tcg()} = tcg_temp_new_i64();
             gen_read_greg_pair({self.reg_tcg()}, {self.reg_num});
-- 
2.34.1