target/xtensa: avoid integer overflow in next_page PC check

If the PC is in the last page of the address space, next_page_start
overflows to 0. Fix it.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index 4f6d03059feb65e33cd623adce108d37d02dbbf9..aad496347d7ad26aef33ff83cb4ac8663a21b431 100644 (file)
--- a/target/xtensa/translate.c
+++ b/target/xtensa/translate.c
@@ -1061,8 +1061,7 @@ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb)
     int insn_count = 0;
     int max_insns = tb_cflags(tb) & CF_COUNT_MASK;
     uint32_t pc_start = tb->pc;
-    uint32_t next_page_start =
-        (pc_start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
+    uint32_t page_start = pc_start & TARGET_PAGE_MASK;
 
     if (max_insns == 0) {
         max_insns = CF_COUNT_MASK;
@@ -1162,9 +1161,9 @@ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb)
         }
     } while (dc.is_jmp == DISAS_NEXT &&
             insn_count < max_insns &&
-            dc.pc < next_page_start &&
-            dc.pc + xtensa_insn_len(env, &dc) <= next_page_start &&
-            !tcg_op_buf_full());
+            dc.pc - page_start < TARGET_PAGE_SIZE &&
+            dc.pc - page_start + xtensa_insn_len(env, &dc) <= TARGET_PAGE_SIZE
+            && !tcg_op_buf_full());
 done:
     reset_sar_tracker(&dc);
     if (dc.icount) {