Re: [Qemu-devel] [PATCH 04/10] target/xtensa: avoid integer overflow in next_page PC check

[Max Filippov]

On Tue, Apr 10, 2018 at 9:19 AM, Emilio G. Cota  wrote:
> If the PC is in the last page of the address space, next_page_start
> overflows to 0. Fix it.
>
> Cc: Max Filippov 
> Signed-off-by: Emilio G. Cota 
> ---
>  target/xtensa/translate.c | 9 -
>  1 file changed, 4 insertions(+), 5 deletions(-)

Acked-by: Max Filippov 

-- 
Thanks.
-- Max

[Qemu-devel] [PATCH 04/10] target/xtensa: avoid integer overflow in next_page PC check

[Emilio G. Cota]

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

Cc: Max Filippov 
Signed-off-by: Emilio G. Cota 
---
 target/xtensa/translate.c | 9 -
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index 4f6d030..aad4963 100644
--- 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, ) <= next_page_start &&
-!tcg_op_buf_full());
+dc.pc - page_start < TARGET_PAGE_SIZE &&
+dc.pc - page_start + xtensa_insn_len(env, ) <= TARGET_PAGE_SIZE
+&& !tcg_op_buf_full());
 done:
 reset_sar_tracker();
 if (dc.icount) {
-- 
2.7.4