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[1/4] target/s390x: Fix CLC corrupting cc_src

Message ID 20231031053718.347100-2-iii@linux.ibm.com
State New
Headers show
Series target/s390x: CC fixes | expand

Commit Message

Ilya Leoshkevich Oct. 31, 2023, 5:32 a.m. UTC 
CLC updates cc_src before accessing the second operand; if the latter
is inaccessible, the former ends up containing a bogus value.

Fix by reading cc_src into a temporary first.

Fixes: 4f7403d52b1c ("target-s390: Convert CLC")
Closes: https://gitlab.com/qemu-project/qemu/-/issues/1865
Cc: qemu-stable@nongnu.org
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 target/s390x/tcg/translate.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Richard Henderson Oct. 31, 2023, 10:49 p.m. UTC | #1 
On 10/30/23 22:32, Ilya Leoshkevich wrote:
> CLC updates cc_src before accessing the second operand; if the latter
> is inaccessible, the former ends up containing a bogus value.
> 
> Fix by reading cc_src into a temporary first.
> 
> Fixes: 4f7403d52b1c ("target-s390: Convert CLC")
> Closes: https://gitlab.com/qemu-project/qemu/-/issues/1865
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>   target/s390x/tcg/translate.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~
diff mbox series

Patch

diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 4bae1509f50..a0d6a2a35dd 100644
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -2007,6 +2007,7 @@  static DisasJumpType op_cksm(DisasContext *s, DisasOps *o)
 static DisasJumpType op_clc(DisasContext *s, DisasOps *o)
 {
     int l = get_field(s, l1);
+    TCGv_i64 src;
     TCGv_i32 vl;
     MemOp mop;
 
@@ -2016,9 +2017,11 @@  static DisasJumpType op_clc(DisasContext *s, DisasOps *o)
     case 4:
     case 8:
         mop = ctz32(l + 1) | MO_TE;
-        tcg_gen_qemu_ld_tl(cc_src, o->addr1, get_mem_index(s), mop);
+        /* Do not update cc_src yet: loading cc_dst may cause an exception. */
+        src = tcg_temp_new_i64();
+        tcg_gen_qemu_ld_tl(src, o->addr1, get_mem_index(s), mop);
         tcg_gen_qemu_ld_tl(cc_dst, o->in2, get_mem_index(s), mop);
-        gen_op_update2_cc_i64(s, CC_OP_LTUGTU_64, cc_src, cc_dst);
+        gen_op_update2_cc_i64(s, CC_OP_LTUGTU_64, src, cc_dst);
         return DISAS_NEXT;
     default:
         vl = tcg_constant_i32(l);