qemu-kvm/kvm-target-s390x-Fix-determination-of-overflow-condition.patch

From 2ddea7186ae50c1f29d790027e8aa98894e51694 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= <clg@redhat.com>
Date: Tue, 23 May 2023 12:34:33 +0200
Subject: [PATCH 10/22] target/s390x: Fix determination of overflow condition
 code after addition
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RH-Author: Cédric Le Goater <clg@redhat.com>
RH-MergeRequest: 279: Backport latest s390x-related fixes from upstream QEMU for qemu-kvm in RHEL 8.9
RH-Bugzilla: 2169308 2209605
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: David Hildenbrand <david@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Commit: [9/21] e8b946ff4e521e0367cb03fcd918a2f8af8bd4d5

Bugzilla: https://bugzilla.redhat.com/2169308

commit 5a2e67a691501bc4dd81c46c81b8f1881c8bd5df
Author: Bruno Haible <bruno@clisp.org>
Date:   Wed Mar 23 17:26:20 2022 +0100

    target/s390x: Fix determination of overflow condition code after addition

    This program currently prints different results when run with TCG instead
    of running on real s390x hardware:

     #include <stdio.h>

     int overflow_32 (int x, int y)
     {
       int sum;
       return ! __builtin_add_overflow (x, y, &sum);
     }

     int overflow_64 (long long x, long long y)
     {
       long sum;
       return ! __builtin_add_overflow (x, y, &sum);
     }

     int a1 = -2147483648;
     int b1 = -2147483648;
     long long a2 = -9223372036854775808L;
     long long b2 = -9223372036854775808L;

     int main ()
     {
       {
         int a = a1;
         int b = b1;
         printf ("a = 0x%x, b = 0x%x\n", a, b);
         printf ("no_overflow = %d\n", overflow_32 (a, b));
       }
       {
         long long a = a2;
         long long b = b2;
         printf ("a = 0x%llx, b = 0x%llx\n", a, b);
         printf ("no_overflow = %d\n", overflow_64 (a, b));
       }
     }

    Signed-off-by: Bruno Haible <bruno@clisp.org>
    Resolves: https://gitlab.com/qemu-project/qemu/-/issues/616
    Message-Id: <20220323162621.139313-2-thuth@redhat.com>
    Signed-off-by: Thomas Huth <thuth@redhat.com>

Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 target/s390x/tcg/cc_helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/s390x/tcg/cc_helper.c b/target/s390x/tcg/cc_helper.c
index 8d04097f78..e11cdb745d 100644
--- a/target/s390x/tcg/cc_helper.c
+++ b/target/s390x/tcg/cc_helper.c
@@ -136,7 +136,7 @@ static uint32_t cc_calc_subu(uint64_t borrow_out, uint64_t result)
 
 static uint32_t cc_calc_add_64(int64_t a1, int64_t a2, int64_t ar)
 {
-    if ((a1 > 0 && a2 > 0 && ar < 0) || (a1 < 0 && a2 < 0 && ar > 0)) {
+    if ((a1 > 0 && a2 > 0 && ar < 0) || (a1 < 0 && a2 < 0 && ar >= 0)) {
         return 3; /* overflow */
     } else {
         if (ar < 0) {
@@ -196,7 +196,7 @@ static uint32_t cc_calc_comp_64(int64_t dst)
 
 static uint32_t cc_calc_add_32(int32_t a1, int32_t a2, int32_t ar)
 {
-    if ((a1 > 0 && a2 > 0 && ar < 0) || (a1 < 0 && a2 < 0 && ar > 0)) {
+    if ((a1 > 0 && a2 > 0 && ar < 0) || (a1 < 0 && a2 < 0 && ar >= 0)) {
         return 3; /* overflow */
     } else {
         if (ar < 0) {
-- 
2.37.3