[PULL 12/15] tests/tcg/s390x: Test STCKF condition code on a faulting store

[Eric Farman <farman@linux.ibm.com>]

From: Ilya Leoshkevich <iii@linux.ibm.com>

Add a small test to prevent regressions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260714203206.363028-3-iii@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 tests/tcg/s390x/Makefile.target |  1 +
 tests/tcg/s390x/stckf.c         | 44 +++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)
 create mode 100644 tests/tcg/s390x/stckf.c

diff --git a/tests/tcg/s390x/Makefile.target b/tests/tcg/s390x/Makefile.target
index 48cba4cdfa..97c0f02190 100644
--- a/tests/tcg/s390x/Makefile.target
+++ b/tests/tcg/s390x/Makefile.target
@@ -50,6 +50,7 @@ TESTS+=cvb
 TESTS+=ts
 TESTS+=ex-smc
 TESTS+=divide-to-integer
+TESTS+=stckf
 
 cdsg: CFLAGS+=-pthread
 cdsg: LDFLAGS+=-pthread
diff --git a/tests/tcg/s390x/stckf.c b/tests/tcg/s390x/stckf.c
new file mode 100644
index 0000000000..51c8c9df9f
--- /dev/null
+++ b/tests/tcg/s390x/stckf.c
@@ -0,0 +1,44 @@
+/*
+ * Test that a faulting STORE CLOCK FAST does not clobber the condition code.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <assert.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static void handle_sigsegv(int sig, siginfo_t *info, void *ucontext)
+{
+    mcontext_t *mcontext = &((ucontext_t *)ucontext)->uc_mcontext;
+
+    /* The condition code must be the one set by SLGR, not garbage. */
+    _exit(((mcontext->psw.mask >> 44) & 3) == 3 ? EXIT_SUCCESS : EXIT_FAILURE);
+}
+
+int main(void)
+{
+    struct sigaction act = {
+        .sa_sigaction = handle_sigsegv,
+        .sa_flags = SA_SIGINFO,
+    };
+    int err;
+
+    err = sigaction(SIGSEGV, &act, NULL);
+    assert(err == 0);
+
+    asm volatile(
+        "lghi %%r1,100\n"
+        "lghi %%r2,0\n"
+        "clgr %%r1,%%r2\n"  /* CC_OP_LTUGTU_64 */
+                            /* cc_src=100 is not valid for CC_OP_SUBU */
+        "ipm %%r0\n"        /* force cc_src to env */
+        "lghi %%r3,5\n"
+        "lghi %%r4,3\n"
+        "slgr %%r3,%%r4\n"  /* CC_OP_SUBU, cc=3 */
+        "lghi %%r5,0\n"
+        "stckf 0(%%r5)\n"   /* faults; cc must stay 3 */
+        : : : "r0", "r1", "r2", "r3", "r4", "r5", "cc", "memory");
+
+    return EXIT_FAILURE;
+}
-- 
2.55.0