[PATCH 1/2] target/s390x: Fix VSTL with a large length

[PATCH 1/2] target/s390x: Fix VSTL with a large length

[Ilya Leoshkevich]

The length is always truncated to 16 bytes. Do not probe more than
that.

Cc: qemu-stable@nongnu.org
Fixes: 0e0a5b49ad58 ("s390x/tcg: Implement VECTOR STORE WITH LENGTH")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 target/s390x/tcg/vec_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/s390x/tcg/vec_helper.c b/target/s390x/tcg/vec_helper.c
index 48d86722b2d..dafc4c3582c 100644
--- a/target/s390x/tcg/vec_helper.c
+++ b/target/s390x/tcg/vec_helper.c
@@ -193,7 +193,7 @@ void HELPER(vstl)(CPUS390XState *env, const void *v1, uint64_t addr,
                   uint64_t bytes)
 {
     /* Probe write access before actually modifying memory */
-    probe_write_access(env, addr, bytes, GETPC());
+    probe_write_access(env, addr, MIN(bytes, 16), GETPC());
 
     if (likely(bytes >= 16)) {
         cpu_stq_data_ra(env, addr, s390_vec_read_element64(v1, 0), GETPC());
-- 
2.41.0

[PATCH 2/2] tests/tcg/s390x: Test VSTL

[Ilya Leoshkevich]

Add a small test to prevent regressions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 tests/tcg/s390x/Makefile.target |  1 +
 tests/tcg/s390x/vstl.c          | 37 +++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 tests/tcg/s390x/vstl.c

diff --git a/tests/tcg/s390x/Makefile.target b/tests/tcg/s390x/Makefile.target
index 649c1e520e6..e3e22c6f7e3 100644
--- a/tests/tcg/s390x/Makefile.target
+++ b/tests/tcg/s390x/Makefile.target
@@ -60,6 +60,7 @@ Z13_TESTS=vistr
 Z13_TESTS+=lcbb
 Z13_TESTS+=locfhr
 Z13_TESTS+=vcksm
+Z13_TESTS+=vstl
 $(Z13_TESTS): CFLAGS+=-march=z13 -O2
 TESTS+=$(Z13_TESTS)
 
diff --git a/tests/tcg/s390x/vstl.c b/tests/tcg/s390x/vstl.c
new file mode 100644
index 00000000000..bece952c7ee
--- /dev/null
+++ b/tests/tcg/s390x/vstl.c
@@ -0,0 +1,37 @@
+/*
+ * Test the VSTL instruction.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <assert.h>
+#include <stdlib.h>
+#include "vx.h"
+
+static inline void vstl(S390Vector *v1, void *db2, size_t r3)
+{
+    asm("vstl %[v1],%[r3],%[db2]"
+        : [db2] "=Q" (*(char *)db2)
+        : [v1] "v" (v1->v), [r3] "r" (r3)
+        : "memory");
+}
+
+int main(void)
+{
+    uint64_t buf[3] = {0x1122334455667788ULL, 0x99aabbccddeeffULL,
+                       0x5a5a5a5a5a5a5a5aULL};
+    S390Vector v = {.d[0] = 0x1234567887654321ULL,
+                    .d[1] = 0x9abcdef00fedcba9ULL};
+
+    vstl(&v, buf, 0);
+    assert(buf[0] == 0x1222334455667788ULL);
+
+    vstl(&v, buf, 1);
+    assert(buf[0] == 0x1234334455667788ULL);
+
+    vstl(&v, buf, -1);
+    assert(buf[0] == 0x1234567887654321ULL);
+    assert(buf[1] == 0x9abcdef00fedcba9ULL);
+    assert(buf[2] == 0x5a5a5a5a5a5a5a5aULL);
+
+    return EXIT_SUCCESS;
+}
-- 
2.41.0

Re: [PATCH 1/2] target/s390x: Fix VSTL with a large length

[David Hildenbrand]

On 05.08.23 01:55, Ilya Leoshkevich wrote:
> The length is always truncated to 16 bytes. Do not probe more than
> that.
> 
> Cc: qemu-stable@nongnu.org
> Fixes: 0e0a5b49ad58 ("s390x/tcg: Implement VECTOR STORE WITH LENGTH")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>   target/s390x/tcg/vec_helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target/s390x/tcg/vec_helper.c b/target/s390x/tcg/vec_helper.c
> index 48d86722b2d..dafc4c3582c 100644
> --- a/target/s390x/tcg/vec_helper.c
> +++ b/target/s390x/tcg/vec_helper.c
> @@ -193,7 +193,7 @@ void HELPER(vstl)(CPUS390XState *env, const void *v1, uint64_t addr,
>                     uint64_t bytes)
>   {
>       /* Probe write access before actually modifying memory */
> -    probe_write_access(env, addr, bytes, GETPC());
> +    probe_write_access(env, addr, MIN(bytes, 16), GETPC());
>   
>       if (likely(bytes >= 16)) {
>           cpu_stq_data_ra(env, addr, s390_vec_read_element64(v1, 0), GETPC());

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb