[PATCH] linux-user/host/s390: Add vector instructions to host_signal_write()

[PATCH] linux-user/host/s390: Add vector instructions to host_signal_write()

[Ilya Leoshkevich]

The new noexec test fails on s390x with "unexpected SEGV". This test
overwrites code using libc's memcpy(), which uses VSTL instruction.
host_signal_write() does not recognize it, which causes SEGV to be
incorrectly forwarded to the test.

Add all vector instructions that write to memory to
host_signal_write().

Reported-by: Thomas Huth <thuth@redhat.com>
Fixes: ab12c95d3f19 ("target/s390x: Make translator stop before the end of a page")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 linux-user/include/host/s390/host-signal.h | 25 ++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/linux-user/include/host/s390/host-signal.h b/linux-user/include/host/s390/host-signal.h
index 25fefa00bd..e6d3ec26dc 100644
--- a/linux-user/include/host/s390/host-signal.h
+++ b/linux-user/include/host/s390/host-signal.h
@@ -87,6 +87,31 @@ static inline bool host_signal_write(siginfo_t *info, host_sigcontext *uc)
             return true;
         }
         break;
+    case 0xe6:
+        switch (pinsn[2] & 0xff) {
+        case 0x09: /* VSTEBRH */
+        case 0x0a: /* VSTEBRG */
+        case 0x0b: /* VSTEBRF */
+        case 0x0e: /* VSTBR */
+        case 0x0f: /* VSTER */
+        case 0x3f: /* VSTRLR */
+            return true;
+        }
+        break;
+    case 0xe7:
+        switch (pinsn[2] & 0xff) {
+        case 0x08: /* VSTEB */
+        case 0x09: /* VSTEH */
+        case 0x0a: /* VSTEG */
+        case 0x0b: /* VSTEF */
+        case 0x0e: /* VST */
+        case 0x1a: /* VSCEG */
+        case 0x1b: /* VSCEF */
+        case 0x3e: /* VSTM */
+        case 0x3f: /* VSTL */
+            return true;
+        }
+        break;
     case 0xeb: /* RSY format insns */
         switch (pinsn[2] & 0xff) {
         case 0x14: /* CSY */
-- 
2.37.2

Re: [PATCH] linux-user/host/s390: Add vector instructions to host_signal_write()

[Thomas Huth]

On 20/09/2022 13.39, Ilya Leoshkevich wrote:
> The new noexec test fails on s390x with "unexpected SEGV". This test
> overwrites code using libc's memcpy(), which uses VSTL instruction.
> host_signal_write() does not recognize it, which causes SEGV to be
> incorrectly forwarded to the test.
> 
> Add all vector instructions that write to memory to
> host_signal_write().
> 
> Reported-by: Thomas Huth <thuth@redhat.com>
> Fixes: ab12c95d3f19 ("target/s390x: Make translator stop before the end of a page")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>   linux-user/include/host/s390/host-signal.h | 25 ++++++++++++++++++++++
>   1 file changed, 25 insertions(+)

Thanks, this fixes the segfault for me, indeed!

Tested-by: Thomas Huth <thuth@redhat.com>