linux-user/host/s390: Populate host_signal.h

Split host_signal_pc and host_signal_write out of user-exec.c.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

2 files changed, 94 insertions, 2 deletions

diff --git a/linux-user/host/s390/host-signal.h b/linux-user/host/s390/host-signal.h
index f4b4d65031..26990e4893 100644
--- a/linux-user/host/s390/host-signal.h
+++ b/linux-user/host/s390/host-signal.h
@@ -1 +1,93 @@
-#define HOST_SIGNAL_PLACEHOLDER
+/*
+ * host-signal.h: signal info dependent on the host architecture
+ *
+ * Copyright (c) 2003-2005 Fabrice Bellard
+ * Copyright (c) 2021 Linaro Limited
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef S390_HOST_SIGNAL_H
+#define S390_HOST_SIGNAL_H
+
+static inline uintptr_t host_signal_pc(ucontext_t *uc)
+{
+    return uc->uc_mcontext.psw.addr;
+}
+
+static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
+{
+    uint16_t *pinsn = (uint16_t *)host_signal_pc(uc);
+
+    /*
+     * ??? On linux, the non-rt signal handler has 4 (!) arguments instead
+     * of the normal 2 arguments.  The 4th argument contains the "Translation-
+     * Exception Identification for DAT Exceptions" from the hardware (aka
+     * "int_parm_long"), which does in fact contain the is_write value.
+     * The rt signal handler, as far as I can tell, does not give this value
+     * at all.  Not that we could get to it from here even if it were.
+     * So fall back to parsing instructions.  Treat read-modify-write ones as
+     * writes, which is not fully correct, but for tracking self-modifying code
+     * this is better than treating them as reads.  Checking si_addr page flags
+     * might be a viable improvement, albeit a racy one.
+     */
+    /* ??? This is not even close to complete.  */
+    switch (pinsn[0] >> 8) {
+    case 0x50: /* ST */
+    case 0x42: /* STC */
+    case 0x40: /* STH */
+    case 0xba: /* CS */
+    case 0xbb: /* CDS */
+        return true;
+    case 0xc4: /* RIL format insns */
+        switch (pinsn[0] & 0xf) {
+        case 0xf: /* STRL */
+        case 0xb: /* STGRL */
+        case 0x7: /* STHRL */
+            return true;
+        }
+        break;
+    case 0xc8: /* SSF format insns */
+        switch (pinsn[0] & 0xf) {
+        case 0x2: /* CSST */
+            return true;
+        }
+        break;
+    case 0xe3: /* RXY format insns */
+        switch (pinsn[2] & 0xff) {
+        case 0x50: /* STY */
+        case 0x24: /* STG */
+        case 0x72: /* STCY */
+        case 0x70: /* STHY */
+        case 0x8e: /* STPQ */
+        case 0x3f: /* STRVH */
+        case 0x3e: /* STRV */
+        case 0x2f: /* STRVG */
+            return true;
+        }
+        break;
+    case 0xeb: /* RSY format insns */
+        switch (pinsn[2] & 0xff) {
+        case 0x14: /* CSY */
+        case 0x30: /* CSG */
+        case 0x31: /* CDSY */
+        case 0x3e: /* CDSG */
+        case 0xe4: /* LANG */
+        case 0xe6: /* LAOG */
+        case 0xe7: /* LAXG */
+        case 0xe8: /* LAAG */
+        case 0xea: /* LAALG */
+        case 0xf4: /* LAN */
+        case 0xf6: /* LAO */
+        case 0xf7: /* LAX */
+        case 0xfa: /* LAAL */
+        case 0xf8: /* LAA */
+            return true;
+        }
+        break;
+    }
+    return false;
+}
+
+#endif
diff --git a/linux-user/host/s390x/host-signal.h b/linux-user/host/s390x/host-signal.h
index f4b4d65031..0e83f9358d 100644
--- a/linux-user/host/s390x/host-signal.h
+++ b/linux-user/host/s390x/host-signal.h
@@ -1 +1 @@
-#define HOST_SIGNAL_PLACEHOLDER
+#include "../s390/host-signal.h"