linux-user: cleanup unused linux-user/include/host directories

Alpha and 31-bit s390 lack the assembly fragment to handle signals
occurring at the same time as system calls, so they cannot run
linux-user emulation anymore.  Drop the host-signal.h files for
them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Message-ID: <20230808120303.585509-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

linux-user/include/host/s390x/host-signal.h

@@ -1 +1,138 @@
-#include "../s390/host-signal.h"
+/*
+ * 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
+
+/* The third argument to a SA_SIGINFO handler is ucontext_t. */
+typedef ucontext_t host_sigcontext;
+
+static inline uintptr_t host_signal_pc(host_sigcontext *uc)
+{
+    return uc->uc_mcontext.psw.addr;
+}
+
+static inline void host_signal_set_pc(host_sigcontext *uc, uintptr_t pc)
+{
+    uc->uc_mcontext.psw.addr = pc;
+}
+
+static inline void *host_signal_mask(host_sigcontext *uc)
+{
+    return &uc->uc_sigmask;
+}
+
+static inline bool host_signal_write(siginfo_t *info, host_sigcontext *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 0x44: /* EX */
+    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 0xc6: /* RIL-b format insns */
+        switch (pinsn[0] & 0xf) {
+        case 0x0: /* EXRL */
+            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 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 */
+        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