* Fixes for SIGILL and SIGFPE of the s390x linux-user target

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Merge remote-tracking branch 'remotes/thuth-gitlab/tags/pull-request-2021-08-03' into staging

* Fixes for SIGILL and SIGFPE of the s390x linux-user target

# gpg: Signature made Tue 03 Aug 2021 14:30:54 BST
# gpg:                using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5
# gpg:                issuer "thuth@redhat.com"
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg:                 aka "Thomas Huth <thuth@redhat.com>" [full]
# gpg:                 aka "Thomas Huth <huth@tuxfamily.org>" [full]
# gpg:                 aka "Thomas Huth <th.huth@posteo.de>" [unknown]
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3  EAB9 2ED9 D774 FE70 2DB5

* remotes/thuth-gitlab/tags/pull-request-2021-08-03:
  tests/tcg: Test that compare-and-trap raises SIGFPE
  linux-user/s390x: signal with SIGFPE on compare-and-trap
  target/s390x: Fix SIGILL and SIGFPE psw.addr reporting

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

linux-user/s390x/cpu_loop.c

@@ -25,6 +25,35 @@
 /* s390x masks the fault address it reports in si_addr for SIGSEGV and SIGBUS */
 #define S390X_FAIL_ADDR_MASK -4096LL
 
+static int get_pgm_data_si_code(int dxc_code)
+{
+    switch (dxc_code) {
+    /* Non-simulated IEEE exceptions */
+    case 0x80:
+        return TARGET_FPE_FLTINV;
+    case 0x40:
+        return TARGET_FPE_FLTDIV;
+    case 0x20:
+    case 0x28:
+    case 0x2c:
+        return TARGET_FPE_FLTOVF;
+    case 0x10:
+    case 0x18:
+    case 0x1c:
+        return TARGET_FPE_FLTUND;
+    case 0x08:
+    case 0x0c:
+        return TARGET_FPE_FLTRES;
+    }
+    /*
+     * Non-IEEE and simulated IEEE:
+     * Includes compare-and-trap, quantum exception, etc.
+     * Simulated IEEE are included here to match current
+     * s390x linux kernel.
+     */
+    return 0;
+}
+
 void cpu_loop(CPUS390XState *env)
 {
     CPUState *cs = env_cpu(env);
@@ -64,7 +93,13 @@ void cpu_loop(CPUS390XState *env)
         case EXCP_DEBUG:
             sig = TARGET_SIGTRAP;
             n = TARGET_TRAP_BRKPT;
-            goto do_signal_pc;
+            /*
+             * For SIGTRAP the PSW must point after the instruction, which it
+             * already does thanks to s390x_tr_tb_stop(). si_addr doesn't need
+             * to be filled.
+             */
+            addr = 0;
+            goto do_signal;
         case EXCP_PGM:
             n = env->int_pgm_code;
             switch (n) {
@@ -100,28 +135,13 @@ void cpu_loop(CPUS390XState *env)
 
             case PGM_DATA:
                 n = (env->fpc >> 8) & 0xff;
-                if (n == 0xff) {
+                if (n == 0) {
-                    /* compare-and-trap */
-                    goto do_sigill_opn;
-                } else {
-                    /* An IEEE exception, simulated or otherwise.  */
-                    if (n & 0x80) {
-                        n = TARGET_FPE_FLTINV;
-                    } else if (n & 0x40) {
-                        n = TARGET_FPE_FLTDIV;
-                    } else if (n & 0x20) {
-                        n = TARGET_FPE_FLTOVF;
-                    } else if (n & 0x10) {
-                        n = TARGET_FPE_FLTUND;
-                    } else if (n & 0x08) {
-                        n = TARGET_FPE_FLTRES;
-                    } else {
-                        /* ??? Quantum exception; BFP, DFP error.  */
                     goto do_sigill_opn;
                 }
+
                 sig = TARGET_SIGFPE;
+                n = get_pgm_data_si_code(n);
                 goto do_signal_pc;
-                }
 
             default:
                 fprintf(stderr, "Unhandled program exception: %#x\n", n);
@@ -132,6 +152,10 @@ void cpu_loop(CPUS390XState *env)
 
         do_signal_pc:
             addr = env->psw.addr;
+            /*
+             * For SIGILL and SIGFPE the PSW must point after the instruction.
+             */
+            env->psw.addr += env->int_pgm_ilen;
         do_signal:
             info.si_signo = sig;
             info.si_errno = 0;

tests/tcg/s390x/Makefile.target

@@ -8,4 +8,4 @@ TESTS+=exrl-trtr
 TESTS+=pack
 TESTS+=mvo
 TESTS+=mvc
-
+TESTS+=trap

tests/tcg/s390x/trap.c

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2021 IBM Corp.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+
+static void error1(const char *filename, int line, const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    fprintf(stderr, "%s:%d: ", filename, line);
+    vfprintf(stderr, fmt, ap);
+    fprintf(stderr, "\n");
+    va_end(ap);
+    exit(1);
+}
+
+static int __chk_error(const char *filename, int line, int ret)
+{
+    if (ret < 0) {
+        error1(filename, line, "%m (ret=%d, errno=%d/%s)",
+               ret, errno, strerror(errno));
+    }
+    return ret;
+}
+
+#define error(fmt, ...) error1(__FILE__, __LINE__, fmt, ## __VA_ARGS__)
+
+#define chk_error(ret) __chk_error(__FILE__, __LINE__, (ret))
+
+int sigfpe_count;
+int sigill_count;
+
+static void sig_handler(int sig, siginfo_t *si, void *puc)
+{
+    if (sig == SIGFPE) {
+        if (si->si_code != 0) {
+            error("unexpected si_code: 0x%x != 0", si->si_code);
+        }
+        ++sigfpe_count;
+        return;
+    }
+
+    if (sig == SIGILL) {
+        ++sigill_count;
+        return;
+    }
+
+    error("unexpected signal 0x%x\n", sig);
+}
+
+int main(int argc, char **argv)
+{
+    sigfpe_count = sigill_count = 0;
+
+    struct sigaction act;
+
+    /* Set up SIG handler */
+    act.sa_sigaction = sig_handler;
+    sigemptyset(&act.sa_mask);
+    act.sa_flags = SA_SIGINFO;
+    chk_error(sigaction(SIGFPE, &act, NULL));
+    chk_error(sigaction(SIGILL, &act, NULL));
+
+    uint64_t z = 0x0ull;
+    uint64_t lz = 0xffffffffffffffffull;
+    asm volatile (
+        "lg %%r13,%[lz]\n"
+        "cgitne %%r13,0\n" /* SIGFPE */
+        "lg %%r13,%[z]\n"
+        "cgitne %%r13,0\n" /* no trap */
+        "nopr\n"
+        "lg %%r13,%[lz]\n"
+        "citne %%r13,0\n" /* SIGFPE */
+        "lg %%r13,%[z]\n"
+        "citne %%r13,0\n" /* no trap */
+        "nopr\n"
+        :
+        : [z] "m" (z), [lz] "m" (lz)
+        : "memory", "r13");
+
+    if (sigfpe_count != 2) {
+        error("unexpected SIGFPE count: %d != 2", sigfpe_count);
+    }
+    if (sigill_count != 0) {
+        error("unexpected SIGILL count: %d != 0", sigill_count);
+    }
+
+    printf("PASS\n");
+    return 0;
+}