*-user: plugin syscalls

To avoid too much duplication add a wrapper that the existing trace
and the new plugin calls can live in. We could move the -strace code
here as well but that is left for a future series as the code is
subtly different between the bsd and linux.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[AJB: wrap in syscall-trace.h, expand commit msg]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

bsd-user/syscall.c

@@ -26,6 +26,7 @@
 
 #include "qemu.h"
 #include "qemu-common.h"
+#include "user/syscall-trace.h"
 
 //#define DEBUG
 
@@ -322,7 +323,8 @@ abi_long do_freebsd_syscall(void *cpu_env, int num, abi_long arg1,
 #ifdef DEBUG
     gemu_log("freebsd syscall %d\n", num);
 #endif
-    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8);
+    record_syscall_start(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
+
     if(do_strace)
         print_freebsd_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -403,7 +405,8 @@ abi_long do_freebsd_syscall(void *cpu_env, int num, abi_long arg1,
 #endif
     if (do_strace)
         print_freebsd_syscall_ret(num, ret);
-    trace_guest_user_syscall_ret(cpu, num, ret);
+
+    record_syscall_return(cpu, num, ret);
     return ret;
  efault:
     ret = -TARGET_EFAULT;
@@ -421,7 +424,9 @@ abi_long do_netbsd_syscall(void *cpu_env, int num, abi_long arg1,
 #ifdef DEBUG
     gemu_log("netbsd syscall %d\n", num);
 #endif
-    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
+
+    record_syscall_start(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
+
     if(do_strace)
         print_netbsd_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -479,7 +484,8 @@ abi_long do_netbsd_syscall(void *cpu_env, int num, abi_long arg1,
 #endif
     if (do_strace)
         print_netbsd_syscall_ret(num, ret);
-    trace_guest_user_syscall_ret(cpu, num, ret);
+
+    record_syscall_return(cpu, num, ret);
     return ret;
  efault:
     ret = -TARGET_EFAULT;
@@ -497,7 +503,9 @@ abi_long do_openbsd_syscall(void *cpu_env, int num, abi_long arg1,
 #ifdef DEBUG
     gemu_log("openbsd syscall %d\n", num);
 #endif
-    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
+
+    record_syscall_start(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
+
     if(do_strace)
         print_openbsd_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -555,7 +563,8 @@ abi_long do_openbsd_syscall(void *cpu_env, int num, abi_long arg1,
 #endif
     if (do_strace)
         print_openbsd_syscall_ret(num, ret);
-    trace_guest_user_syscall_ret(cpu, num, ret);
+
+    record_syscall_return(cpu, num, ret);
     return ret;
  efault:
     ret = -TARGET_EFAULT;

include/user/syscall-trace.h

@@ -0,0 +1,40 @@
+/*
+ * Common System Call Tracing Wrappers for *-user
+ *
+ * Copyright (c) 2019 Linaro
+ * Written by Alex Bennée <alex.bennee@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef _SYSCALL_TRACE_H_
+#define _SYSCALL_TRACE_H_
+
+/*
+ * These helpers just provide a common place for the various
+ * subsystems that want to track syscalls to put their hooks in. We
+ * could potentially unify the -strace code here as well.
+ */
+
+static inline void record_syscall_start(void *cpu, int num,
+                                        abi_long arg1, abi_long arg2,
+                                        abi_long arg3, abi_long arg4,
+                                        abi_long arg5, abi_long arg6,
+                                        abi_long arg7, abi_long arg8)
+{
+    trace_guest_user_syscall(cpu, num,
+                             arg1, arg2, arg3, arg4,
+                             arg5, arg6, arg7, arg8);
+    qemu_plugin_vcpu_syscall(cpu, num,
+                             arg1, arg2, arg3, arg4,
+                             arg5, arg6, arg7, arg8);
+}
+
+static inline void record_syscall_return(void *cpu, int num, abi_long ret)
+{
+    trace_guest_user_syscall_ret(cpu, num, ret);
+    qemu_plugin_vcpu_syscall_ret(cpu, num, ret);
+}
+
+
+#endif /* _SYSCALL_TRACE_H_ */

linux-user/syscall.c

@@ -112,6 +112,7 @@
 
 #include "qemu.h"
 #include "qemu/guest-random.h"
+#include "user/syscall-trace.h"
 #include "qapi/error.h"
 #include "fd-trans.h"
 
@@ -11984,8 +11985,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
     }
 #endif
 
-    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4,
+    record_syscall_start(cpu, num, arg1,
-                             arg5, arg6, arg7, arg8);
+                         arg2, arg3, arg4, arg5, arg6, arg7, arg8);
 
     if (unlikely(do_strace)) {
         print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
@@ -11997,6 +11998,6 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
                           arg5, arg6, arg7, arg8);
     }
 
-    trace_guest_user_syscall_ret(cpu, num, ret);
+    record_syscall_return(cpu, num, ret);
     return ret;
 }