trace: [*-user] Add events to trace guest syscalls in syscall emulation mode

Adds two events to trace syscalls in syscall emulation mode (*-user):

* guest_user_syscall: Emitted before the syscall is emulated; contains
  the syscall number and arguments.

* guest_user_syscall_ret: Emitted after the syscall is emulated;
  contains the syscall number and return value.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Message-id: 146651712411.12388.10024905980452504938.stgit@fimbulvetr.bsc.es
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

bsd-user/syscall.c

@@ -315,12 +315,14 @@ abi_long do_freebsd_syscall(void *cpu_env, int num, abi_long arg1,
                             abi_long arg5, abi_long arg6, abi_long arg7,
                             abi_long arg8)
 {
+    CPUState *cpu = ENV_GET_CPU(cpu_env);
     abi_long ret;
     void *p;
 
 #ifdef DEBUG
     gemu_log("freebsd syscall %d\n", num);
 #endif
+    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8);
     if(do_strace)
         print_freebsd_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -400,6 +402,7 @@ 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);
     return ret;
  efault:
     ret = -TARGET_EFAULT;
@@ -410,12 +413,14 @@ abi_long do_netbsd_syscall(void *cpu_env, int num, abi_long arg1,
                            abi_long arg2, abi_long arg3, abi_long arg4,
                            abi_long arg5, abi_long arg6)
 {
+    CPUState *cpu = ENV_GET_CPU(cpu_env);
     abi_long ret;
     void *p;
 
 #ifdef DEBUG
     gemu_log("netbsd syscall %d\n", num);
 #endif
+    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
     if(do_strace)
         print_netbsd_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -472,6 +477,7 @@ 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);
     return ret;
  efault:
     ret = -TARGET_EFAULT;
@@ -482,12 +488,14 @@ abi_long do_openbsd_syscall(void *cpu_env, int num, abi_long arg1,
                             abi_long arg2, abi_long arg3, abi_long arg4,
                             abi_long arg5, abi_long arg6)
 {
+    CPUState *cpu = ENV_GET_CPU(cpu_env);
     abi_long ret;
     void *p;
 
 #ifdef DEBUG
     gemu_log("openbsd syscall %d\n", num);
 #endif
+    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, 0, 0);
     if(do_strace)
         print_openbsd_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -544,6 +552,7 @@ 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);
     return ret;
  efault:
     ret = -TARGET_EFAULT;

linux-user/syscall.c

@@ -6690,6 +6690,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
 #ifdef DEBUG
     gemu_log("syscall %d", num);
 #endif
+    trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8);
     if(do_strace)
         print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
 
@@ -11182,6 +11183,7 @@ fail:
 #endif
     if(do_strace)
         print_syscall_ret(num, ret);
+    trace_guest_user_syscall_ret(cpu, num, ret);
     return ret;
 efault:
     ret = -TARGET_EFAULT;

trace-events

@@ -156,3 +156,19 @@ memory_region_tb_write(int cpu_index, uint64_t addr, uint64_t value, unsigned si
 #
 # Targets: TCG(all)
 disable vcpu tcg guest_mem_before(TCGv vaddr, uint8_t info) "info=%d", "vaddr=0x%016"PRIx64" info=%d"
+
+# @num: System call number.
+# @arg*: System call argument value.
+#
+# Start executing a guest system call in syscall emulation mode.
+#
+# Targets: TCG(all)
+disable vcpu guest_user_syscall(uint64_t num, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5, uint64_t arg6, uint64_t arg7, uint64_t arg8) "num=0x%016"PRIx64" arg1=0x%016"PRIx64" arg2=0x%016"PRIx64" arg3=0x%016"PRIx64" arg4=0x%016"PRIx64" arg5=0x%016"PRIx64" arg6=0x%016"PRIx64" arg7=0x%016"PRIx64" arg8=0x%016"PRIx64
+
+# @num: System call number.
+# @ret: System call result value.
+#
+# Finish executing a guest system call in syscall emulation mode.
+#
+# Targets: TCG(all)
+disable vcpu guest_user_syscall_ret(uint64_t num, uint64_t ret) "num=0x%016"PRIx64" ret=0x%016"PRIx64