Add support for generating a systemtap tapset static probes

This introduces generation of a qemu.stp/qemu-system-XXX.stp
files which provides tapsets with friendly names for static
probes & their arguments. Instead of

    probe process("qemu").mark("qemu_malloc") {
        printf("Malloc %d %p\n", $arg1, $arg2);
    }

It is now possible todo

    probe qemu.system.i386.qemu_malloc {
        printf("Malloc %d %p\n", size, ptr);
    }

There is one tapset defined per target arch, for both
user and system emulators.

* Makefile.target: Generate stp files for each target
* tracetool: Support for generating systemtap tapsets
* configure: Check for whether systemtap is available
  with the DTrace backend

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

3 files changed, 146 insertions, 18 deletions

diff --git a/Makefile.target b/Makefile.target
index 31c968c029..2800f473b7 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -41,7 +41,27 @@ kvm.o kvm-all.o vhost.o vhost_net.o: QEMU_CFLAGS+=$(KVM_CFLAGS)
 config-target.h: config-target.h-timestamp
 config-target.h-timestamp: config-target.mak
 
-all: $(PROGS)
+ifdef CONFIG_SYSTEMTAP_TRACE
+stap: $(QEMU_PROG).stp
+
+ifdef CONFIG_USER_ONLY
+TARGET_TYPE=user
+else
+TARGET_TYPE=system
+endif
+
+$(QEMU_PROG).stp:
+	$(call quiet-command,sh $(SRC_PATH)/tracetool \
+		--$(TRACE_BACKEND) \
+		--binary $(bindir)/$(QEMU_PROG) \
+		--target-arch $(TARGET_ARCH) \
+		--target-type $(TARGET_TYPE) \
+		--stap < $(SRC_PATH)/trace-events > $(QEMU_PROG).stp,"  GEN   $(QEMU_PROG).stp")
+else
+stap:
+endif
+
+all: $(PROGS) stap
 
 # Dummy command so that make thinks it has done something
 	@true
@@ -341,6 +361,9 @@ clean:
 	rm -f *.o *.a *~ $(PROGS) nwfpe/*.o fpu/*.o
 	rm -f *.d */*.d tcg/*.o ide/*.o
 	rm -f hmp-commands.h qmp-commands.h gdbstub-xml.c
+ifdef CONFIG_SYSTEMTAP_TRACE
+	rm -f *.stp
+endif
 
 install: all
 ifneq ($(PROGS),)
@@ -349,6 +372,10 @@ ifneq ($(STRIP),)
 	$(STRIP) $(patsubst %,"$(DESTDIR)$(bindir)/%",$(PROGS))
 endif
 endif
+ifdef CONFIG_SYSTEMTAP_TRACE
+	$(INSTALL_DIR) "$(DESTDIR)$(datadir)/../systemtap/tapset"
+	$(INSTALL_DATA) $(QEMU_PROG).stp "$(DESTDIR)$(datadir)/../systemtap/tapset"
+endif
 
 # Include automatically generated dependency files
 -include $(wildcard *.d */*.d)
diff --git a/configure b/configure
index f8dad3eb00..2917874f96 100755
--- a/configure
+++ b/configure
@@ -2203,6 +2203,10 @@ if test "$trace_backend" = "dtrace"; then
     echo
     exit 1
   fi
+  trace_backend_stap="no"
+  if has 'stap' ; then
+    trace_backend_stap="yes"
+  fi
 fi
 
 ##########################################
@@ -2645,6 +2649,9 @@ fi
 if test "$trace_backend" = "simple"; then
   trace_file="\"$trace_file-%u\""
 fi
+if test "$trace_backend" = "dtrace" -a "$trace_backend_stap" = "yes" ; then
+  echo "CONFIG_SYSTEMTAP_TRACE=y" >> $config_host_mak
+fi
 echo "CONFIG_TRACE_FILE=$trace_file" >> $config_host_mak
 
 echo "TOOLS=$tools" >> $config_host_mak
diff --git a/tracetool b/tracetool
index 1ade103baf..fce491c505 100755
--- a/tracetool
+++ b/tracetool
@@ -23,9 +23,16 @@ Backends:
   --dtrace  DTrace/SystemTAP backend
 
 Output formats:
-  -h    Generate .h file
-  -c    Generate .c file
-  -d    Generate .d file (DTrace only)
+  -h     Generate .h file
+  -c     Generate .c file
+  -d     Generate .d file (DTrace only)
+  --stap Generate .stp file (DTrace with SystemTAP only)
+
+Options:
+  --binary      [path]  Full path to QEMU binary
+  --target-arch [arch]  QEMU emulator target arch
+  --target-type [type]  QEMU emulator target type ('system' or 'user')
+
 EOF
     exit 1
 }
@@ -396,6 +403,51 @@ linetod_end_dtrace()
 EOF
 }
 
+linetostap_begin_dtrace()
+{
+    return
+}
+
+linetostap_dtrace()
+{
+    local i arg name args arglist state
+    name=$(get_name "$1")
+    args=$(get_args "$1")
+    arglist=$(get_argnames "$1", "")
+    state=$(get_state "$1")
+    if [ "$state" = "0" ] ; then
+        name=${name##disable }
+    fi
+
+    # Define prototype for probe arguments
+    cat <<EOF
+probe qemu.$targettype.$targetarch.$name = process("$binary").mark("$name")
+{
+EOF
+
+    i=1
+    for arg in $arglist
+    do
+        # 'limit' is a reserved keyword
+        if [ "$arg" = "limit" ]; then
+          arg="_limit"
+        fi
+        cat <<EOF
+  $arg = \$arg$i;
+EOF
+	i="$((i+1))"
+    done
+
+    cat <<EOF
+}
+EOF
+}
+
+linetostap_end_dtrace()
+{
+    return
+}
+
 # Process stdin by calling begin, line, and end functions for the backend
 convert()
 {
@@ -461,19 +513,61 @@ tracetod()
     convert d
 }
 
-# Choose backend
-case "$1" in
-"--nop" | "--simple" | "--ust" | "--dtrace") backend="${1#--}" ;;
-*) usage ;;
-esac
-shift
-
-case "$1" in
-"-h") tracetoh ;;
-"-c") tracetoc ;;
-"-d") tracetod ;;
-"--check-backend") exit 0 ;; # used by ./configure to test for backend
-*) usage ;;
-esac
+tracetostap()
+{
+    if [ $backend != "dtrace" ]; then
+       echo "SystemTAP tapset generator not applicable to $backend backend"
+       exit 1
+    fi
+    if [ -z "$binary" ]; then
+       echo "--binary is required for SystemTAP tapset generator"
+       exit 1
+    fi
+    if [ -z "$targettype" ]; then
+       echo "--target-type is required for SystemTAP tapset generator"
+       exit 1
+    fi
+    if [ -z "$targetarch" ]; then
+       echo "--target-arch is required for SystemTAP tapset generator"
+       exit 1
+    fi
+    echo "/* This file is autogenerated by tracetool, do not edit. */"
+    convert stap
+}
+
+
+backend=
+output=
+binary=
+targettype=
+targetarch=
+
+
+until [ -z "$1" ]
+do
+  case "$1" in
+    "--nop" | "--simple" | "--ust" | "--dtrace") backend="${1#--}" ;;
+
+    "--binary") shift ; binary="$1" ;;
+    "--target-arch") shift ; targetarch="$1" ;;
+    "--target-type") shift ; targettype="$1" ;;
+
+    "-h" | "-c" | "-d") output="${1#-}" ;;
+    "--stap") output="${1#--}" ;;
+
+    "--check-backend") exit 0 ;; # used by ./configure to test for backend
+
+    *)
+      usage;;
+  esac
+  shift
+done
+
+if [ "$backend" = "" -o "$output" = "" ]; then
+  usage
+fi
+
+gen="traceto$output"
+"$gen"
 
 exit 0