tools: allow keeping tools for old kernels

Many of the tools rely on kprobes and internal kernel structs which are
not stable. This means that tools may break with newer kernel versions
and bpftrace syntax does not always allow to support all kernels within
a single script.

This introduces a new directory tools/old/ which will contain versions
of tools for older kernels.

Since the container images used in CI may require some of the old tool
versions, this also introduces a new env variable TOOLS_TEST_OLDVERSION
which makes tools-parsing-test.sh use old versions of chosen tools.

.github/workflows/ci.yml

@@ -167,6 +167,7 @@ jobs:
         -e CC="${CC}"
         -e CXX="${CXX}"
         -e GTEST_FILTER="$GTEST_FILTER"
+        -e TOOLS_TEST_OLDVERSION="$TOOLS_TEST_OLDVERSION"
         bpftrace-builder-$BASE-llvm-$LLVM_VERSION
         ${PWD}/build-$TYPE-$BASE
         $TYPE

.github/workflows/embedded.yml

@@ -93,6 +93,7 @@ jobs:
         -e RUNTIME_TEST_DISABLE="${RUNTIME_TEST_DISABLE}"
         -e VENDOR_GTEST="${VENDOR_GTEST}"
         -e BUILD_LIBBPF="${BUILD_LIBBPF}"
+        -e TOOLS_TEST_OLDVERSION="$TOOLS_TEST_OLDVERSION"
         bpftrace-embedded-${{ matrix.env['BASE'] }}
         $(pwd)/build-embedded ${TYPE}
         -j`nproc`

tests/tools-parsing-test.sh

@@ -15,6 +15,8 @@ EXIT_STATUS=0;
 
 TOOLDIR=""
 
+OLDTOOLS=${TOOLS_TEST_OLDVERSION:-}
+
 function tooldir() {
     for dir in "../../tools" "/vagrant/tools"; do
         if [[ -d "$dir" ]]; then
@@ -30,11 +32,16 @@ function tooldir() {
 tooldir
 
 for f in "$TOOLDIR"/*.bt; do
-  if $BPFTRACE_EXECUTABLE --unsafe -d $f 2>/dev/null >/dev/null; then
-    echo "$f    passed"
+  if [[ $OLDTOOLS =~ $(basename $f) ]]; then
+      tool=$(dirname $f)/old/$(basename $f)
+  else
+      tool=$f
+  fi
+  if $BPFTRACE_EXECUTABLE --unsafe -d $tool 2>/dev/null >/dev/null; then
+    echo "$tool    passed"
   else
-    echo "$f    failed";
-    $BPFTRACE_EXECUTABLE --unsafe -d $f;
+    echo "$tool    failed";
+    $BPFTRACE_EXECUTABLE --unsafe -d $tool;
     EXIT_STATUS=1;
   fi
 done

tools/CMakeLists.txt

@@ -3,3 +3,4 @@ file(GLOB TXT_FILES *.txt)
 list(REMOVE_ITEM TXT_FILES ${CMAKE_CURRENT_SOURCE_DIR}/CMakeLists.txt)
 install(FILES ${BT_FILES} DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/bpftrace/tools)
 install(FILES ${TXT_FILES} DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/bpftrace/tools/doc)
+add_subdirectory(old)

tools/old/CMakeLists.txt

@@ -0,0 +1,2 @@
+file(GLOB BT_FILES *.bt)
+install(FILES ${BT_FILES} DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/bpftrace/tools/old)