crash.kernel: improve and document debuginfo and module loading

In an ideal world, debuginfo packages would be installed under /usr/lib/debug and gdb would locate debuginfo automatically. Practically, this isn't the case. Recent SUSE kernel debuginfo packages don't create the symlinks for modules for automatic loading. Even if they did, the more common use case is to maintain a cache of debuginfo files outside of /usr/lib/debug. This commit improves the handling of the loading of modules and debuginfo. We have some sane defaults, documented in crash.kernel and add some command line options to override those. Signed-off-by: Jeff Mahoney <jeffm@suse.com>
prakashsurya · Apr 29, 2019 · Apr 29, 2019 · Sep 19, 2018 · Apr 29, 2019 · Apr 29, 2019
commit 9a86bc6c55accb9babc39b105556cb27fe0fab0b
diff --git a/crash.sh b/crash.sh
@@ -3,38 +3,98 @@
 
 usage() {
 cat <<END >&2
-usage: $(basename $0) [-d|--search-dir <debuginfo/module dir>] <vmlinux> <vmcore>
+usage: $(basename $0) [options] <vmlinux> <vmcore>
 
-Debugging options:
---gdb           Run the embedded gdb underneath a separate gdb instance.
-                This is useful for debugging issues in gdb that are seen
-                while running crash-python.
---valgrind      Run the embedded gdb underneath valgrind.
-                This is useful for debugging memory leaks in gdb patches.
---nofiles       Start up without loading any object files.
-                This is useful for testing delayed lookup error handling.
+Options:
+-r <dir> | --root <dir>
+    Use the specified directory as the root for all file searches.  When
+    using properly configured .build-id symbolic links, this is the
+    best method to use as the debuginfo will be loaded automatically via
+    gdb without searching for filenames.
+
+-m <dir> | --modules <dir>
+    Use the specified directory to search for modules
+
+-d <dir> | --modules-debuginfo <dir>
+    Use the specified directory to search for module debuginfo
+
+-D <dir> | --vmlinux-debuginfo <dir>
+    Use the specified directory to search for vmlinux debuginfo
+
+-b <dir> | --build-dir <dir>
+    Use the specified directory as the root for all file searches.  This
+    directory should be the root of a built kernel source tree.  This is
+    shorthand for "-r <dir> -m . -d . -D ." and will override preceding
+    options.
 
+Debugging options:
+--debug
+    Enable noisy output for debugging the debugger
+-v | --verbose
+    Enable verbose output for debugging the debugger
+--gdb
+    Run the embedded gdb underneath a separate gdb instance.  This is useful
+    for debugging issues in gdb that are seen while running crash-python.
+--valgrind
+    Run the embedded gdb underneath valgrind.  This is useful
+    for debugging memory leaks in gdb patches.
 END
 exit 1
 }
 
-TEMP=$(getopt -o 'd:h' --long 'search-dir:,gdb,valgrind,nofiles,help' -n "$(basename $0)" -- "$@")
+TEMP=$(getopt -o 'vr:d:m:D:b:h' --long 'verbose,root:,modules-debuginfo:,modules:,vmlinux-debuginfo:,build-dir:,debug,gdb,valgrind,help' -n "$(basename $0)" -- "$@")
 
 if [ $? -ne 0 ]; then
-    echo "Terminating." >&2
-    exit 1
+    usage
 fi
 
 eval set -- "$TEMP"
 unset TEMP
 
+VERBOSE=False
+DEBUG=False
+
 while true; do
     case "$1" in
-        '-d'|'--search-dir')
-            SEARCHDIRS="$SEARCHDIRS $2"
+        '-r'|'--root')
+            SEARCH_DIRS="$SEARCH_DIRS $2"
+            shift 2
+            continue
+        ;;
+        '-m'|'--modules')
+            MODULES="$MODULES $2"
+            shift 2
+            continue
+        ;;
+        '-d'|'--modules-debuginfo')
+            MODULES_DEBUGINFO="$MODULES_DEBUGINFO $2"
+            shift 2
+            continue
+        ;;
+        '-D'|'--vmlinux-debuginfo')
+            VMLINUX_DEBUGINFO="$VMLINUX_DEBUGINFO $2"
+            shift 2
+            continue
+        ;;
+        '-b'|'--build-dir')
+            SEARCH_DIRS="$2"
+            VMLINUX_DEBUGINFO="."
+            MODULES="."
+            MODULES_DEBUGINFO="."
             shift 2
             continue
+            ;;
+        '-v'|'--verbose')
+            VERBOSE="True"
+            shift
+            continue
+        ;;
+        '--debug')
+            DEBUG="True"
+            shift
+            continue
         ;;
+
         '--gdb')
             DEBUGMODE=gdb
             shift
@@ -45,11 +105,6 @@ while true; do
             shift
             continue
             ;;
-        '--nofiles')
-            NOFILES=yes
-            shift
-            continue
-            ;;
         '-h'|'--help')
             usage ;;
         '--')
@@ -63,7 +118,7 @@ while true; do
     esac
 done
 
-if [ "$#" -ne 2 -a -z "$NOFILES" ]; then
+if [ "$#" -ne 2 ]; then
     usage
 fi
 
@@ -111,7 +166,15 @@ else
 fi
 
 VMCORE=$2
+for path in $SEARCH_DIRS; do
+    if test -n "$DFD"; then
+        DFD="$DFD:$path"
+    else
+        DFD="$path"
+    fi
+done
 cat << EOF >> $GDBINIT
+set debug-file-directory $DFD:/usr/lib/debug
 set build-id-verbose 0
 set python print-stack full
 set prompt py-crash> 
@@ -132,13 +195,40 @@ import sys
 import traceback
 try:
     import crash.session
+    from crash.kernel import CrashKernel
 except RuntimeError as e:
     print("crash-python: {}, exiting".format(str(e)), file=sys.stderr)
     traceback.print_exc()
     sys.exit(1)
-path = "$SEARCHDIRS".split(' ')
+
+roots = None
+module_path = None
+module_debuginfo_path = None
+vmlinux_debuginfo = None
+verbose=$VERBOSE
+debug=$DEBUG
+
+s = "$SEARCH_DIRS"
+if len(s) > 0:
+    roots = s.split(" ")
+
+s = "$VMLINUX_DEBUGINFO"
+if len(s) > 0:
+    vmlinux_debuginfo = s.split(" ")
+
+s = "$MODULES"
+if len(s) > 0:
+    module_path = s.split(" ")
+
+s = "$MODULES_DEBUGINFO"
+if len(s) > 0:
+    module_debuginfo_path = s.split(" ")
+
 try:
-    x = crash.session.Session(path)
+    kernel = CrashKernel(roots, vmlinux_debuginfo, module_path,
+                         module_debuginfo_path, verbose, debug)
+
+    x = crash.session.Session(kernel, verbose=verbose, debug=debug)
     print("The 'pyhelp' command will list the command extensions.")
 except gdb.error as e:
     print("crash-python: {}, exiting".format(str(e)), file=sys.stderr)