uprobe: Make -p switch respect all process' threads

Signed-off-by: Sasha Goldshtein <goldshtn@gmail.com>

examples/uprobe_example.txt

@@ -286,12 +286,13 @@ a different method of stack walking.
 Use -h to print the USAGE message:
 
 # ./uprobe -h
-USAGE: uprobe [-FhHsv] [-d secs] [-p PID] {-l target |
+USAGE: uprobe [-FhHsv] [-d secs] [-p PID] [-L TID] {-l target |
               uprobe_definition [filter]}
                  -F              # force. trace despite warnings.
                  -d seconds      # trace duration, and use buffers
                  -l target       # list functions from this executable
-                 -p PID          # PID to match on I/O issue
+                 -p PID          # PID to match on events
+                 -L TID          # thread id to match on events
                  -v              # view format file (don't trace)
                  -H              # include column headers
                  -s              # show user stack traces

man/man8/uprobe.8

@@ -3,7 +3,7 @@
 uprobe \- trace a given uprobe definition. User-level dynamic tracing. Uses Linux ftrace. EXPERIMENTAL.
 .SH SYNOPSIS
 .B uprobe
-[\-FhHsv] [\-d secs] [\-p PID] {\-l target | uprobe_definition [filter]}
+[\-FhHsv] [\-d secs] [\-p PID] [\-L TID] {\-l target | uprobe_definition [filter]}
 .SH DESCRIPTION
 This will create, trace, then destroy a given uprobe definition. See
 Documentation/trace/uprobetracer.txt in the Linux kernel source for the
@@ -70,6 +70,9 @@ for use in a custom filter.
 \-p PID
 Only trace user-level functions when this process ID is on-CPU.
 .TP
+\-L TID
+Only trace user-level functions when this thread ID is on-CPU.
+.TP
 uprobe_definition
 A full uprobe definition, as documented by Documentation/trace/uprobetracer.txt
 in the Linux kernel source. Note that the probe alias name is optional with

user/uprobe

@@ -8,7 +8,7 @@
 # syntax of a uprobe definition, and "uprobe -h" for examples. With this tool,
 # the probe alias is optional (it will default to something meaningful).
 #
-# USAGE: ./uprobe [-FhHsv] [-d secs] [-p pid] {-l target |
+# USAGE: ./uprobe [-FhHsv] [-d secs] [-p pid] [-L tid] {-l target |
 #                 uprobe_definition [filter]}
 #
 # Run "uprobe -h" for full usage.
@@ -63,20 +63,21 @@
 ### default variables
 tracing=/sys/kernel/debug/tracing
 flock=/var/tmp/.ftrace-lock; wroteflock=0
-opt_duration=0; duration=; opt_pid=0; pid=; opt_filter=0; filter=
-opt_view=0; opt_headers=0; opt_stack=0; dmesg=2; debug=0; opt_force=0
-opt_list=0; target=
+opt_duration=0; duration=; opt_pid=0; pid=; opt_tid=0; tid=
+opt_filter=0; filter=; opt_view=0; opt_headers=0; opt_stack=0; dmesg=2
+debug=0; opt_force=0; opt_list=0; target=
 PATH=$PATH:/usr/bin:/sbin	# ensure we find objdump, ldconfig
 trap ':' INT QUIT TERM PIPE HUP	# sends execution to end tracing section
 
 function usage {
 	cat <<-END >&2
-	USAGE: uprobe [-FhHsv] [-d secs] [-p PID] {-l target |
+	USAGE: uprobe [-FhHsv] [-d secs] [-p PID] [-L TID] {-l target |
 	              uprobe_definition [filter]}
 	                 -F              # force. trace despite warnings.
 	                 -d seconds      # trace duration, and use buffers
 	                 -l target       # list functions from this executable
 	                 -p PID          # PID to match on events
+	                 -L TID          # thread id to match on events
 	                 -v              # view format file (don't trace)
 	                 -H              # include column headers
 	                 -s              # show user stack traces
@@ -192,12 +193,13 @@ function set_addr {
 }
 
 ### process options
-while getopts Fd:hHl:p:sv opt
+while getopts Fd:hHl:p:L:sv opt
 do
 	case $opt in
 	F)	opt_force=1 ;;
 	d)	opt_duration=1; duration=$OPTARG ;;
 	p)	opt_pid=1; pid=$OPTARG ;;
+	L)	opt_tid=1; tid=$OPTARG ;;
 	l)	opt_list=1; target=$OPTARG ;;
 	H)	opt_headers=1 ;;
 	s)	opt_stack=1 ;;
@@ -248,12 +250,21 @@ done
 
 ### option logic
 [[ "$uprobe" == "" ]] && usage
-(( opt_pid && opt_filter )) && die "ERROR: use either -p or a filter."
+(( opt_pid + opt_filter + opt_tid > 1 )) && \
+	die "ERROR: use at most one of -p, -L, or filter."
 (( opt_duration && opt_view )) && die "ERROR: use either -d or -v."
 if (( opt_pid )); then
 	# convert to filter
 	opt_filter=1
-	filter="common_pid == $pid"
+	# ftrace common_pid is thread id from user's perspective
+	for tid in /proc/$pid/task/*; do
+		filter="$filter || common_pid == ${tid##*/}"
+	done
+	filter=${filter:3}  # trim leading ' || ' (four characters)
+fi
+if (( opt_tid )); then
+	opt_filter=1
+	filter="common_pid == $tid"
 fi
 if [[ "$uprobe" != p:* && "$uprobe" != r:* ]]; then
 	echo >&2 "ERROR: invalid uprobe definition (should start with p: or r:)"