tools: bpftool: add "prog run" subcommand to test-run programs

Add a new "bpftool prog run" subcommand to run a loaded program on input
data (and possibly with input context) passed by the user.

Print output data (and output context if relevant) into a file or into
the console. Print return value and duration for the test run into the
console.

A "repeat" argument can be passed to run the program several times in a
row.

The command does not perform any kind of verification based on program
type (Is this program type allowed to use an input context?) or on data
consistency (Can I work with empty input data?), this is left to the
kernel.

Example invocation:

    # perl -e 'print "\x0" x 14' | ./bpftool prog run \
            pinned /sys/fs/bpf/sample_ret0 \
            data_in - data_out - repeat 5
    0000000 0000 0000 0000 0000 0000 0000 0000      | ........ ......
    Return value: 0, duration (average): 260ns

When one of data_in or ctx_in is "-", bpftool reads from standard input,
in binary format. Other formats (JSON, hexdump) might be supported (via
an optional command line keyword like "data_fmt_in") in the future if
relevant, but this would require doing more parsing in bpftool.

v2:
- Fix argument names for function check_single_stdin(). (Yonghong)

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpf/bpftool/Documentation/bpftool-prog.rst

@@ -29,6 +29,7 @@ PROG COMMANDS
 |	**bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
 |	**bpftool** **prog detach** *PROG* *ATTACH_TYPE* [*MAP*]
 |	**bpftool** **prog tracelog**
+|	**bpftool** **prog run** *PROG* **data_in** *FILE* [**data_out** *FILE* [**data_size_out** *L*]] [**ctx_in** *FILE* [**ctx_out** *FILE* [**ctx_size_out** *M*]]] [**repeat** *N*]
 |	**bpftool** **prog help**
 |
 |	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
@@ -146,6 +147,39 @@ DESCRIPTION
 		  streaming data from BPF programs to user space, one can use
 		  perf events (see also **bpftool-map**\ (8)).
 
+	**bpftool prog run** *PROG* **data_in** *FILE* [**data_out** *FILE* [**data_size_out** *L*]] [**ctx_in** *FILE* [**ctx_out** *FILE* [**ctx_size_out** *M*]]] [**repeat** *N*]
+		  Run BPF program *PROG* in the kernel testing infrastructure
+		  for BPF, meaning that the program works on the data and
+		  context provided by the user, and not on actual packets or
+		  monitored functions etc. Return value and duration for the
+		  test run are printed out to the console.
+
+		  Input data is read from the *FILE* passed with **data_in**.
+		  If this *FILE* is "**-**", input data is read from standard
+		  input. Input context, if any, is read from *FILE* passed with
+		  **ctx_in**. Again, "**-**" can be used to read from standard
+		  input, but only if standard input is not already in use for
+		  input data. If a *FILE* is passed with **data_out**, output
+		  data is written to that file. Similarly, output context is
+		  written to the *FILE* passed with **ctx_out**. For both
+		  output flows, "**-**" can be used to print to the standard
+		  output (as plain text, or JSON if relevant option was
+		  passed). If output keywords are omitted, output data and
+		  context are discarded. Keywords **data_size_out** and
+		  **ctx_size_out** are used to pass the size (in bytes) for the
+		  output buffers to the kernel, although the default of 32 kB
+		  should be more than enough for most cases.
+
+		  Keyword **repeat** is used to indicate the number of
+		  consecutive runs to perform. Note that output data and
+		  context printed to files correspond to the last of those
+		  runs. The duration printed out at the end of the runs is an
+		  average over all runs performed by the command.
+
+		  Not all program types support test run. Among those which do,
+		  not all of them can take the **ctx_in**/**ctx_out**
+		  arguments. bpftool does not perform checks on program types.
+
 	**bpftool prog help**
 		  Print short help message.
 

tools/bpf/bpftool/bash-completion/bpftool

@@ -408,10 +408,34 @@ _bpftool()
                 tracelog)
                     return 0
                     ;;
+                run)
+                    if [[ ${#words[@]} -lt 5 ]]; then
+                        _filedir
+                        return 0
+                    fi
+                    case $prev in
+                        id)
+                            _bpftool_get_prog_ids
+                            return 0
+                            ;;
+                        data_in|data_out|ctx_in|ctx_out)
+                            _filedir
+                            return 0
+                            ;;
+                        repeat|data_size_out|ctx_size_out)
+                            return 0
+                            ;;
+                        *)
+                            _bpftool_once_attr 'data_in data_out data_size_out \
+                                ctx_in ctx_out ctx_size_out repeat'
+                            return 0
+                            ;;
+                    esac
+                    ;;
                 *)
                     [[ $prev == $object ]] && \
-                        COMPREPLY=( $( compgen -W 'dump help pin attach detach load \
-                            show list tracelog' -- "$cur" ) )
+                        COMPREPLY=( $( compgen -W 'dump help pin attach detach \
+                            load show list tracelog run' -- "$cur" ) )
                     ;;
             esac
             ;;

tools/bpf/bpftool/main.c

@@ -117,6 +117,35 @@ bool is_prefix(const char *pfx, const char *str)
 	return !memcmp(str, pfx, strlen(pfx));
 }
 
+/* Last argument MUST be NULL pointer */
+int detect_common_prefix(const char *arg, ...)
+{
+	unsigned int count = 0;
+	const char *ref;
+	char msg[256];
+	va_list ap;
+
+	snprintf(msg, sizeof(msg), "ambiguous prefix: '%s' could be '", arg);
+	va_start(ap, arg);
+	while ((ref = va_arg(ap, const char *))) {
+		if (!is_prefix(arg, ref))
+			continue;
+		count++;
+		if (count > 1)
+			strncat(msg, "' or '", sizeof(msg) - strlen(msg) - 1);
+		strncat(msg, ref, sizeof(msg) - strlen(msg) - 1);
+	}
+	va_end(ap);
+	strncat(msg, "'", sizeof(msg) - strlen(msg) - 1);
+
+	if (count >= 2) {
+		p_err(msg);
+		return -1;
+	}
+
+	return 0;
+}
+
 void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep)
 {
 	unsigned char *data = arg;

tools/bpf/bpftool/main.h

@@ -101,6 +101,7 @@ void p_err(const char *fmt, ...);
 void p_info(const char *fmt, ...);
 
 bool is_prefix(const char *pfx, const char *str);
+int detect_common_prefix(const char *arg, ...);
 void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep);
 void usage(void) __noreturn;