[PATCH bpf-next v3 0/7] bpftool: Add inline annotations when dumping program CFGs

[PATCH bpf-next v3 0/7] bpftool: Add inline annotations when dumping program CFGs

[Quentin Monnet]

This set contains some improvements for bpftool's "visual" program dump
option, which produces the control flow graph in a DOT format. The main
objective is to add support for inline annotations on such graphs, so that
we can have the C source code for the program showing up alongside the
instructions, when available. The last commits also make it possible to
display the line numbers or the bare opcodes in the graph, as supported by
regular program dumps.

v3:
- Fixed formatting of DOT graph: escape spaces, and remove indent that
  would cause some unwanted spaces to show up in the resulting graph.
- Don't print line information if the record is empty.
- Add '<' and ' ' to the list of escaped characters for generting the
  DOT graph.
- Truncate long file paths, use shorter field names ("line", "col") for
  code location information in the graph, add missing separator space.
- Add a commit to return an error if JSON output and CFG are both
  required.
- Add a drive-by, clean up commit for bash completion (avoid unnecessary
  calls to _bpftool_once_attr()).

v2: Replace fputc(..., stdout) with putchar(...) in dotlabel_puts().

Quentin Monnet (7):
  bpftool: Fix documentation about line info display for prog dumps
  bpftool: Fix bug for long instructions in program CFG dumps
  bpftool: Support inline annotations when dumping the CFG of a program
  bpftool: Return an error on prog dumps if both CFG and JSON are
    required
  bpftool: Support "opcodes", "linum", "visual" simultaneously
  bpftool: Support printing opcodes and source file references in CFG
  bpftool: Clean up _bpftool_once_attr() calls in bash completion

 .../bpftool/Documentation/bpftool-prog.rst    | 18 ++--
 tools/bpf/bpftool/bash-completion/bpftool     | 42 +++++-----
 tools/bpf/bpftool/btf_dumper.c                | 83 +++++++++++++++++++
 tools/bpf/bpftool/cfg.c                       | 29 ++++---
 tools/bpf/bpftool/cfg.h                       |  5 +-
 tools/bpf/bpftool/main.h                      |  2 +
 tools/bpf/bpftool/prog.c                      | 78 ++++++++---------
 tools/bpf/bpftool/xlated_dumper.c             | 54 +++++++++++-
 tools/bpf/bpftool/xlated_dumper.h             |  3 +-
 9 files changed, 226 insertions(+), 88 deletions(-)

-- 
2.34.1

[PATCH bpf-next v3 1/7] bpftool: Fix documentation about line info display for prog dumps

[Quentin Monnet]

The documentation states that when line_info is available when dumping a
program, the source line will be displayed "by default". There is no
notion of "default" here: the line is always displayed if available,
there is no way currently to turn it off.

In the next sentence, the documentation states that if "linum" is used
on the command line, the relevant filename, line, and column will be
displayed "on top of the source line". This is incorrect, as they are
currently displayed on the right side of the source line (or on top of
the eBPF instruction, not the source).

This commit fixes the documentation to address these points.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/Documentation/bpftool-prog.rst | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index 14de72544995..06d1e4314406 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -106,9 +106,8 @@ DESCRIPTION
 		  CFG in DOT format, on standard output.
 
 		  If the programs have line_info available, the source line will
-		  be displayed by default.  If **linum** is specified,
-		  the filename, line number and line column will also be
-		  displayed on top of the source line.
+		  be displayed.  If **linum** is specified, the filename, line
+		  number and line column will also be displayed.
 
 	**bpftool prog dump jited**  *PROG* [{ **file** *FILE* | **opcodes** | **linum** }]
 		  Dump jited image (host machine code) of the program.
@@ -120,9 +119,8 @@ DESCRIPTION
 		  **opcodes** controls if raw opcodes will be printed.
 
 		  If the prog has line_info available, the source line will
-		  be displayed by default.  If **linum** is specified,
-		  the filename, line number and line column will also be
-		  displayed on top of the source line.
+		  be displayed.  If **linum** is specified, the filename, line
+		  number and line column will also be displayed.
 
 	**bpftool prog pin** *PROG* *FILE*
 		  Pin program *PROG* as *FILE*.
-- 
2.34.1

[PATCH bpf-next v3 2/7] bpftool: Fix bug for long instructions in program CFG dumps

[Quentin Monnet]

When dumping the control flow graphs for programs using the 16-byte long
load instruction, we need to skip the second part of this instruction
when looking for the next instruction to process. Otherwise, we end up
printing "BUG_ld_00" from the kernel disassembler in the CFG.

Fixes: efcef17a6d65 ("tools: bpftool: generate .dot graph from CFG information")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/xlated_dumper.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index 6fe3134ae45d..3daa05d9bbb7 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -372,8 +372,15 @@ void dump_xlated_for_graph(struct dump_data *dd, void *buf_start, void *buf_end,
 	struct bpf_insn *insn_start = buf_start;
 	struct bpf_insn *insn_end = buf_end;
 	struct bpf_insn *cur = insn_start;
+	bool double_insn = false;
 
 	for (; cur <= insn_end; cur++) {
+		if (double_insn) {
+			double_insn = false;
+			continue;
+		}
+		double_insn = cur->code == (BPF_LD | BPF_IMM | BPF_DW);
+
 		printf("% 4d: ", (int)(cur - insn_start + start_idx));
 		print_bpf_insn(&cbs, cur, true);
 		if (cur != insn_end)
-- 
2.34.1

[PATCH bpf-next v3 3/7] bpftool: Support inline annotations when dumping the CFG of a program

[Quentin Monnet]

We support dumping the control flow graph of loaded programs to the DOT
format with bpftool, but so far this feature wouldn't display the source
code lines available through BTF along with the eBPF bytecode. Let's add
support for these annotations, to make it easier to read the graph.

In prog.c, we move the call to dump_xlated_cfg() in order to pass and
use the full struct dump_data, instead of creating a minimal one in
draw_bb_node().

We pass the pointer to this struct down to dump_xlated_for_graph() in
xlated_dumper.c, where most of the logics is added. We deal with BTF
mostly like we do for plain or JSON output, except that we cannot use a
"nr_skip" value to skip a given number of linfo records (we don't
process the BPF instructions linearly, and apart from the root of the
graph we don't know how many records we should skip, so we just store
the last linfo and make sure the new one we find is different before
printing it).

When printing the source instructions to the label of a DOT graph node,
there are a few subtleties to address. We want some special newline
markers, and there are some characters that we must escape. To deal with
them, we introduce a new dedicated function btf_dump_linfo_dotlabel() in
btf_dumper.c. We'll reuse this function in a later commit to format the
filepath, line, and column references as well.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/btf_dumper.c    | 34 +++++++++++++++++++++++++++++++
 tools/bpf/bpftool/cfg.c           | 23 +++++++++------------
 tools/bpf/bpftool/cfg.h           |  4 +++-
 tools/bpf/bpftool/main.h          |  2 ++
 tools/bpf/bpftool/prog.c          | 17 +++++++---------
 tools/bpf/bpftool/xlated_dumper.c | 34 +++++++++++++++++++++++++++++--
 6 files changed, 88 insertions(+), 26 deletions(-)

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index e7f6ec3a8f35..583aa843df92 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -821,3 +821,37 @@ void btf_dump_linfo_json(const struct btf *btf,
 					BPF_LINE_INFO_LINE_COL(linfo->line_col));
 	}
 }
+
+static void dotlabel_puts(const char *s)
+{
+	for (; *s; ++s) {
+		switch (*s) {
+		case '\\':
+		case '"':
+		case '{':
+		case '}':
+		case '<':
+		case '>':
+		case '|':
+		case ' ':
+			putchar('\\');
+			__fallthrough;
+		default:
+			putchar(*s);
+		}
+	}
+}
+
+void btf_dump_linfo_dotlabel(const struct btf *btf,
+			     const struct bpf_line_info *linfo)
+{
+	const char *line = btf__name_by_offset(btf, linfo->line_off);
+
+	if (!line || !strlen(line))
+		return;
+	line = ltrim(line);
+
+	printf("; ");
+	dotlabel_puts(line);
+	printf("\\l\\\n");
+}
diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c
index 1951219a9af7..9fdc1f0cdd6e 100644
--- a/tools/bpf/bpftool/cfg.c
+++ b/tools/bpf/bpftool/cfg.c
@@ -380,7 +380,8 @@ static void cfg_destroy(struct cfg *cfg)
 	}
 }
 
-static void draw_bb_node(struct func_node *func, struct bb_node *bb)
+static void
+draw_bb_node(struct func_node *func, struct bb_node *bb, struct dump_data *dd)
 {
 	const char *shape;
 
@@ -398,13 +399,9 @@ static void draw_bb_node(struct func_node *func, struct bb_node *bb)
 		printf("EXIT");
 	} else {
 		unsigned int start_idx;
-		struct dump_data dd = {};
-
-		printf("{");
-		kernel_syms_load(&dd);
+		printf("{\\\n");
 		start_idx = bb->head - func->start;
-		dump_xlated_for_graph(&dd, bb->head, bb->tail, start_idx);
-		kernel_syms_destroy(&dd);
+		dump_xlated_for_graph(dd, bb->head, bb->tail, start_idx);
 		printf("}");
 	}
 
@@ -430,12 +427,12 @@ static void draw_bb_succ_edges(struct func_node *func, struct bb_node *bb)
 	}
 }
 
-static void func_output_bb_def(struct func_node *func)
+static void func_output_bb_def(struct func_node *func, struct dump_data *dd)
 {
 	struct bb_node *bb;
 
 	list_for_each_entry(bb, &func->bbs, l) {
-		draw_bb_node(func, bb);
+		draw_bb_node(func, bb, dd);
 	}
 }
 
@@ -455,7 +452,7 @@ static void func_output_edges(struct func_node *func)
 	       func_idx, ENTRY_BLOCK_INDEX, func_idx, EXIT_BLOCK_INDEX);
 }
 
-static void cfg_dump(struct cfg *cfg)
+static void cfg_dump(struct cfg *cfg, struct dump_data *dd)
 {
 	struct func_node *func;
 
@@ -463,14 +460,14 @@ static void cfg_dump(struct cfg *cfg)
 	list_for_each_entry(func, &cfg->funcs, l) {
 		printf("subgraph \"cluster_%d\" {\n\tstyle=\"dashed\";\n\tcolor=\"black\";\n\tlabel=\"func_%d ()\";\n",
 		       func->idx, func->idx);
-		func_output_bb_def(func);
+		func_output_bb_def(func, dd);
 		func_output_edges(func);
 		printf("}\n");
 	}
 	printf("}\n");
 }
 
-void dump_xlated_cfg(void *buf, unsigned int len)
+void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len)
 {
 	struct bpf_insn *insn = buf;
 	struct cfg cfg;
@@ -479,7 +476,7 @@ void dump_xlated_cfg(void *buf, unsigned int len)
 	if (cfg_build(&cfg, insn, len))
 		return;
 
-	cfg_dump(&cfg);
+	cfg_dump(&cfg, dd);
 
 	cfg_destroy(&cfg);
 }
diff --git a/tools/bpf/bpftool/cfg.h b/tools/bpf/bpftool/cfg.h
index e144257ea6d2..909d17e6d4c2 100644
--- a/tools/bpf/bpftool/cfg.h
+++ b/tools/bpf/bpftool/cfg.h
@@ -4,6 +4,8 @@
 #ifndef __BPF_TOOL_CFG_H
 #define __BPF_TOOL_CFG_H
 
-void dump_xlated_cfg(void *buf, unsigned int len);
+#include "xlated_dumper.h"
+
+void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len);
 
 #endif /* __BPF_TOOL_CFG_H */
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 0ef373cef4c7..e9ee514b22d4 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -229,6 +229,8 @@ void btf_dump_linfo_plain(const struct btf *btf,
 			  const char *prefix, bool linum);
 void btf_dump_linfo_json(const struct btf *btf,
 			 const struct bpf_line_info *linfo, bool linum);
+void btf_dump_linfo_dotlabel(const struct btf *btf,
+			     const struct bpf_line_info *linfo);
 
 struct nlattr;
 struct ifinfomsg;
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index afbe3ec342c8..d855118f0d96 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -840,11 +840,6 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 					      false))
 				goto exit_free;
 		}
-	} else if (visual) {
-		if (json_output)
-			jsonw_null(json_wtr);
-		else
-			dump_xlated_cfg(buf, member_len);
 	} else {
 		kernel_syms_load(&dd);
 		dd.nr_jited_ksyms = info->nr_jited_ksyms;
@@ -854,12 +849,14 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		dd.finfo_rec_size = info->func_info_rec_size;
 		dd.prog_linfo = prog_linfo;
 
-		if (json_output)
-			dump_xlated_json(&dd, buf, member_len, opcodes,
-					 linum);
+		if (json_output && visual)
+			jsonw_null(json_wtr);
+		else if (json_output)
+			dump_xlated_json(&dd, buf, member_len, opcodes, linum);
+		else if (visual)
+			dump_xlated_cfg(&dd, buf, member_len);
 		else
-			dump_xlated_plain(&dd, buf, member_len, opcodes,
-					  linum);
+			dump_xlated_plain(&dd, buf, member_len, opcodes, linum);
 		kernel_syms_destroy(&dd);
 	}
 
diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index 3daa05d9bbb7..2ee83561b945 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -369,21 +369,51 @@ void dump_xlated_for_graph(struct dump_data *dd, void *buf_start, void *buf_end,
 		.cb_imm		= print_imm,
 		.private_data	= dd,
 	};
+	const struct bpf_prog_linfo *prog_linfo = dd->prog_linfo;
+	const struct bpf_line_info *last_linfo = NULL;
+	struct bpf_func_info *record = dd->func_info;
 	struct bpf_insn *insn_start = buf_start;
 	struct bpf_insn *insn_end = buf_end;
 	struct bpf_insn *cur = insn_start;
+	struct btf *btf = dd->btf;
 	bool double_insn = false;
+	char func_sig[1024];
 
 	for (; cur <= insn_end; cur++) {
+		unsigned int insn_off;
+
 		if (double_insn) {
 			double_insn = false;
 			continue;
 		}
 		double_insn = cur->code == (BPF_LD | BPF_IMM | BPF_DW);
 
-		printf("% 4d: ", (int)(cur - insn_start + start_idx));
+		insn_off = (unsigned int)(cur - insn_start + start_idx);
+		if (btf && record) {
+			if (record->insn_off == insn_off) {
+				btf_dumper_type_only(btf, record->type_id,
+						     func_sig,
+						     sizeof(func_sig));
+				if (func_sig[0] != '\0')
+					printf("; %s:\\l\\\n", func_sig);
+				record = (void *)record + dd->finfo_rec_size;
+			}
+		}
+
+		if (prog_linfo) {
+			const struct bpf_line_info *linfo;
+
+			linfo = bpf_prog_linfo__lfind(prog_linfo, insn_off, 0);
+			if (linfo && linfo != last_linfo) {
+				btf_dump_linfo_dotlabel(btf, linfo);
+				last_linfo = linfo;
+			}
+		}
+
+		printf("%d: ", insn_off);
 		print_bpf_insn(&cbs, cur, true);
+
 		if (cur != insn_end)
-			printf(" | ");
+			printf("| ");
 	}
 }
-- 
2.34.1

[PATCH bpf-next v3 4/7] bpftool: Return an error on prog dumps if both CFG and JSON are required

[Quentin Monnet]

We do not support JSON output for control flow graphs of programs with
bpftool. So far, requiring both the CFG and JSON output would result in
producing a null JSON object. It makes more sense to raise an error
directly when parsing command line arguments and options, so that users
know they won't get any output they might expect.

If JSON is required for the graph, we leave it to Graphviz instead:

    # bpftool prog dump xlated <REF> visual | dot -Tjson

Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/bash-completion/bpftool | 9 ++++++---
 tools/bpf/bpftool/prog.c                  | 8 +++++---
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 35f26f7c1124..a3cb07172789 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -255,16 +255,19 @@ _bpftool_map_update_get_name()
 
 _bpftool()
 {
-    local cur prev words objword
+    local cur prev words objword json=0
     _init_completion || return
 
     # Deal with options
     if [[ ${words[cword]} == -* ]]; then
         local c='--version --json --pretty --bpffs --mapcompat --debug \
-	       --use-loader --base-btf'
+            --use-loader --base-btf'
         COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
         return 0
     fi
+    if _bpftool_search_list -j --json -p --pretty; then
+        json=1
+    fi
 
     # Deal with simplest keywords
     case $prev in
@@ -367,7 +370,7 @@ _bpftool()
                             ;;
                         *)
                             _bpftool_once_attr 'file'
-                            if _bpftool_search_list 'xlated'; then
+                            if _bpftool_search_list 'xlated' && [[ "$json" == 0 ]]; then
                                 COMPREPLY+=( $( compgen -W 'opcodes visual linum' -- \
                                     "$cur" ) )
                             else
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index d855118f0d96..736defc6e5d0 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -849,9 +849,7 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		dd.finfo_rec_size = info->func_info_rec_size;
 		dd.prog_linfo = prog_linfo;
 
-		if (json_output && visual)
-			jsonw_null(json_wtr);
-		else if (json_output)
+		if (json_output)
 			dump_xlated_json(&dd, buf, member_len, opcodes, linum);
 		else if (visual)
 			dump_xlated_cfg(&dd, buf, member_len);
@@ -940,6 +938,10 @@ static int do_dump(int argc, char **argv)
 		usage();
 		goto exit_close;
 	}
+	if (json_output && visual) {
+		p_err("'visual' is not compatible with JSON output");
+		goto exit_close;
+	}
 
 	if (json_output && nb_fds > 1)
 		jsonw_start_array(json_wtr);	/* root array */
-- 
2.34.1

[PATCH bpf-next v3 5/7] bpftool: Support "opcodes", "linum", "visual" simultaneously

[Quentin Monnet]

When dumping a program, the keywords "opcodes" (for printing the raw
opcodes), "linum" (for displaying the filename, line number, column
number along with the source code), and "visual" (for generating the
control flow graph for translated programs) are mutually exclusive. But
there's no reason why they should be. Let's make it possible to pass
several of them at once. The "file FILE" option, which makes bpftool
output a binary image to a file, remains incompatible with the others.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 .../bpftool/Documentation/bpftool-prog.rst    |  8 +--
 tools/bpf/bpftool/bash-completion/bpftool     | 17 +++---
 tools/bpf/bpftool/prog.c                      | 61 ++++++++++---------
 3 files changed, 47 insertions(+), 39 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index 06d1e4314406..9443c524bb76 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -28,8 +28,8 @@ PROG COMMANDS
 =============
 
 |	**bpftool** **prog** { **show** | **list** } [*PROG*]
-|	**bpftool** **prog dump xlated** *PROG* [{**file** *FILE* | **opcodes** | **visual** | **linum**}]
-|	**bpftool** **prog dump jited**  *PROG* [{**file** *FILE* | **opcodes** | **linum**}]
+|	**bpftool** **prog dump xlated** *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] [**visual**] }]
+|	**bpftool** **prog dump jited**  *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] }]
 |	**bpftool** **prog pin** *PROG* *FILE*
 |	**bpftool** **prog** { **load** | **loadall** } *OBJ* *PATH* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**]
 |	**bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
@@ -88,7 +88,7 @@ DESCRIPTION
 		  programs. On such kernels bpftool will automatically emit this
 		  information as well.
 
-	**bpftool prog dump xlated** *PROG* [{ **file** *FILE* | **opcodes** | **visual** | **linum** }]
+	**bpftool prog dump xlated** *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] [**visual**] }]
 		  Dump eBPF instructions of the programs from the kernel. By
 		  default, eBPF will be disassembled and printed to standard
 		  output in human-readable format. In this case, **opcodes**
@@ -109,7 +109,7 @@ DESCRIPTION
 		  be displayed.  If **linum** is specified, the filename, line
 		  number and line column will also be displayed.
 
-	**bpftool prog dump jited**  *PROG* [{ **file** *FILE* | **opcodes** | **linum** }]
+	**bpftool prog dump jited**  *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] }]
 		  Dump jited image (host machine code) of the program.
 
 		  If *FILE* is specified image will be written to a file,
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index a3cb07172789..69c64dc18b1d 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -271,7 +271,7 @@ _bpftool()
 
     # Deal with simplest keywords
     case $prev in
-        help|hex|opcodes|visual|linum)
+        help|hex)
             return 0
             ;;
         tag)
@@ -369,13 +369,16 @@ _bpftool()
                             return 0
                             ;;
                         *)
-                            _bpftool_once_attr 'file'
+                            # "file" is not compatible with other keywords here
+                            if _bpftool_search_list 'file'; then
+                                return 0
+                            fi
+                            if ! _bpftool_search_list 'linum opcodes visual'; then
+                                _bpftool_once_attr 'file'
+                            fi
+                            _bpftool_once_attr 'linum opcodes'
                             if _bpftool_search_list 'xlated' && [[ "$json" == 0 ]]; then
-                                COMPREPLY+=( $( compgen -W 'opcodes visual linum' -- \
-                                    "$cur" ) )
-                            else
-                                COMPREPLY+=( $( compgen -W 'opcodes linum' -- \
-                                    "$cur" ) )
+                                _bpftool_once_attr 'visual'
                             fi
                             return 0
                             ;;
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 736defc6e5d0..092525a6933a 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -905,37 +905,42 @@ static int do_dump(int argc, char **argv)
 	if (nb_fds < 1)
 		goto exit_free;
 
-	if (is_prefix(*argv, "file")) {
-		NEXT_ARG();
-		if (!argc) {
-			p_err("expected file path");
-			goto exit_close;
-		}
-		if (nb_fds > 1) {
-			p_err("several programs matched");
-			goto exit_close;
-		}
+	while (argc) {
+		if (is_prefix(*argv, "file")) {
+			NEXT_ARG();
+			if (!argc) {
+				p_err("expected file path");
+				goto exit_close;
+			}
+			if (nb_fds > 1) {
+				p_err("several programs matched");
+				goto exit_close;
+			}
+
+			filepath = *argv;
+			NEXT_ARG();
+		} else if (is_prefix(*argv, "opcodes")) {
+			opcodes = true;
+			NEXT_ARG();
+		} else if (is_prefix(*argv, "visual")) {
+			if (nb_fds > 1) {
+				p_err("several programs matched");
+				goto exit_close;
+			}
 
-		filepath = *argv;
-		NEXT_ARG();
-	} else if (is_prefix(*argv, "opcodes")) {
-		opcodes = true;
-		NEXT_ARG();
-	} else if (is_prefix(*argv, "visual")) {
-		if (nb_fds > 1) {
-			p_err("several programs matched");
+			visual = true;
+			NEXT_ARG();
+		} else if (is_prefix(*argv, "linum")) {
+			linum = true;
+			NEXT_ARG();
+		} else {
+			usage();
 			goto exit_close;
 		}
-
-		visual = true;
-		NEXT_ARG();
-	} else if (is_prefix(*argv, "linum")) {
-		linum = true;
-		NEXT_ARG();
 	}
 
-	if (argc) {
-		usage();
+	if (filepath && (opcodes || visual || linum)) {
+		p_err("'file' is not compatible with 'opcodes', 'visual', or 'linum'");
 		goto exit_close;
 	}
 	if (json_output && visual) {
@@ -2419,8 +2424,8 @@ static int do_help(int argc, char **argv)
 
 	fprintf(stderr,
 		"Usage: %1$s %2$s { show | list } [PROG]\n"
-		"       %1$s %2$s dump xlated PROG [{ file FILE | opcodes | visual | linum }]\n"
-		"       %1$s %2$s dump jited  PROG [{ file FILE | opcodes | linum }]\n"
+		"       %1$s %2$s dump xlated PROG [{ file FILE | [opcodes] [linum] [visual] }]\n"
+		"       %1$s %2$s dump jited  PROG [{ file FILE | [opcodes] [linum] }]\n"
 		"       %1$s %2$s pin   PROG FILE\n"
 		"       %1$s %2$s { load | loadall } OBJ  PATH \\\n"
 		"                         [type TYPE] [dev NAME] \\\n"
-- 
2.34.1

[PATCH bpf-next v3 6/7] bpftool: Support printing opcodes and source file references in CFG

[Quentin Monnet]

Add support for displaying opcodes or/and file references (filepath,
line and column numbers) when dumping the control flow graphs of loaded
BPF programs with bpftool.

The filepaths in the records are absolute. To avoid blocks on the graph
to get too wide, we truncate them when they get too long (but we always
keep the entire file name). In the unlikely case where the resulting
file name is ambiguous, it remains possible to get the full path with a
regular dump (no CFG).

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/btf_dumper.c    | 51 ++++++++++++++++++++++++++++++-
 tools/bpf/bpftool/cfg.c           | 22 ++++++++-----
 tools/bpf/bpftool/cfg.h           |  3 +-
 tools/bpf/bpftool/main.h          |  2 +-
 tools/bpf/bpftool/prog.c          |  2 +-
 tools/bpf/bpftool/xlated_dumper.c | 15 +++++++--
 tools/bpf/bpftool/xlated_dumper.h |  3 +-
 7 files changed, 83 insertions(+), 15 deletions(-)

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index 583aa843df92..6c5e0e82da22 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -842,8 +842,37 @@ static void dotlabel_puts(const char *s)
 	}
 }
 
+static const char *shorten_path(const char *path)
+{
+	const unsigned int MAX_PATH_LEN = 32;
+	size_t len = strlen(path);
+	const char *shortpath;
+
+	if (len <= MAX_PATH_LEN)
+		return path;
+
+	/* Search for last '/' under the MAX_PATH_LEN limit */
+	shortpath = strchr(path + len - MAX_PATH_LEN, '/');
+	if (shortpath) {
+		if (shortpath < path + strlen("..."))
+			/* We removed a very short prefix, e.g. "/w", and we'll
+			 * make the path longer by prefixing with the ellipsis.
+			 * Not worth it, keep initial path.
+			 */
+			return path;
+		return shortpath;
+	}
+
+	/* File base name length is > MAX_PATH_LEN, search for last '/' */
+			shortpath = strrchr(path, '/');
+	if (shortpath)
+		return shortpath;
+
+	return path;
+}
+
 void btf_dump_linfo_dotlabel(const struct btf *btf,
-			     const struct bpf_line_info *linfo)
+			     const struct bpf_line_info *linfo, bool linum)
 {
 	const char *line = btf__name_by_offset(btf, linfo->line_off);
 
@@ -851,6 +880,26 @@ void btf_dump_linfo_dotlabel(const struct btf *btf,
 		return;
 	line = ltrim(line);
 
+	if (linum) {
+		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
+		const char *shortfile;
+
+		/* More forgiving on file because linum option is
+		 * expected to provide more info than the already
+		 * available src line.
+		 */
+		if (!file)
+			shortfile = "";
+		else
+			shortfile = shorten_path(file);
+
+		printf("; [%s", shortfile > file ? "..." : "");
+		dotlabel_puts(shortfile);
+		printf(" line:%u col:%u]\\l\\\n",
+		       BPF_LINE_INFO_LINE_NUM(linfo->line_col),
+		       BPF_LINE_INFO_LINE_COL(linfo->line_col));
+	}
+
 	printf("; ");
 	dotlabel_puts(line);
 	printf("\\l\\\n");
diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c
index 9fdc1f0cdd6e..eec437cca2ea 100644
--- a/tools/bpf/bpftool/cfg.c
+++ b/tools/bpf/bpftool/cfg.c
@@ -381,7 +381,8 @@ static void cfg_destroy(struct cfg *cfg)
 }
 
 static void
-draw_bb_node(struct func_node *func, struct bb_node *bb, struct dump_data *dd)
+draw_bb_node(struct func_node *func, struct bb_node *bb, struct dump_data *dd,
+	     bool opcodes, bool linum)
 {
 	const char *shape;
 
@@ -401,7 +402,8 @@ draw_bb_node(struct func_node *func, struct bb_node *bb, struct dump_data *dd)
 		unsigned int start_idx;
 		printf("{\\\n");
 		start_idx = bb->head - func->start;
-		dump_xlated_for_graph(dd, bb->head, bb->tail, start_idx);
+		dump_xlated_for_graph(dd, bb->head, bb->tail, start_idx,
+				      opcodes, linum);
 		printf("}");
 	}
 
@@ -427,12 +429,14 @@ static void draw_bb_succ_edges(struct func_node *func, struct bb_node *bb)
 	}
 }
 
-static void func_output_bb_def(struct func_node *func, struct dump_data *dd)
+static void
+func_output_bb_def(struct func_node *func, struct dump_data *dd,
+		   bool opcodes, bool linum)
 {
 	struct bb_node *bb;
 
 	list_for_each_entry(bb, &func->bbs, l) {
-		draw_bb_node(func, bb, dd);
+		draw_bb_node(func, bb, dd, opcodes, linum);
 	}
 }
 
@@ -452,7 +456,8 @@ static void func_output_edges(struct func_node *func)
 	       func_idx, ENTRY_BLOCK_INDEX, func_idx, EXIT_BLOCK_INDEX);
 }
 
-static void cfg_dump(struct cfg *cfg, struct dump_data *dd)
+static void
+cfg_dump(struct cfg *cfg, struct dump_data *dd, bool opcodes, bool linum)
 {
 	struct func_node *func;
 
@@ -460,14 +465,15 @@ static void cfg_dump(struct cfg *cfg, struct dump_data *dd)
 	list_for_each_entry(func, &cfg->funcs, l) {
 		printf("subgraph \"cluster_%d\" {\n\tstyle=\"dashed\";\n\tcolor=\"black\";\n\tlabel=\"func_%d ()\";\n",
 		       func->idx, func->idx);
-		func_output_bb_def(func, dd);
+		func_output_bb_def(func, dd, opcodes, linum);
 		func_output_edges(func);
 		printf("}\n");
 	}
 	printf("}\n");
 }
 
-void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len)
+void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len,
+		     bool opcodes, bool linum)
 {
 	struct bpf_insn *insn = buf;
 	struct cfg cfg;
@@ -476,7 +482,7 @@ void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len)
 	if (cfg_build(&cfg, insn, len))
 		return;
 
-	cfg_dump(&cfg, dd);
+	cfg_dump(&cfg, dd, opcodes, linum);
 
 	cfg_destroy(&cfg);
 }
diff --git a/tools/bpf/bpftool/cfg.h b/tools/bpf/bpftool/cfg.h
index 909d17e6d4c2..b3793f4e1783 100644
--- a/tools/bpf/bpftool/cfg.h
+++ b/tools/bpf/bpftool/cfg.h
@@ -6,6 +6,7 @@
 
 #include "xlated_dumper.h"
 
-void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len);
+void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len,
+		     bool opcodes, bool linum);
 
 #endif /* __BPF_TOOL_CFG_H */
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index e9ee514b22d4..00d11ca6d3f2 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -230,7 +230,7 @@ void btf_dump_linfo_plain(const struct btf *btf,
 void btf_dump_linfo_json(const struct btf *btf,
 			 const struct bpf_line_info *linfo, bool linum);
 void btf_dump_linfo_dotlabel(const struct btf *btf,
-			     const struct bpf_line_info *linfo);
+			     const struct bpf_line_info *linfo, bool linum);
 
 struct nlattr;
 struct ifinfomsg;
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 092525a6933a..430f72306409 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -852,7 +852,7 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		if (json_output)
 			dump_xlated_json(&dd, buf, member_len, opcodes, linum);
 		else if (visual)
-			dump_xlated_cfg(&dd, buf, member_len);
+			dump_xlated_cfg(&dd, buf, member_len, opcodes, linum);
 		else
 			dump_xlated_plain(&dd, buf, member_len, opcodes, linum);
 		kernel_syms_destroy(&dd);
diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index 2ee83561b945..da608e10c843 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -361,7 +361,8 @@ void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
 }
 
 void dump_xlated_for_graph(struct dump_data *dd, void *buf_start, void *buf_end,
-			   unsigned int start_idx)
+			   unsigned int start_idx,
+			   bool opcodes, bool linum)
 {
 	const struct bpf_insn_cbs cbs = {
 		.cb_print	= print_insn_for_graph,
@@ -405,7 +406,7 @@ void dump_xlated_for_graph(struct dump_data *dd, void *buf_start, void *buf_end,
 
 			linfo = bpf_prog_linfo__lfind(prog_linfo, insn_off, 0);
 			if (linfo && linfo != last_linfo) {
-				btf_dump_linfo_dotlabel(btf, linfo);
+				btf_dump_linfo_dotlabel(btf, linfo, linum);
 				last_linfo = linfo;
 			}
 		}
@@ -413,6 +414,16 @@ void dump_xlated_for_graph(struct dump_data *dd, void *buf_start, void *buf_end,
 		printf("%d: ", insn_off);
 		print_bpf_insn(&cbs, cur, true);
 
+		if (opcodes) {
+			printf("\\ \\ \\ \\ ");
+			fprint_hex(stdout, cur, 8, " ");
+			if (double_insn && cur <= insn_end - 1) {
+				printf(" ");
+				fprint_hex(stdout, cur + 1, 8, " ");
+			}
+			printf("\\l\\\n");
+		}
+
 		if (cur != insn_end)
 			printf("| ");
 	}
diff --git a/tools/bpf/bpftool/xlated_dumper.h b/tools/bpf/bpftool/xlated_dumper.h
index 54847e174273..9a946377b0e6 100644
--- a/tools/bpf/bpftool/xlated_dumper.h
+++ b/tools/bpf/bpftool/xlated_dumper.h
@@ -34,6 +34,7 @@ void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
 void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
 		       bool opcodes, bool linum);
 void dump_xlated_for_graph(struct dump_data *dd, void *buf, void *buf_end,
-			   unsigned int start_index);
+			   unsigned int start_index,
+			   bool opcodes, bool linum);
 
 #endif
-- 
2.34.1

[PATCH bpf-next v3 7/7] bpftool: Clean up _bpftool_once_attr() calls in bash completion

[Quentin Monnet]

In bpftool's bash completion file, function _bpftool_once_attr() is able
to process multiple arguments. There are a few locations where this
function is called multiple times in a row, each time for a single
argument; let's pass all arguments instead to minimize the number of
function calls required for the completion.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/bash-completion/bpftool | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 69c64dc18b1d..e7234d1a5306 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -508,10 +508,7 @@ _bpftool()
                             ;;
                         *)
                             COMPREPLY=( $( compgen -W "map" -- "$cur" ) )
-                            _bpftool_once_attr 'type'
-                            _bpftool_once_attr 'dev'
-                            _bpftool_once_attr 'pinmaps'
-                            _bpftool_once_attr 'autoattach'
+                            _bpftool_once_attr 'type dev pinmaps autoattach'
                             return 0
                             ;;
                     esac
@@ -736,16 +733,10 @@ _bpftool()
                             esac
                             ;;
                         *)
-                            _bpftool_once_attr 'type'
-                            _bpftool_once_attr 'key'
-                            _bpftool_once_attr 'value'
-                            _bpftool_once_attr 'entries'
-                            _bpftool_once_attr 'name'
-                            _bpftool_once_attr 'flags'
+                            _bpftool_once_attr 'type key value entries name flags dev'
                             if _bpftool_search_list 'array_of_maps' 'hash_of_maps'; then
                                 _bpftool_once_attr 'inner_map'
                             fi
-                            _bpftool_once_attr 'dev'
                             return 0
                             ;;
                     esac
@@ -886,8 +877,7 @@ _bpftool()
                             return 0
                             ;;
                         *)
-                            _bpftool_once_attr 'cpu'
-                            _bpftool_once_attr 'index'
+                            _bpftool_once_attr 'cpu index'
                             return 0
                             ;;
                     esac
-- 
2.34.1

Re: [PATCH bpf-next v3 0/7] bpftool: Add inline annotations when dumping program CFGs

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Wed,  5 Apr 2023 14:21:13 +0100 you wrote:
> This set contains some improvements for bpftool's "visual" program dump
> option, which produces the control flow graph in a DOT format. The main
> objective is to add support for inline annotations on such graphs, so that
> we can have the C source code for the program showing up alongside the
> instructions, when available. The last commits also make it possible to
> display the line numbers or the bare opcodes in the graph, as supported by
> regular program dumps.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3,1/7] bpftool: Fix documentation about line info display for prog dumps
    https://git.kernel.org/bpf/bpf-next/c/e27f0f1620b6
  - [bpf-next,v3,2/7] bpftool: Fix bug for long instructions in program CFG dumps
    https://git.kernel.org/bpf/bpf-next/c/67cf52cdb6c8
  - [bpf-next,v3,3/7] bpftool: Support inline annotations when dumping the CFG of a program
    https://git.kernel.org/bpf/bpf-next/c/9fd496848b1c
  - [bpf-next,v3,4/7] bpftool: Return an error on prog dumps if both CFG and JSON are required
    https://git.kernel.org/bpf/bpf-next/c/05a06be72289
  - [bpf-next,v3,5/7] bpftool: Support "opcodes", "linum", "visual" simultaneously
    https://git.kernel.org/bpf/bpf-next/c/9b79f02722bb
  - [bpf-next,v3,6/7] bpftool: Support printing opcodes and source file references in CFG
    https://git.kernel.org/bpf/bpf-next/c/7483a7a70a12
  - [bpf-next,v3,7/7] bpftool: Clean up _bpftool_once_attr() calls in bash completion
    https://git.kernel.org/bpf/bpf-next/c/7319296855f1

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH bpf-next v3 3/7] bpftool: Support inline annotations when dumping the CFG of a program

[Sven Schnelle]

Quentin Monnet <quentin@isovalent.com> writes:

> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
> index e7f6ec3a8f35..583aa843df92 100644
> --- a/tools/bpf/bpftool/btf_dumper.c
> +++ b/tools/bpf/bpftool/btf_dumper.c
> @@ -821,3 +821,37 @@ void btf_dump_linfo_json(const struct btf *btf,
>  					BPF_LINE_INFO_LINE_COL(linfo->line_col));
>  	}
>  }
> +
> +static void dotlabel_puts(const char *s)
> +{
> +	for (; *s; ++s) {
> +		switch (*s) {
> +		case '\\':
> +		case '"':
> +		case '{':
> +		case '}':
> +		case '<':
> +		case '>':
> +		case '|':
> +		case ' ':
> +			putchar('\\');
> +			__fallthrough;

Is __fallthrough correct? I see the following compile error on s390 in
linux-next (20230412):

  CC      btf_dumper.o
btf_dumper.c: In function ‘dotlabel_puts’:
btf_dumper.c:838:25: error: ‘__fallthrough’ undeclared (first use in this function); did you mean ‘fallthrough’?
  838 |                         __fallthrough;
      |                         ^~~~~~~~~~~~~

removing the two underscores fixes this.

> +		default:
> +			putchar(*s);
> +		}
> +	}
> +}

Thanks,
Sven

Re: [PATCH bpf-next v3 3/7] bpftool: Support inline annotations when dumping the CFG of a program

[Quentin Monnet]

2023-04-12 08:04 UTC+0200 ~ Sven Schnelle <svens@linux.ibm.com>
> Quentin Monnet <quentin@isovalent.com> writes:
> 
>> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
>> index e7f6ec3a8f35..583aa843df92 100644
>> --- a/tools/bpf/bpftool/btf_dumper.c
>> +++ b/tools/bpf/bpftool/btf_dumper.c
>> @@ -821,3 +821,37 @@ void btf_dump_linfo_json(const struct btf *btf,
>>  					BPF_LINE_INFO_LINE_COL(linfo->line_col));
>>  	}
>>  }
>> +
>> +static void dotlabel_puts(const char *s)
>> +{
>> +	for (; *s; ++s) {
>> +		switch (*s) {
>> +		case '\\':
>> +		case '"':
>> +		case '{':
>> +		case '}':
>> +		case '<':
>> +		case '>':
>> +		case '|':
>> +		case ' ':
>> +			putchar('\\');
>> +			__fallthrough;
> 
> Is __fallthrough correct? I see the following compile error on s390 in
> linux-next (20230412):
> 
>   CC      btf_dumper.o
> btf_dumper.c: In function ‘dotlabel_puts’:
> btf_dumper.c:838:25: error: ‘__fallthrough’ undeclared (first use in this function); did you mean ‘fallthrough’?
>   838 |                         __fallthrough;
>       |                         ^~~~~~~~~~~~~
> 
> removing the two underscores fixes this.

I thought so? Perf seems to use the double underscores as well. Just
"fallthrough" does not seem to be the right fix anyway, it gives me an
error similar to yours on x86_64 with "fallthrough" undeclared.

The definition should be pulled from tools/include/linux/compiler.h (and
.../compiler-gcc.h). I thought this file would be at least included from
bpftool's main.h, in turn included in btf_dumper.c. Looking at the chain
of inclusions, on my system I get the following path:

    $ CFLAGS=-H make btf_dumper.o
    [...]
    . /root/dev/linux/tools/include/linux/bitops.h
    [...]
    .. /root/dev/linux/tools/include/linux/bits.h
    [...]
    ... /root/dev/linux/tools/include/linux/build_bug.h
    .... /root/dev/linux/tools/include/linux/compiler.h
    ..... /root/dev/linux/tools/include/linux/compiler_types.h
    ...... /root/dev/linux/tools/include/linux/compiler-gcc.h
    [...]

What do you get on your side?

If you add "#include <linux/compiler.h>" to btf_dumper.c directly, does
it fix the issue?

Quentin

Re: [PATCH bpf-next v3 3/7] bpftool: Support inline annotations when dumping the CFG of a program

[Sven Schnelle]

Quentin Monnet <quentin@isovalent.com> writes:

> 2023-04-12 08:04 UTC+0200 ~ Sven Schnelle <svens@linux.ibm.com>
>> Quentin Monnet <quentin@isovalent.com> writes:
>> 
>>> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
>>> index e7f6ec3a8f35..583aa843df92 100644
>>> --- a/tools/bpf/bpftool/btf_dumper.c
>>> +++ b/tools/bpf/bpftool/btf_dumper.c
>>> @@ -821,3 +821,37 @@ void btf_dump_linfo_json(const struct btf *btf,
>>>  					BPF_LINE_INFO_LINE_COL(linfo->line_col));
>>>  	}
>>>  }
>>> +
>>> +static void dotlabel_puts(const char *s)
>>> +{
>>> +	for (; *s; ++s) {
>>> +		switch (*s) {
>>> +		case '\\':
>>> +		case '"':
>>> +		case '{':
>>> +		case '}':
>>> +		case '<':
>>> +		case '>':
>>> +		case '|':
>>> +		case ' ':
>>> +			putchar('\\');
>>> +			__fallthrough;
>> 
>> Is __fallthrough correct? I see the following compile error on s390 in
>> linux-next (20230412):
>> 
>>   CC      btf_dumper.o
>> btf_dumper.c: In function ‘dotlabel_puts’:
>> btf_dumper.c:838:25: error: ‘__fallthrough’ undeclared (first use in this function); did you mean ‘fallthrough’?
>>   838 |                         __fallthrough;
>>       |                         ^~~~~~~~~~~~~
>> 
>> removing the two underscores fixes this.
>
> I thought so? Perf seems to use the double underscores as well. Just
> "fallthrough" does not seem to be the right fix anyway, it gives me an
> error similar to yours on x86_64 with "fallthrough" undeclared.
>
> The definition should be pulled from tools/include/linux/compiler.h (and
> .../compiler-gcc.h). I thought this file would be at least included from
> bpftool's main.h, in turn included in btf_dumper.c. Looking at the chain
> of inclusions, on my system I get the following path:
>
>     $ CFLAGS=-H make btf_dumper.o
>     [...]
>     . /root/dev/linux/tools/include/linux/bitops.h
>     [...]
>     .. /root/dev/linux/tools/include/linux/bits.h
>     [...]
>     ... /root/dev/linux/tools/include/linux/build_bug.h
>     .... /root/dev/linux/tools/include/linux/compiler.h
>     ..... /root/dev/linux/tools/include/linux/compiler_types.h
>     ...... /root/dev/linux/tools/include/linux/compiler-gcc.h
>     [...]
>
> What do you get on your side?
>
> If you add "#include <linux/compiler.h>" to btf_dumper.c directly, does
> it fix the issue?

This seems to clash with:

commit f7a858bffcddaaf70c71b6b656e7cc21b6107cec
Author: Liam Howlett <liam.howlett@oracle.com>
Date:   Fri Nov 25 15:50:16 2022 +0000

    tools: Rename __fallthrough to fallthrough

    Rename the fallthrough attribute to better align with the kernel
    version.  Copy the definition from include/linux/compiler_attributes.h
    including the #else clause.  Adding the #else clause allows the tools
    compiler.h header to drop the check for a definition entirely and keeps
    both definitions together.

    Change any __fallthrough statements to fallthrough anywhere it was used
    within perf.

    This allows other tools to use the same key word as the kernel.

Which was also merged in linux-next.

Re: [PATCH bpf-next v3 3/7] bpftool: Support inline annotations when dumping the CFG of a program

[Quentin Monnet]

2023-04-12 14:26 UTC+0200 ~ Sven Schnelle <svens@linux.ibm.com>
> Quentin Monnet <quentin@isovalent.com> writes:
> 
>> 2023-04-12 08:04 UTC+0200 ~ Sven Schnelle <svens@linux.ibm.com>
>>> Quentin Monnet <quentin@isovalent.com> writes:
>>>
>>>> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
>>>> index e7f6ec3a8f35..583aa843df92 100644
>>>> --- a/tools/bpf/bpftool/btf_dumper.c
>>>> +++ b/tools/bpf/bpftool/btf_dumper.c
>>>> @@ -821,3 +821,37 @@ void btf_dump_linfo_json(const struct btf *btf,
>>>>  					BPF_LINE_INFO_LINE_COL(linfo->line_col));
>>>>  	}
>>>>  }
>>>> +
>>>> +static void dotlabel_puts(const char *s)
>>>> +{
>>>> +	for (; *s; ++s) {
>>>> +		switch (*s) {
>>>> +		case '\\':
>>>> +		case '"':
>>>> +		case '{':
>>>> +		case '}':
>>>> +		case '<':
>>>> +		case '>':
>>>> +		case '|':
>>>> +		case ' ':
>>>> +			putchar('\\');
>>>> +			__fallthrough;
>>>
>>> Is __fallthrough correct? I see the following compile error on s390 in
>>> linux-next (20230412):
>>>
>>>   CC      btf_dumper.o
>>> btf_dumper.c: In function ‘dotlabel_puts’:
>>> btf_dumper.c:838:25: error: ‘__fallthrough’ undeclared (first use in this function); did you mean ‘fallthrough’?
>>>   838 |                         __fallthrough;
>>>       |                         ^~~~~~~~~~~~~
>>>
>>> removing the two underscores fixes this.
>>
>> I thought so? Perf seems to use the double underscores as well. Just
>> "fallthrough" does not seem to be the right fix anyway, it gives me an
>> error similar to yours on x86_64 with "fallthrough" undeclared.
>>
>> The definition should be pulled from tools/include/linux/compiler.h (and
>> .../compiler-gcc.h). I thought this file would be at least included from
>> bpftool's main.h, in turn included in btf_dumper.c. Looking at the chain
>> of inclusions, on my system I get the following path:
>>
>>     $ CFLAGS=-H make btf_dumper.o
>>     [...]
>>     . /root/dev/linux/tools/include/linux/bitops.h
>>     [...]
>>     .. /root/dev/linux/tools/include/linux/bits.h
>>     [...]
>>     ... /root/dev/linux/tools/include/linux/build_bug.h
>>     .... /root/dev/linux/tools/include/linux/compiler.h
>>     ..... /root/dev/linux/tools/include/linux/compiler_types.h
>>     ...... /root/dev/linux/tools/include/linux/compiler-gcc.h
>>     [...]
>>
>> What do you get on your side?
>>
>> If you add "#include <linux/compiler.h>" to btf_dumper.c directly, does
>> it fix the issue?
> 
> This seems to clash with:
> 
> commit f7a858bffcddaaf70c71b6b656e7cc21b6107cec
> Author: Liam Howlett <liam.howlett@oracle.com>
> Date:   Fri Nov 25 15:50:16 2022 +0000
> 
>     tools: Rename __fallthrough to fallthrough
> 
>     Rename the fallthrough attribute to better align with the kernel
>     version.  Copy the definition from include/linux/compiler_attributes.h
>     including the #else clause.  Adding the #else clause allows the tools
>     compiler.h header to drop the check for a definition entirely and keeps
>     both definitions together.
> 
>     Change any __fallthrough statements to fallthrough anywhere it was used
>     within perf.
> 
>     This allows other tools to use the same key word as the kernel.
> 
> Which was also merged in linux-next.

Right, I was not aware of this commit. In that case, replacing with
"fallthrough" in linux-next makes sense indeed.

Thomas Richter just submitted that fix at
https://lore.kernel.org/all/20230412123636.2358949-1-tmricht@linux.ibm.com/.

Thanks!
Quentin