[PATCH bpf-next v4 0/8] bpftool: Add LLVM as default library for disassembling JIT-ed programs

[PATCH bpf-next v4 0/8] bpftool: Add LLVM as default library for disassembling JIT-ed programs

[Quentin Monnet]

To disassemble instructions for JIT-ed programs, bpftool has relied on the
libbfd library. This has been problematic in the past: libbfd's interface
is not meant to be stable and has changed several times, hence the
detection of the two related features from the Makefile
(disassembler-four-args and disassembler-init-styled). When it comes to
shipping bpftool, this has also caused issues with several distribution
maintainers unwilling to support the feature (for example, Debian's page
for binutils-dev, libbfd's package, says: "Note that building Debian
packages which depend on the shared libbfd is Not Allowed.").

This patchset adds support for LLVM as the primary library for
disassembling instructions for JIT-ed programs.

We keep libbfd as a fallback. One reason for this is that currently it
works well, we have all we need in terms of features detection in the
Makefile, so it provides a fallback for disassembling JIT-ed programs if
libbfd is installed but LLVM is not. The other reason is that libbfd
supports nfp instruction for Netronome's SmartNICs and can be used to
disassemble offloaded programs, something that LLVM cannot do (Niklas
confirmed that the feature is still in use). However, if libbfd's interface
breaks again in the future, we might reconsider keeping support for it.

v4:
  - Rebase to address a conflict with commit 2c76238eaddd ("bpftool: Add
    "bootstrap" feature to version output").

v3:
  - Extend commit description (patch 6) with notes on llvm-dev and LLVM's
    disassembler stability.

v2:
  - Pass callback when creating the LLVM disassembler, so that the
    branch targets are printed as addresses (instead of byte offsets).
  - Add last commit to "support" other arch with LLVM, although we don't
    know any supported triple yet.
  - Use $(LLVM_CONFIG) instead of llvm-config in Makefile.
  - Pass components to llvm-config --libs to limit the number of
    libraries to pass on the command line, in Makefile.
  - Rebase split of FEATURE_TESTS and FEATURE_DISPLAY in Makefile.

Quentin Monnet (8):
  bpftool: Define _GNU_SOURCE only once
  bpftool: Remove asserts from JIT disassembler
  bpftool: Split FEATURE_TESTS/FEATURE_DISPLAY definitions in Makefile
  bpftool: Group libbfd defs in Makefile, only pass them if we use
    libbfd
  bpftool: Refactor disassembler for JIT-ed programs
  bpftool: Add LLVM as default library for disassembling JIT-ed programs
  bpftool: Support setting alternative arch for JIT disasm with LLVM
  bpftool: Add llvm feature to "bpftool version"

 .../bpftool/Documentation/common_options.rst  |   8 +-
 tools/bpf/bpftool/Makefile                    |  72 +++--
 tools/bpf/bpftool/common.c                    |  12 +-
 tools/bpf/bpftool/iter.c                      |   2 +
 tools/bpf/bpftool/jit_disasm.c                | 261 +++++++++++++++---
 tools/bpf/bpftool/main.c                      |   7 +
 tools/bpf/bpftool/main.h                      |  32 +--
 tools/bpf/bpftool/map.c                       |   1 -
 tools/bpf/bpftool/net.c                       |   2 +
 tools/bpf/bpftool/perf.c                      |   2 +
 tools/bpf/bpftool/prog.c                      |  23 +-
 tools/bpf/bpftool/xlated_dumper.c             |   2 +
 12 files changed, 319 insertions(+), 105 deletions(-)

-- 
2.34.1

[PATCH bpf-next v4 1/8] bpftool: Define _GNU_SOURCE only once

[Quentin Monnet]

_GNU_SOURCE is defined in several source files for bpftool, but only one
of them takes the precaution of checking whether the value is already
defined. Add #ifndef for other occurrences too.

This is in preparation for the support of disassembling JIT-ed programs
with LLVM, with $(llvm-config --cflags) passing -D_GNU_SOURCE as a
compilation argument.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
---
 tools/bpf/bpftool/common.c        | 2 ++
 tools/bpf/bpftool/iter.c          | 2 ++
 tools/bpf/bpftool/jit_disasm.c    | 2 ++
 tools/bpf/bpftool/net.c           | 2 ++
 tools/bpf/bpftool/perf.c          | 2 ++
 tools/bpf/bpftool/prog.c          | 2 ++
 tools/bpf/bpftool/xlated_dumper.c | 2 ++
 7 files changed, 14 insertions(+)

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 8727765add88..4c2e909a2d67 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2017-2018 Netronome Systems, Inc. */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/bpf/bpftool/iter.c b/tools/bpf/bpftool/iter.c
index f88fdc820d23..a3e6b167153d 100644
--- a/tools/bpf/bpftool/iter.c
+++ b/tools/bpf/bpftool/iter.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (C) 2020 Facebook
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <unistd.h>
 #include <linux/err.h>
 #include <bpf/libbpf.h>
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index aaf99a0168c9..71cb258ab0ee 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -11,7 +11,9 @@
  * Licensed under the GNU General Public License, version 2.0 (GPLv2)
  */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdint.h>
diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index 526a332c48e6..c40e44c938ae 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (C) 2018 Facebook
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
diff --git a/tools/bpf/bpftool/perf.c b/tools/bpf/bpftool/perf.c
index 226ec2c39052..91743445e4c7 100644
--- a/tools/bpf/bpftool/perf.c
+++ b/tools/bpf/bpftool/perf.c
@@ -2,7 +2,9 @@
 // Copyright (C) 2018 Facebook
 // Author: Yonghong Song <yhs@fb.com>
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 10ec29cb4598..dbf5489b8fde 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2017-2018 Netronome Systems, Inc. */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index 2d9cd6a7b3c8..6fe3134ae45d 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2018 Netronome Systems, Inc. */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
-- 
2.34.1

[PATCH bpf-next v4 2/8] bpftool: Remove asserts from JIT disassembler

[Quentin Monnet]

The JIT disassembler in bpftool is the only components (with the JSON
writer) using asserts to check the return values of functions. But it
does not do so in a consistent way, and diasm_print_insn() returns no
value, although sometimes the operation failed.

Remove the asserts, and instead check the return values, print messages
on errors, and propagate the error to the caller from prog.c.

Remove the inclusion of assert.h from jit_disasm.c, and also from map.c
where it is unused.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
---
 tools/bpf/bpftool/jit_disasm.c | 51 +++++++++++++++++++++++-----------
 tools/bpf/bpftool/main.h       | 25 +++++++++--------
 tools/bpf/bpftool/map.c        |  1 -
 tools/bpf/bpftool/prog.c       | 15 ++++++----
 4 files changed, 57 insertions(+), 35 deletions(-)

diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index 71cb258ab0ee..723a9b799a0c 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -18,7 +18,6 @@
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdlib.h>
-#include <assert.h>
 #include <unistd.h>
 #include <string.h>
 #include <bfd.h>
@@ -31,14 +30,18 @@
 #include "json_writer.h"
 #include "main.h"
 
-static void get_exec_path(char *tpath, size_t size)
+static int get_exec_path(char *tpath, size_t size)
 {
 	const char *path = "/proc/self/exe";
 	ssize_t len;
 
 	len = readlink(path, tpath, size - 1);
-	assert(len > 0);
+	if (len <= 0)
+		return -1;
+
 	tpath[len] = 0;
+
+	return 0;
 }
 
 static int oper_count;
@@ -99,30 +102,39 @@ static int fprintf_json_styled(void *out,
 	return r;
 }
 
-void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		       const char *arch, const char *disassembler_options,
-		       const struct btf *btf,
-		       const struct bpf_prog_linfo *prog_linfo,
-		       __u64 func_ksym, unsigned int func_idx,
-		       bool linum)
+int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
+		      const char *arch, const char *disassembler_options,
+		      const struct btf *btf,
+		      const struct bpf_prog_linfo *prog_linfo,
+		      __u64 func_ksym, unsigned int func_idx,
+		      bool linum)
 {
 	const struct bpf_line_info *linfo = NULL;
 	disassembler_ftype disassemble;
+	int count, i, pc = 0, err = -1;
 	struct disassemble_info info;
 	unsigned int nr_skip = 0;
-	int count, i, pc = 0;
 	char tpath[PATH_MAX];
 	bfd *bfdf;
 
 	if (!len)
-		return;
+		return -1;
 
 	memset(tpath, 0, sizeof(tpath));
-	get_exec_path(tpath, sizeof(tpath));
+	if (get_exec_path(tpath, sizeof(tpath))) {
+		p_err("failed to create disasembler (get_exec_path)");
+		return -1;
+	}
 
 	bfdf = bfd_openr(tpath, NULL);
-	assert(bfdf);
-	assert(bfd_check_format(bfdf, bfd_object));
+	if (!bfdf) {
+		p_err("failed to create disassembler (bfd_openr)");
+		return -1;
+	}
+	if (!bfd_check_format(bfdf, bfd_object)) {
+		p_err("failed to create disassembler (bfd_check_format)");
+		goto exit_close;
+	}
 
 	if (json_output)
 		init_disassemble_info_compat(&info, stdout,
@@ -141,7 +153,7 @@ void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 			bfdf->arch_info = inf;
 		} else {
 			p_err("No libbfd support for %s", arch);
-			return;
+			goto exit_close;
 		}
 	}
 
@@ -162,7 +174,10 @@ void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 #else
 	disassemble = disassembler(bfdf);
 #endif
-	assert(disassemble);
+	if (!disassemble) {
+		p_err("failed to create disassembler");
+		goto exit_close;
+	}
 
 	if (json_output)
 		jsonw_start_array(json_wtr);
@@ -226,7 +241,11 @@ void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 	if (json_output)
 		jsonw_end_array(json_wtr);
 
+	err = 0;
+
+exit_close:
 	bfd_close(bfdf);
+	return err;
 }
 
 int disasm_init(void)
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 5e5060c2ac04..c9e171082cf6 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -173,22 +173,23 @@ int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
 
 struct bpf_prog_linfo;
 #ifdef HAVE_LIBBFD_SUPPORT
-void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		       const char *arch, const char *disassembler_options,
-		       const struct btf *btf,
-		       const struct bpf_prog_linfo *prog_linfo,
-		       __u64 func_ksym, unsigned int func_idx,
-		       bool linum);
+int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
+		      const char *arch, const char *disassembler_options,
+		      const struct btf *btf,
+		      const struct bpf_prog_linfo *prog_linfo,
+		      __u64 func_ksym, unsigned int func_idx,
+		      bool linum);
 int disasm_init(void);
 #else
 static inline
-void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		       const char *arch, const char *disassembler_options,
-		       const struct btf *btf,
-		       const struct bpf_prog_linfo *prog_linfo,
-		       __u64 func_ksym, unsigned int func_idx,
-		       bool linum)
+int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
+		      const char *arch, const char *disassembler_options,
+		      const struct btf *btf,
+		      const struct bpf_prog_linfo *prog_linfo,
+		      __u64 func_ksym, unsigned int func_idx,
+		      bool linum)
 {
+	return 0;
 }
 static inline int disasm_init(void)
 {
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 9a6ca9f31133..3087ced658ad 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2017-2018 Netronome Systems, Inc. */
 
-#include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/err.h>
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index dbf5489b8fde..93dfb89b85e3 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -822,10 +822,11 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 					printf("%s:\n", sym_name);
 				}
 
-				disasm_print_insn(img, lens[i], opcodes,
-						  name, disasm_opt, btf,
-						  prog_linfo, ksyms[i], i,
-						  linum);
+				if (disasm_print_insn(img, lens[i], opcodes,
+						      name, disasm_opt, btf,
+						      prog_linfo, ksyms[i], i,
+						      linum))
+					goto exit_free;
 
 				img += lens[i];
 
@@ -838,8 +839,10 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 			if (json_output)
 				jsonw_end_array(json_wtr);
 		} else {
-			disasm_print_insn(buf, member_len, opcodes, name,
-					  disasm_opt, btf, NULL, 0, 0, false);
+			if (disasm_print_insn(buf, member_len, opcodes, name,
+					      disasm_opt, btf, NULL, 0, 0,
+					      false))
+				goto exit_free;
 		}
 	} else if (visual) {
 		if (json_output)
-- 
2.34.1

[PATCH bpf-next v4 3/8] bpftool: Split FEATURE_TESTS/FEATURE_DISPLAY definitions in Makefile

[Quentin Monnet]

Make FEATURE_TESTS and FEATURE_DISPLAY easier to read and less likely to
be subject to conflicts on updates by having one feature per line.

Suggested-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
---
 tools/bpf/bpftool/Makefile | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 4a95c017ad4c..0218d6a1cae7 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -93,11 +93,20 @@ INSTALL ?= install
 RM ?= rm -f
 
 FEATURE_USER = .bpftool
-FEATURE_TESTS = libbfd libbfd-liberty libbfd-liberty-z \
-	disassembler-four-args disassembler-init-styled libcap \
-	clang-bpf-co-re
-FEATURE_DISPLAY = libbfd libbfd-liberty libbfd-liberty-z \
-	libcap clang-bpf-co-re
+
+FEATURE_TESTS := clang-bpf-co-re
+FEATURE_TESTS += libcap
+FEATURE_TESTS += libbfd
+FEATURE_TESTS += libbfd-liberty
+FEATURE_TESTS += libbfd-liberty-z
+FEATURE_TESTS += disassembler-four-args
+FEATURE_TESTS += disassembler-init-styled
+
+FEATURE_DISPLAY := clang-bpf-co-re
+FEATURE_DISPLAY += libcap
+FEATURE_DISPLAY += libbfd
+FEATURE_DISPLAY += libbfd-liberty
+FEATURE_DISPLAY += libbfd-liberty-z
 
 check_feat := 1
 NON_CHECK_FEAT_TARGETS := clean uninstall doc doc-clean doc-install doc-uninstall
-- 
2.34.1

[PATCH bpf-next v4 4/8] bpftool: Group libbfd defs in Makefile, only pass them if we use libbfd

[Quentin Monnet]

Bpftool uses libbfd for disassembling JIT-ed programs. But the feature
is optional, and the tool can be compiled without libbfd support. The
Makefile sets the relevant variables accordingly. It also sets variables
related to libbfd's interface, given that it has changed over time.

Group all those libbfd-related definitions so that it's easier to
understand what we are testing for, and only use variables related to
libbfd's interface if we need libbfd in the first place.

In addition to make the Makefile clearer, grouping the definitions
related to disassembling JIT-ed programs will help support alternatives
to libbfd.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
---
 tools/bpf/bpftool/Makefile | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 0218d6a1cae7..1c81f4d514bb 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -124,13 +124,6 @@ include $(FEATURES_DUMP)
 endif
 endif
 
-ifeq ($(feature-disassembler-four-args), 1)
-CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
-endif
-ifeq ($(feature-disassembler-init-styled), 1)
-    CFLAGS += -DDISASM_INIT_STYLED
-endif
-
 LIBS = $(LIBBPF) -lelf -lz
 LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz
 ifeq ($(feature-libcap), 1)
@@ -142,9 +135,7 @@ include $(wildcard $(OUTPUT)*.d)
 
 all: $(OUTPUT)bpftool
 
-BFD_SRCS = jit_disasm.c
-
-SRCS = $(filter-out $(BFD_SRCS),$(wildcard *.c))
+SRCS := $(wildcard *.c)
 
 ifeq ($(feature-libbfd),1)
   LIBS += -lbfd -ldl -lopcodes
@@ -154,9 +145,21 @@ else ifeq ($(feature-libbfd-liberty-z),1)
   LIBS += -lbfd -ldl -lopcodes -liberty -lz
 endif
 
+# If one of the above feature combinations is set, we support libbfd
 ifneq ($(filter -lbfd,$(LIBS)),)
-CFLAGS += -DHAVE_LIBBFD_SUPPORT
-SRCS += $(BFD_SRCS)
+  CFLAGS += -DHAVE_LIBBFD_SUPPORT
+
+  # Libbfd interface changed over time, figure out what we need
+  ifeq ($(feature-disassembler-four-args), 1)
+    CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
+  endif
+  ifeq ($(feature-disassembler-init-styled), 1)
+    CFLAGS += -DDISASM_INIT_STYLED
+  endif
+endif
+ifeq ($(filter -DHAVE_LIBBFD_SUPPORT,$(CFLAGS)),)
+  # No support for JIT disassembly
+  SRCS := $(filter-out jit_disasm.c,$(SRCS))
 endif
 
 HOST_CFLAGS = $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\
-- 
2.34.1

[PATCH bpf-next v4 5/8] bpftool: Refactor disassembler for JIT-ed programs

[Quentin Monnet]

Refactor disasm_print_insn() to extract the code specific to libbfd and
move it to dedicated functions. There is no functional change. This is
in preparation for supporting an alternative library for disassembling
the instructions.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
---
 tools/bpf/bpftool/jit_disasm.c | 133 ++++++++++++++++++++++-----------
 1 file changed, 88 insertions(+), 45 deletions(-)

diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index 723a9b799a0c..e31ad3950fd6 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -30,6 +30,14 @@
 #include "json_writer.h"
 #include "main.h"
 
+static int oper_count;
+
+typedef struct {
+	struct disassemble_info *info;
+	disassembler_ftype disassemble;
+	bfd *bfdf;
+} disasm_ctx_t;
+
 static int get_exec_path(char *tpath, size_t size)
 {
 	const char *path = "/proc/self/exe";
@@ -44,7 +52,6 @@ static int get_exec_path(char *tpath, size_t size)
 	return 0;
 }
 
-static int oper_count;
 static int printf_json(void *out, const char *fmt, va_list ap)
 {
 	char *s;
@@ -102,46 +109,44 @@ static int fprintf_json_styled(void *out,
 	return r;
 }
 
-int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		      const char *arch, const char *disassembler_options,
-		      const struct btf *btf,
-		      const struct bpf_prog_linfo *prog_linfo,
-		      __u64 func_ksym, unsigned int func_idx,
-		      bool linum)
+static int init_context(disasm_ctx_t *ctx, const char *arch,
+			const char *disassembler_options,
+			unsigned char *image, ssize_t len)
 {
-	const struct bpf_line_info *linfo = NULL;
-	disassembler_ftype disassemble;
-	int count, i, pc = 0, err = -1;
-	struct disassemble_info info;
-	unsigned int nr_skip = 0;
+	struct disassemble_info *info;
 	char tpath[PATH_MAX];
 	bfd *bfdf;
 
-	if (!len)
-		return -1;
-
 	memset(tpath, 0, sizeof(tpath));
 	if (get_exec_path(tpath, sizeof(tpath))) {
 		p_err("failed to create disasembler (get_exec_path)");
 		return -1;
 	}
 
-	bfdf = bfd_openr(tpath, NULL);
-	if (!bfdf) {
+	ctx->bfdf = bfd_openr(tpath, NULL);
+	if (!ctx->bfdf) {
 		p_err("failed to create disassembler (bfd_openr)");
 		return -1;
 	}
-	if (!bfd_check_format(bfdf, bfd_object)) {
+	if (!bfd_check_format(ctx->bfdf, bfd_object)) {
 		p_err("failed to create disassembler (bfd_check_format)");
-		goto exit_close;
+		goto err_close;
 	}
+	bfdf = ctx->bfdf;
+
+	ctx->info = malloc(sizeof(struct disassemble_info));
+	if (!ctx->info) {
+		p_err("mem alloc failed");
+		goto err_close;
+	}
+	info = ctx->info;
 
 	if (json_output)
-		init_disassemble_info_compat(&info, stdout,
+		init_disassemble_info_compat(info, stdout,
 					     (fprintf_ftype) fprintf_json,
 					     fprintf_json_styled);
 	else
-		init_disassemble_info_compat(&info, stdout,
+		init_disassemble_info_compat(info, stdout,
 					     (fprintf_ftype) fprintf,
 					     fprintf_styled);
 
@@ -153,31 +158,76 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 			bfdf->arch_info = inf;
 		} else {
 			p_err("No libbfd support for %s", arch);
-			goto exit_close;
+			goto err_free;
 		}
 	}
 
-	info.arch = bfd_get_arch(bfdf);
-	info.mach = bfd_get_mach(bfdf);
+	info->arch = bfd_get_arch(bfdf);
+	info->mach = bfd_get_mach(bfdf);
 	if (disassembler_options)
-		info.disassembler_options = disassembler_options;
-	info.buffer = image;
-	info.buffer_length = len;
+		info->disassembler_options = disassembler_options;
+	info->buffer = image;
+	info->buffer_length = len;
 
-	disassemble_init_for_target(&info);
+	disassemble_init_for_target(info);
 
 #ifdef DISASM_FOUR_ARGS_SIGNATURE
-	disassemble = disassembler(info.arch,
-				   bfd_big_endian(bfdf),
-				   info.mach,
-				   bfdf);
+	ctx->disassemble = disassembler(info->arch,
+					bfd_big_endian(bfdf),
+					info->mach,
+					bfdf);
 #else
-	disassemble = disassembler(bfdf);
+	ctx->disassemble = disassembler(bfdf);
 #endif
-	if (!disassemble) {
+	if (!ctx->disassemble) {
 		p_err("failed to create disassembler");
-		goto exit_close;
+		goto err_free;
 	}
+	return 0;
+
+err_free:
+	free(info);
+err_close:
+	bfd_close(ctx->bfdf);
+	return -1;
+}
+
+static void destroy_context(disasm_ctx_t *ctx)
+{
+	free(ctx->info);
+	bfd_close(ctx->bfdf);
+}
+
+static int
+disassemble_insn(disasm_ctx_t *ctx, __maybe_unused unsigned char *image,
+		 __maybe_unused ssize_t len, int pc)
+{
+	return ctx->disassemble(pc, ctx->info);
+}
+
+int disasm_init(void)
+{
+	bfd_init();
+	return 0;
+}
+
+int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
+		      const char *arch, const char *disassembler_options,
+		      const struct btf *btf,
+		      const struct bpf_prog_linfo *prog_linfo,
+		      __u64 func_ksym, unsigned int func_idx,
+		      bool linum)
+{
+	const struct bpf_line_info *linfo = NULL;
+	unsigned int nr_skip = 0;
+	int count, i, pc = 0;
+	disasm_ctx_t ctx;
+
+	if (!len)
+		return -1;
+
+	if (init_context(&ctx, arch, disassembler_options, image, len))
+		return -1;
 
 	if (json_output)
 		jsonw_start_array(json_wtr);
@@ -205,7 +255,8 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 			printf("%4x:\t", pc);
 		}
 
-		count = disassemble(pc, &info);
+		count = disassemble_insn(&ctx, image, len, pc);
+
 		if (json_output) {
 			/* Operand array, was started in fprintf_json. Before
 			 * that, make sure we have a _null_ value if no operand
@@ -241,15 +292,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 	if (json_output)
 		jsonw_end_array(json_wtr);
 
-	err = 0;
+	destroy_context(&ctx);
 
-exit_close:
-	bfd_close(bfdf);
-	return err;
-}
-
-int disasm_init(void)
-{
-	bfd_init();
 	return 0;
 }
-- 
2.34.1

[PATCH bpf-next v4 6/8] bpftool: Add LLVM as default library for disassembling JIT-ed programs

[Quentin Monnet]

To disassemble instructions for JIT-ed programs, bpftool has relied on
the libbfd library. This has been problematic in the past: libbfd's
interface is not meant to be stable and has changed several times. For
building bpftool, we have to detect how the libbfd version on the system
behaves, which is why we have to handle features disassembler-four-args
and disassembler-init-styled in the Makefile. When it comes to shipping
bpftool, this has also caused issues with several distribution
maintainers unwilling to support the feature (see for example Debian's
page for binutils-dev, which ships libbfd: "Note that building Debian
packages which depend on the shared libbfd is Not Allowed." [0]).

For these reasons, we add support for LLVM as an alternative to libbfd
for disassembling instructions of JIT-ed programs. Thanks to the
preparation work in the previous commits, it's easy to add the library
by passing the relevant compilation options in the Makefile, and by
adding the functions for setting up the LLVM disassembler in file
jit_disasm.c.

The LLVM disassembler requires the LLVM development package (usually
llvm-dev or llvm-devel).

The expectation is that the interface for this disassembler will be more
stable. There is a note in LLVM's Developer Policy [1] stating that the
stability for the C API is "best effort" and not guaranteed, but at
least there is some effort to keep compatibility when possible (which
hasn't really been the case for libbfd so far). Furthermore, the Debian
page for the related LLVM package does not caution against linking to
the lib, as binutils-dev page does.

Naturally, the display of disassembled instructions comes with a few
minor differences. Here is a sample output with libbfd (already
supported before this patch):

    # bpftool prog dump jited id 56
    bpf_prog_6deef7357e7b4530:
       0:   nopl   0x0(%rax,%rax,1)
       5:   xchg   %ax,%ax
       7:   push   %rbp
       8:   mov    %rsp,%rbp
       b:   push   %rbx
       c:   push   %r13
       e:   push   %r14
      10:   mov    %rdi,%rbx
      13:   movzwq 0xb4(%rbx),%r13
      1b:   xor    %r14d,%r14d
      1e:   or     $0x2,%r14d
      22:   mov    $0x1,%eax
      27:   cmp    $0x2,%r14
      2b:   jne    0x000000000000002f
      2d:   xor    %eax,%eax
      2f:   pop    %r14
      31:   pop    %r13
      33:   pop    %rbx
      34:   leave
      35:   ret

LLVM supports several variants that we could set when initialising the
disassembler, for example with:

    LLVMSetDisasmOptions(*ctx,
                         LLVMDisassembler_Option_AsmPrinterVariant);

but the default printer is used for now. Here is the output with LLVM:

    # bpftool prog dump jited id 56
    bpf_prog_6deef7357e7b4530:
       0:   nopl    (%rax,%rax)
       5:   nop
       7:   pushq   %rbp
       8:   movq    %rsp, %rbp
       b:   pushq   %rbx
       c:   pushq   %r13
       e:   pushq   %r14
      10:   movq    %rdi, %rbx
      13:   movzwq  180(%rbx), %r13
      1b:   xorl    %r14d, %r14d
      1e:   orl     $2, %r14d
      22:   movl    $1, %eax
      27:   cmpq    $2, %r14
      2b:   jne     0x2f
      2d:   xorl    %eax, %eax
      2f:   popq    %r14
      31:   popq    %r13
      33:   popq    %rbx
      34:   leave
      35:   retq

The LLVM disassembler comes as the default choice, with libbfd as a
fall-back.

Of course, we could replace libbfd entirely and avoid supporting two
different libraries. One reason for keeping libbfd is that, right now,
it works well, we have all we need in terms of features detection in the
Makefile, so it provides a fallback for disassembling JIT-ed programs if
libbfd is installed but LLVM is not. The other motivation is that libbfd
supports nfp instruction for Netronome's SmartNICs and can be used to
disassemble offloaded programs, something that LLVM cannot do. If
libbfd's interface breaks again in the future, we might reconsider
keeping support for it.

[0] https://packages.debian.org/buster/binutils-dev
[1] https://llvm.org/docs/DeveloperPolicy.html#c-api-changes

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
 tools/bpf/bpftool/Makefile     |  46 +++++++++-----
 tools/bpf/bpftool/jit_disasm.c | 112 ++++++++++++++++++++++++++++++++-
 tools/bpf/bpftool/main.h       |   4 +-
 3 files changed, 140 insertions(+), 22 deletions(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 1c81f4d514bb..787b857d3fb5 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -95,6 +95,7 @@ RM ?= rm -f
 FEATURE_USER = .bpftool
 
 FEATURE_TESTS := clang-bpf-co-re
+FEATURE_TESTS += llvm
 FEATURE_TESTS += libcap
 FEATURE_TESTS += libbfd
 FEATURE_TESTS += libbfd-liberty
@@ -103,6 +104,7 @@ FEATURE_TESTS += disassembler-four-args
 FEATURE_TESTS += disassembler-init-styled
 
 FEATURE_DISPLAY := clang-bpf-co-re
+FEATURE_DISPLAY += llvm
 FEATURE_DISPLAY += libcap
 FEATURE_DISPLAY += libbfd
 FEATURE_DISPLAY += libbfd-liberty
@@ -137,27 +139,37 @@ all: $(OUTPUT)bpftool
 
 SRCS := $(wildcard *.c)
 
-ifeq ($(feature-libbfd),1)
-  LIBS += -lbfd -ldl -lopcodes
-else ifeq ($(feature-libbfd-liberty),1)
-  LIBS += -lbfd -ldl -lopcodes -liberty
-else ifeq ($(feature-libbfd-liberty-z),1)
-  LIBS += -lbfd -ldl -lopcodes -liberty -lz
-endif
+ifeq ($(feature-llvm),1)
+  # If LLVM is available, use it for JIT disassembly
+  CFLAGS  += -DHAVE_LLVM_SUPPORT
+  LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
+  CFLAGS  += $(shell $(LLVM_CONFIG) --cflags --libs $(LLVM_CONFIG_LIB_COMPONENTS))
+  LIBS    += $(shell $(LLVM_CONFIG) --libs $(LLVM_CONFIG_LIB_COMPONENTS))
+  LDFLAGS += $(shell $(LLVM_CONFIG) --ldflags)
+else
+  # Fall back on libbfd
+  ifeq ($(feature-libbfd),1)
+    LIBS += -lbfd -ldl -lopcodes
+  else ifeq ($(feature-libbfd-liberty),1)
+    LIBS += -lbfd -ldl -lopcodes -liberty
+  else ifeq ($(feature-libbfd-liberty-z),1)
+    LIBS += -lbfd -ldl -lopcodes -liberty -lz
+  endif
 
-# If one of the above feature combinations is set, we support libbfd
-ifneq ($(filter -lbfd,$(LIBS)),)
-  CFLAGS += -DHAVE_LIBBFD_SUPPORT
+  # If one of the above feature combinations is set, we support libbfd
+  ifneq ($(filter -lbfd,$(LIBS)),)
+    CFLAGS += -DHAVE_LIBBFD_SUPPORT
 
-  # Libbfd interface changed over time, figure out what we need
-  ifeq ($(feature-disassembler-four-args), 1)
-    CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
-  endif
-  ifeq ($(feature-disassembler-init-styled), 1)
-    CFLAGS += -DDISASM_INIT_STYLED
+    # Libbfd interface changed over time, figure out what we need
+    ifeq ($(feature-disassembler-four-args), 1)
+      CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
+    endif
+    ifeq ($(feature-disassembler-init-styled), 1)
+      CFLAGS += -DDISASM_INIT_STYLED
+    endif
   endif
 endif
-ifeq ($(filter -DHAVE_LIBBFD_SUPPORT,$(CFLAGS)),)
+ifeq ($(filter -DHAVE_LLVM_SUPPORT -DHAVE_LIBBFD_SUPPORT,$(CFLAGS)),)
   # No support for JIT disassembly
   SRCS := $(filter-out jit_disasm.c,$(SRCS))
 endif
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index e31ad3950fd6..c28b21f90cb9 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -20,18 +20,123 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
-#include <bfd.h>
-#include <dis-asm.h>
 #include <sys/stat.h>
 #include <limits.h>
 #include <bpf/libbpf.h>
+
+#ifdef HAVE_LLVM_SUPPORT
+#include <llvm-c/Core.h>
+#include <llvm-c/Disassembler.h>
+#include <llvm-c/Target.h>
+#include <llvm-c/TargetMachine.h>
+#endif
+
+#ifdef HAVE_LIBBFD_SUPPORT
+#include <bfd.h>
+#include <dis-asm.h>
 #include <tools/dis-asm-compat.h>
+#endif
 
 #include "json_writer.h"
 #include "main.h"
 
 static int oper_count;
 
+#ifdef HAVE_LLVM_SUPPORT
+#define DISASM_SPACER
+
+typedef LLVMDisasmContextRef disasm_ctx_t;
+
+static int printf_json(char *s)
+{
+	s = strtok(s, " \t");
+	jsonw_string_field(json_wtr, "operation", s);
+
+	jsonw_name(json_wtr, "operands");
+	jsonw_start_array(json_wtr);
+	oper_count = 1;
+
+	while ((s = strtok(NULL, " \t,()")) != 0) {
+		jsonw_string(json_wtr, s);
+		oper_count++;
+	}
+	return 0;
+}
+
+/* This callback to set the ref_type is necessary to have the LLVM disassembler
+ * print PC-relative addresses instead of byte offsets for branch instruction
+ * targets.
+ */
+static const char *
+symbol_lookup_callback(__maybe_unused void *disasm_info,
+		       __maybe_unused uint64_t ref_value,
+		       uint64_t *ref_type, __maybe_unused uint64_t ref_PC,
+		       __maybe_unused const char **ref_name)
+{
+	*ref_type = LLVMDisassembler_ReferenceType_InOut_None;
+	return NULL;
+}
+
+static int
+init_context(disasm_ctx_t *ctx, const char *arch,
+	     __maybe_unused const char *disassembler_options,
+	     __maybe_unused unsigned char *image, __maybe_unused ssize_t len)
+{
+	char *triple;
+
+	if (arch) {
+		p_err("Architecture %s not supported", arch);
+		return -1;
+	}
+
+	triple = LLVMGetDefaultTargetTriple();
+	if (!triple) {
+		p_err("Failed to retrieve triple");
+		return -1;
+	}
+	*ctx = LLVMCreateDisasm(triple, NULL, 0, NULL, symbol_lookup_callback);
+	LLVMDisposeMessage(triple);
+
+	if (!*ctx) {
+		p_err("Failed to create disassembler");
+		return -1;
+	}
+
+	return 0;
+}
+
+static void destroy_context(disasm_ctx_t *ctx)
+{
+	LLVMDisposeMessage(*ctx);
+}
+
+static int
+disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc)
+{
+	char buf[256];
+	int count;
+
+	count = LLVMDisasmInstruction(*ctx, image + pc, len - pc, pc,
+				      buf, sizeof(buf));
+	if (json_output)
+		printf_json(buf);
+	else
+		printf("%s", buf);
+
+	return count;
+}
+
+int disasm_init(void)
+{
+	LLVMInitializeNativeTarget();
+	LLVMInitializeNativeDisassembler();
+	return 0;
+}
+#endif /* HAVE_LLVM_SUPPORT */
+
+#ifdef HAVE_LIBBFD_SUPPORT
+#define DISASM_SPACER "\t"
+
 typedef struct {
 	struct disassemble_info *info;
 	disassembler_ftype disassemble;
@@ -210,6 +315,7 @@ int disasm_init(void)
 	bfd_init();
 	return 0;
 }
+#endif /* HAVE_LIBBPFD_SUPPORT */
 
 int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 		      const char *arch, const char *disassembler_options,
@@ -252,7 +358,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 			if (linfo)
 				btf_dump_linfo_plain(btf, linfo, "; ",
 						     linum);
-			printf("%4x:\t", pc);
+			printf("%4x:" DISASM_SPACER, pc);
 		}
 
 		count = disassemble_insn(&ctx, image, len, pc);
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index c9e171082cf6..9a149c67aa5d 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -172,7 +172,7 @@ int map_parse_fds(int *argc, char ***argv, int **fds);
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
 
 struct bpf_prog_linfo;
-#ifdef HAVE_LIBBFD_SUPPORT
+#if defined(HAVE_LLVM_SUPPORT) || defined(HAVE_LIBBFD_SUPPORT)
 int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 		      const char *arch, const char *disassembler_options,
 		      const struct btf *btf,
@@ -193,7 +193,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 }
 static inline int disasm_init(void)
 {
-	p_err("No libbfd support");
+	p_err("No JIT disassembly support");
 	return -1;
 }
 #endif
-- 
2.34.1

[PATCH bpf-next v4 7/8] bpftool: Support setting alternative arch for JIT disasm with LLVM

[Quentin Monnet]

For offloaded BPF programs, instead of failing to create the
LLVM disassembler without even looking for a triple at all, do run the
function that attempts to retrieve a valid architecture name for the
device.

It will still fail for the LLVM disassembler, because currently we have
no valid triple to return (NFP disassembly is not supported by LLVM).
But failing in that function is more logical than to assume in
jit_disasm.c that passing an "arch" name is simply not supported.

Suggested-by: Song Liu <song@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/common.c     | 10 ++++++----
 tools/bpf/bpftool/jit_disasm.c | 15 +++++++--------
 tools/bpf/bpftool/main.h       |  3 +--
 tools/bpf/bpftool/prog.c       |  6 ++----
 4 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 4c2e909a2d67..e4d33bc8bbbf 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -627,12 +627,11 @@ static int read_sysfs_netdev_hex_int(char *devname, const char *entry_name)
 }
 
 const char *
-ifindex_to_bfd_params(__u32 ifindex, __u64 ns_dev, __u64 ns_ino,
-		      const char **opt)
+ifindex_to_arch(__u32 ifindex, __u64 ns_dev, __u64 ns_ino, const char **opt)
 {
+	__maybe_unused int device_id;
 	char devname[IF_NAMESIZE];
 	int vendor_id;
-	int device_id;
 
 	if (!ifindex_to_name_ns(ifindex, ns_dev, ns_ino, devname)) {
 		p_err("Can't get net device name for ifindex %d: %s", ifindex,
@@ -647,6 +646,7 @@ ifindex_to_bfd_params(__u32 ifindex, __u64 ns_dev, __u64 ns_ino,
 	}
 
 	switch (vendor_id) {
+#ifdef HAVE_LIBBFD_SUPPORT
 	case 0x19ee:
 		device_id = read_sysfs_netdev_hex_int(devname, "device");
 		if (device_id != 0x4000 &&
@@ -655,8 +655,10 @@ ifindex_to_bfd_params(__u32 ifindex, __u64 ns_dev, __u64 ns_ino,
 			p_info("Unknown NFP device ID, assuming it is NFP-6xxx arch");
 		*opt = "ctx4";
 		return "NFP-6xxx";
+#endif /* HAVE_LIBBFD_SUPPORT */
+	/* No NFP support in LLVM, we have no valid triple to return. */
 	default:
-		p_err("Can't get bfd arch name for device vendor id 0x%04x",
+		p_err("Can't get arch name for device vendor id 0x%04x",
 		      vendor_id);
 		return NULL;
 	}
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index c28b21f90cb9..58a5017034a2 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -84,12 +84,10 @@ init_context(disasm_ctx_t *ctx, const char *arch,
 {
 	char *triple;
 
-	if (arch) {
-		p_err("Architecture %s not supported", arch);
-		return -1;
-	}
-
-	triple = LLVMGetDefaultTargetTriple();
+	if (arch)
+		triple = LLVMNormalizeTargetTriple(arch);
+	else
+		triple = LLVMGetDefaultTargetTriple();
 	if (!triple) {
 		p_err("Failed to retrieve triple");
 		return -1;
@@ -128,8 +126,9 @@ disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc)
 
 int disasm_init(void)
 {
-	LLVMInitializeNativeTarget();
-	LLVMInitializeNativeDisassembler();
+	LLVMInitializeAllTargetInfos();
+	LLVMInitializeAllTargetMCs();
+	LLVMInitializeAllDisassemblers();
 	return 0;
 }
 #endif /* HAVE_LLVM_SUPPORT */
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 9a149c67aa5d..467d8472df0c 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -203,8 +203,7 @@ void print_hex_data_json(uint8_t *data, size_t len);
 unsigned int get_page_size(void);
 unsigned int get_possible_cpus(void);
 const char *
-ifindex_to_bfd_params(__u32 ifindex, __u64 ns_dev, __u64 ns_ino,
-		      const char **opt);
+ifindex_to_arch(__u32 ifindex, __u64 ns_dev, __u64 ns_ino, const char **opt);
 
 struct btf_dumper {
 	const struct btf *btf;
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 93dfb89b85e3..a858b907da16 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -764,10 +764,8 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		const char *name = NULL;
 
 		if (info->ifindex) {
-			name = ifindex_to_bfd_params(info->ifindex,
-						     info->netns_dev,
-						     info->netns_ino,
-						     &disasm_opt);
+			name = ifindex_to_arch(info->ifindex, info->netns_dev,
+					       info->netns_ino, &disasm_opt);
 			if (!name)
 				goto exit_free;
 		}
-- 
2.34.1

[PATCH bpf-next v4 8/8] bpftool: Add llvm feature to "bpftool version"

[Quentin Monnet]

Similarly to "libbfd", add a "llvm" feature to the output of command
"bpftool version" to indicate that LLVM is used for disassembling JIT-ed
programs. This feature is mutually exclusive (from Makefile definitions)
with "libbfd".

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
 tools/bpf/bpftool/Documentation/common_options.rst | 8 ++++----
 tools/bpf/bpftool/main.c                           | 7 +++++++
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/common_options.rst b/tools/bpf/bpftool/Documentation/common_options.rst
index 4107a586b68b..05350a1aadf9 100644
--- a/tools/bpf/bpftool/Documentation/common_options.rst
+++ b/tools/bpf/bpftool/Documentation/common_options.rst
@@ -7,10 +7,10 @@
 	  Print bpftool's version number (similar to **bpftool version**), the
 	  number of the libbpf version in use, and optional features that were
 	  included when bpftool was compiled. Optional features include linking
-	  against libbfd to provide the disassembler for JIT-ted programs
-	  (**bpftool prog dump jited**) and usage of BPF skeletons (some
-	  features like **bpftool prog profile** or showing pids associated to
-	  BPF objects may rely on it).
+	  against LLVM or libbfd to provide the disassembler for JIT-ted
+	  programs (**bpftool prog dump jited**) and usage of BPF skeletons
+	  (some features like **bpftool prog profile** or showing pids
+	  associated to BPF objects may rely on it).
 
 -j, --json
 	  Generate JSON output. For commands that cannot produce JSON, this
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index b22223df4431..741e50ee0b6c 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -119,6 +119,11 @@ static int do_version(int argc, char **argv)
 #else
 	const bool has_libbfd = false;
 #endif
+#ifdef HAVE_LLVM_SUPPORT
+	const bool has_llvm = true;
+#else
+	const bool has_llvm = false;
+#endif
 #ifdef BPFTOOL_WITHOUT_SKELETONS
 	const bool has_skeletons = false;
 #else
@@ -154,6 +159,7 @@ static int do_version(int argc, char **argv)
 		jsonw_name(json_wtr, "features");
 		jsonw_start_object(json_wtr);	/* features */
 		jsonw_bool_field(json_wtr, "libbfd", has_libbfd);
+		jsonw_bool_field(json_wtr, "llvm", has_llvm);
 		jsonw_bool_field(json_wtr, "libbpf_strict", !legacy_libbpf);
 		jsonw_bool_field(json_wtr, "skeletons", has_skeletons);
 		jsonw_bool_field(json_wtr, "bootstrap", bootstrap);
@@ -172,6 +178,7 @@ static int do_version(int argc, char **argv)
 		printf("using libbpf %s\n", libbpf_version_string());
 		printf("features:");
 		print_feature("libbfd", has_libbfd, &nb_features);
+		print_feature("llvm", has_llvm, &nb_features);
 		print_feature("libbpf_strict", !legacy_libbpf, &nb_features);
 		print_feature("skeletons", has_skeletons, &nb_features);
 		print_feature("bootstrap", bootstrap, &nb_features);
-- 
2.34.1

Re: [PATCH bpf-next v4 0/8] bpftool: Add LLVM as default library for disassembling JIT-ed programs

[patchwork-bot+netdevbpf]

Hello:

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

On Tue, 25 Oct 2022 16:03:21 +0100 you wrote:
> To disassemble instructions for JIT-ed programs, bpftool has relied on the
> libbfd library. This has been problematic in the past: libbfd's interface
> is not meant to be stable and has changed several times, hence the
> detection of the two related features from the Makefile
> (disassembler-four-args and disassembler-init-styled). When it comes to
> shipping bpftool, this has also caused issues with several distribution
> maintainers unwilling to support the feature (for example, Debian's page
> for binutils-dev, libbfd's package, says: "Note that building Debian
> packages which depend on the shared libbfd is Not Allowed.").
> 
> [...]

Here is the summary with links:
  - [bpf-next,v4,1/8] bpftool: Define _GNU_SOURCE only once
    https://git.kernel.org/bpf/bpf-next/c/b3d84af7cdfc
  - [bpf-next,v4,2/8] bpftool: Remove asserts from JIT disassembler
    https://git.kernel.org/bpf/bpf-next/c/55b4de58d0e2
  - [bpf-next,v4,3/8] bpftool: Split FEATURE_TESTS/FEATURE_DISPLAY definitions in Makefile
    https://git.kernel.org/bpf/bpf-next/c/108326d6fa6c
  - [bpf-next,v4,4/8] bpftool: Group libbfd defs in Makefile, only pass them if we use libbfd
    https://git.kernel.org/bpf/bpf-next/c/2ea4d86a5093
  - [bpf-next,v4,5/8] bpftool: Refactor disassembler for JIT-ed programs
    https://git.kernel.org/bpf/bpf-next/c/e1947c750ffe
  - [bpf-next,v4,6/8] bpftool: Add LLVM as default library for disassembling JIT-ed programs
    https://git.kernel.org/bpf/bpf-next/c/eb9d1acf634b
  - [bpf-next,v4,7/8] bpftool: Support setting alternative arch for JIT disasm with LLVM
    https://git.kernel.org/bpf/bpf-next/c/ce4f66086235
  - [bpf-next,v4,8/8] bpftool: Add llvm feature to "bpftool version"
    https://git.kernel.org/bpf/bpf-next/c/08b8191ba7f9

You are awesome, thank you!
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