diff mbox series

[SRU,BIONIC,v3,2/4] bpftool: make libbfd optional

Message ID 20191120114823.27955-3-quentin.monnet@netronome.com
State New
Headers show
Series add bpftool to linux-tools-common | expand

Commit Message

Quentin Monnet Nov. 20, 2019, 11:48 a.m. UTC 
From: Stanislav Fomichev <sdf@google.com>

BugLink: https://bugs.launchpad.net/bugs/1774815

Make it possible to build bpftool without libbfd. libbfd and libopcodes are
typically provided in dev/dbg packages (binutils-dev in debian) which we
usually don't have installed on the fleet machines and we'd like a way to have
bpftool version that works without installing any additional packages.
This excludes support for disassembling jit-ted code and prints an error if
the user tries to use these features.

Tested by:
cat > FEATURES_DUMP.bpftool <<EOF
feature-libbfd=0
feature-disassembler-four-args=1
feature-reallocarray=0
feature-libelf=1
feature-libelf-mmap=1
feature-bpf=1
EOF
FEATURES_DUMP=$PWD/FEATURES_DUMP.bpftool make
ldd bpftool | grep libbfd

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
(backported from commit 29a9c10e4110e368443f0b606d71557edee7f2cc)
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
---
 tools/bpf/bpftool/Makefile     | 13 +++++++++++--
 tools/bpf/bpftool/jit_disasm.c |  6 ++++++
 tools/bpf/bpftool/main.c       |  3 ---
 tools/bpf/bpftool/main.h       | 13 +++++++++++++
 tools/bpf/bpftool/prog.c       |  3 +++
 5 files changed, 33 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 9e433c3f8bbe..b0a1cbde0819 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -53,7 +53,7 @@  CC = gcc
 CFLAGS += -O2
 CFLAGS += -W -Wall -Wextra -Wno-unused-parameter -Wshadow
 CFLAGS += -D__EXPORTED_HEADERS__ -I$(srctree)/tools/include/uapi -I$(srctree)/tools/include -I$(srctree)/tools/lib/bpf -I$(srctree)/kernel/bpf/
-LIBS = -lelf -lbfd -lopcodes $(LIBBPF)
+LIBS = -lelf $(LIBBPF)
 
 FEATURE_USER = .bpftool
 FEATURE_TESTS = libbfd disassembler-four-args
@@ -83,7 +83,16 @@  include $(wildcard *.d)
 
 all: $(OUTPUT)bpftool
 
-SRCS=$(wildcard *.c)
+BFD_SRCS = jit_disasm.c
+
+SRCS = $(filter-out $(BFD_SRCS),$(wildcard *.c))
+
+ifeq ($(feature-libbfd),1)
+CFLAGS += -DHAVE_LIBBFD_SUPPORT
+SRCS += $(BFD_SRCS)
+LIBS += -lbfd -lopcodes
+endif
+
 OBJS=$(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o
 
 $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index 034d91284ae5..ec046e3061d6 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -170,3 +170,9 @@  void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes)
 
 	bfd_close(bfdf);
 }
+
+int disasm_init(void)
+{
+	bfd_init();
+	return 0;
+}
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index d294bc8168be..b11429bb65cb 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -33,7 +33,6 @@ 
 
 /* Author: Jakub Kicinski <kubakici@wp.pl> */
 
-#include <bfd.h>
 #include <ctype.h>
 #include <errno.h>
 #include <getopt.h>
@@ -327,8 +326,6 @@  int main(int argc, char **argv)
 	if (argc < 0)
 		usage();
 
-	bfd_init();
-
 	ret = cmd_select(cmds, argc, argv, do_help);
 
 	if (json_output)
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index bff330b49791..af86de84ff30 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -117,7 +117,20 @@  int do_map(int argc, char **arg);
 
 int prog_parse_fd(int *argc, char ***argv);
 
+#ifdef HAVE_LIBBFD_SUPPORT
 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes);
+int disasm_init(void);
+#else
+static inline
+void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes)
+{
+}
+static inline int disasm_init(void)
+{
+	p_err("No libbfd support");
+	return -1;
+}
+#endif
 void print_hex_data_json(uint8_t *data, size_t len);
 
 #endif
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 26df1a936ebf..caede2cd784a 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -521,6 +521,9 @@  static int do_dump(int argc, char **argv)
 	int fd;
 
 	if (is_prefix(*argv, "jited")) {
+		if (disasm_init())
+			return -1;
+
 		member_len = &info.jited_prog_len;
 		member_ptr = &info.jited_prog_insns;
 	} else if (is_prefix(*argv, "xlated")) {