Andrii Nakryiko 166750bc1d libbpf: Support libbpf-provided extern variables
Add support for extern variables, provided to BPF program by libbpf. Currently
the following extern variables are supported:
  - LINUX_KERNEL_VERSION; version of a kernel in which BPF program is
    executing, follows KERNEL_VERSION() macro convention, can be 4- and 8-byte
    long;
  - CONFIG_xxx values; a set of values of actual kernel config. Tristate,
    boolean, strings, and integer values are supported.

Set of possible values is determined by declared type of extern variable.
Supported types of variables are:
- Tristate values. Are represented as `enum libbpf_tristate`. Accepted values
  are **strictly** 'y', 'n', or 'm', which are represented as TRI_YES, TRI_NO,
  or TRI_MODULE, respectively.
- Boolean values. Are represented as bool (_Bool) types. Accepted values are
  'y' and 'n' only, turning into true/false values, respectively.
- Single-character values. Can be used both as a substritute for
  bool/tristate, or as a small-range integer:
  - 'y'/'n'/'m' are represented as is, as characters 'y', 'n', or 'm';
  - integers in a range [-128, 127] or [0, 255] (depending on signedness of
    char in target architecture) are recognized and represented with
    respective values of char type.
- Strings. String values are declared as fixed-length char arrays. String of
  up to that length will be accepted and put in first N bytes of char array,
  with the rest of bytes zeroed out. If config string value is longer than
  space alloted, it will be truncated and warning message emitted. Char array
  is always zero terminated. String literals in config have to be enclosed in
  double quotes, just like C-style string literals.
- Integers. 8-, 16-, 32-, and 64-bit integers are supported, both signed and
  unsigned variants. Libbpf enforces parsed config value to be in the
  supported range of corresponding integer type. Integers values in config can
  be:
  - decimal integers, with optional + and - signs;
  - hexadecimal integers, prefixed with 0x or 0X;
  - octal integers, starting with 0.

Config file itself is searched in /boot/config-$(uname -r) location with
fallback to /proc/config.gz, unless config path is specified explicitly
through bpf_object_open_opts' kernel_config_path option. Both gzipped and
plain text formats are supported. Libbpf adds explicit dependency on zlib
because of this, but this shouldn't be a problem, given libelf already depends
on zlib.

All detected extern variables, are put into a separate .extern internal map.
It, similarly to .rodata map, is marked as read-only from BPF program side, as
well as is frozen on load. This allows BPF verifier to track extern values as
constants and perform enhanced branch prediction and dead code elimination.
This can be relied upon for doing kernel version/feature detection and using
potentially unsupported field relocations or BPF helpers in a CO-RE-based BPF
program, while still having a single version of BPF program running on old and
new kernels. Selftests are validating this explicitly for unexisting BPF
helper.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191214014710.3449601-3-andriin@fb.com
2019-12-15 16:41:12 -08:00

347 lines
12 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
include ../../../../scripts/Kbuild.include
include ../../../scripts/Makefile.arch
CURDIR := $(abspath .)
TOOLSDIR := $(abspath ../../..)
LIBDIR := $(TOOLSDIR)/lib
BPFDIR := $(LIBDIR)/bpf
TOOLSINCDIR := $(TOOLSDIR)/include
BPFTOOLDIR := $(TOOLSDIR)/bpf/bpftool
APIDIR := $(TOOLSINCDIR)/uapi
GENDIR := $(abspath ../../../../include/generated)
GENHDR := $(GENDIR)/autoconf.h
ifneq ($(wildcard $(GENHDR)),)
GENFLAGS := -DHAVE_GENHDR
endif
CLANG ?= clang
LLC ?= llc
LLVM_OBJCOPY ?= llvm-objcopy
BPF_GCC ?= $(shell command -v bpf-gcc;)
CFLAGS += -g -Wall -O2 $(GENFLAGS) -I$(APIDIR) -I$(LIBDIR) -I$(BPFDIR) \
-I$(GENDIR) -I$(TOOLSINCDIR) -I$(CURDIR) \
-Dbpf_prog_load=bpf_prog_test_load \
-Dbpf_load_program=bpf_test_load_program
LDLIBS += -lcap -lelf -lz -lrt -lpthread
# Order correspond to 'make run_tests' order
TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
test_sock test_btf test_sockmap get_cgroup_id_user test_socket_cookie \
test_cgroup_storage \
test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
test_cgroup_attach test_progs-no_alu32
# Also test bpf-gcc, if present
ifneq ($(BPF_GCC),)
TEST_GEN_PROGS += test_progs-bpf_gcc
endif
TEST_GEN_FILES =
TEST_FILES = test_lwt_ip_encap.o \
test_tc_edt.o
# Order correspond to 'make run_tests' order
TEST_PROGS := test_kmod.sh \
test_xdp_redirect.sh \
test_xdp_meta.sh \
test_xdp_veth.sh \
test_offload.py \
test_sock_addr.sh \
test_tunnel.sh \
test_lwt_seg6local.sh \
test_lirc_mode2.sh \
test_skb_cgroup_id.sh \
test_flow_dissector.sh \
test_xdp_vlan_mode_generic.sh \
test_xdp_vlan_mode_native.sh \
test_lwt_ip_encap.sh \
test_tcp_check_syncookie.sh \
test_tc_tunnel.sh \
test_tc_edt.sh \
test_xdping.sh \
test_bpftool_build.sh
TEST_PROGS_EXTENDED := with_addr.sh \
with_tunnels.sh \
tcp_client.py \
tcp_server.py \
test_xdp_vlan.sh
# Compile but not part of 'make run_tests'
TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \
test_lirc_mode2_user xdping test_cpp
TEST_CUSTOM_PROGS = urandom_read
include ../lib.mk
# Define simple and short `make test_progs`, `make test_sysctl`, etc targets
# to build individual tests.
# NOTE: Semicolon at the end is critical to override lib.mk's default static
# rule for binaries.
$(notdir $(TEST_GEN_PROGS) \
$(TEST_PROGS) \
$(TEST_PROGS_EXTENDED) \
$(TEST_GEN_PROGS_EXTENDED) \
$(TEST_CUSTOM_PROGS)): %: $(OUTPUT)/% ;
$(OUTPUT)/urandom_read: urandom_read.c
$(CC) -o $@ $< -Wl,--build-id
$(OUTPUT)/test_stub.o: test_stub.c
$(CC) -c $(CFLAGS) -o $@ $<
BPFOBJ := $(OUTPUT)/libbpf.a
$(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/test_stub.o $(BPFOBJ)
$(OUTPUT)/test_dev_cgroup: cgroup_helpers.c
$(OUTPUT)/test_skb_cgroup_id_user: cgroup_helpers.c
$(OUTPUT)/test_sock: cgroup_helpers.c
$(OUTPUT)/test_sock_addr: cgroup_helpers.c
$(OUTPUT)/test_socket_cookie: cgroup_helpers.c
$(OUTPUT)/test_sockmap: cgroup_helpers.c
$(OUTPUT)/test_tcpbpf_user: cgroup_helpers.c
$(OUTPUT)/test_tcpnotify_user: cgroup_helpers.c trace_helpers.c
$(OUTPUT)/get_cgroup_id_user: cgroup_helpers.c
$(OUTPUT)/test_cgroup_storage: cgroup_helpers.c
$(OUTPUT)/test_netcnt: cgroup_helpers.c
$(OUTPUT)/test_sock_fields: cgroup_helpers.c
$(OUTPUT)/test_sysctl: cgroup_helpers.c
$(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
.PHONY: force
# force a rebuild of BPFOBJ when its dependencies are updated
force:
DEFAULT_BPFTOOL := $(OUTPUT)/tools/usr/local/sbin/bpftool
BPFTOOL ?= $(DEFAULT_BPFTOOL)
$(DEFAULT_BPFTOOL): force
$(MAKE) -C $(BPFTOOLDIR) DESTDIR=$(OUTPUT)/tools install
$(BPFOBJ): force
$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/
BPF_HELPERS := $(BPFDIR)/bpf_helper_defs.h $(wildcard $(BPFDIR)/bpf_*.h)
$(BPFDIR)/bpf_helper_defs.h:
$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/ bpf_helper_defs.h
# Get Clang's default includes on this system, as opposed to those seen by
# '-target bpf'. This fixes "missing" files on some architectures/distros,
# such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
#
# Use '-idirafter': Don't interfere with include mechanics except where the
# build would have failed anyways.
define get_sys_includes
$(shell $(1) -v -E - </dev/null 2>&1 \
| sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }')
endef
# Determine target endianness.
IS_LITTLE_ENDIAN = $(shell $(CC) -dM -E - </dev/null | \
grep 'define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__')
MENDIAN=$(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \
-I. -I./include/uapi -I$(APIDIR) \
-I$(BPFDIR) -I$(abspath $(OUTPUT)/../usr/include)
CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
-Wno-compare-distinct-pointer-types
$(OUTPUT)/test_l4lb_noinline.o: BPF_CFLAGS += -fno-inline
$(OUTPUT)/test_xdp_noinline.o: BPF_CFLAGS += -fno-inline
$(OUTPUT)/flow_dissector_load.o: flow_dissector_load.h
# Build BPF object using Clang
# $1 - input .c file
# $2 - output .o file
# $3 - CFLAGS
# $4 - LDFLAGS
define CLANG_BPF_BUILD_RULE
($(CLANG) $3 -O2 -target bpf -emit-llvm \
-c $1 -o - || echo "BPF obj compilation failed") | \
$(LLC) -mattr=dwarfris -march=bpf -mcpu=probe $4 -filetype=obj -o $2
endef
# Similar to CLANG_BPF_BUILD_RULE, but with disabled alu32
define CLANG_NOALU32_BPF_BUILD_RULE
($(CLANG) $3 -O2 -target bpf -emit-llvm \
-c $1 -o - || echo "BPF obj compilation failed") | \
$(LLC) -march=bpf -mcpu=v2 $4 -filetype=obj -o $2
endef
# Similar to CLANG_BPF_BUILD_RULE, but using native Clang and bpf LLC
define CLANG_NATIVE_BPF_BUILD_RULE
($(CLANG) $3 -O2 -emit-llvm \
-c $1 -o - || echo "BPF obj compilation failed") | \
$(LLC) -march=bpf -mcpu=probe $4 -filetype=obj -o $2
endef
# Build BPF object using GCC
define GCC_BPF_BUILD_RULE
$(BPF_GCC) $3 $4 -O2 -c $1 -o $2
endef
SKEL_BLACKLIST := btf__% test_pinning_invalid.c
# Set up extra TRUNNER_XXX "temporary" variables in the environment (relies on
# $eval()) and pass control to DEFINE_TEST_RUNNER_RULES.
# Parameters:
# $1 - test runner base binary name (e.g., test_progs)
# $2 - test runner extra "flavor" (e.g., no_alu32, gcc-bpf, etc)
define DEFINE_TEST_RUNNER
TRUNNER_OUTPUT := $(OUTPUT)$(if $2,/)$2
TRUNNER_BINARY := $1$(if $2,-)$2
TRUNNER_TEST_OBJS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.test.o, \
$$(notdir $$(wildcard $(TRUNNER_TESTS_DIR)/*.c)))
TRUNNER_EXTRA_OBJS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.o, \
$$(filter %.c,$(TRUNNER_EXTRA_SOURCES)))
TRUNNER_EXTRA_HDRS := $$(filter %.h,$(TRUNNER_EXTRA_SOURCES))
TRUNNER_TESTS_HDR := $(TRUNNER_TESTS_DIR)/tests.h
TRUNNER_BPF_SRCS := $$(notdir $$(wildcard $(TRUNNER_BPF_PROGS_DIR)/*.c))
TRUNNER_BPF_OBJS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.o, $$(TRUNNER_BPF_SRCS))
TRUNNER_BPF_SKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.skel.h, \
$$(filter-out $(SKEL_BLACKLIST), \
$$(TRUNNER_BPF_SRCS)))
# Evaluate rules now with extra TRUNNER_XXX variables above already defined
$$(eval $$(call DEFINE_TEST_RUNNER_RULES,$1,$2))
endef
# Using TRUNNER_XXX variables, provided by callers of DEFINE_TEST_RUNNER and
# set up by DEFINE_TEST_RUNNER itself, create test runner build rules with:
# $1 - test runner base binary name (e.g., test_progs)
# $2 - test runner extra "flavor" (e.g., no_alu32, gcc-bpf, etc)
define DEFINE_TEST_RUNNER_RULES
ifeq ($($(TRUNNER_OUTPUT)-dir),)
$(TRUNNER_OUTPUT)-dir := y
$(TRUNNER_OUTPUT):
mkdir -p $$@
endif
# ensure we set up BPF objects generation rule just once for a given
# input/output directory combination
ifeq ($($(TRUNNER_BPF_PROGS_DIR)$(if $2,-)$2-bpfobjs),)
$(TRUNNER_BPF_PROGS_DIR)$(if $2,-)$2-bpfobjs := y
$(TRUNNER_BPF_OBJS): $(TRUNNER_OUTPUT)/%.o: \
$(TRUNNER_BPF_PROGS_DIR)/%.c \
$(TRUNNER_BPF_PROGS_DIR)/*.h \
$$(BPF_HELPERS) | $(TRUNNER_OUTPUT)
$$(call $(TRUNNER_BPF_BUILD_RULE),$$<,$$@, \
$(TRUNNER_BPF_CFLAGS), \
$(TRUNNER_BPF_LDFLAGS))
$(TRUNNER_BPF_SKELS): $(TRUNNER_OUTPUT)/%.skel.h: \
$(TRUNNER_OUTPUT)/%.o \
| $(BPFTOOL) $(TRUNNER_OUTPUT)
$$(BPFTOOL) gen skeleton $$< > $$@
endif
# ensure we set up tests.h header generation rule just once
ifeq ($($(TRUNNER_TESTS_DIR)-tests-hdr),)
$(TRUNNER_TESTS_DIR)-tests-hdr := y
$(TRUNNER_TESTS_HDR): $(TRUNNER_TESTS_DIR)/*.c
$$(shell ( cd $(TRUNNER_TESTS_DIR); \
echo '/* Generated header, do not edit */'; \
ls *.c 2> /dev/null | \
sed -e 's@\([^\.]*\)\.c@DEFINE_TEST(\1)@'; \
) > $$@)
endif
# compile individual test files
# Note: we cd into output directory to ensure embedded BPF object is found
$(TRUNNER_TEST_OBJS): $(TRUNNER_OUTPUT)/%.test.o: \
$(TRUNNER_TESTS_DIR)/%.c \
$(TRUNNER_EXTRA_HDRS) \
$(TRUNNER_BPF_OBJS) \
$(TRUNNER_BPF_SKELS) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
cd $$(@D) && $$(CC) $$(CFLAGS) -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F)
$(TRUNNER_EXTRA_OBJS): $(TRUNNER_OUTPUT)/%.o: \
%.c \
$(TRUNNER_EXTRA_HDRS) \
$(TRUNNER_TESTS_HDR) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
$$(CC) $$(CFLAGS) -c $$< $$(LDLIBS) -o $$@
# only copy extra resources if in flavored build
$(TRUNNER_BINARY)-extras: $(TRUNNER_EXTRA_FILES) | $(TRUNNER_OUTPUT)
ifneq ($2,)
cp -a $$^ $(TRUNNER_OUTPUT)/
endif
$(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS) \
$(TRUNNER_EXTRA_OBJS) $$(BPFOBJ) \
| $(TRUNNER_BINARY)-extras
$$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) -o $$@
endef
# Define test_progs test runner.
TRUNNER_TESTS_DIR := prog_tests
TRUNNER_BPF_PROGS_DIR := progs
TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \
flow_dissector_load.h
TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read \
$(wildcard progs/btf_dump_test_case_*.c)
TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
TRUNNER_BPF_CFLAGS := -I. -I$(OUTPUT) $(BPF_CFLAGS) $(CLANG_CFLAGS)
TRUNNER_BPF_LDFLAGS := -mattr=+alu32
$(eval $(call DEFINE_TEST_RUNNER,test_progs))
# Define test_progs-no_alu32 test runner.
TRUNNER_BPF_BUILD_RULE := CLANG_NOALU32_BPF_BUILD_RULE
TRUNNER_BPF_LDFLAGS :=
$(eval $(call DEFINE_TEST_RUNNER,test_progs,no_alu32))
# Define test_progs BPF-GCC-flavored test runner.
ifneq ($(BPF_GCC),)
TRUNNER_BPF_BUILD_RULE := GCC_BPF_BUILD_RULE
TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(call get_sys_includes,gcc)
TRUNNER_BPF_LDFLAGS :=
$(eval $(call DEFINE_TEST_RUNNER,test_progs,bpf_gcc))
endif
# Define test_maps test runner.
TRUNNER_TESTS_DIR := map_tests
TRUNNER_BPF_PROGS_DIR := progs
TRUNNER_EXTRA_SOURCES := test_maps.c
TRUNNER_EXTRA_FILES :=
TRUNNER_BPF_BUILD_RULE := $$(error no BPF objects should be built)
TRUNNER_BPF_CFLAGS :=
TRUNNER_BPF_LDFLAGS :=
$(eval $(call DEFINE_TEST_RUNNER,test_maps))
# Define test_verifier test runner.
# It is much simpler than test_maps/test_progs and sufficiently different from
# them (e.g., test.h is using completely pattern), that it's worth just
# explicitly defining all the rules explicitly.
verifier/tests.h: verifier/*.c
$(shell ( cd verifier/; \
echo '/* Generated header, do not edit */'; \
echo '#ifdef FILL_ARRAY'; \
ls *.c 2> /dev/null | sed -e 's@\(.*\)@#include \"\1\"@'; \
echo '#endif' \
) > verifier/tests.h)
$(OUTPUT)/test_verifier: test_verifier.c verifier/tests.h $(BPFOBJ) | $(OUTPUT)
$(CC) $(CFLAGS) $(filter %.a %.o %.c,$^) $(LDLIBS) -o $@
# Make sure we are able to include and link libbpf against c++.
$(OUTPUT)/test_cpp: test_cpp.cpp $(BPFOBJ)
$(CXX) $(CFLAGS) $^ $(LDLIBS) -o $@
EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) \
prog_tests/tests.h map_tests/tests.h verifier/tests.h \
feature $(OUTPUT)/*.o $(OUTPUT)/no_alu32 $(OUTPUT)/bpf_gcc \
tools *.skel.h