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author | Daniel Borkmann <daniel@iogearbox.net> | 2018-02-09 00:26:18 +0100 |
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committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-02-09 00:26:28 +0100 |
commit | d977ae593b2d3f9ef0df795eda93f4e6bc92b323 (patch) | |
tree | 0e3c09034cb8bc79fea586681d4de51689a23325 | |
parent | 69fe98edee48b4c3c7d90cb7eea1f1662202137d (diff) | |
parent | e3d91b0ca523d53158f435a3e13df7f0cb360ea2 (diff) | |
download | linux-d977ae593b2d3f9ef0df795eda93f4e6bc92b323.tar.bz2 |
Merge branch 'bpf-libbpf-relo-fix-and-tests'
Jesper Dangaard Brouer says:
====================
While playing with using libbpf for the Suricata project, we had
issues LLVM >= 4.0.1 generating ELF files that could not be loaded
with libbpf (tools/lib/bpf/).
During the troubleshooting phase, I wrote a test program and improved
the debugging output in libbpf. I turned this into a selftests
program, and it also serves as a code example for libbpf in itself.
I discovered that there are at least three ELF load issues with
libbpf. I left them as TODO comments in (tools/testing/selftests/bpf)
test_libbpf.sh. I've only fixed the load issue with eh_frames, and
other types of relo-section that does not have exec flags. We can
work on the other issues later.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
-rw-r--r-- | tools/include/uapi/linux/bpf_common.h | 7 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.c | 51 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/Makefile | 12 | ||||
-rwxr-xr-x | tools/testing/selftests/bpf/test_libbpf.sh | 49 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/test_libbpf_open.c | 150 |
5 files changed, 253 insertions, 16 deletions
diff --git a/tools/include/uapi/linux/bpf_common.h b/tools/include/uapi/linux/bpf_common.h index 18be90725ab0..ee97668bdadb 100644 --- a/tools/include/uapi/linux/bpf_common.h +++ b/tools/include/uapi/linux/bpf_common.h @@ -15,9 +15,10 @@ /* ld/ldx fields */ #define BPF_SIZE(code) ((code) & 0x18) -#define BPF_W 0x00 -#define BPF_H 0x08 -#define BPF_B 0x10 +#define BPF_W 0x00 /* 32-bit */ +#define BPF_H 0x08 /* 16-bit */ +#define BPF_B 0x10 /* 8-bit */ +/* eBPF BPF_DW 0x18 64-bit */ #define BPF_MODE(code) ((code) & 0xe0) #define BPF_IMM 0x00 #define BPF_ABS 0x20 diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index c64840365433..97073d649c1a 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -319,8 +319,8 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx, prog->section_name = strdup(section_name); if (!prog->section_name) { - pr_warning("failed to alloc name for prog under section %s\n", - section_name); + pr_warning("failed to alloc name for prog under section(%d) %s\n", + idx, section_name); goto errout; } @@ -742,6 +742,24 @@ bpf_object__init_maps(struct bpf_object *obj) return 0; } +static bool section_have_execinstr(struct bpf_object *obj, int idx) +{ + Elf_Scn *scn; + GElf_Shdr sh; + + scn = elf_getscn(obj->efile.elf, idx); + if (!scn) + return false; + + if (gelf_getshdr(scn, &sh) != &sh) + return false; + + if (sh.sh_flags & SHF_EXECINSTR) + return true; + + return false; +} + static int bpf_object__elf_collect(struct bpf_object *obj) { Elf *elf = obj->efile.elf; @@ -763,29 +781,29 @@ static int bpf_object__elf_collect(struct bpf_object *obj) idx++; if (gelf_getshdr(scn, &sh) != &sh) { - pr_warning("failed to get section header from %s\n", - obj->path); + pr_warning("failed to get section(%d) header from %s\n", + idx, obj->path); err = -LIBBPF_ERRNO__FORMAT; goto out; } name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name); if (!name) { - pr_warning("failed to get section name from %s\n", - obj->path); + pr_warning("failed to get section(%d) name from %s\n", + idx, obj->path); err = -LIBBPF_ERRNO__FORMAT; goto out; } data = elf_getdata(scn, 0); if (!data) { - pr_warning("failed to get section data from %s(%s)\n", - name, obj->path); + pr_warning("failed to get section(%d) data from %s(%s)\n", + idx, name, obj->path); err = -LIBBPF_ERRNO__FORMAT; goto out; } - pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n", - name, (unsigned long)data->d_size, + pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n", + idx, name, (unsigned long)data->d_size, (int)sh.sh_link, (unsigned long)sh.sh_flags, (int)sh.sh_type); @@ -825,6 +843,14 @@ static int bpf_object__elf_collect(struct bpf_object *obj) } else if (sh.sh_type == SHT_REL) { void *reloc = obj->efile.reloc; int nr_reloc = obj->efile.nr_reloc + 1; + int sec = sh.sh_info; /* points to other section */ + + /* Only do relo for section with exec instructions */ + if (!section_have_execinstr(obj, sec)) { + pr_debug("skip relo %s(%d) for section(%d)\n", + name, idx, sec); + continue; + } reloc = realloc(reloc, sizeof(*obj->efile.reloc) * nr_reloc); @@ -840,6 +866,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj) obj->efile.reloc[n].shdr = sh; obj->efile.reloc[n].data = data; } + } else { + pr_debug("skip section(%d) %s\n", idx, name); } if (err) goto out; @@ -1119,8 +1147,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj) prog = bpf_object__find_prog_by_idx(obj, idx); if (!prog) { - pr_warning("relocation failed: no %d section\n", - idx); + pr_warning("relocation failed: no section(%d)\n", idx); return -LIBBPF_ERRNO__RELOC; } diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 566d6adc172a..5c43c187f27c 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -13,6 +13,7 @@ endif CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include LDLIBS += -lcap -lelf -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 @@ -22,15 +23,24 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \ sample_map_ret0.o test_tcpbpf_kern.o -TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh \ +# Order correspond to 'make run_tests' order +TEST_PROGS := test_kmod.sh \ + test_libbpf.sh \ + test_xdp_redirect.sh \ + test_xdp_meta.sh \ test_offload.py +# Compile but not part of 'make run_tests' +TEST_GEN_PROGS_EXTENDED = test_libbpf_open + include ../lib.mk BPFOBJ := $(OUTPUT)/libbpf.a cgroup_helpers.c $(TEST_GEN_PROGS): $(BPFOBJ) +$(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/libbpf.a + .PHONY: force # force a rebuild of BPFOBJ when its dependencies are updated diff --git a/tools/testing/selftests/bpf/test_libbpf.sh b/tools/testing/selftests/bpf/test_libbpf.sh new file mode 100755 index 000000000000..d97dc914cd49 --- /dev/null +++ b/tools/testing/selftests/bpf/test_libbpf.sh @@ -0,0 +1,49 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +export TESTNAME=test_libbpf + +# Determine selftest success via shell exit code +exit_handler() +{ + if (( $? == 0 )); then + echo "selftests: $TESTNAME [PASS]"; + else + echo "$TESTNAME: failed at file $LAST_LOADED" 1>&2 + echo "selftests: $TESTNAME [FAILED]"; + fi +} + +libbpf_open_file() +{ + LAST_LOADED=$1 + if [ -n "$VERBOSE" ]; then + ./test_libbpf_open $1 + else + ./test_libbpf_open --quiet $1 + fi +} + +# Exit script immediately (well catched by trap handler) if any +# program/thing exits with a non-zero status. +set -e + +# (Use 'trap -l' to list meaning of numbers) +trap exit_handler 0 2 3 6 9 + +libbpf_open_file test_l4lb.o + +# TODO: fix libbpf to load noinline functions +# [warning] libbpf: incorrect bpf_call opcode +#libbpf_open_file test_l4lb_noinline.o + +# TODO: fix test_xdp_meta.c to load with libbpf +# [warning] libbpf: test_xdp_meta.o doesn't provide kernel version +#libbpf_open_file test_xdp_meta.o + +# TODO: fix libbpf to handle .eh_frame +# [warning] libbpf: relocation failed: no section(10) +#libbpf_open_file ../../../../samples/bpf/tracex3_kern.o + +# Success +exit 0 diff --git a/tools/testing/selftests/bpf/test_libbpf_open.c b/tools/testing/selftests/bpf/test_libbpf_open.c new file mode 100644 index 000000000000..8fcd1c076add --- /dev/null +++ b/tools/testing/selftests/bpf/test_libbpf_open.c @@ -0,0 +1,150 @@ +/* SPDX-License-Identifier: GPL-2.0 + * Copyright (c) 2018 Jesper Dangaard Brouer, Red Hat Inc. + */ +static const char *__doc__ = + "Libbpf test program for loading BPF ELF object files"; + +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <stdarg.h> +#include <bpf/libbpf.h> +#include <getopt.h> + +static const struct option long_options[] = { + {"help", no_argument, NULL, 'h' }, + {"debug", no_argument, NULL, 'D' }, + {"quiet", no_argument, NULL, 'q' }, + {0, 0, NULL, 0 } +}; + +static void usage(char *argv[]) +{ + int i; + + printf("\nDOCUMENTATION:\n%s\n\n", __doc__); + printf(" Usage: %s (options-see-below) BPF_FILE\n", argv[0]); + printf(" Listing options:\n"); + for (i = 0; long_options[i].name != 0; i++) { + printf(" --%-12s", long_options[i].name); + printf(" short-option: -%c", + long_options[i].val); + printf("\n"); + } + printf("\n"); +} + +#define DEFINE_PRINT_FN(name, enabled) \ +static int libbpf_##name(const char *fmt, ...) \ +{ \ + va_list args; \ + int ret; \ + \ + va_start(args, fmt); \ + if (enabled) { \ + fprintf(stderr, "[" #name "] "); \ + ret = vfprintf(stderr, fmt, args); \ + } \ + va_end(args); \ + return ret; \ +} +DEFINE_PRINT_FN(warning, 1) +DEFINE_PRINT_FN(info, 1) +DEFINE_PRINT_FN(debug, 1) + +#define EXIT_FAIL_LIBBPF EXIT_FAILURE +#define EXIT_FAIL_OPTION 2 + +int test_walk_progs(struct bpf_object *obj, bool verbose) +{ + struct bpf_program *prog; + int cnt = 0; + + bpf_object__for_each_program(prog, obj) { + cnt++; + if (verbose) + printf("Prog (count:%d) section_name: %s\n", cnt, + bpf_program__title(prog, false)); + } + return 0; +} + +int test_walk_maps(struct bpf_object *obj, bool verbose) +{ + struct bpf_map *map; + int cnt = 0; + + bpf_map__for_each(map, obj) { + cnt++; + if (verbose) + printf("Map (count:%d) name: %s\n", cnt, + bpf_map__name(map)); + } + return 0; +} + +int test_open_file(char *filename, bool verbose) +{ + struct bpf_object *bpfobj = NULL; + long err; + + if (verbose) + printf("Open BPF ELF-file with libbpf: %s\n", filename); + + /* Load BPF ELF object file and check for errors */ + bpfobj = bpf_object__open(filename); + err = libbpf_get_error(bpfobj); + if (err) { + char err_buf[128]; + libbpf_strerror(err, err_buf, sizeof(err_buf)); + if (verbose) + printf("Unable to load eBPF objects in file '%s': %s\n", + filename, err_buf); + return EXIT_FAIL_LIBBPF; + } + test_walk_progs(bpfobj, verbose); + test_walk_maps(bpfobj, verbose); + + if (verbose) + printf("Close BPF ELF-file with libbpf: %s\n", + bpf_object__name(bpfobj)); + bpf_object__close(bpfobj); + + return 0; +} + +int main(int argc, char **argv) +{ + char filename[1024] = { 0 }; + bool verbose = 1; + int longindex = 0; + int opt; + + libbpf_set_print(libbpf_warning, libbpf_info, NULL); + + /* Parse commands line args */ + while ((opt = getopt_long(argc, argv, "hDq", + long_options, &longindex)) != -1) { + switch (opt) { + case 'D': + libbpf_set_print(libbpf_warning, libbpf_info, + libbpf_debug); + break; + case 'q': /* Use in scripting mode */ + verbose = 0; + break; + case 'h': + default: + usage(argv); + return EXIT_FAIL_OPTION; + } + } + if (optind >= argc) { + usage(argv); + printf("ERROR: Expected BPF_FILE argument after options\n"); + return EXIT_FAIL_OPTION; + } + snprintf(filename, sizeof(filename), "%s", argv[optind]); + + return test_open_file(filename, verbose); +} |