From 8c88181ed452707f3815827225517b1964463b95 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 8 Feb 2018 12:48:12 +0100 Subject: bpf: Sync kernel ABI header with tooling header for bpf_common.h I recently fixed up a lot of commits that forgot to keep the tooling headers in sync. And then I forgot to do the same thing in commit cb5f7334d479 ("bpf: add comments to BPF ld/ldx sizes"). Let correct that before people notice ;-). Lawrence did partly fix/sync this for bpf.h in commit d6d4f60c3a09 ("bpf: add selftest for tcpbpf"). Fixes: cb5f7334d479 ("bpf: add comments to BPF ld/ldx sizes") Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Daniel Borkmann --- tools/include/uapi/linux/bpf_common.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 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 -- cgit v1.2.3 From 077c066a6c5445423147496e6c9b9a2c2d2ee762 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 8 Feb 2018 12:48:17 +0100 Subject: tools/libbpf: improve the pr_debug statements to contain section numbers While debugging a bpf ELF loading issue, I needed to correlate the ELF section number with the failed relocation section reference. Thus, add section numbers/index to the pr_debug. In debug mode, also print section that were skipped. This helped me identify that a section (.eh_frame) was skipped, and this was the reason the relocation section (.rel.eh_frame) could not find that section number. The section numbers corresponds to the readelf tools Section Headers [Nr]. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Daniel Borkmann --- tools/lib/bpf/libbpf.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index c64840365433..0c794f7fc050 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; } @@ -763,29 +763,29 @@ 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); @@ -840,6 +840,8 @@ 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 +1121,7 @@ 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; } -- cgit v1.2.3 From 864db336c677c288d81524c30a656804785902f9 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 8 Feb 2018 12:48:22 +0100 Subject: selftests/bpf: add test program for loading BPF ELF files V2: Moved program into selftests/bpf from tools/libbpf This program can be used on its own for testing/debugging if a BPF ELF-object file can be loaded with libbpf (from tools/lib/bpf). If something is wrong with the ELF object, the program have a --debug mode that will display the ELF sections and especially the skipped sections. This allows for quickly identifying the problematic ELF section number, which can be corrolated with the readelf tool. The program signal error via return codes, and also have a --quiet mode, which is practical for use in scripts like selftests/bpf. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Daniel Borkmann --- tools/testing/selftests/bpf/Makefile | 2 +- tools/testing/selftests/bpf/test_libbpf_open.c | 150 +++++++++++++++++++++++++ 2 files changed, 151 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/test_libbpf_open.c diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 566d6adc172a..3f48da0866ba 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -20,7 +20,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \ sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \ test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \ - sample_map_ret0.o test_tcpbpf_kern.o + sample_map_ret0.o test_tcpbpf_kern.o test_libbpf_open TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh \ test_offload.py 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 +#include +#include +#include +#include +#include + +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); +} -- cgit v1.2.3 From f09b2e382e9a7053e3ae6f2fb6535efd5760cf5d Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 8 Feb 2018 12:48:27 +0100 Subject: selftests/bpf: add selftest that use test_libbpf_open This script test_libbpf.sh will be part of the 'make run_tests' invocation, but can also be invoked manually in this directory, and a verbose mode can be enabled via setting the environment variable $VERBOSE like: $ VERBOSE=yes ./test_libbpf.sh The script contains some tests that are commented out, as they currently fail. They are reminders about what we need to improve for the libbpf loader library. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Daniel Borkmann --- tools/testing/selftests/bpf/Makefile | 14 +++++++-- tools/testing/selftests/bpf/test_libbpf.sh | 49 ++++++++++++++++++++++++++++++ 2 files changed, 61 insertions(+), 2 deletions(-) create mode 100755 tools/testing/selftests/bpf/test_libbpf.sh diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 3f48da0866ba..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 @@ -20,17 +21,26 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \ sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \ test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \ - sample_map_ret0.o test_tcpbpf_kern.o test_libbpf_open + 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 -- cgit v1.2.3 From e3d91b0ca523d53158f435a3e13df7f0cb360ea2 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 8 Feb 2018 12:48:32 +0100 Subject: tools/libbpf: handle issues with bpf ELF objects containing .eh_frames V3: More generic skipping of relo-section (suggested by Daniel) If clang >= 4.0.1 is missing the option '-target bpf', it will cause llc/llvm to create two ELF sections for "Exception Frames", with section names '.eh_frame' and '.rel.eh_frame'. The BPF ELF loader library libbpf fails when loading files with these sections. The other in-kernel BPF ELF loader in samples/bpf/bpf_load.c, handle this gracefully. And iproute2 loader also seems to work with these "eh" sections. The issue in libbpf is caused by bpf_object__elf_collect() skipping some sections, and later when performing relocation it will be pointing to a skipped section, as these sections cannot be found by bpf_object__find_prog_by_idx() in bpf_object__collect_reloc(). This is a general issue that also occurs for other sections, like debug sections which are also skipped and can have relo section. As suggested by Daniel. To avoid keeping state about all skipped sections, instead perform a direct qlookup in the ELF object. Lookup the section that the relo-section points to and check if it contains executable machine instructions (denoted by the sh_flags SHF_EXECINSTR). Use this check to also skip irrelevant relo-sections. Note, for samples/bpf/ the '-target bpf' parameter to clang cannot be used due to incompatibility with asm embedded headers, that some of the samples include. This is explained in more details by Yonghong Song in bpf_devel_QA. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Daniel Borkmann --- tools/lib/bpf/libbpf.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0c794f7fc050..97073d649c1a 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -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; @@ -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); -- cgit v1.2.3