From dde7b3f5f2f458297aeccfd4783e53ab8ca046db Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 13 Mar 2021 13:09:17 -0800 Subject: [PATCH 1/4] libbpf: Add explicit padding to bpf_xdp_set_link_opts Adding such anonymous padding fixes the issue with uninitialized portions of bpf_xdp_set_link_opts when using LIBBPF_DECLARE_OPTS macro with inline field initialization: DECLARE_LIBBPF_OPTS(bpf_xdp_set_link_opts, opts, .old_fd = -1); When such code is compiled in debug mode, compiler is generating code that leaves padding bytes uninitialized, which triggers error inside libbpf APIs that do strict zero initialization checks for OPTS structs. Adding anonymous padding field fixes the issue. Fixes: bd5ca3ef93cd ("libbpf: Add function to set link XDP fd while specifying old program") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210313210920.1959628-2-andrii@kernel.org --- tools/lib/bpf/libbpf.h | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 3c35eb401931..3d690d4e785c 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -507,6 +507,7 @@ struct xdp_link_info { struct bpf_xdp_set_link_opts { size_t sz; int old_fd; + size_t :0; }; #define bpf_xdp_set_link_opts__last_field old_fd From 4bbb3583687051ef99966ddaeb1730441b777d40 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 13 Mar 2021 13:09:18 -0800 Subject: [PATCH 2/4] bpftool: Fix maybe-uninitialized warnings Somehow when bpftool is compiled in -Og mode, compiler produces new warnings about possibly uninitialized variables. Fix all the reported problems. Fixes: 2119f2189df1 ("bpftool: add C output format option to btf dump subcommand") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210313210920.1959628-3-andrii@kernel.org --- tools/bpf/bpftool/btf.c | 3 +++ tools/bpf/bpftool/main.c | 3 +-- tools/bpf/bpftool/map.c | 2 +- 3 files changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 985610c3f193..62953bbf68b4 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -546,6 +546,7 @@ static int do_dump(int argc, char **argv) NEXT_ARG(); if (argc < 1) { p_err("expecting value for 'format' option\n"); + err = -EINVAL; goto done; } if (strcmp(*argv, "c") == 0) { @@ -555,11 +556,13 @@ static int do_dump(int argc, char **argv) } else { p_err("unrecognized format specifier: '%s', possible values: raw, c", *argv); + err = -EINVAL; goto done; } NEXT_ARG(); } else { p_err("unrecognized option: '%s'", *argv); + err = -EINVAL; goto done; } } diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c index b86f450e6fce..d9afb730136a 100644 --- a/tools/bpf/bpftool/main.c +++ b/tools/bpf/bpftool/main.c @@ -276,7 +276,7 @@ static int do_batch(int argc, char **argv) int n_argc; FILE *fp; char *cp; - int err; + int err = 0; int i; if (argc < 2) { @@ -370,7 +370,6 @@ static int do_batch(int argc, char **argv) } else { if (!json_output) printf("processed %d commands\n", lines); - err = 0; } err_close: if (fp != stdin) diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index b400364ee054..09ae0381205b 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -100,7 +100,7 @@ static int do_dump_btf(const struct btf_dumper *d, void *value) { __u32 value_id; - int ret; + int ret = 0; /* start of key-value pair */ jsonw_start_object(d->jw); From 105b842ba4ef2ddc287645cb33f90b960c16075b Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 13 Mar 2021 13:09:19 -0800 Subject: [PATCH 3/4] selftests/bpf: Fix maybe-uninitialized warning in xdpxceiver test MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit xsk_ring_prod__reserve() doesn't necessarily set idx in some conditions, so from static analysis point of view compiler is right about the problems like: In file included from xdpxceiver.c:92: xdpxceiver.c: In function ‘xsk_populate_fill_ring’: /data/users/andriin/linux/tools/testing/selftests/bpf/tools/include/bpf/xsk.h:119:20: warning: ‘idx’ may be used uninitialized in this function [-Wmaybe-uninitialized] return &addrs[idx & fill->mask]; ~~~~^~~~~~~~~~~~ xdpxceiver.c:300:6: note: ‘idx’ was declared here u32 idx; ^~~ xdpxceiver.c: In function ‘tx_only’: xdpxceiver.c:596:30: warning: ‘idx’ may be used uninitialized in this function [-Wmaybe-uninitialized] struct xdp_desc *tx_desc = xsk_ring_prod__tx_desc(&xsk->tx, idx + i); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fix two warnings reported by compiler by pre-initializing variable. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210313210920.1959628-4-andrii@kernel.org --- tools/testing/selftests/bpf/xdpxceiver.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/xdpxceiver.c b/tools/testing/selftests/bpf/xdpxceiver.c index 8b0f7fdd9003..1e21a3172687 100644 --- a/tools/testing/selftests/bpf/xdpxceiver.c +++ b/tools/testing/selftests/bpf/xdpxceiver.c @@ -297,7 +297,7 @@ static void xsk_configure_umem(struct ifobject *data, void *buffer, u64 size) static void xsk_populate_fill_ring(struct xsk_umem_info *umem) { int ret, i; - u32 idx; + u32 idx = 0; ret = xsk_ring_prod__reserve(&umem->fq, XSK_RING_PROD__DEFAULT_NUM_DESCS, &idx); if (ret != XSK_RING_PROD__DEFAULT_NUM_DESCS) @@ -584,7 +584,7 @@ static void rx_pkt(struct xsk_socket_info *xsk, struct pollfd *fds) static void tx_only(struct xsk_socket_info *xsk, u32 *frameptr, int batch_size) { - u32 idx; + u32 idx = 0; unsigned int i; bool tx_invalid_test = stat_test_type == STAT_TEST_TX_INVALID; u32 len = tx_invalid_test ? XSK_UMEM__DEFAULT_FRAME_SIZE + 1 : PKT_SIZE; From 252e3cbf2b623422b359b965b94060e8d68597e1 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 13 Mar 2021 13:09:20 -0800 Subject: [PATCH 4/4] selftests/bpf: Build everything in debug mode Build selftests, bpftool, and libbpf in debug mode with DWARF data to facilitate easier debugging. In terms of impact on building and running selftests. Build is actually faster now: BEFORE: make -j60 380.21s user 37.87s system 1466% cpu 28.503 total AFTER: make -j60 345.47s user 37.37s system 1599% cpu 23.939 total test_progs runtime seems to be the same: BEFORE: real 1m5.139s user 0m1.600s sys 0m43.977s AFTER: real 1m3.799s user 0m1.721s sys 0m42.420s Huge difference is being able to debug issues throughout test_progs, bpftool, and libbpf without constantly updating 3 Makefiles by hand (including GDB seeing the source code without any extra incantations). Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210313210920.1959628-5-andrii@kernel.org --- tools/testing/selftests/bpf/Makefile | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index c3999587bc23..d0db2b673c6f 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -21,7 +21,7 @@ endif BPF_GCC ?= $(shell command -v bpf-gcc;) SAN_CFLAGS ?= -CFLAGS += -g -rdynamic -Wall -O2 $(GENFLAGS) $(SAN_CFLAGS) \ +CFLAGS += -g -Og -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS) \ -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) \ -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT) \ -Dbpf_prog_load=bpf_prog_test_load \ @@ -201,6 +201,7 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \ $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool $(Q)$(MAKE) $(submake_extras) -C $(BPFTOOLDIR) \ CC=$(HOSTCC) LD=$(HOSTLD) \ + EXTRA_CFLAGS='-g -Og' \ OUTPUT=$(HOST_BUILD_DIR)/bpftool/ \ prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install @@ -218,6 +219,7 @@ $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ ../../../include/uapi/linux/bpf.h \ | $(INCLUDE_DIR) $(BUILD_DIR)/libbpf $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \ + EXTRA_CFLAGS='-g -Og' \ DESTDIR=$(SCRATCH_DIR) prefix= all install_headers ifneq ($(BPFOBJ),$(HOST_BPFOBJ)) @@ -225,7 +227,8 @@ $(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ ../../../include/uapi/linux/bpf.h \ | $(INCLUDE_DIR) $(HOST_BUILD_DIR)/libbpf $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) \ - OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \ + EXTRA_CFLAGS='-g -Og' \ + OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \ DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers endif