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libbpf: Streamline bpf_attr and perf_event_attr initialization

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Make sure that entire libbpf code base is initializing bpf_attr and
perf_event_attr with memset(0). Also for bpf_attr make sure we
clear and pass to kernel only relevant parts of bpf_attr. bpf_attr is
a huge union of independent sub-command attributes, so there is no need
to clear and pass entire union bpf_attr, which over time grows quite
a lot and for most commands this growth is completely irrelevant.

Few cases where we were relying on compiler initialization of BPF UAPI
structs (like bpf_prog_info, bpf_map_info, etc) with `= {};` were
switched to memset(0) pattern for future-proofing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/20220816001929.369487-3-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko
2022-08-15 17:19:27 -07:00
committed by Andrii Nakryiko
parent 06c4624c8c
commit f7cee4152f
4 changed files with 138 additions and 91 deletions
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10
src/skel_internal.h
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@@ -285,6 +285,8 @@ static inline int skel_link_create(int prog_fd, int target_fd,
static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
{
const size_t prog_load_attr_sz = offsetofend(union bpf_attr, fd_array);
const size_t test_run_attr_sz = offsetofend(union bpf_attr, test);
int map_fd = -1, prog_fd = -1, key = 0, err;
union bpf_attr attr;
@@ -302,7 +304,7 @@ static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
goto out;
}
memset(&attr, 0, sizeof(attr));
memset(&attr, 0, prog_load_attr_sz);
attr.prog_type = BPF_PROG_TYPE_SYSCALL;
attr.insns = (long) opts->insns;
attr.insn_cnt = opts->insns_sz / sizeof(struct bpf_insn);
@@ -313,18 +315,18 @@ static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
attr.log_size = opts->ctx->log_size;
attr.log_buf = opts->ctx->log_buf;
attr.prog_flags = BPF_F_SLEEPABLE;
err = prog_fd = skel_sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
err = prog_fd = skel_sys_bpf(BPF_PROG_LOAD, &attr, prog_load_attr_sz);
if (prog_fd < 0) {
opts->errstr = "failed to load loader prog";
set_err;
goto out;
}
memset(&attr, 0, sizeof(attr));
memset(&attr, 0, test_run_attr_sz);
attr.test.prog_fd = prog_fd;
attr.test.ctx_in = (long) opts->ctx;
attr.test.ctx_size_in = opts->ctx->sz;
err = skel_sys_bpf(BPF_PROG_RUN, &attr, sizeof(attr));
err = skel_sys_bpf(BPF_PROG_RUN, &attr, test_run_attr_sz);
if (err < 0 || (int)attr.test.retval < 0) {
opts->errstr = "failed to execute loader prog";
if (err < 0) {