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author | Yonghong Song <yhs@fb.com> | 2020-05-09 10:59:07 -0700 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-05-09 17:05:26 -0700 |
commit | e5158d987b72c3f318b4b52a01ac6f3997bd0c00 (patch) | |
tree | 7297cfe0ea166ab5064887fd9af91c9e52bdfc83 /kernel/bpf | |
parent | 367ec3e4834cbd611401c2c40a23c22c825474f1 (diff) | |
download | linux-e5158d987b72c3f318b4b52a01ac6f3997bd0c00.tar.bz2 |
bpf: Implement common macros/helpers for target iterators
Macro DEFINE_BPF_ITER_FUNC is implemented so target
can define an init function to capture the BTF type
which represents the target.
The bpf_iter_meta is a structure holding meta data, common
to all targets in the bpf program.
Additional marker functions are called before or after
bpf_seq_read() show()/next()/stop() callback functions
to help calculate precise seq_num and whether call bpf_prog
inside stop().
Two functions, bpf_iter_get_info() and bpf_iter_run_prog(),
are implemented so target can get needed information from
bpf_iter infrastructure and can run the program.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175907.2475956-1-yhs@fb.com
Diffstat (limited to 'kernel/bpf')
-rw-r--r-- | kernel/bpf/bpf_iter.c | 85 |
1 files changed, 80 insertions, 5 deletions
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index 090f09b0eacb..30efd15cd4a0 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -41,6 +41,33 @@ static atomic64_t session_id; static int prepare_seq_file(struct file *file, struct bpf_iter_link *link); +static void bpf_iter_inc_seq_num(struct seq_file *seq) +{ + struct bpf_iter_priv_data *iter_priv; + + iter_priv = container_of(seq->private, struct bpf_iter_priv_data, + target_private); + iter_priv->seq_num++; +} + +static void bpf_iter_dec_seq_num(struct seq_file *seq) +{ + struct bpf_iter_priv_data *iter_priv; + + iter_priv = container_of(seq->private, struct bpf_iter_priv_data, + target_private); + iter_priv->seq_num--; +} + +static void bpf_iter_done_stop(struct seq_file *seq) +{ + struct bpf_iter_priv_data *iter_priv; + + iter_priv = container_of(seq->private, struct bpf_iter_priv_data, + target_private); + iter_priv->done_stop = true; +} + /* bpf_seq_read, a customized and simpler version for bpf iterator. * no_llseek is assumed for this file. * The following are differences from seq_read(): @@ -93,6 +120,10 @@ static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size, err = seq->op->show(seq, p); if (err > 0) { + /* object is skipped, decrease seq_num, so next + * valid object can reuse the same seq_num. + */ + bpf_iter_dec_seq_num(seq); seq->count = 0; } else if (err < 0 || seq_has_overflowed(seq)) { if (!err) @@ -117,11 +148,15 @@ static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size, if (IS_ERR_OR_NULL(p)) break; + /* got a valid next object, increase seq_num */ + bpf_iter_inc_seq_num(seq); + if (seq->count >= size) break; err = seq->op->show(seq, p); if (err > 0) { + bpf_iter_dec_seq_num(seq); seq->count = offs; } else if (err < 0 || seq_has_overflowed(seq)) { seq->count = offs; @@ -138,11 +173,15 @@ stop: offs = seq->count; /* bpf program called if !p */ seq->op->stop(seq, p); - if (!p && seq_has_overflowed(seq)) { - seq->count = offs; - if (offs == 0) { - err = -E2BIG; - goto done; + if (!p) { + if (!seq_has_overflowed(seq)) { + bpf_iter_done_stop(seq); + } else { + seq->count = offs; + if (offs == 0) { + err = -E2BIG; + goto done; + } } } @@ -453,3 +492,39 @@ free_fd: put_unused_fd(fd); return err; } + +struct bpf_prog *bpf_iter_get_info(struct bpf_iter_meta *meta, bool in_stop) +{ + struct bpf_iter_priv_data *iter_priv; + struct seq_file *seq; + void *seq_priv; + + seq = meta->seq; + if (seq->file->f_op != &bpf_iter_fops) + return NULL; + + seq_priv = seq->private; + iter_priv = container_of(seq_priv, struct bpf_iter_priv_data, + target_private); + + if (in_stop && iter_priv->done_stop) + return NULL; + + meta->session_id = iter_priv->session_id; + meta->seq_num = iter_priv->seq_num; + + return iter_priv->prog; +} + +int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx) +{ + int ret; + + rcu_read_lock(); + migrate_disable(); + ret = BPF_PROG_RUN(prog, ctx); + migrate_enable(); + rcu_read_unlock(); + + return ret == 0 ? 0 : -EAGAIN; +} |