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authorYonghong Song <yhs@fb.com>2020-05-09 20:59:07 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-05-10 03:05:26 +0300
commite5158d987b72c3f318b4b52a01ac6f3997bd0c00 (patch)
tree7297cfe0ea166ab5064887fd9af91c9e52bdfc83 /kernel
parent367ec3e4834cbd611401c2c40a23c22c825474f1 (diff)
downloadlinux-e5158d987b72c3f318b4b52a01ac6f3997bd0c00.tar.xz
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')
-rw-r--r--kernel/bpf/bpf_iter.c85
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;
+}