Commit 367ec3e4 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

bpf: Create file bpf iterator 



To produce a file bpf iterator, the fd must be
corresponding to a link_fd assocciated with a
trace/iter program. When the pinned file is
opened, a seq_file will be generated.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175906.2475893-1-yhs@fb.com
parent ac51d99b

include/linux/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -1022,6 +1022,7 @@ static inline void bpf_enable_instrumentation(void) 


extern const struct file_operations bpf_map_fops;

extern const struct file_operations bpf_prog_fops;

extern const struct file_operations bpf_iter_fops;



#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \

	extern const struct bpf_prog_ops _name ## _prog_ops; \
@@ -1145,6 +1146,7 @@ void bpf_iter_unreg_target(const char *target); 
bool bpf_iter_prog_supported(struct bpf_prog *prog);

int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);

int bpf_iter_new_fd(struct bpf_link *link);

bool bpf_link_is_iter(struct bpf_link *link);



int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);

int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);

kernel/bpf/bpf_iter.c

+16 −1
Original line number Diff line number Diff line
@@ -39,6 +39,8 @@ static DEFINE_MUTEX(link_mutex); 
/* incremented on every opened seq_file */

static atomic64_t session_id;



static int prepare_seq_file(struct file *file, struct bpf_iter_link *link);



/* 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():
@@ -162,6 +164,13 @@ done: 
	return copied;

}



static int iter_open(struct inode *inode, struct file *file)

{

	struct bpf_iter_link *link = inode->i_private;



	return prepare_seq_file(file, link);

}



static int iter_release(struct inode *inode, struct file *file)

{

	struct bpf_iter_priv_data *iter_priv;
@@ -183,7 +192,8 @@ static int iter_release(struct inode *inode, struct file *file) 
	return seq_release_private(inode, file);

}



static const struct file_operations bpf_iter_fops = {

const struct file_operations bpf_iter_fops = {

	.open		= iter_open,

	.llseek		= no_llseek,

	.read		= bpf_seq_read,

	.release	= iter_release,
@@ -310,6 +320,11 @@ static const struct bpf_link_ops bpf_iter_link_lops = { 
	.update_prog = bpf_iter_link_replace,

};



bool bpf_link_is_iter(struct bpf_link *link)

{

	return link->ops == &bpf_iter_link_lops;

}



int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)

{

	struct bpf_link_primer link_primer;

kernel/bpf/inode.c

+4 −1
Original line number Diff line number Diff line
@@ -358,8 +358,11 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg) 


static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg)

{

	struct bpf_link *link = arg;



	return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops,

			     &bpffs_obj_fops);

			     bpf_link_is_iter(link) ?

			     &bpf_iter_fops : &bpffs_obj_fops);

}



static struct dentry *

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