From: Roman Gushchin <guro@fb.com>
Date: Thu, 2 Aug 2018 14:27:19 -0700
Subject: bpf: pass a pointer to a cgroup storage using pcpu variable
Patch-mainline: v4.19-rc1
Git-commit: aa0ad5b0391e268bdecf6cda31268388844f8afd
References: bsc#1109837

This commit introduces the bpf_cgroup_storage_set() helper,
which will be used to pass a pointer to a cgroup storage
to the bpf helper.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/bpf-cgroup.h |   15 +++++++++++++++
 kernel/bpf/local_storage.c |    2 ++
 2 files changed, 17 insertions(+)

--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -3,6 +3,7 @@
 
 #include <linux/errno.h>
 #include <linux/jump_label.h>
+#include <linux/percpu.h>
 #include <linux/rbtree.h>
 #include <uapi/linux/bpf.h>
 
@@ -20,6 +21,8 @@ struct bpf_cgroup_storage;
 extern struct static_key_false cgroup_bpf_enabled_key;
 #define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key)
 
+DECLARE_PER_CPU(void*, bpf_cgroup_storage);
+
 struct bpf_cgroup_storage_map;
 
 struct bpf_storage_buffer {
@@ -96,6 +99,17 @@ int __cgroup_bpf_run_filter_sock_ops(str
 int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
 				      short access, enum bpf_attach_type type);
 
+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage)
+{
+	struct bpf_storage_buffer *buf;
+
+	if (!storage)
+		return;
+
+	buf = READ_ONCE(storage->buf);
+	this_cpu_write(bpf_cgroup_storage, &buf->data[0]);
+}
+
 struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog);
 void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage);
 void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
@@ -249,6 +263,7 @@ static inline int cgroup_bpf_prog_query(
 	return -EINVAL;
 }
 
+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage) {}
 static inline int bpf_cgroup_storage_assign(struct bpf_prog *prog,
 					    struct bpf_map *map) { return 0; }
 static inline void bpf_cgroup_storage_release(struct bpf_prog *prog,
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -7,6 +7,8 @@
 #include <linux/rbtree.h>
 #include <linux/slab.h>
 
+DEFINE_PER_CPU(void*, bpf_cgroup_storage);
+
 #ifdef CONFIG_CGROUP_BPF
 
 #define LOCAL_STORAGE_CREATE_FLAG_MASK					\