From: Björn Töpel <bjorn.topel@xxxxxxxxx>
This commit adds a BPF dispatcher for XDP. The dispatcher is updated
from the XDP control-path, dev_xdp_install(), and used when an XDP
program is run via bpf_prog_run_xdp().
Signed-off-by: Björn Töpel <bjorn.topel@xxxxxxxxx>
---
include/linux/bpf.h | 15 +++++++++++++++
include/linux/filter.h | 40 ++++++++++++++++++++++++----------------
kernel/bpf/syscall.c | 26 ++++++++++++++++++--------
net/core/dev.c | 19 ++++++++++++++++++-
net/core/filter.c | 8 ++++++++
5 files changed, 83 insertions(+), 25 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e6a9d74d4e30..ed32b5d901a1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -488,6 +488,14 @@ struct bpf_dispatcher {
u32 image_off;
};
+static __always_inline unsigned int bpf_dispatcher_nopfunc(
+ const void *ctx,
+ const struct bpf_insn *insnsi,
+ unsigned int (*bpf_func)(const void *,
+ const struct bpf_insn *))
+{
+ return bpf_func(ctx, insnsi);
+}
#ifdef CONFIG_BPF_JIT
struct bpf_trampoline *bpf_trampoline_lookup(u64 key);
int bpf_trampoline_link_prog(struct bpf_prog *prog);
@@ -997,6 +1005,8 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog);
+struct bpf_prog *bpf_prog_by_id(u32 id);
+
#else /* !CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get(u32 ufd)
{
@@ -1128,6 +1138,11 @@ static inline int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
static inline void bpf_map_put(struct bpf_map *map)
{
}
+
+static inline struct bpf_prog *bpf_prog_by_id(u32 id)
+{
+ return ERR_PTR(-ENOTSUPP);
+}
#endif /* CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
diff --git a/include/linux/filter.h b/include/linux/filter.h
index a141cb07e76a..37ac7025031d 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -559,23 +559,26 @@ struct sk_filter {
DECLARE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
-#define BPF_PROG_RUN(prog, ctx) ({ \
- u32 ret; \
- cant_sleep(); \
- if (static_branch_unlikely(&bpf_stats_enabled_key)) { \
- struct bpf_prog_stats *stats; \
- u64 start = sched_clock(); \
- ret = (*(prog)->bpf_func)(ctx, (prog)->insnsi); \
- stats = this_cpu_ptr(prog->aux->stats); \
- u64_stats_update_begin(&stats->syncp); \
- stats->cnt++; \
- stats->nsecs += sched_clock() - start; \
- u64_stats_update_end(&stats->syncp); \
- } else { \
- ret = (*(prog)->bpf_func)(ctx, (prog)->insnsi); \
- } \
+#define __BPF_PROG_RUN(prog, ctx, dfunc) ({ \
+ u32 ret; \
+ cant_sleep(); \
+ if (static_branch_unlikely(&bpf_stats_enabled_key)) { \
+ struct bpf_prog_stats *stats; \
+ u64 start = sched_clock(); \
+ ret = dfunc(ctx, (prog)->insnsi, (prog)->bpf_func); \
+ stats = this_cpu_ptr(prog->aux->stats); \
+ u64_stats_update_begin(&stats->syncp); \
+ stats->cnt++; \
+ stats->nsecs += sched_clock() - start; \
+ u64_stats_update_end(&stats->syncp); \
+ } else { \
+ ret = dfunc(ctx, (prog)->insnsi, (prog)->bpf_func); \
+ } \
ret; })
+#define BPF_PROG_RUN(prog, ctx) __BPF_PROG_RUN(prog, ctx, \
+ bpf_dispatcher_nopfunc)
+
#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
struct bpf_skb_data_end {
@@ -699,6 +702,8 @@ static inline u32 bpf_prog_run_clear_cb(const struct bpf_prog *prog,
return res;
}
+DECLARE_BPF_DISPATCHER(bpf_dispatcher_xdp)
+
static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
struct xdp_buff *xdp)
{
@@ -708,9 +713,12 @@ static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
* already takes rcu_read_lock() when fetching the program, so
* it's not necessary here anymore.
*/
- return BPF_PROG_RUN(prog, xdp);
+ return __BPF_PROG_RUN(prog, xdp,
+ BPF_DISPATCHER_FUNC(bpf_dispatcher_xdp));
}
+void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog *prog);
+
static inline u32 bpf_prog_insn_size(const struct bpf_prog *prog)
{
return prog->len * sizeof(struct bpf_insn);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e3461ec59570..1a67d468637b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2305,17 +2305,12 @@ static int bpf_obj_get_next_id(const union bpf_attr *attr,
#define BPF_PROG_GET_FD_BY_ID_LAST_FIELD prog_id
-static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
+struct bpf_prog *bpf_prog_by_id(u32 id)
{
struct bpf_prog *prog;
- u32 id = attr->prog_id;
- int fd;
-
- if (CHECK_ATTR(BPF_PROG_GET_FD_BY_ID))
- return -EINVAL;
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
+ if (!id)
+ return ERR_PTR(-ENOENT);
spin_lock_bh(&prog_idr_lock);
prog = idr_find(&prog_idr, id);
@@ -2324,7 +2319,22 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
else
prog = ERR_PTR(-ENOENT);
spin_unlock_bh(&prog_idr_lock);
+ return prog;
+}
+
+static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
+{
+ struct bpf_prog *prog;
+ u32 id = attr->prog_id;
+ int fd;
+
+ if (CHECK_ATTR(BPF_PROG_GET_FD_BY_ID))
+ return -EINVAL;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ prog = bpf_prog_by_id(id);
if (IS_ERR(prog))
return PTR_ERR(prog);
diff --git a/net/core/dev.c b/net/core/dev.c
index 2c277b8aba38..255d3cf35360 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8542,7 +8542,17 @@ static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
struct netlink_ext_ack *extack, u32 flags,
struct bpf_prog *prog)
{
+ bool non_hw = !(flags & XDP_FLAGS_HW_MODE);
+ struct bpf_prog *prev_prog = NULL;
struct netdev_bpf xdp;
+ int err;
+
+ if (non_hw) {
+ prev_prog = bpf_prog_by_id(__dev_xdp_query(dev, bpf_op,
+ XDP_QUERY_PROG));
+ if (IS_ERR(prev_prog))
+ prev_prog = NULL;
+ }
memset(&xdp, 0, sizeof(xdp));
if (flags & XDP_FLAGS_HW_MODE)
@@ -8553,7 +8563,14 @@ static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
xdp.flags = flags;
xdp.prog = prog;
- return bpf_op(dev, &xdp);
+ err = bpf_op(dev, &xdp);
+ if (!err && non_hw)
+ bpf_prog_change_xdp(prev_prog, prog);
+
+ if (prev_prog)
+ bpf_prog_put(prev_prog);
+
+ return err;
}
static void dev_xdp_uninstall(struct net_device *dev)
diff --git a/net/core/filter.c b/net/core/filter.c
index f1e703eed3d2..a411f7835dee 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8940,3 +8940,11 @@ const struct bpf_verifier_ops sk_reuseport_verifier_ops = {
const struct bpf_prog_ops sk_reuseport_prog_ops = {
};
#endif /* CONFIG_INET */
+
+DEFINE_BPF_DISPATCHER(bpf_dispatcher_xdp)
+
+void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog *prog)
+{
+ bpf_dispatcher_change_prog(BPF_DISPATCHER_PTR(bpf_dispatcher_xdp),
+ prev_prog, prog);
+}
--
2.20.1
