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bpf, xdp: Start using the BPF dispatcher for XDP

Browse Source 
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@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191213175112.30208-4-bjorn.topel@gmail.com
This commit is contained in:
Björn Töpel 2019-12-13 18:51:09 +01:00 committed by Alexei Starovoitov
parent 75ccbef636
commit 7e6897f959
5 changed files with 83 additions and 25 deletions
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15
include/linux/bpf.h
View File

@ -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,

40
include/linux/filter.h
View File

@ -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);

26
kernel/bpf/syscall.c
View File

@ -2338,6 +2338,23 @@ static int bpf_obj_get_next_id(const union bpf_attr *attr,
#define BPF_PROG_GET_FD_BY_ID_LAST_FIELD prog_id
struct bpf_prog *bpf_prog_by_id(u32 id)
{
struct bpf_prog *prog;
if (!id)
return ERR_PTR(-ENOENT);
spin_lock_bh(&prog_idr_lock);
prog = idr_find(&prog_idr, id);
if (prog)
prog = bpf_prog_inc_not_zero(prog);
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;
@ -2350,14 +2367,7 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
spin_lock_bh(&prog_idr_lock);
prog = idr_find(&prog_idr, id);
if (prog)
prog = bpf_prog_inc_not_zero(prog);
else
prog = ERR_PTR(-ENOENT);
spin_unlock_bh(&prog_idr_lock);
prog = bpf_prog_by_id(id);
if (IS_ERR(prog))
return PTR_ERR(prog);

19
net/core/dev.c
View File

@ -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)

8
net/core/filter.c
View File

@ -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);
}