diff options
| -rw-r--r-- | include/linux/bpf.h | 39 | ||||
| -rw-r--r-- | kernel/bpf/dispatcher.c | 22 |
2 files changed, 46 insertions, 15 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 5cd95716b441..74c6f449d81e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -27,6 +27,7 @@ #include <linux/bpfptr.h> #include <linux/btf.h> #include <linux/rcupdate_trace.h> +#include <linux/static_call.h> struct bpf_verifier_env; struct bpf_verifier_log; @@ -953,6 +954,10 @@ struct bpf_dispatcher { void *rw_image; u32 image_off; struct bpf_ksym ksym; +#ifdef CONFIG_HAVE_STATIC_CALL + struct static_call_key *sc_key; + void *sc_tramp; +#endif }; static __always_inline __nocfi unsigned int bpf_dispatcher_nop_func( @@ -970,6 +975,34 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key, struct bpf_attach_target_info *tgt_info); void bpf_trampoline_put(struct bpf_trampoline *tr); int arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int num_funcs); + +/* + * When the architecture supports STATIC_CALL replace the bpf_dispatcher_fn + * indirection with a direct call to the bpf program. If the architecture does + * not have STATIC_CALL, avoid a double-indirection. + */ +#ifdef CONFIG_HAVE_STATIC_CALL + +#define __BPF_DISPATCHER_SC_INIT(_name) \ + .sc_key = &STATIC_CALL_KEY(_name), \ + .sc_tramp = STATIC_CALL_TRAMP_ADDR(_name), + +#define __BPF_DISPATCHER_SC(name) \ + DEFINE_STATIC_CALL(bpf_dispatcher_##name##_call, bpf_dispatcher_nop_func) + +#define __BPF_DISPATCHER_CALL(name) \ + static_call(bpf_dispatcher_##name##_call)(ctx, insnsi, bpf_func) + +#define __BPF_DISPATCHER_UPDATE(_d, _new) \ + __static_call_update((_d)->sc_key, (_d)->sc_tramp, (_new)) + +#else +#define __BPF_DISPATCHER_SC_INIT(name) +#define __BPF_DISPATCHER_SC(name) +#define __BPF_DISPATCHER_CALL(name) bpf_func(ctx, insnsi) +#define __BPF_DISPATCHER_UPDATE(_d, _new) +#endif + #define BPF_DISPATCHER_INIT(_name) { \ .mutex = __MUTEX_INITIALIZER(_name.mutex), \ .func = &_name##_func, \ @@ -981,25 +1014,29 @@ int arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int num_func .name = #_name, \ .lnode = LIST_HEAD_INIT(_name.ksym.lnode), \ }, \ + __BPF_DISPATCHER_SC_INIT(_name##_call) \ } #define DEFINE_BPF_DISPATCHER(name) \ + __BPF_DISPATCHER_SC(name); \ noinline __nocfi unsigned int bpf_dispatcher_##name##_func( \ const void *ctx, \ const struct bpf_insn *insnsi, \ bpf_func_t bpf_func) \ { \ - return bpf_func(ctx, insnsi); \ + return __BPF_DISPATCHER_CALL(name); \ } \ EXPORT_SYMBOL(bpf_dispatcher_##name##_func); \ struct bpf_dispatcher bpf_dispatcher_##name = \ BPF_DISPATCHER_INIT(bpf_dispatcher_##name); + #define DECLARE_BPF_DISPATCHER(name) \ unsigned int bpf_dispatcher_##name##_func( \ const void *ctx, \ const struct bpf_insn *insnsi, \ bpf_func_t bpf_func); \ extern struct bpf_dispatcher bpf_dispatcher_##name; + #define BPF_DISPATCHER_FUNC(name) bpf_dispatcher_##name##_func #define BPF_DISPATCHER_PTR(name) (&bpf_dispatcher_##name) void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index fa64b80b8bca..7dfb8d0d5202 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -4,6 +4,7 @@ #include <linux/hash.h> #include <linux/bpf.h> #include <linux/filter.h> +#include <linux/static_call.h> /* The BPF dispatcher is a multiway branch code generator. The * dispatcher is a mechanism to avoid the performance penalty of an @@ -104,17 +105,11 @@ static int bpf_dispatcher_prepare(struct bpf_dispatcher *d, void *image, void *b static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs) { - void *old, *new, *tmp; - u32 noff; - int err; - - if (!prev_num_progs) { - old = NULL; - noff = 0; - } else { - old = d->image + d->image_off; + void *new, *tmp; + u32 noff = 0; + + if (prev_num_progs) noff = d->image_off ^ (PAGE_SIZE / 2); - } new = d->num_progs ? d->image + noff : NULL; tmp = d->num_progs ? d->rw_image + noff : NULL; @@ -128,11 +123,10 @@ static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs) return; } - err = bpf_arch_text_poke(d->func, BPF_MOD_JUMP, old, new); - if (err || !new) - return; + __BPF_DISPATCHER_UPDATE(d, new ?: &bpf_dispatcher_nop_func); - d->image_off = noff; + if (new) + d->image_off = noff; } void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, |