Introduce io_uring BPF struct ops implementing the loop_step callback, which will allow BPF to overwrite the default io_uring event loop logic. The callback takes an io_uring context, the main role of which is to be passed to io_uring kfuncs. The other argument is a struct iou_loop_params, which BPF can use to request CQ waiting and communicate other parameters. See the event loop description in the previous patch for more details. Signed-off-by: Pavel Begunkov --- io_uring/Kconfig | 5 ++ io_uring/Makefile | 1 + io_uring/bpf-ops.c | 127 ++++++++++++++++++++++++++++++++++++++++++++ io_uring/bpf-ops.h | 14 +++++ io_uring/io_uring.c | 1 + 5 files changed, 148 insertions(+) create mode 100644 io_uring/bpf-ops.c create mode 100644 io_uring/bpf-ops.h diff --git a/io_uring/Kconfig b/io_uring/Kconfig index a7ae23cf1035..a283d9e53787 100644 --- a/io_uring/Kconfig +++ b/io_uring/Kconfig @@ -14,3 +14,8 @@ config IO_URING_BPF def_bool y depends on BPF depends on NET + +config IO_URING_BPF_OPS + def_bool y + depends on IO_URING + depends on BPF_SYSCALL && BPF_JIT && DEBUG_INFO_BTF diff --git a/io_uring/Makefile b/io_uring/Makefile index 1c1f47de32a4..c54e328d1410 100644 --- a/io_uring/Makefile +++ b/io_uring/Makefile @@ -25,3 +25,4 @@ obj-$(CONFIG_NET) += net.o cmd_net.o obj-$(CONFIG_PROC_FS) += fdinfo.o obj-$(CONFIG_IO_URING_MOCK_FILE) += mock_file.o obj-$(CONFIG_IO_URING_BPF) += bpf_filter.o +obj-$(CONFIG_IO_URING_BPF_OPS) += bpf-ops.o diff --git a/io_uring/bpf-ops.c b/io_uring/bpf-ops.c new file mode 100644 index 000000000000..975db5a78188 --- /dev/null +++ b/io_uring/bpf-ops.c @@ -0,0 +1,127 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include +#include +#include + +#include "io_uring.h" +#include "register.h" +#include "bpf-ops.h" +#include "loop.h" + +static const struct btf_type *loop_params_type; + +static int io_bpf_ops__loop_step(struct io_ring_ctx *ctx, + struct iou_loop_params *lp) +{ + return IOU_LOOP_STOP; +} + +static struct io_uring_bpf_ops io_bpf_ops_stubs = { + .loop_step = io_bpf_ops__loop_step, +}; + +static bool bpf_io_is_valid_access(int off, int size, + enum bpf_access_type type, + const struct bpf_prog *prog, + struct bpf_insn_access_aux *info) +{ + if (type != BPF_READ) + return false; + if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS) + return false; + if (off % size != 0) + return false; + + return btf_ctx_access(off, size, type, prog, info); +} + +static int bpf_io_btf_struct_access(struct bpf_verifier_log *log, + const struct bpf_reg_state *reg, int off, + int size) +{ + const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id); + + if (t == loop_params_type) { + if (off + size <= offsetofend(struct iou_loop_params, cq_wait_idx)) + return SCALAR_VALUE; + } + + return -EACCES; +} + +static const struct bpf_verifier_ops bpf_io_verifier_ops = { + .get_func_proto = bpf_base_func_proto, + .is_valid_access = bpf_io_is_valid_access, + .btf_struct_access = bpf_io_btf_struct_access, +}; + +static const struct btf_type * +io_lookup_struct_type(struct btf *btf, const char *name) +{ + s32 type_id; + + type_id = btf_find_by_name_kind(btf, name, BTF_KIND_STRUCT); + if (type_id < 0) + return NULL; + return btf_type_by_id(btf, type_id); +} + +static int bpf_io_init(struct btf *btf) +{ + loop_params_type = io_lookup_struct_type(btf, "iou_loop_params"); + if (!loop_params_type) { + pr_err("io_uring: Failed to locate iou_loop_params\n"); + return -EINVAL; + } + + return 0; +} + +static int bpf_io_check_member(const struct btf_type *t, + const struct btf_member *member, + const struct bpf_prog *prog) +{ + return 0; +} + +static int bpf_io_init_member(const struct btf_type *t, + const struct btf_member *member, + void *kdata, const void *udata) +{ + return 0; +} + +static int bpf_io_reg(void *kdata, struct bpf_link *link) +{ + return -EOPNOTSUPP; +} + +static void bpf_io_unreg(void *kdata, struct bpf_link *link) +{ +} + +static struct bpf_struct_ops bpf_ring_ops = { + .verifier_ops = &bpf_io_verifier_ops, + .reg = bpf_io_reg, + .unreg = bpf_io_unreg, + .check_member = bpf_io_check_member, + .init_member = bpf_io_init_member, + .init = bpf_io_init, + .cfi_stubs = &io_bpf_ops_stubs, + .name = "io_uring_bpf_ops", + .owner = THIS_MODULE, +}; + +static int __init io_uring_bpf_init(void) +{ + int ret; + + ret = register_bpf_struct_ops(&bpf_ring_ops, io_uring_bpf_ops); + if (ret) { + pr_err("io_uring: Failed to register struct_ops (%d)\n", ret); + return ret; + } + + return 0; +} +__initcall(io_uring_bpf_init); diff --git a/io_uring/bpf-ops.h b/io_uring/bpf-ops.h new file mode 100644 index 000000000000..e8a08ae2df0a --- /dev/null +++ b/io_uring/bpf-ops.h @@ -0,0 +1,14 @@ +// SPDX-License-Identifier: GPL-2.0 +#ifndef IOU_BPF_OPS_H +#define IOU_BPF_OPS_H + +#include + +struct io_uring_bpf_ops { + int (*loop_step)(struct io_ring_ctx *ctx, struct iou_loop_params *lp); + + __u32 ring_fd; + void *priv; +}; + +#endif /* IOU_BPF_OPS_H */ diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 0c8bb4e8480a..548ea5a080a0 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -87,6 +87,7 @@ #include "msg_ring.h" #include "memmap.h" #include "zcrx.h" +#include "bpf-ops.h" #include "timeout.h" #include "poll.h" -- 2.52.0