linux/net/bpf/bpf_dummy_struct_ops.c
Andrii Nakryiko 66c8473135 bpf: move sleepable flag from bpf_prog_aux to bpf_prog
prog->aux->sleepable is checked very frequently as part of (some) BPF
program run hot paths. So this extra aux indirection seems wasteful and
on busy systems might cause unnecessary memory cache misses.

Let's move sleepable flag into prog itself to eliminate unnecessary
pointer dereference.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Message-ID: <20240309004739.2961431-1-andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-11 16:41:25 -07:00

272 lines
6.4 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021. Huawei Technologies Co., Ltd
*/
#include <linux/kernel.h>
#include <linux/bpf_verifier.h>
#include <linux/bpf.h>
#include <linux/btf.h>
static struct bpf_struct_ops bpf_bpf_dummy_ops;
/* A common type for test_N with return value in bpf_dummy_ops */
typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
static int dummy_ops_test_ret_function(struct bpf_dummy_ops_state *state, ...)
{
return 0;
}
struct bpf_dummy_ops_test_args {
u64 args[MAX_BPF_FUNC_ARGS];
struct bpf_dummy_ops_state state;
};
static struct btf *bpf_dummy_ops_btf;
static struct bpf_dummy_ops_test_args *
dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
{
__u32 size_in;
struct bpf_dummy_ops_test_args *args;
void __user *ctx_in;
void __user *u_state;
size_in = kattr->test.ctx_size_in;
if (size_in != sizeof(u64) * nr)
return ERR_PTR(-EINVAL);
args = kzalloc(sizeof(*args), GFP_KERNEL);
if (!args)
return ERR_PTR(-ENOMEM);
ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
if (copy_from_user(args->args, ctx_in, size_in))
goto out;
/* args[0] is 0 means state argument of test_N will be NULL */
u_state = u64_to_user_ptr(args->args[0]);
if (u_state && copy_from_user(&args->state, u_state,
sizeof(args->state)))
goto out;
return args;
out:
kfree(args);
return ERR_PTR(-EFAULT);
}
static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args)
{
void __user *u_state;
u_state = u64_to_user_ptr(args->args[0]);
if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state)))
return -EFAULT;
return 0;
}
static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
{
dummy_ops_test_ret_fn test = (void *)image + cfi_get_offset();
struct bpf_dummy_ops_state *state = NULL;
/* state needs to be NULL if args[0] is 0 */
if (args->args[0])
state = &args->state;
return test(state, args->args[1], args->args[2],
args->args[3], args->args[4]);
}
extern const struct bpf_link_ops bpf_struct_ops_link_lops;
int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
const struct btf_type *func_proto;
struct bpf_dummy_ops_test_args *args;
struct bpf_tramp_links *tlinks;
struct bpf_tramp_link *link = NULL;
void *image = NULL;
unsigned int op_idx;
u32 image_off = 0;
int prog_ret;
s32 type_id;
int err;
type_id = btf_find_by_name_kind(bpf_dummy_ops_btf,
bpf_bpf_dummy_ops.name,
BTF_KIND_STRUCT);
if (type_id < 0)
return -EINVAL;
if (prog->aux->attach_btf_id != type_id)
return -EOPNOTSUPP;
func_proto = prog->aux->attach_func_proto;
args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
if (IS_ERR(args))
return PTR_ERR(args);
tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
if (!tlinks) {
err = -ENOMEM;
goto out;
}
link = kzalloc(sizeof(*link), GFP_USER);
if (!link) {
err = -ENOMEM;
goto out;
}
/* prog doesn't take the ownership of the reference from caller */
bpf_prog_inc(prog);
bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
op_idx = prog->expected_attach_type;
err = bpf_struct_ops_prepare_trampoline(tlinks, link,
&st_ops->func_models[op_idx],
&dummy_ops_test_ret_function,
&image, &image_off,
true);
if (err < 0)
goto out;
arch_protect_bpf_trampoline(image, PAGE_SIZE);
prog_ret = dummy_ops_call_op(image, args);
err = dummy_ops_copy_args(args);
if (err)
goto out;
if (put_user(prog_ret, &uattr->test.retval))
err = -EFAULT;
out:
kfree(args);
bpf_struct_ops_image_free(image);
if (link)
bpf_link_put(&link->link);
kfree(tlinks);
return err;
}
static int bpf_dummy_init(struct btf *btf)
{
bpf_dummy_ops_btf = btf;
return 0;
}
static bool bpf_dummy_ops_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
}
static int bpf_dummy_ops_check_member(const struct btf_type *t,
const struct btf_member *member,
const struct bpf_prog *prog)
{
u32 moff = __btf_member_bit_offset(t, member) / 8;
switch (moff) {
case offsetof(struct bpf_dummy_ops, test_sleepable):
break;
default:
if (prog->sleepable)
return -EINVAL;
}
return 0;
}
static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
const struct bpf_reg_state *reg,
int off, int size)
{
const struct btf_type *state;
const struct btf_type *t;
s32 type_id;
type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state",
BTF_KIND_STRUCT);
if (type_id < 0)
return -EINVAL;
t = btf_type_by_id(reg->btf, reg->btf_id);
state = btf_type_by_id(reg->btf, type_id);
if (t != state) {
bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
return -EACCES;
}
if (off + size > sizeof(struct bpf_dummy_ops_state)) {
bpf_log(log, "write access at off %d with size %d\n", off, size);
return -EACCES;
}
return NOT_INIT;
}
static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
.is_valid_access = bpf_dummy_ops_is_valid_access,
.btf_struct_access = bpf_dummy_ops_btf_struct_access,
};
static int bpf_dummy_init_member(const struct btf_type *t,
const struct btf_member *member,
void *kdata, const void *udata)
{
return -EOPNOTSUPP;
}
static int bpf_dummy_reg(void *kdata)
{
return -EOPNOTSUPP;
}
static void bpf_dummy_unreg(void *kdata)
{
}
static int bpf_dummy_test_1(struct bpf_dummy_ops_state *cb)
{
return 0;
}
static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2,
char a3, unsigned long a4)
{
return 0;
}
static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb)
{
return 0;
}
static struct bpf_dummy_ops __bpf_bpf_dummy_ops = {
.test_1 = bpf_dummy_test_1,
.test_2 = bpf_dummy_test_2,
.test_sleepable = bpf_dummy_test_sleepable,
};
static struct bpf_struct_ops bpf_bpf_dummy_ops = {
.verifier_ops = &bpf_dummy_verifier_ops,
.init = bpf_dummy_init,
.check_member = bpf_dummy_ops_check_member,
.init_member = bpf_dummy_init_member,
.reg = bpf_dummy_reg,
.unreg = bpf_dummy_unreg,
.name = "bpf_dummy_ops",
.cfi_stubs = &__bpf_bpf_dummy_ops,
.owner = THIS_MODULE,
};
static int __init bpf_dummy_struct_ops_init(void)
{
return register_bpf_struct_ops(&bpf_bpf_dummy_ops, bpf_dummy_ops);
}
late_initcall(bpf_dummy_struct_ops_init);