mirror of
https://github.com/torvalds/linux.git
synced 2025-11-04 10:40:15 +02:00
c04167ce2c
This patch adds the possibility to obtain raw_smp_processor_id() in
eBPF. Currently, this is only possible in classic BPF where commit
da2033c282 ("filter: add SKF_AD_RXHASH and SKF_AD_CPU") has added
facilities for this.
Perhaps most importantly, this would also allow us to track per CPU
statistics with eBPF maps, or to implement a poor-man's per CPU data
structure through eBPF maps.
Example function proto-type looks like:
u32 (*smp_processor_id)(void) = (void *)BPF_FUNC_get_smp_processor_id;
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
113 lines
3.4 KiB
C
113 lines
3.4 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of version 2 of the GNU General Public
|
|
* License as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*/
|
|
#include <linux/bpf.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/random.h>
|
|
#include <linux/smp.h>
|
|
|
|
/* If kernel subsystem is allowing eBPF programs to call this function,
|
|
* inside its own verifier_ops->get_func_proto() callback it should return
|
|
* bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
|
|
*
|
|
* Different map implementations will rely on rcu in map methods
|
|
* lookup/update/delete, therefore eBPF programs must run under rcu lock
|
|
* if program is allowed to access maps, so check rcu_read_lock_held in
|
|
* all three functions.
|
|
*/
|
|
static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
|
|
{
|
|
/* verifier checked that R1 contains a valid pointer to bpf_map
|
|
* and R2 points to a program stack and map->key_size bytes were
|
|
* initialized
|
|
*/
|
|
struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
|
|
void *key = (void *) (unsigned long) r2;
|
|
void *value;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
value = map->ops->map_lookup_elem(map, key);
|
|
|
|
/* lookup() returns either pointer to element value or NULL
|
|
* which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type
|
|
*/
|
|
return (unsigned long) value;
|
|
}
|
|
|
|
const struct bpf_func_proto bpf_map_lookup_elem_proto = {
|
|
.func = bpf_map_lookup_elem,
|
|
.gpl_only = false,
|
|
.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
|
.arg2_type = ARG_PTR_TO_MAP_KEY,
|
|
};
|
|
|
|
static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
|
|
{
|
|
struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
|
|
void *key = (void *) (unsigned long) r2;
|
|
void *value = (void *) (unsigned long) r3;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
return map->ops->map_update_elem(map, key, value, r4);
|
|
}
|
|
|
|
const struct bpf_func_proto bpf_map_update_elem_proto = {
|
|
.func = bpf_map_update_elem,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
|
.arg2_type = ARG_PTR_TO_MAP_KEY,
|
|
.arg3_type = ARG_PTR_TO_MAP_VALUE,
|
|
.arg4_type = ARG_ANYTHING,
|
|
};
|
|
|
|
static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
|
|
{
|
|
struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
|
|
void *key = (void *) (unsigned long) r2;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
return map->ops->map_delete_elem(map, key);
|
|
}
|
|
|
|
const struct bpf_func_proto bpf_map_delete_elem_proto = {
|
|
.func = bpf_map_delete_elem,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
|
.arg2_type = ARG_PTR_TO_MAP_KEY,
|
|
};
|
|
|
|
static u64 bpf_get_prandom_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
|
|
{
|
|
return prandom_u32();
|
|
}
|
|
|
|
const struct bpf_func_proto bpf_get_prandom_u32_proto = {
|
|
.func = bpf_get_prandom_u32,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
};
|
|
|
|
static u64 bpf_get_smp_processor_id(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
|
|
{
|
|
return raw_smp_processor_id();
|
|
}
|
|
|
|
const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
|
|
.func = bpf_get_smp_processor_id,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
};
|