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bpf: Make the bpf_prog_array_map more generic

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All the map backends are of generic nature. In order to avoid
adding much special code into the eBPF core, rewrite part of
the bpf_prog_array map code and make it more generic. So the
new perf_event_array map type can reuse most of code with
bpf_prog_array map and add fewer lines of special code.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wang Nan 2015-08-06 07:02:33 +00:00 committed by David S. Miller
parent ffe8690c85
commit 2a36f0b92e
5 changed files with 60 additions and 38 deletions
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6
arch/x86/net/bpf_jit_comp.c
View File

@ -246,7 +246,7 @@ static void emit_prologue(u8 **pprog)
* goto out;
* if (++tail_call_cnt > MAX_TAIL_CALL_CNT)
* goto out;
* prog = array->prog[index];
* prog = array->ptrs[index];
* if (prog == NULL)
* goto out;
* goto *(prog->bpf_func + prologue_size);
@ -284,9 +284,9 @@ static void emit_bpf_tail_call(u8 **pprog)
EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */
EMIT2_off32(0x89, 0x85, -STACKSIZE + 36); /* mov dword ptr [rbp - 516], eax */
/* prog = array->prog[index]; */
/* prog = array->ptrs[index]; */
EMIT4_off32(0x48, 0x8D, 0x84, 0xD6, /* lea rax, [rsi + rdx * 8 + offsetof(...)] */
offsetof(struct bpf_array, prog));
offsetof(struct bpf_array, ptrs));
EMIT3(0x48, 0x8B, 0x00); /* mov rax, qword ptr [rax] */
/* if (prog == NULL)

8
include/linux/bpf.h
View File

@ -24,6 +24,10 @@ struct bpf_map_ops {
void *(*map_lookup_elem)(struct bpf_map *map, void *key);
int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
int (*map_delete_elem)(struct bpf_map *map, void *key);
/* funcs called by prog_array and perf_event_array map */
void *(*map_fd_get_ptr) (struct bpf_map *map, int fd);
void (*map_fd_put_ptr) (void *ptr);
};
struct bpf_map {
@ -142,13 +146,13 @@ struct bpf_array {
bool owner_jited;
union {
char value[0] __aligned(8);
struct bpf_prog *prog[0] __aligned(8);
void *ptrs[0] __aligned(8);
};
};
#define MAX_TAIL_CALL_CNT 32
u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
void bpf_prog_array_map_clear(struct bpf_map *map);
void bpf_fd_array_map_clear(struct bpf_map *map);
bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
const struct bpf_func_proto *bpf_get_trace_printk_proto(void);

78
kernel/bpf/arraymap.c
View File

@ -150,15 +150,15 @@ static int __init register_array_map(void)
}
late_initcall(register_array_map);
static struct bpf_map *prog_array_map_alloc(union bpf_attr *attr)
static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
{
/* only bpf_prog file descriptors can be stored in prog_array map */
/* only file descriptors can be stored in this type of map */
if (attr->value_size != sizeof(u32))
return ERR_PTR(-EINVAL);
return array_map_alloc(attr);
}
static void prog_array_map_free(struct bpf_map *map)
static void fd_array_map_free(struct bpf_map *map)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
@ -167,21 +167,21 @@ static void prog_array_map_free(struct bpf_map *map)
/* make sure it's empty */
for (i = 0; i < array->map.max_entries; i++)
BUG_ON(array->prog[i] != NULL);
BUG_ON(array->ptrs[i] != NULL);
kvfree(array);
}
static void *prog_array_map_lookup_elem(struct bpf_map *map, void *key)
static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
{
return NULL;
}
/* only called from syscall */
static int prog_array_map_update_elem(struct bpf_map *map, void *key,
static int fd_array_map_update_elem(struct bpf_map *map, void *key,
void *value, u64 map_flags)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *prog, *old_prog;
void *new_ptr, *old_ptr;
u32 index = *(u32 *)key, ufd;
if (map_flags != BPF_ANY)
@ -191,57 +191,75 @@ static int prog_array_map_update_elem(struct bpf_map *map, void *key,
return -E2BIG;
ufd = *(u32 *)value;
prog = bpf_prog_get(ufd);
if (IS_ERR(prog))
return PTR_ERR(prog);
new_ptr = map->ops->map_fd_get_ptr(map, ufd);
if (IS_ERR(new_ptr))
return PTR_ERR(new_ptr);
if (!bpf_prog_array_compatible(array, prog)) {
bpf_prog_put(prog);
return -EINVAL;
}
old_prog = xchg(array->prog + index, prog);
if (old_prog)
bpf_prog_put_rcu(old_prog);
old_ptr = xchg(array->ptrs + index, new_ptr);
if (old_ptr)
map->ops->map_fd_put_ptr(old_ptr);
return 0;
}
static int prog_array_map_delete_elem(struct bpf_map *map, void *key)
static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *old_prog;
void *old_ptr;
u32 index = *(u32 *)key;
if (index >= array->map.max_entries)
return -E2BIG;
old_prog = xchg(array->prog + index, NULL);
if (old_prog) {
bpf_prog_put_rcu(old_prog);
old_ptr = xchg(array->ptrs + index, NULL);
if (old_ptr) {
map->ops->map_fd_put_ptr(old_ptr);
return 0;
} else {
return -ENOENT;
}
}
static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *prog = bpf_prog_get(fd);
if (IS_ERR(prog))
return prog;
if (!bpf_prog_array_compatible(array, prog)) {
bpf_prog_put(prog);
return ERR_PTR(-EINVAL);
}
return prog;
}
static void prog_fd_array_put_ptr(void *ptr)
{
struct bpf_prog *prog = ptr;
bpf_prog_put_rcu(prog);
}
/* decrement refcnt of all bpf_progs that are stored in this map */
void bpf_prog_array_map_clear(struct bpf_map *map)
void bpf_fd_array_map_clear(struct bpf_map *map)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
for (i = 0; i < array->map.max_entries; i++)
prog_array_map_delete_elem(map, &i);
fd_array_map_delete_elem(map, &i);
}
static const struct bpf_map_ops prog_array_ops = {
.map_alloc = prog_array_map_alloc,
.map_free = prog_array_map_free,
.map_alloc = fd_array_map_alloc,
.map_free = fd_array_map_free,
.map_get_next_key = array_map_get_next_key,
.map_lookup_elem = prog_array_map_lookup_elem,
.map_update_elem = prog_array_map_update_elem,
.map_delete_elem = prog_array_map_delete_elem,
.map_lookup_elem = fd_array_map_lookup_elem,
.map_update_elem = fd_array_map_update_elem,
.map_delete_elem = fd_array_map_delete_elem,
.map_fd_get_ptr = prog_fd_array_get_ptr,
.map_fd_put_ptr = prog_fd_array_put_ptr,
};
static struct bpf_map_type_list prog_array_type __read_mostly = {

2
kernel/bpf/core.c
View File

@ -450,7 +450,7 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
tail_call_cnt++;
prog = READ_ONCE(array->prog[index]);
prog = READ_ONCE(array->ptrs[index]);
if (unlikely(!prog))
goto out;

2
kernel/bpf/syscall.c
View File

@ -72,7 +72,7 @@ static int bpf_map_release(struct inode *inode, struct file *filp)
/* prog_array stores refcnt-ed bpf_prog pointers
* release them all when user space closes prog_array_fd
*/
bpf_prog_array_map_clear(map);
bpf_fd_array_map_clear(map);
bpf_map_put(map);
return 0;