[PATCH 06/15] bpf: Move ksym_tnode to bpf_ksym

Jiri Olsa
2020-03-12T19:56:51Z

Moving ksym_tnode list node to 'struct bpf_ksym' object,
so the symbol itself can be chained and used in other
objects like bpf_trampoline and bpf_dispatcher.

We need bpf_ksym object to be linked both in bpf_kallsyms
via lnode for /proc/kallsyms and in bpf_tree via tnode for
bpf address lookup functions like __bpf_address_lookup or
bpf_prog_kallsyms_find.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
include/linux/bpf.h | 2 +-
kernel/bpf/core.c | 24 ++++++++++--------------
2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index de624c4f66ec..c5afff03b0f4 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -477,6 +477,7 @@ struct bpf_ksym {
unsigned long end;
char name[KSYM_NAME_LEN];
struct list_head lnode;
+ struct latch_tree_node tnode;
};

enum bpf_tramp_prog_type {
@@ -659,7 +660,6 @@ struct bpf_prog_aux {
void *jit_data; /* JIT specific data. arch dependent */
struct bpf_jit_poke_descriptor *poke_tab;
u32 size_poke_tab;
- struct latch_tree_node ksym_tnode;
struct bpf_ksym ksym;
const struct bpf_prog_ops *ops;
struct bpf_map **used_maps;
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 084abfbc3362..df0caa4bc9cc 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -572,31 +572,27 @@ bpf_prog_ksym_set_name(struct bpf_prog *prog)
*sym = 0;
}

-static __always_inline unsigned long
-bpf_get_prog_addr_start(struct latch_tree_node *n)
+static unsigned long bpf_get_ksym_start(struct latch_tree_node *n)
{
- const struct bpf_prog_aux *aux;
-
- aux = container_of(n, struct bpf_prog_aux, ksym_tnode);
- return aux->ksym.start;
+ return container_of(n, struct bpf_ksym, tnode)->start;
}

static __always_inline bool bpf_tree_less(struct latch_tree_node *a,
struct latch_tree_node *b)
{
- return bpf_get_prog_addr_start(a) < bpf_get_prog_addr_start(b);
+ return bpf_get_ksym_start(a) < bpf_get_ksym_start(b);
}

static __always_inline int bpf_tree_comp(void *key, struct latch_tree_node *n)
{
unsigned long val = (unsigned long)key;
- const struct bpf_prog_aux *aux;
+ const struct bpf_ksym *ksym;

- aux = container_of(n, struct bpf_prog_aux, ksym_tnode);
+ ksym = container_of(n, struct bpf_ksym, tnode);

- if (val < aux->ksym.start)
+ if (val < ksym->start)
return -1;
- if (val >= aux->ksym.end)
+ if (val >= ksym->end)
return 1;

return 0;
@@ -615,7 +611,7 @@ static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux)
{
WARN_ON_ONCE(!list_empty(&aux->ksym.lnode));
list_add_tail_rcu(&aux->ksym.lnode, &bpf_kallsyms);
- latch_tree_insert(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops);
+ latch_tree_insert(&aux->ksym.tnode, &bpf_tree, &bpf_tree_ops);
}

static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux)
@@ -623,7 +619,7 @@ static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux)
if (list_empty(&aux->ksym.lnode))
return;

- latch_tree_erase(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops);
+ latch_tree_erase(&aux->ksym.tnode, &bpf_tree, &bpf_tree_ops);
list_del_rcu(&aux->ksym.lnode);
}

@@ -668,7 +664,7 @@ static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr)

n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops);
return n ?
- container_of(n, struct bpf_prog_aux, ksym_tnode)->prog :
+ container_of(n, struct bpf_prog_aux, ksym.tnode)->prog :
NULL;
}

--
2.24.1