[PATCH 05/15] bpf: Move lnode list node to struct bpf_ksym

Jiri Olsa
2020-03-12T19:56:43Z

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

Changing iterator to bpf_ksym in bpf_get_kallsym function.

The ksym->start is holding the prog->bpf_func value,
so it's ok to use it as value in bpf_get_kallsym.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
include/linux/bpf.h | 2 +-
kernel/bpf/core.c | 22 +++++++++++-----------
2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e1cd64f2bf05..de624c4f66ec 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -476,6 +476,7 @@ struct bpf_ksym {
unsigned long start;
unsigned long end;
char name[KSYM_NAME_LEN];
+ struct list_head lnode;
};

enum bpf_tramp_prog_type {
@@ -659,7 +660,6 @@ struct bpf_prog_aux {
struct bpf_jit_poke_descriptor *poke_tab;
u32 size_poke_tab;
struct latch_tree_node ksym_tnode;
- struct list_head ksym_lnode;
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 f86cb15d6f2e..084abfbc3362 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -97,7 +97,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag
fp->aux->prog = fp;
fp->jit_requested = ebpf_jit_enabled();

- INIT_LIST_HEAD_RCU(&fp->aux->ksym_lnode);
+ INIT_LIST_HEAD_RCU(&fp->aux->ksym.lnode);

return fp;
}
@@ -613,18 +613,18 @@ static struct latch_tree_root bpf_tree __cacheline_aligned;

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);
+ 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);
}

static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux)
{
- if (list_empty(&aux->ksym_lnode))
+ if (list_empty(&aux->ksym.lnode))
return;

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

static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp)
@@ -634,8 +634,8 @@ static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp)

static bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp)
{
- return list_empty(&fp->aux->ksym_lnode) ||
- fp->aux->ksym_lnode.prev == LIST_POISON2;
+ return list_empty(&fp->aux->ksym.lnode) ||
+ fp->aux->ksym.lnode.prev == LIST_POISON2;
}

void bpf_prog_kallsyms_add(struct bpf_prog *fp)
@@ -729,7 +729,7 @@ const struct exception_table_entry *search_bpf_extables(unsigned long addr)
int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *sym)
{
- struct bpf_prog_aux *aux;
+ struct bpf_ksym *ksym;
unsigned int it = 0;
int ret = -ERANGE;

@@ -737,13 +737,13 @@ int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
return ret;

rcu_read_lock();
- list_for_each_entry_rcu(aux, &bpf_kallsyms, ksym_lnode) {
+ list_for_each_entry_rcu(ksym, &bpf_kallsyms, lnode) {
if (it++ != symnum)
continue;

- strncpy(sym, aux->ksym.name, KSYM_NAME_LEN);
+ strncpy(sym, ksym->name, KSYM_NAME_LEN);

- *value = (unsigned long)aux->prog->bpf_func;
+ *value = ksym->start;
*type = BPF_SYM_ELF_TYPE;

ret = 0;
--
2.24.1