[PATCH 09/15] bpf: Add bpf_ksym_add/del functions

Jiri Olsa
2020-03-12T19:57:09Z

Separating /proc/kallsyms add/del code and adding bpf_ksym_add/del
functions for that.

Moving bpf_prog_ksym_node_add/del functions to __bpf_ksym_add/del
and changing their argument to 'struct bpf_ksym' object. This way
we can call them for other bpf objects types like trampoline and
dispatcher.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
include/linux/bpf.h | 3 +++
kernel/bpf/core.c | 33 +++++++++++++++++++--------------
2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 739ec3f562bf..83920cbce24c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -584,6 +584,9 @@ struct bpf_image {
#define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image))
bool is_bpf_image_address(unsigned long address);
void *bpf_image_alloc(void);
+/* Called only from JIT-enabled code, so there's no need for stubs. */
+void bpf_ksym_add(struct bpf_ksym *ksym);
+void bpf_ksym_del(struct bpf_ksym *ksym);
#else
static inline struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
{
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 92577a81122a..cc360bfde1fe 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -607,20 +607,29 @@ static DEFINE_SPINLOCK(bpf_lock);
static LIST_HEAD(bpf_kallsyms);
static struct latch_tree_root bpf_tree __cacheline_aligned;

-static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux)
+void bpf_ksym_add(struct bpf_ksym *ksym)
{
- 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);
+ spin_lock_bh(&bpf_lock);
+ WARN_ON_ONCE(!list_empty(&ksym->lnode));
+ list_add_tail_rcu(&ksym->lnode, &bpf_kallsyms);
+ latch_tree_insert(&ksym->tnode, &bpf_tree, &bpf_tree_ops);
+ spin_unlock_bh(&bpf_lock);
}

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

- latch_tree_erase(&aux->ksym.tnode, &bpf_tree, &bpf_tree_ops);
- list_del_rcu(&aux->ksym.lnode);
+ latch_tree_erase(&ksym->tnode, &bpf_tree, &bpf_tree_ops);
+ list_del_rcu(&ksym->lnode);
+}
+
+void bpf_ksym_del(struct bpf_ksym *ksym)
+{
+ spin_lock_bh(&bpf_lock);
+ __bpf_ksym_del(ksym);
+ spin_unlock_bh(&bpf_lock);
}

static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp)
@@ -644,9 +653,7 @@ void bpf_prog_kallsyms_add(struct bpf_prog *fp)
bpf_prog_ksym_set_name(fp);
fp->aux->ksym.prog = true;

- spin_lock_bh(&bpf_lock);
- bpf_prog_ksym_node_add(fp->aux);
- spin_unlock_bh(&bpf_lock);
+ bpf_ksym_add(&fp->aux->ksym);
}

void bpf_prog_kallsyms_del(struct bpf_prog *fp)
@@ -654,9 +661,7 @@ void bpf_prog_kallsyms_del(struct bpf_prog *fp)
if (!bpf_prog_kallsyms_candidate(fp))
return;

- spin_lock_bh(&bpf_lock);
- bpf_prog_ksym_node_del(fp->aux);
- spin_unlock_bh(&bpf_lock);
+ bpf_ksym_del(&fp->aux->ksym);
}

static struct bpf_ksym *bpf_ksym_find(unsigned long addr)
--
2.24.1