When unwinding the stack we need to identify each
address to successfully continue. Adding latch tree
to keep trampolines for quick lookup during the
unwind.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
include/linux/bpf.h | 6 ++++++
kernel/bpf/core.c | 2 ++
kernel/bpf/trampoline.c | 35 +++++++++++++++++++++++++++++++++++
3 files changed, 43 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b14e51d56a82..66825c821ac9 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -470,6 +470,7 @@ struct bpf_trampoline {
/* Executable image of trampoline */
void *image;
u64 selector;
+ struct latch_tree_node tnode;
};
#define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */
@@ -502,6 +503,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key);
int bpf_trampoline_link_prog(struct bpf_prog *prog);
int bpf_trampoline_unlink_prog(struct bpf_prog *prog);
void bpf_trampoline_put(struct bpf_trampoline *tr);
+bool is_bpf_trampoline(void *addr);
void *bpf_jit_alloc_exec_page(void);
#define BPF_DISPATCHER_INIT(name) { \
.mutex = __MUTEX_INITIALIZER(name.mutex), \
@@ -555,6 +557,10 @@ static inline void bpf_trampoline_put(struct bpf_trampoline *tr) {}
static inline void bpf_dispatcher_change_prog(struct bpf_dispatcher *d,
struct bpf_prog *from,
struct bpf_prog *to) {}
+static inline bool is_bpf_trampoline(void *addr)
+{
+ return false;
+}
#endif
struct bpf_func_info_aux {
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 29d47aae0dd1..63a515b5aa7b 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -704,6 +704,8 @@ bool is_bpf_text_address(unsigned long addr)
rcu_read_lock();
ret = bpf_prog_kallsyms_find(addr) != NULL;
+ if (!ret)
+ ret = is_bpf_trampoline((void*) addr);
rcu_read_unlock();
return ret;
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 505f4e4b31d2..4b5f0d0b0072 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -4,16 +4,44 @@
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/ftrace.h>
+#include <linux/rbtree_latch.h>
/* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */
#define TRAMPOLINE_HASH_BITS 10
#define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS)
static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE];
+static struct latch_tree_root tree __cacheline_aligned;
/* serializes access to trampoline_table */
static DEFINE_MUTEX(trampoline_mutex);
+static __always_inline bool tree_less(struct latch_tree_node *a,
+ struct latch_tree_node *b)
+{
+ struct bpf_trampoline *ta = container_of(a, struct bpf_trampoline, tnode);
+ struct bpf_trampoline *tb = container_of(b, struct bpf_trampoline, tnode);
+
+ return ta->image < tb->image;
+}
+
+static __always_inline int tree_comp(void *addr, struct latch_tree_node *n)
+{
+ struct bpf_trampoline *tr = container_of(n, struct bpf_trampoline, tnode);
+
+ if (addr < tr->image)
+ return -1;
+ if (addr >= tr->image + PAGE_SIZE)
+ return 1;
+
+ return 0;
+}
+
+static const struct latch_tree_ops tree_ops = {
+ .less = tree_less,
+ .comp = tree_comp,
+};
+
void *bpf_jit_alloc_exec_page(void)
{
void *image;
@@ -30,6 +58,11 @@ void *bpf_jit_alloc_exec_page(void)
return image;
}
+bool is_bpf_trampoline(void *addr)
+{
+ return latch_tree_find(addr, &tree, &tree_ops) != NULL;
+}
+
struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
{
struct bpf_trampoline *tr;
@@ -65,6 +98,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
for (i = 0; i < BPF_TRAMP_MAX; i++)
INIT_HLIST_HEAD(&tr->progs_hlist[i]);
tr->image = image;
+ latch_tree_insert(&tr->tnode, &tree, &tree_ops);
out:
mutex_unlock(&trampoline_mutex);
return tr;
@@ -252,6 +286,7 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
goto out;
bpf_jit_free_exec(tr->image);
hlist_del(&tr->hlist);
+ latch_tree_erase(&tr->tnode, &tree, &tree_ops);
kfree(tr);
out:
mutex_unlock(&trampoline_mutex);
--
2.21.1
