Merge branch 'trampoline-fixes'

Jiri Olsa says:

====================
hi,
sending 2 fixes to fix kernel support for loading
trampoline programs in bcc/bpftrace and allow to
unwind through trampoline/dispatcher.

Original rfc post [1].

Speedup output of perf bench while running klockstat.py
on kprobes vs trampolines:

    Without:
            $ perf bench sched messaging -l 50000
            ...
                 Total time: 18.571 [sec]

    With current kprobe tracing:
            $ perf bench sched messaging -l 50000
            ...
                 Total time: 183.395 [sec]

    With kfunc tracing:
            $ perf bench sched messaging -l 50000
            ...
                 Total time: 39.773 [sec]

v4 changes:
  - rebased on latest bpf-next/master
  - removed image tree mutex and use trampoline_mutex instead
  - checking directly for string pointer in patch 1 [Alexei]
  - skipped helpers patches, as they are no longer needed [Alexei]

v3 changes:
  - added ack from John Fastabend for patch 1
  - move out is_bpf_image_address from is_bpf_text_address call [David]

v2 changes:
  - make the unwind work for dispatcher as well
  - added test for allowed trampolines count
  - used raw tp pt_regs nest-arrays for trampoline helpers

thanks,
jirka

[1] https://lore.kernel.org/netdev/20191229143740.29143-1-jolsa@kernel.org/
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a9687861fd7e..8e9ad3943cd9 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -525,7 +525,6 @@ 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);
-void *bpf_jit_alloc_exec_page(void);
 #define BPF_DISPATCHER_INIT(name) {			\
 	.mutex = __MUTEX_INITIALIZER(name.mutex),	\
 	.func = &name##func,				\
@@ -557,6 +556,13 @@ void *bpf_jit_alloc_exec_page(void);
 #define BPF_DISPATCHER_PTR(name) (&name)
 void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from,
 				struct bpf_prog *to);
+struct bpf_image {
+	struct latch_tree_node tnode;
+	unsigned char data[];
+};
+#define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image))
+bool is_bpf_image_address(unsigned long address);
+void *bpf_image_alloc(void);
 #else
 static inline struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 {
@@ -578,6 +584,10 @@ 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_image_address(unsigned long address)
+{
+	return false;
+}
 #endif
 
 struct bpf_func_info_aux {