Merge branch 'Add bpf_get_func_ip helper'

Jiri Olsa says:

====================
Add bpf_get_func_ip helper that returns IP address of the
caller function for trampoline and krobe programs.

There're 2 specific implementation of the bpf_get_func_ip
helper, one for trampoline progs and one for kprobe/kretprobe
progs.

The trampoline helper call is replaced/inlined by the verifier
with simple move instruction. The kprobe/kretprobe is actual
helper call that returns prepared caller address.

Also available at:
  https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  bpf/get_func_ip

v4 changes:
  - dropped jit/x86 check for get_func_ip tracing check [Alexei]
  - added code to bpf_get_func_ip_tracing [Alexei]
    and tested that it works without inlining [Alexei]
  - changed has_get_func_ip to check_get_func_ip [Andrii]
  - replaced test assert loop with explicit asserts [Andrii]
  - adde bpf_program__attach_kprobe_opts function
    and use it for offset setup [Andrii]
  - used bpf_program__set_autoload(false) for test6 [Andrii]
  - added Masami's ack

v3 changes:
  - resend with Masami in cc and v3 in each patch subject

v2 changes:
  - use kprobe_running to get kprobe instead of cpu var [Masami]
  - added support to add kprobe on function+offset
    and test for that [Alan]
====================

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

3 files changed, 14 insertions, 1 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a9a4a480a6d0..94d77dc7ce35 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -579,6 +579,11 @@ struct btf_func_model {
  */
 #define BPF_TRAMP_F_SKIP_FRAME		BIT(2)
 
+/* Store IP address of the caller on the trampoline stack,
+ * so it's available for trampoline's programs.
+ */
+#define BPF_TRAMP_F_IP_ARG		BIT(3)
+
 /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50
  * bytes on x86.  Pick a number to fit into BPF_IMAGE_SIZE / 2
  */
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 472f97074da0..ba36989f711a 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -559,7 +559,8 @@ struct bpf_prog {
 				kprobe_override:1, /* Do we override a kprobe? */
 				has_callchain_buf:1, /* callchain buffer allocated? */
 				enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
-				call_get_stack:1; /* Do we call bpf_get_stack() or bpf_get_stackid() */
+				call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */
+				call_get_func_ip:1; /* Do we call get_func_ip() */
 	enum bpf_prog_type	type;		/* Type of BPF program */
 	enum bpf_attach_type	expected_attach_type; /* For some prog types */
 	u32			len;		/* Number of filter blocks */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3544ec5234f0..2db6925e04f4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4841,6 +4841,12 @@ union bpf_attr {
  *		**-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier.
  *		**-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its
  *		own timer which would have led to a deadlock otherwise.
+ *
+ * u64 bpf_get_func_ip(void *ctx)
+ * 	Description
+ * 		Get address of the traced function (for tracing and kprobe programs).
+ * 	Return
+ * 		Address of the traced function.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5016,6 +5022,7 @@ union bpf_attr {
 	FN(timer_set_callback),		\
 	FN(timer_start),		\
 	FN(timer_cancel),		\
+	FN(get_func_ip),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper