Merge branch 'bpf: Support bpf_get_func_ip helper in uprobes'

Jiri Olsa says:

====================
adding support for bpf_get_func_ip helper for uprobe program to return
probed address for both uprobe and return uprobe as suggested by Andrii
in [1].

We agreed that uprobe can have special use of bpf_get_func_ip helper
that differs from kprobe.

The kprobe bpf_get_func_ip returns:
  - address of the function if probe is attach on function entry
    for both kprobe and return kprobe
  - 0 if the probe is not attach on function entry

The uprobe bpf_get_func_ip returns:
  - address of the probe for both uprobe and return uprobe

The reason for this semantic change is that kernel can't really tell
if the probe user space address is function entry.

v3 changes:
  - removed bpf_get_func_ip_uprobe helper function [Yonghong]

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

[1] https://lore.kernel.org/bpf/CAEf4BzZ=xLVkG5eurEuvLU79wAMtwho7ReR+XJAgwhFF4M-7Cg@mail.gmail.com/
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

2 files changed, 13 insertions, 3 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index abe75063630b..db3fe5a61b05 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1819,6 +1819,7 @@ struct bpf_cg_run_ctx {
 struct bpf_trace_run_ctx {
 	struct bpf_run_ctx run_ctx;
 	u64 bpf_cookie;
+	bool is_uprobe;
 };
 
 struct bpf_tramp_run_ctx {
@@ -1867,6 +1868,8 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 	if (unlikely(!array))
 		return ret;
 
+	run_ctx.is_uprobe = false;
+
 	migrate_disable();
 	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
 	item = &array->items[0];
@@ -1891,8 +1894,8 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
  * rcu-protected dynamically sized maps.
  */
 static __always_inline u32
-bpf_prog_run_array_sleepable(const struct bpf_prog_array __rcu *array_rcu,
-			     const void *ctx, bpf_prog_run_fn run_prog)
+bpf_prog_run_array_uprobe(const struct bpf_prog_array __rcu *array_rcu,
+			  const void *ctx, bpf_prog_run_fn run_prog)
 {
 	const struct bpf_prog_array_item *item;
 	const struct bpf_prog *prog;
@@ -1906,6 +1909,8 @@ bpf_prog_run_array_sleepable(const struct bpf_prog_array __rcu *array_rcu,
 	rcu_read_lock_trace();
 	migrate_disable();
 
+	run_ctx.is_uprobe = true;
+
 	array = rcu_dereference_check(array_rcu, rcu_read_lock_trace_held());
 	if (unlikely(!array))
 		goto out;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 70da85200695..d21deb46f49f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5086,9 +5086,14 @@ union bpf_attr {
  * u64 bpf_get_func_ip(void *ctx)
  * 	Description
  * 		Get address of the traced function (for tracing and kprobe programs).
+ *
+ * 		When called for kprobe program attached as uprobe it returns
+ * 		probe address for both entry and return uprobe.
+ *
  * 	Return
- * 		Address of the traced function.
+ * 		Address of the traced function for kprobe.
  * 		0 for kprobes placed within the function (not at the entry).
+ * 		Address of the probe for uprobe and return uprobe.
  *
  * u64 bpf_get_attach_cookie(void *ctx)
  * 	Description