[PATCHv8 bpf-next 04/13] bpf: Add support for uprobe multi session context

[Jiri Olsa <jolsa@kernel.org>]

Placing bpf_session_run_ctx layer in between bpf_run_ctx and
bpf_uprobe_multi_run_ctx, so the session data can be retrieved
from uprobe_multi link.

Plus granting session kfuncs access to uprobe session programs.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/trace/bpf_trace.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 5f10994376d0..01868039d7bc 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3098,7 +3098,7 @@ struct bpf_uprobe_multi_link {
 };
 
 struct bpf_uprobe_multi_run_ctx {
-	struct bpf_run_ctx run_ctx;
+	struct bpf_session_run_ctx session_ctx;
 	unsigned long entry_ip;
 	struct bpf_uprobe *uprobe;
 };
@@ -3211,16 +3211,22 @@ static const struct bpf_link_ops bpf_uprobe_multi_link_lops = {
 
 static int uprobe_prog_run(struct bpf_uprobe *uprobe,
 			   unsigned long entry_ip,
-			   struct pt_regs *regs)
+			   struct pt_regs *regs,
+			   bool is_return, void *data)
 {
 	struct bpf_uprobe_multi_link *link = uprobe->link;
 	struct bpf_uprobe_multi_run_ctx run_ctx = {
+		.session_ctx = {
+			.is_return = is_return,
+			.data = data,
+		},
 		.entry_ip = entry_ip,
 		.uprobe = uprobe,
 	};
 	struct bpf_prog *prog = link->link.prog;
 	bool sleepable = prog->sleepable;
 	struct bpf_run_ctx *old_run_ctx;
+	int err;
 
 	if (link->task && !same_thread_group(current, link->task))
 		return 0;
@@ -3232,8 +3238,8 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
 
 	migrate_disable();
 
-	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
-	bpf_prog_run(link->link.prog, regs);
+	old_run_ctx = bpf_set_run_ctx(&run_ctx.session_ctx.run_ctx);
+	err = bpf_prog_run(link->link.prog, regs);
 	bpf_reset_run_ctx(old_run_ctx);
 
 	migrate_enable();
@@ -3242,7 +3248,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
 		rcu_read_unlock_trace();
 	else
 		rcu_read_unlock();
-	return 0;
+	return err;
 }
 
 static bool
@@ -3262,7 +3268,7 @@ uprobe_multi_link_handler(struct uprobe_consumer *con, struct pt_regs *regs,
 	int ret;
 
 	uprobe = container_of(con, struct bpf_uprobe, consumer);
-	ret = uprobe_prog_run(uprobe, instruction_pointer(regs), regs);
+	ret = uprobe_prog_run(uprobe, instruction_pointer(regs), regs, false, data);
 	if (uprobe->session)
 		return ret ? UPROBE_HANDLER_IGNORE : 0;
 	return 0;
@@ -3275,7 +3281,7 @@ uprobe_multi_link_ret_handler(struct uprobe_consumer *con, unsigned long func, s
 	struct bpf_uprobe *uprobe;
 
 	uprobe = container_of(con, struct bpf_uprobe, consumer);
-	uprobe_prog_run(uprobe, func, regs);
+	uprobe_prog_run(uprobe, func, regs, true, data);
 	return 0;
 }
 
@@ -3283,7 +3289,8 @@ static u64 bpf_uprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
 {
 	struct bpf_uprobe_multi_run_ctx *run_ctx;
 
-	run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx, run_ctx);
+	run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx,
+			       session_ctx.run_ctx);
 	return run_ctx->entry_ip;
 }
 
@@ -3291,7 +3298,8 @@ static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
 {
 	struct bpf_uprobe_multi_run_ctx *run_ctx;
 
-	run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx, run_ctx);
+	run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx,
+			       session_ctx.run_ctx);
 	return run_ctx->uprobe->cookie;
 }
 
@@ -3485,7 +3493,7 @@ static int bpf_kprobe_multi_filter(const struct bpf_prog *prog, u32 kfunc_id)
 	if (!btf_id_set8_contains(&kprobe_multi_kfunc_set_ids, kfunc_id))
 		return 0;
 
-	if (!is_kprobe_session(prog))
+	if (!is_kprobe_session(prog) && !is_uprobe_session(prog))
 		return -EACCES;
 
 	return 0;
-- 
2.46.2