[RFC bpf-next 03/10] bpf: Add support for uprobe multi session context

Jiri Olsa
2024-06-04T20:03:14Z

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.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/trace/bpf_trace.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 53b111c8e887..4392807ee8d9 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3181,7 +3181,7 @@ 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;
};
@@ -3294,10 +3294,15 @@ 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,
};
@@ -3316,7 +3321,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,

migrate_disable();

- old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
+ 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);

@@ -3345,7 +3350,7 @@ uprobe_multi_link_handler(struct uprobe_consumer *con, struct pt_regs *regs)
struct bpf_uprobe *uprobe;

uprobe = container_of(con, struct bpf_uprobe, consumer);
- return uprobe_prog_run(uprobe, instruction_pointer(regs), regs);
+ return uprobe_prog_run(uprobe, instruction_pointer(regs), regs, false, NULL);
}

static int
@@ -3354,7 +3359,7 @@ 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);
- return uprobe_prog_run(uprobe, func, regs);
+ return uprobe_prog_run(uprobe, func, regs, true, NULL);
}

static int
@@ -3364,7 +3369,7 @@ uprobe_multi_link_handler_session(struct uprobe_consumer *con, struct pt_regs *r
struct bpf_uprobe *uprobe;

uprobe = container_of(con, struct bpf_uprobe, consumer);
- return uprobe_prog_run(uprobe, instruction_pointer(regs), regs);
+ return uprobe_prog_run(uprobe, instruction_pointer(regs), regs, false, data);
}

static int
@@ -3374,14 +3379,14 @@ uprobe_multi_link_ret_handler_session(struct uprobe_consumer *con, unsigned long
struct bpf_uprobe *uprobe;

uprobe = container_of(con, struct bpf_uprobe, consumer);
- return uprobe_prog_run(uprobe, func, regs);
+ return uprobe_prog_run(uprobe, func, regs, true, data);
}

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;
}

@@ -3389,7 +3394,7 @@ 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;
}

@@ -3586,7 +3591,8 @@ 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;
--
2.45.1