[PATCH RFC bpf-next 1/3] bpf: report probe fault to BPF stderr

[Menglong Dong <menglong8.dong@gmail.com>]

Introduce the function bpf_prog_report_probe_violation(), which is used
to report the memory probe fault to the user by the BPF stderr.

Signed-off-by: Menglong Dong <menglong.dong@linux.dev>
---
 include/linux/bpf.h      |  1 +
 kernel/trace/bpf_trace.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6338e54a9b1f..a31c5ce56c32 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2902,6 +2902,7 @@ void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
 void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);
 void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr);
 void bpf_prog_report_arena_violation(bool write, unsigned long addr, unsigned long fault_ip);
+void bpf_prog_report_probe_violation(bool write, unsigned long fault_ip);
 
 #else /* !CONFIG_BPF_SYSCALL */
 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 8f23f5273bab..9bd03a9f53db 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2055,6 +2055,24 @@ void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
 	module_put(mod);
 }
 
+void bpf_prog_report_probe_violation(bool write, unsigned long fault_ip)
+{
+	struct bpf_stream_stage ss;
+	struct bpf_prog *prog;
+
+	rcu_read_lock();
+	prog = bpf_prog_ksym_find(fault_ip);
+	rcu_read_unlock();
+	if (!prog)
+		return;
+
+	bpf_stream_stage(ss, prog, BPF_STDERR, ({
+		bpf_stream_printk(ss, "ERROR: Probe %s access faule, insn=0x%lx\n",
+				  write ? "WRITE" : "READ", fault_ip);
+		bpf_stream_dump_stack(ss);
+	}));
+}
+
 static __always_inline
 void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args)
 {
-- 
2.51.0