[PATCH 4/7] bpf: Add bpf_get_func_ip helper for kprobe programs

Jiri Olsa
2021-07-07T19:46:58Z

Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs,
so it's now possible to call bpf_get_func_ip from both kprobe and
kretprobe programs.

Taking the caller's address from 'struct kprobe::addr', which is
defined for both kprobe and kretprobe.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
include/uapi/linux/bpf.h | 2 +-
kernel/bpf/verifier.c | 2 ++
kernel/trace/bpf_trace.c | 17 +++++++++++++++++
tools/include/uapi/linux/bpf.h | 2 +-
4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 83e87ffdbb6e..4894f99a1993 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4783,7 +4783,7 @@ union bpf_attr {
*
* u64 bpf_get_func_ip(void *ctx)
* Description
- * Get address of the traced function (for tracing programs).
+ * Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
*/
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f975a3aa9368..79eb9d81a198 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5979,6 +5979,8 @@ static int has_get_func_ip(struct bpf_verifier_env *env)
return -ENOTSUPP;
}
return 0;
+ } else if (type == BPF_PROG_TYPE_KPROBE) {
+ return 0;
}

verbose(env, "func %s#%d not supported for program type %d\n",
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9edd3b1a00ad..55acf56b0c3a 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -17,6 +17,7 @@
#include <linux/error-injection.h>
#include <linux/btf_ids.h>
#include <linux/bpf_lsm.h>
+#include <linux/kprobes.h>

#include <net/bpf_sk_storage.h>

@@ -961,6 +962,20 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = {
.arg1_type = ARG_PTR_TO_CTX,
};

+BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
+{
+ struct kprobe *kp = kprobe_running();
+
+ return kp ? (u64) kp->addr : 0;
+}
+
+static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
+ .func = bpf_get_func_ip_kprobe,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
@@ -1092,6 +1107,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_override_return:
return &bpf_override_return_proto;
#endif
+ case BPF_FUNC_get_func_ip:
+ return &bpf_get_func_ip_proto_kprobe;
default:
return bpf_tracing_func_proto(func_id, prog);
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 83e87ffdbb6e..4894f99a1993 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4783,7 +4783,7 @@ union bpf_attr {
*
* u64 bpf_get_func_ip(void *ctx)
* Description
- * Get address of the traced function (for tracing programs).
+ * Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
*/
--
2.31.1