[PATCH RFC bpf-next 5/7] bpf: introduce bpf_arch_text_poke_type

[Menglong Dong]

Introduce the function bpf_arch_text_poke_type(), which is able to specify
both the current and new opcode. If it is not implemented by the arch,
bpf_arch_text_poke() will be called directly if the current opcode is the
same as the new one. Otherwise, -EOPNOTSUPP will be returned.

Signed-off-by: Menglong Dong <dongml2@xxxxxxxxxxxxxxx>
---
 include/linux/bpf.h |  4 ++++
 kernel/bpf/core.c   | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d65a71042aa3..aec7c65539f5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3711,6 +3711,10 @@ enum bpf_text_poke_type {
 	BPF_MOD_JUMP,
 };
 
+int bpf_arch_text_poke_type(void *ip, enum bpf_text_poke_type old_t,
+			    enum bpf_text_poke_type new_t, void *addr1,
+			    void *addr2);
+
 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 		       void *addr1, void *addr2);
 
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index d595fe512498..608c636e6cf0 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -3135,6 +3135,16 @@ int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 	return -ENOTSUPP;
 }
 
+int __weak bpf_arch_text_poke_type(void *ip, enum bpf_text_poke_type old_t,
+				   enum bpf_text_poke_type new_t, void *old_addr,
+				   void *new_addr)
+{
+	if (old_t == new_t)
+		return bpf_arch_text_poke(ip, old_t, old_addr, new_addr);
+
+	return -EOPNOTSUPP;
+}
+
 void * __weak bpf_arch_text_copy(void *dst, void *src, size_t len)
 {
 	return ERR_PTR(-ENOTSUPP);
-- 
2.51.2