The current implementation of bpf_arch_text_poke() requires 5 nops
at patch site which is not applicable for kernel/module functions.
With CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS=y, this can be done
by ftrace instead.
See the following commit for details:
* commit b91e014f078e ("bpf: Make BPF trampoline use register_ftrace_direct() API")
* commit 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support")
Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx>
---
arch/loongarch/net/bpf_jit.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
index 7b7e449b9ea9..35b13d91a979 100644
--- a/arch/loongarch/net/bpf_jit.c
+++ b/arch/loongarch/net/bpf_jit.c
@@ -1294,8 +1294,11 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type,
u32 old_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP};
u32 new_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP};
- if (!is_kernel_text((unsigned long)ip) &&
- !is_bpf_text_address((unsigned long)ip))
+ if (!is_bpf_text_address((unsigned long)ip))
+ /* Only poking bpf text is supported. Since kernel function
+ * entry is set up by ftrace, we reply on ftrace to poke kernel
+ * functions.
+ */
return -ENOTSUPP;
ret = emit_jump_or_nops(old_addr, ip, old_insns, is_call);
--
2.43.5
