Commit 3d770bd1 authored by Hengqi Chen's avatar Hengqi Chen Committed by Huacai Chen
Browse files

LoongArch: BPF: No text_poke() for kernel text 



The current implementation of bpf_arch_text_poke() requires 5 nops
at patch site which is not applicable for kernel/module functions.
Because LoongArch reserves ONLY 2 nops at the function entry. With
CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS=y, this can be done by ftrace
instead.

See the following commit for details:
  * commit b91e014f ("bpf: Make BPF trampoline use register_ftrace_direct() API")
  * commit 9cdc3b6a ("LoongArch: ftrace: Add direct call support")

Cc: stable@vger.kernel.org
Tested-by: default avatarVincent Li <vincent.mc.li@gmail.com>
Signed-off-by: default avatarHengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent b0f50dc0

arch/loongarch/net/bpf_jit.c

+4 −2
Original line number Diff line number Diff line
@@ -1292,8 +1292,10 @@ 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))

	/* Only poking bpf text is supported. Since kernel function entry

	 * is set up by ftrace, we rely on ftrace to poke kernel functions.

	 */

	if (!is_bpf_text_address((unsigned long)ip))

		return -ENOTSUPP;



	ret = emit_jump_or_nops(old_addr, ip, old_insns, is_call);