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LoongArch: BPF: No text_poke() for kernel text

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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 b91e014f07 ("bpf: Make BPF trampoline use register_ftrace_direct() API")
  * commit 9cdc3b6a29 ("LoongArch: ftrace: Add direct call support")

Cc: stable@vger.kernel.org
Tested-by: Vincent Li <vincent.mc.li@gmail.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Hengqi Chen
2025-10-02 22:39:52 +08:00
committed by Huacai Chen
parent b0f50dc09b
commit 3d770bd11b
1 changed files with 4 additions and 2 deletions
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6
arch/loongarch/net/bpf_jit.c
View File

@@ -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);