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| author | Hengqi Chen <hengqi.chen@gmail.com> | 2025-10-02 22:39:52 +0800 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2025-10-02 22:39:52 +0800 |
| commit | 3d770bd11b943066db11dba7be0b6f0d81cb5d50 (patch) | |
| tree | 11a23b5a2a10bc82a8ee86cabbeaf625ffb91a62 | |
| parent | b0f50dc09bf008b2e581d5e6ad570d325725881c (diff) | |
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 b91e014f078e ("bpf: Make BPF trampoline use register_ftrace_direct() API")
* commit 9cdc3b6a299c ("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>
| -rw-r--r-- | arch/loongarch/net/bpf_jit.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index bee2e8e340e7..33e8942cc961 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -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); |