diff options
| author | Chenghao Duan <duanchenghao@kylinos.cn> | 2026-01-06 10:55:02 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-01-08 10:17:21 +0100 |
| commit | e7a7d7e629c2abcc0ade47b148ebe71d5832ead9 (patch) | |
| tree | 80b402349d8dae289e5d90c84b5420d0b7a20d47 | |
| parent | 845306163962454083f97d9a2e22f67f94ac8e1f (diff) | |
LoongArch: BPF: Enhance the bpf_arch_text_poke() function
commit 73721d8676771c6c7b06d4e636cc053fc76afefd upstream.
Enhance the bpf_arch_text_poke() function to enable accurate location
of BPF program entry points.
When modifying the entry point of a BPF program, skip the "move t0, ra"
instruction to ensure the correct logic and copy of the jump address.
Cc: stable@vger.kernel.org
Fixes: 677e6123e3d2 ("LoongArch: BPF: Disable trampoline for kernel module function trace")
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/loongarch/net/bpf_jit.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 95c214e2cf09..87ff02513787 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -1307,6 +1307,10 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, void *old_addr, void *new_addr) { int ret; + unsigned long size = 0; + unsigned long offset = 0; + void *image = NULL; + char namebuf[KSYM_NAME_LEN]; bool is_call = (poke_type == BPF_MOD_CALL); u32 old_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP}; u32 new_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP}; @@ -1314,9 +1318,20 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, /* 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)) + if (!__bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf)) return -ENOTSUPP; + image = ip - offset; + + /* zero offset means we're poking bpf prog entry */ + if (offset == 0) { + /* skip to the nop instruction in bpf prog entry: + * move t0, ra + * nop + */ + ip = image + LOONGARCH_INSN_SIZE; + } + ret = emit_jump_or_nops(old_addr, ip, old_insns, is_call); if (ret) return ret; |