From: Chenghao Duan duanchenghao@kylinos.cn
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 --- arch/loongarch/net/bpf_jit.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
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;