On Wed, Dec 17, 2025 at 2:15 PM Chenghao Duan <[email protected]> wrote: > > 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. > > Signed-off-by: Chenghao Duan <[email protected]> > --- > arch/loongarch/net/bpf_jit.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c > index 3dbabacc8856..0c16a1b18e8f 100644 > --- a/arch/loongarch/net/bpf_jit.c > +++ b/arch/loongarch/net/bpf_jit.c > @@ -1290,6 +1290,10 @@ int bpf_arch_text_poke(void *ip, enum > bpf_text_poke_type old_t, > void *new_addr)
The signature of bpf_arch_text_poke() was changed in v6.19 ([1]), please rebase. [1]: https://github.com/torvalds/linux/commit/ae4a3160d19cd16b874737ebc1798c7bc2fe3c9e > { > int ret; > + unsigned long size = 0; > + unsigned long offset = 0; > + char namebuf[KSYM_NAME_LEN]; > + void *image = NULL; > bool is_call; > u32 old_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP}; > u32 new_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP}; > @@ -1297,9 +1301,18 @@ int bpf_arch_text_poke(void *ip, enum > bpf_text_poke_type old_t, > /* 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; > + > is_call = old_t == BPF_MOD_CALL; > ret = emit_jump_or_nops(old_addr, ip, old_insns, is_call); > if (ret) > -- > 2.25.1 >
