On Mon, Dec 22, 2025 at 9:50 AM Chenghao Duan <[email protected]> wrote:
>
> On Sat, Dec 20, 2025 at 10:07:25PM +0800, Hengqi Chen wrote:
> > 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
>
> Thank you for your review and for pointing out the API change in v6.19.
>
> I believe my patch series already accounts for this. It was developed on
> top of commit ae4a3160d19c ("bpf: specify the old and new poke_type for
> bpf_arch_text_poke"),
> so all modifications to bpf_arch_text_poke() call sites within my
> patches should already be using the updated signature.
Fine, it seems like the LoongArch tree is not up-to-date.
>
> Please let me know if you find any inconsistencies or if further
> adjustments are needed.
>
> Best regards,
> Chenghao
>
> >
> > > {
> > > 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
> > >
