[v4] Fix the failure issue of the module_attach test case

[PATCH v4 6/7] LoongArch: BPF: Enhance the bpf_arch_text_poke() function

Posted by Chenghao Duan 1 month, 3 weeks ago

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 <duanchenghao@kylinos.cn>
---
 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)
 {
 	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

Re: [PATCH v4 6/7] LoongArch: BPF: Enhance the bpf_arch_text_poke() function

Posted by Hengqi Chen 1 month, 3 weeks ago

On Wed, Dec 17, 2025 at 2:15 PM Chenghao Duan <duanchenghao@kylinos.cn> 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 <duanchenghao@kylinos.cn>
> ---
>  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
>

Re: [PATCH v4 6/7] LoongArch: BPF: Enhance the bpf_arch_text_poke() function

Posted by Chenghao Duan 1 month, 2 weeks ago

On Sat, Dec 20, 2025 at 10:07:25PM +0800, Hengqi Chen wrote:
> On Wed, Dec 17, 2025 at 2:15 PM Chenghao Duan <duanchenghao@kylinos.cn> 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 <duanchenghao@kylinos.cn>
> > ---
> >  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.

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
> >

Re: [PATCH v4 6/7] LoongArch: BPF: Enhance the bpf_arch_text_poke() function

Posted by Hengqi Chen 1 month, 2 weeks ago

On Mon, Dec 22, 2025 at 9:50 AM Chenghao Duan <duanchenghao@kylinos.cn> 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 <duanchenghao@kylinos.cn> 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 <duanchenghao@kylinos.cn>
> > > ---
> > >  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
> > >

Re: [PATCH v4 6/7] LoongArch: BPF: Enhance the bpf_arch_text_poke() function

Posted by Huacai Chen 1 month, 2 weeks ago

On Tue, Dec 23, 2025 at 10:23 AM Hengqi Chen <hengqi.chen@gmail.com> wrote:
>
> On Mon, Dec 22, 2025 at 9:50 AM Chenghao Duan <duanchenghao@kylinos.cn> 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 <duanchenghao@kylinos.cn> 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 <duanchenghao@kylinos.cn>
> > > > ---
> > > >  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.
LoongArch tree now updated to 6.19-rc2, hope patches can be applied cleanly.

Huacai

>
> >
> > 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
> > > >
>