[v2,2/2] powerpc/bpf: enable kfunc call

Commit Message

Hari Bathini Feb. 1, 2024, 5:12 p.m. UTC

With module addresses supported, override bpf_jit_supports_kfunc_call()
to enable kfunc support. Module address offsets can be more than 32-bit
long, so override bpf_jit_supports_far_kfunc_call() to enable 64-bit
pointers.

Signed-off-by: Hari Bathini <[e-mail]>
---

* No changes since v1.


 arch/powerpc/net/bpf_jit_comp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Comments

Christophe Leroy Feb. 13, 2024, 7:54 a.m. UTC | #1

Le 01/02/2024 à 18:12, Hari Bathini a écrit :
> With module addresses supported, override bpf_jit_supports_kfunc_call()
> to enable kfunc support. Module address offsets can be more than 32-bit
> long, so override bpf_jit_supports_far_kfunc_call() to enable 64-bit
> pointers.

What's the impact on PPC32 ? There are no 64-bit pointers on PPC32.

> 
> Signed-off-by: Hari Bathini <[e-mail]>
> ---
> 
> * No changes since v1.
> 
> 
>   arch/powerpc/net/bpf_jit_comp.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
> index 7b4103b4c929..f896a4213696 100644
> --- a/arch/powerpc/net/bpf_jit_comp.c
> +++ b/arch/powerpc/net/bpf_jit_comp.c
> @@ -359,3 +359,13 @@ void bpf_jit_free(struct bpf_prog *fp)
>   
>   	bpf_prog_unlock_free(fp);
>   }
> +
> +bool bpf_jit_supports_kfunc_call(void)
> +{
> +	return true;
> +}
> +
> +bool bpf_jit_supports_far_kfunc_call(void)
> +{
> +	return true;
> +}

Hari Bathini Feb. 15, 2024, 10:35 a.m. UTC | #2

On 13/02/24 1:24 pm, Christophe Leroy wrote:
> 
> 
> Le 01/02/2024 à 18:12, Hari Bathini a écrit :
>> With module addresses supported, override bpf_jit_supports_kfunc_call()
>> to enable kfunc support. Module address offsets can be more than 32-bit
>> long, so override bpf_jit_supports_far_kfunc_call() to enable 64-bit
>> pointers.
> 
> What's the impact on PPC32 ? There are no 64-bit pointers on PPC32.

Yeah. Not required to return true for PPC32 case and probably not a
good thing to claim support for far kfunc calls for PPC32. Changing to:

+bool bpf_jit_supports_far_kfunc_call(void)
+{
+	return IS_ENABLED(CONFIG_PPC64);
+}

>>
>> Signed-off-by: Hari Bathini <[e-mail]>
>> ---
>>
>> * No changes since v1.
>>
>>
>>    arch/powerpc/net/bpf_jit_comp.c | 10 ++++++++++
>>    1 file changed, 10 insertions(+)
>>
>> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
>> index 7b4103b4c929..f896a4213696 100644
>> --- a/arch/powerpc/net/bpf_jit_comp.c
>> +++ b/arch/powerpc/net/bpf_jit_comp.c
>> @@ -359,3 +359,13 @@ void bpf_jit_free(struct bpf_prog *fp)
>>    
>>    	bpf_prog_unlock_free(fp);
>>    }
>> +
>> +bool bpf_jit_supports_kfunc_call(void)
>> +{
>> +	return true;
>> +}
>> +
>> +bool bpf_jit_supports_far_kfunc_call(void)
>> +{
>> +	return true;
>> +}

Naveen N Rao Feb. 15, 2024, 10:44 a.m. UTC | #3

On Tue, Feb 13, 2024 at 07:54:27AM +0000, Christophe Leroy wrote:
> 
> 
> Le 01/02/2024 à 18:12, Hari Bathini a écrit :
> > With module addresses supported, override bpf_jit_supports_kfunc_call()
> > to enable kfunc support. Module address offsets can be more than 32-bit
> > long, so override bpf_jit_supports_far_kfunc_call() to enable 64-bit
> > pointers.
> 
> What's the impact on PPC32 ? There are no 64-bit pointers on PPC32.

Looking at commit 1cf3bfc60f98 ("bpf: Support 64-bit pointers to 
kfuncs"), which added bpf_jit_supports_far_kfunc_call(), that does look 
to be very specific to platforms where module addresses are farther than 
s32. This is true for powerpc 64-bit, but shouldn't be needed for 
32-bit.

> 
> > 
> > Signed-off-by: Hari Bathini <[e-mail]>
> > ---
> > 
> > * No changes since v1.
> > 
> > 
> >   arch/powerpc/net/bpf_jit_comp.c | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> > 
> > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
> > index 7b4103b4c929..f896a4213696 100644
> > --- a/arch/powerpc/net/bpf_jit_comp.c
> > +++ b/arch/powerpc/net/bpf_jit_comp.c
> > @@ -359,3 +359,13 @@ void bpf_jit_free(struct bpf_prog *fp)
> >   
> >   	bpf_prog_unlock_free(fp);
> >   }
> > +
> > +bool bpf_jit_supports_kfunc_call(void)
> > +{
> > +	return true;
> > +}
> > +
> > +bool bpf_jit_supports_far_kfunc_call(void)
> > +{
> > +	return true;
> > +}

I am not sure there is value in keeping this as a separate patch since 
all support code for kfunc calls is introduced in an earlier patch.  
Consider folding this into the previous patch.

- Naveen

Patch

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 7b4103b4c929..f896a4213696 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -359,3 +359,13 @@  void bpf_jit_free(struct bpf_prog *fp)
 
 	bpf_prog_unlock_free(fp);
 }
+
+bool bpf_jit_supports_kfunc_call(void)
+{
+	return true;
+}
+
+bool bpf_jit_supports_far_kfunc_call(void)
+{
+	return true;
+}