bpf,powerpc: Add support for bpf arena and arena atomics

[bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions

Posted by Saket Kumar Bhaskar 2 months ago

bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
storing memory values depending on the size (byte, halfword,
word, doubleword).

Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 025524378443..489de21fe3d6 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -409,6 +409,36 @@ asm (
 "		blr				;"
 );
 
+static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off,
+					u32 code, u32 *image)
+{
+	u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
+	u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
+
+	switch (BPF_SIZE(code)) {
+	case BPF_B:
+		EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
+		break;
+	case BPF_H:
+		EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
+		break;
+	case BPF_W:
+		EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
+		break;
+	case BPF_DW:
+		if (off % 4) {
+			EMIT(PPC_RAW_LI(tmp2_reg, off));
+			EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
+		} else {
+			EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int emit_atomic_ld_st(const struct bpf_insn insn, struct codegen_context *ctx, u32 *image)
 {
 	u32 code = insn.code;
-- 
2.43.5

Re: [bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions

Posted by Christophe Leroy 2 months ago


Le 05/08/2025 à 08:27, Saket Kumar Bhaskar a écrit :
> bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
> storing memory values depending on the size (byte, halfword,
> word, doubleword).

Build break with this patch

   CC      arch/powerpc/net/bpf_jit_comp64.o
arch/powerpc/net/bpf_jit_comp64.c:395:12: error: 
'bpf_jit_emit_probe_mem_store' defined but not used 
[-Werror=unused-function]
  static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, 
u32 src_reg, s16 off,
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[4]: *** [scripts/Makefile.build:287: 
arch/powerpc/net/bpf_jit_comp64.o] Error 1


> 
> Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
> ---
>   arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
>   1 file changed, 30 insertions(+)
> 
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index 025524378443..489de21fe3d6 100644
> --- a/arch/powerpc/net/bpf_jit_comp64.c
> +++ b/arch/powerpc/net/bpf_jit_comp64.c
> @@ -409,6 +409,36 @@ asm (
>   "		blr				;"
>   );
>   
> +static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off,
> +					u32 code, u32 *image)
> +{
> +	u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
> +	u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
> +
> +	switch (BPF_SIZE(code)) {
> +	case BPF_B:
> +		EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
> +		break;
> +	case BPF_H:
> +		EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
> +		break;
> +	case BPF_W:
> +		EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
> +		break;
> +	case BPF_DW:
> +		if (off % 4) {
> +			EMIT(PPC_RAW_LI(tmp2_reg, off));
> +			EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
> +		} else {
> +			EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
> +		}
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
>   static int emit_atomic_ld_st(const struct bpf_insn insn, struct codegen_context *ctx, u32 *image)
>   {
>   	u32 code = insn.code;

Re: [bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions

Posted by Venkat Rao Bagalkote 2 months ago

On 05/08/25 1:04 pm, Christophe Leroy wrote:
>
>
> Le 05/08/2025 à 08:27, Saket Kumar Bhaskar a écrit :
>> bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
>> storing memory values depending on the size (byte, halfword,
>> word, doubleword).
>
> Build break with this patch
>
>   CC      arch/powerpc/net/bpf_jit_comp64.o
> arch/powerpc/net/bpf_jit_comp64.c:395:12: error: 
> 'bpf_jit_emit_probe_mem_store' defined but not used 
> [-Werror=unused-function]
>  static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, 
> u32 src_reg, s16 off,
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> make[4]: *** [scripts/Makefile.build:287: 
> arch/powerpc/net/bpf_jit_comp64.o] Error 1
>
I tried this on top of bpf-next, and for me build passed.

Note: I applied 
https://lore.kernel.org/bpf/20250717202935.29018-2-puranjay@kernel.org/ 
before applying current patch.

gcc version 14.2.1 20250110

uname -r: 6.16.0-gf2844c7fdb07

bpf-next repo: 
https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next

HEAD:

commit f3af62b6cee8af9f07012051874af2d2a451f0e5 (origin/master, origin/HEAD)
Author: Tao Chen <chen.dylane@linux.dev>
Date:   Wed Jul 23 22:44:42 2025 +0800

     bpftool: Add bash completion for token argument


Build Success logs:

   TEST-OBJ [test_progs-cpuv4] xdp_vlan.test.o
   TEST-OBJ [test_progs-cpuv4] xdpwall.test.o
   TEST-OBJ [test_progs-cpuv4] xfrm_info.test.o
   BINARY   bench
   BINARY   test_maps
   BINARY   test_progs
   BINARY   test_progs-no_alu32
   BINARY   test_progs-cpuv4


Regards,

Venkat.

>
>>
>> Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
>> ---
>>   arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
>>   1 file changed, 30 insertions(+)
>>
>> diff --git a/arch/powerpc/net/bpf_jit_comp64.c 
>> b/arch/powerpc/net/bpf_jit_comp64.c
>> index 025524378443..489de21fe3d6 100644
>> --- a/arch/powerpc/net/bpf_jit_comp64.c
>> +++ b/arch/powerpc/net/bpf_jit_comp64.c
>> @@ -409,6 +409,36 @@ asm (
>>   "        blr                ;"
>>   );
>>   +static int bpf_jit_emit_probe_mem_store(struct codegen_context 
>> *ctx, u32 src_reg, s16 off,
>> +                    u32 code, u32 *image)
>> +{
>> +    u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
>> +    u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
>> +
>> +    switch (BPF_SIZE(code)) {
>> +    case BPF_B:
>> +        EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
>> +        break;
>> +    case BPF_H:
>> +        EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
>> +        break;
>> +    case BPF_W:
>> +        EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
>> +        break;
>> +    case BPF_DW:
>> +        if (off % 4) {
>> +            EMIT(PPC_RAW_LI(tmp2_reg, off));
>> +            EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
>> +        } else {
>> +            EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
>> +        }
>> +        break;
>> +    default:
>> +        return -EINVAL;
>> +    }
>> +    return 0;
>> +}
>> +
>>   static int emit_atomic_ld_st(const struct bpf_insn insn, struct 
>> codegen_context *ctx, u32 *image)
>>   {
>>       u32 code = insn.code;
>

Re: [bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions

Posted by Christophe Leroy 2 months ago


Le 05/08/2025 à 13:59, Venkat Rao Bagalkote a écrit :
> 
> On 05/08/25 1:04 pm, Christophe Leroy wrote:
>>
>>
>> Le 05/08/2025 à 08:27, Saket Kumar Bhaskar a écrit :
>>> bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
>>> storing memory values depending on the size (byte, halfword,
>>> word, doubleword).
>>
>> Build break with this patch
>>
>>   CC      arch/powerpc/net/bpf_jit_comp64.o
>> arch/powerpc/net/bpf_jit_comp64.c:395:12: error: 
>> 'bpf_jit_emit_probe_mem_store' defined but not used [-Werror=unused- 
>> function]
>>  static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, 
>> u32 src_reg, s16 off,
>>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> cc1: all warnings being treated as errors
>> make[4]: *** [scripts/Makefile.build:287: arch/powerpc/net/ 
>> bpf_jit_comp64.o] Error 1
>>
> I tried this on top of bpf-next, and for me build passed.

Build of _this_ patch (alone) passed ?

This patch defines a static function but doesn't use it, so the build 
must breaks because of that, unless you have set CONFIG_PPC_DISABLE_WERROR.

Following patch starts using this function so then the build doesn't 
break anymore. But until next patch is applied the build doesn't work. 
Both patches have to be squashed together in order to not break 
bisectability of the kernel.

Christophe

> 
> Note: I applied https://eur01.safelinks.protection.outlook.com/? 
> url=https%3A%2F%2Flore.kernel.org%2Fbpf%2F20250717202935.29018-2- 
> puranjay%40kernel.org%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C0468473019834e07ef2b08ddd4179b9c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638899920058624267%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=iZLg9NUWxtH3vO1STI8wRYLzwvhohd2KKTAGYDe3WnM%3D&reserved=0 before applying current patch.
> 
> gcc version 14.2.1 20250110
> 
> uname -r: 6.16.0-gf2844c7fdb07
> 
> bpf-next repo: https://eur01.safelinks.protection.outlook.com/? 
> url=https%3A%2F%2Fkernel.googlesource.com%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fbpf%2Fbpf-next&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C0468473019834e07ef2b08ddd4179b9c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638899920058644309%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=OrMauttrzPbaFYhzKdkH5l%2FltISc95MwitnUC7YLhJQ%3D&reserved=0
> 
> HEAD:
> 
> commit f3af62b6cee8af9f07012051874af2d2a451f0e5 (origin/master, origin/ 
> HEAD)
> Author: Tao Chen <chen.dylane@linux.dev>
> Date:   Wed Jul 23 22:44:42 2025 +0800
> 
>      bpftool: Add bash completion for token argument
> 
> 
> Build Success logs:
> 
>    TEST-OBJ [test_progs-cpuv4] xdp_vlan.test.o
>    TEST-OBJ [test_progs-cpuv4] xdpwall.test.o
>    TEST-OBJ [test_progs-cpuv4] xfrm_info.test.o
>    BINARY   bench
>    BINARY   test_maps
>    BINARY   test_progs
>    BINARY   test_progs-no_alu32
>    BINARY   test_progs-cpuv4
> 
> 
> Regards,
> 
> Venkat.
> 
>>
>>>
>>> Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
>>> ---
>>>   arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
>>>   1 file changed, 30 insertions(+)
>>>
>>> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/ 
>>> bpf_jit_comp64.c
>>> index 025524378443..489de21fe3d6 100644
>>> --- a/arch/powerpc/net/bpf_jit_comp64.c
>>> +++ b/arch/powerpc/net/bpf_jit_comp64.c
>>> @@ -409,6 +409,36 @@ asm (
>>>   "        blr                ;"
>>>   );
>>>   +static int bpf_jit_emit_probe_mem_store(struct codegen_context 
>>> *ctx, u32 src_reg, s16 off,
>>> +                    u32 code, u32 *image)
>>> +{
>>> +    u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
>>> +    u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
>>> +
>>> +    switch (BPF_SIZE(code)) {
>>> +    case BPF_B:
>>> +        EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
>>> +        break;
>>> +    case BPF_H:
>>> +        EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
>>> +        break;
>>> +    case BPF_W:
>>> +        EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
>>> +        break;
>>> +    case BPF_DW:
>>> +        if (off % 4) {
>>> +            EMIT(PPC_RAW_LI(tmp2_reg, off));
>>> +            EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
>>> +        } else {
>>> +            EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
>>> +        }
>>> +        break;
>>> +    default:
>>> +        return -EINVAL;
>>> +    }
>>> +    return 0;
>>> +}
>>> +
>>>   static int emit_atomic_ld_st(const struct bpf_insn insn, struct 
>>> codegen_context *ctx, u32 *image)
>>>   {
>>>       u32 code = insn.code;
>>

Re: [bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions

Posted by Saket Kumar Bhaskar 1 month, 4 weeks ago

On Wed, Aug 06, 2025 at 08:59:59AM +0200, Christophe Leroy wrote:
> 
> 
> Le 05/08/2025 à 13:59, Venkat Rao Bagalkote a écrit :
> > 
> > On 05/08/25 1:04 pm, Christophe Leroy wrote:
> > > 
> > > 
> > > Le 05/08/2025 à 08:27, Saket Kumar Bhaskar a écrit :
> > > > bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
> > > > storing memory values depending on the size (byte, halfword,
> > > > word, doubleword).
> > > 
> > > Build break with this patch
> > > 
> > >   CC      arch/powerpc/net/bpf_jit_comp64.o
> > > arch/powerpc/net/bpf_jit_comp64.c:395:12: error:
> > > 'bpf_jit_emit_probe_mem_store' defined but not used [-Werror=unused-
> > > function]
> > >  static int bpf_jit_emit_probe_mem_store(struct codegen_context
> > > *ctx, u32 src_reg, s16 off,
> > >             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > cc1: all warnings being treated as errors
> > > make[4]: *** [scripts/Makefile.build:287: arch/powerpc/net/
> > > bpf_jit_comp64.o] Error 1
> > > 
> > I tried this on top of bpf-next, and for me build passed.
> 
> Build of _this_ patch (alone) passed ?
> 
> This patch defines a static function but doesn't use it, so the build must
> breaks because of that, unless you have set CONFIG_PPC_DISABLE_WERROR.
> 
> Following patch starts using this function so then the build doesn't break
> anymore. But until next patch is applied the build doesn't work. Both
> patches have to be squashed together in order to not break bisectability of
> the kernel.
> 
> Christophe
> 
Got it Chris, will squash both the patches together in v2.
> > 
> > Note: I applied https://eur01.safelinks.protection.outlook.com/?
> > url=https%3A%2F%2Flore.kernel.org%2Fbpf%2F20250717202935.29018-2- puranjay%40kernel.org%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C0468473019834e07ef2b08ddd4179b9c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638899920058624267%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=iZLg9NUWxtH3vO1STI8wRYLzwvhohd2KKTAGYDe3WnM%3D&reserved=0
> > before applying current patch.
> > 
> > gcc version 14.2.1 20250110
> > 
> > uname -r: 6.16.0-gf2844c7fdb07
> > 
> > bpf-next repo: https://eur01.safelinks.protection.outlook.com/? url=https%3A%2F%2Fkernel.googlesource.com%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fbpf%2Fbpf-next&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C0468473019834e07ef2b08ddd4179b9c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638899920058644309%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=OrMauttrzPbaFYhzKdkH5l%2FltISc95MwitnUC7YLhJQ%3D&reserved=0
> > 
> > HEAD:
> > 
> > commit f3af62b6cee8af9f07012051874af2d2a451f0e5 (origin/master, origin/
> > HEAD)
> > Author: Tao Chen <chen.dylane@linux.dev>
> > Date:   Wed Jul 23 22:44:42 2025 +0800
> > 
> >      bpftool: Add bash completion for token argument
> > 
> > 
> > Build Success logs:
> > 
> >    TEST-OBJ [test_progs-cpuv4] xdp_vlan.test.o
> >    TEST-OBJ [test_progs-cpuv4] xdpwall.test.o
> >    TEST-OBJ [test_progs-cpuv4] xfrm_info.test.o
> >    BINARY   bench
> >    BINARY   test_maps
> >    BINARY   test_progs
> >    BINARY   test_progs-no_alu32
> >    BINARY   test_progs-cpuv4
> > 
> > 
> > Regards,
> > 
> > Venkat.
> > 
> > > 
> > > > 
> > > > Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
> > > > ---
> > > >   arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
> > > >   1 file changed, 30 insertions(+)
> > > > 
> > > > diff --git a/arch/powerpc/net/bpf_jit_comp64.c
> > > > b/arch/powerpc/net/ bpf_jit_comp64.c
> > > > index 025524378443..489de21fe3d6 100644
> > > > --- a/arch/powerpc/net/bpf_jit_comp64.c
> > > > +++ b/arch/powerpc/net/bpf_jit_comp64.c
> > > > @@ -409,6 +409,36 @@ asm (
> > > >   "        blr                ;"
> > > >   );
> > > >   +static int bpf_jit_emit_probe_mem_store(struct
> > > > codegen_context *ctx, u32 src_reg, s16 off,
> > > > +                    u32 code, u32 *image)
> > > > +{
> > > > +    u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
> > > > +    u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
> > > > +
> > > > +    switch (BPF_SIZE(code)) {
> > > > +    case BPF_B:
> > > > +        EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
> > > > +        break;
> > > > +    case BPF_H:
> > > > +        EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
> > > > +        break;
> > > > +    case BPF_W:
> > > > +        EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
> > > > +        break;
> > > > +    case BPF_DW:
> > > > +        if (off % 4) {
> > > > +            EMIT(PPC_RAW_LI(tmp2_reg, off));
> > > > +            EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
> > > > +        } else {
> > > > +            EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
> > > > +        }
> > > > +        break;
> > > > +    default:
> > > > +        return -EINVAL;
> > > > +    }
> > > > +    return 0;
> > > > +}
> > > > +
> > > >   static int emit_atomic_ld_st(const struct bpf_insn insn,
> > > > struct codegen_context *ctx, u32 *image)
> > > >   {
> > > >       u32 code = insn.code;
> > > 
>

[bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions
[bpf-next 2/6] bpf,powerpc: Implement PROBE_MEM32 pseudo instructions
[bpf-next 3/6] bpf,powerpc: Implement bpf_addr_space_cast instruction
[bpf-next 4/6] bpf,powerpc: Introduce bpf_jit_emit_atomic_ops() to emit atomic instructions
[bpf-next 5/6] bpf,powerpc: Implement PROBE_ATOMIC instructions
[bpf-next 6/6] selftests/bpf: Fix arena_spin_lock selftest failure