Re: [PATCH] powerpc/bpf: Enable bpf_probe_read{, str}() on powerpc again

Re: [PATCH] powerpc/bpf: Enable bpf_probe_read{, str}() on powerpc again

[Daniel Borkmann]

On 5/28/20 2:23 PM, Michael Ellerman wrote:
> Petr Mladek <pmladek@suse.com> writes:
>> On Thu 2020-05-28 11:03:43, Michael Ellerman wrote:
>>> Petr Mladek <pmladek@suse.com> writes:
>>>> The commit 0ebeea8ca8a4d1d453a ("bpf: Restrict bpf_probe_read{, str}() only
>>>> to archs where they work") caused that bpf_probe_read{, str}() functions
>>>> were not longer available on architectures where the same logical address
>>>> might have different content in kernel and user memory mapping. These
>>>> architectures should use probe_read_{user,kernel}_str helpers.
>>>>
>>>> For backward compatibility, the problematic functions are still available
>>>> on architectures where the user and kernel address spaces are not
>>>> overlapping. This is defined CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
>>>>
>>>> At the moment, these backward compatible functions are enabled only
>>>> on x86_64, arm, and arm64. Let's do it also on powerpc that has
>>>> the non overlapping address space as well.
>>>>
>>>> Signed-off-by: Petr Mladek <pmladek@suse.com>
>>>
>>> This seems like it should have a Fixes: tag and go into v5.7?
>>
>> Good point:
>>
>> Fixes: commit 0ebeea8ca8a4d1d4 ("bpf: Restrict bpf_probe_read{, str}() only to archs where they work")
>>
>> And yes, it should ideally go into v5.7 either directly or via stable.
>>
>> Should I resend the patch with Fixes and
>> Cc: stable@vger.kernel.org #v45.7 lines, please?
> 
> If it goes into v5.7 then it doesn't need a Cc: stable, and I guess a
> Fixes: tag is nice to have but not so important as it already mentions
> the commit that caused the problem. So a resend probably isn't
> necessary.
> 
> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
> 
> Daniel can you pick this up, or should I?

Yeah I'll take it into bpf tree for v5.7.

Thanks everyone,
Daniel

Re: [PATCH] powerpc/bpf: Enable bpf_probe_read{, str}() on powerpc again

[Michael Ellerman]

Daniel Borkmann <daniel@iogearbox.net> writes:
> On 5/28/20 2:23 PM, Michael Ellerman wrote:
>> Petr Mladek <pmladek@suse.com> writes:
>>> On Thu 2020-05-28 11:03:43, Michael Ellerman wrote:
>>>> Petr Mladek <pmladek@suse.com> writes:
>>>>> The commit 0ebeea8ca8a4d1d453a ("bpf: Restrict bpf_probe_read{, str}() only
>>>>> to archs where they work") caused that bpf_probe_read{, str}() functions
>>>>> were not longer available on architectures where the same logical address
>>>>> might have different content in kernel and user memory mapping. These
>>>>> architectures should use probe_read_{user,kernel}_str helpers.
>>>>>
>>>>> For backward compatibility, the problematic functions are still available
>>>>> on architectures where the user and kernel address spaces are not
>>>>> overlapping. This is defined CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
>>>>>
>>>>> At the moment, these backward compatible functions are enabled only
>>>>> on x86_64, arm, and arm64. Let's do it also on powerpc that has
>>>>> the non overlapping address space as well.
>>>>>
>>>>> Signed-off-by: Petr Mladek <pmladek@suse.com>
>>>>
>>>> This seems like it should have a Fixes: tag and go into v5.7?
>>>
>>> Good point:
>>>
>>> Fixes: commit 0ebeea8ca8a4d1d4 ("bpf: Restrict bpf_probe_read{, str}() only to archs where they work")
>>>
>>> And yes, it should ideally go into v5.7 either directly or via stable.
>>>
>>> Should I resend the patch with Fixes and
>>> Cc: stable@vger.kernel.org #v45.7 lines, please?
>> 
>> If it goes into v5.7 then it doesn't need a Cc: stable, and I guess a
>> Fixes: tag is nice to have but not so important as it already mentions
>> the commit that caused the problem. So a resend probably isn't
>> necessary.
>> 
>> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
>> 
>> Daniel can you pick this up, or should I?
>
> Yeah I'll take it into bpf tree for v5.7.

Thanks.

cheers