Re: [PATCH v3 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size

[Florian Fainelli]

On 11/5/18 1:00 PM, Ard Biesheuvel wrote:
> On 5 November 2018 at 21:51, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
>> On 11/5/18 12:44 PM, Ard Biesheuvel wrote:
>>> On 5 November 2018 at 21:41, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
>>>> On 11/5/18 12:39 PM, Ard Biesheuvel wrote:
>>>>> Hi Florian,
>>>>>
>>>>> On 31 October 2018 at 20:28, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
>>>>>> ARM64 is the only architecture that re-defines
>>>>>> __early_init_dt_declare_initrd() in order for that function to populate
>>>>>> initrd_start/initrd_end with physical addresses instead of virtual
>>>>>> addresses. Instead of having an override we can leverage
>>>>>> drivers/of/fdt.c populating phys_initrd_start/phys_initrd_size to
>>>>>> populate those variables for us.
>>>>>>
>>>>>> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>>>>>> ---
>>>>>>  arch/arm64/mm/init.c | 19 +++++++++----------
>>>>>>  1 file changed, 9 insertions(+), 10 deletions(-)
>>>>>>
>>>>>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>>>>>> index 3cf87341859f..00ef2166bb73 100644
>>>>>> --- a/arch/arm64/mm/init.c
>>>>>> +++ b/arch/arm64/mm/init.c
>>>>>> @@ -72,8 +72,8 @@ static int __init early_initrd(char *p)
>>>>>>         if (*endp == ',') {
>>>>>>                 size = memparse(endp + 1, NULL);
>>>>>>
>>>>>> -               initrd_start = start;
>>>>>> -               initrd_end = start + size;
>>>>>> +               phys_initrd_start = start;
>>>>>> +               phys_initrd_size = size;
>>>>>>         }
>>>>>>         return 0;
>>>>>>  }
>>>>>> @@ -408,14 +408,14 @@ void __init arm64_memblock_init(void)
>>>>>>                 memblock_add(__pa_symbol(_text), (u64)(_end - _text));
>>>>>>         }
>>>>>>
>>>>>> -       if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
>>>>>> +       if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
>>>>>>                 /*
>>>>>>                  * Add back the memory we just removed if it results in the
>>>>>>                  * initrd to become inaccessible via the linear mapping.
>>>>>>                  * Otherwise, this is a no-op
>>>>>>                  */
>>>>>> -               u64 base = initrd_start & PAGE_MASK;
>>>>>> -               u64 size = PAGE_ALIGN(initrd_end) - base;
>>>>>> +               u64 base = phys_initrd_start & PAGE_MASK;
>>>>>> +               u64 size = PAGE_ALIGN(phys_initrd_size);
>>>>>>
>>>>>>                 /*
>>>>>>                  * We can only add back the initrd memory if we don't end up
>>>>>> @@ -460,12 +460,11 @@ void __init arm64_memblock_init(void)
>>>>>>          */
>>>>>>         memblock_reserve(__pa_symbol(_text), _end - _text);
>>>>>>  #ifdef CONFIG_BLK_DEV_INITRD
>>>>>> -       if (initrd_start) {
>>>>>> -               memblock_reserve(initrd_start, initrd_end - initrd_start);
>>>>>> -
>>>>>> +       if (phys_initrd_size) {
>>>>>>                 /* the generic initrd code expects virtual addresses */
>>>>>> -               initrd_start = __phys_to_virt(initrd_start);
>>>>>> -               initrd_end = __phys_to_virt(initrd_end);
>>>>>> +               initrd_start = __phys_to_virt(phys_initrd_start);
>>>>>> +               initrd_end = initrd_start + phys_initrd_size;
>>>>>> +               initrd_below_start_ok = 0;
>>>>>
>>>>> Where is this assignment coming from?
>>>>
>>>> __early_init_dt_declare_initrd() sets initrd_below_start_ok to 1 though
>>>> after patch #5 this is not necessary any more.
>>>
>>> Yes, but why? The original arm64 version of
>>> __early_init_dt_declare_initrd() does not set it but now you set to 1
>>> in the IS_ENABLED(CONFIG_ARM64) section in the generic code and set it
>>> back to 0 here.
>>
>> Humm, it is an if (!IS_ENABLED(CONFIG_ARM64)) condition, so we would not
>> be taking that branch on an ARM64 kernel.
>>
> 
> Right. So now that we are not setting it to 1 on arm64, there is no
> longer a reason to set it to 0 again, no?

Correct, and in fact, this is not a problem either at patch #4 (which
has the custom __early_init_dt_declare_initrd()) or #5 (which removes
it), any other feedback you would like me to address before addressing
Rob's suggestion?

> 
>> If you are saying the assignment is not necessary anymore after patch #5
>> , that is true, though this can only be done a part of part #5, not as
>> part of patch #4 in order not to break initrd functionality in-between
>> patches.
>>
>>>
>>> Or am I missing something?
>>>
>>
>> Not sure, I could be too, it's Monday after all :)
> 
> Yeah :-)
> 


-- 
Florian