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SubjectRe: [PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size
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On 10/31/18 12:03 AM, Mike Rapoport wrote:
> On Tue, Oct 30, 2018 at 04:07:19PM -0700, Florian Fainelli 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@gmail.com>
>> ---
>> arch/arm64/mm/init.c | 21 +++++++++------------
>> 1 file changed, 9 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 3cf87341859f..e95cee656a55 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
>> @@ -460,13 +460,10 @@ void __init arm64_memblock_init(void)
>> */
>> memblock_reserve(__pa_symbol(_text), _end - _text);
>> #ifdef CONFIG_BLK_DEV_INITRD
>> - if (initrd_start) {
>
> There may be no initrd at all, so the condition here would rather become
>
> if (phys_initrd_start)

Or use phys_initrd_size, which would be consistent with how other
architectures typically test for this.

>
>> - memblock_reserve(initrd_start, initrd_end - initrd_start);
>> -
>> - /* the generic initrd code expects virtual addresses */
>> - initrd_start = __phys_to_virt(initrd_start);
>> - initrd_end = __phys_to_virt(initrd_end);
>> - }
>> + /* the generic initrd code expects virtual addresses */
>> + initrd_start = __phys_to_virt(phys_initrd_start);
>> + initrd_end = initrd_start + phys_initrd_size;
>> + initrd_below_start_ok = 0;
>> #endif
>
> I also wonder what is the reason to keep memstart_addr randomization and
> initrd setup interleaved?
>
> What we have now is roughly:
>
> 1) set memstart_addr
> 2) enforce memory_limit
> 3) reserve initrd
> 4) randomize memstart_addr
> 5) reserve text + data
> 6) reserve initrd again and set virtual addresses of initrd_{start,end}
>
> Maybe it's possible to merge (3) into (6) ?

That's kind of orthogonal to this patch series, but it's a valid
question, not sure I would want to tackle that just now though :)
--
Florian

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