[U-Boot] [PATCH 2/9] arm64: Make full va map code more dynamic

[Alexander Graf <agraf@suse.de>]

On 02/24/2016 06:01 PM, Stephen Warren wrote:
> On 02/24/2016 03:55 AM, Alexander Graf wrote:
>>
>>
>> On 23.02.16 14:17, Simon Glass wrote:
>>> Hi Alex,
>>>
>>> On 21 February 2016 at 18:57, Alexander Graf <agraf@suse.de> wrote:
>>>> The idea to generate our pages tables from an array of memory ranges
>>>> is very sound. However, instead of hard coding the code to create up
>>>> to 2 levels of 64k granule page tables, we really should just create
>>>> normal 4k page tables that allow us to set caching attributes on 2M
>>>> or 4k level later on.
>>>>
>>>> So this patch moves the full_va mapping code to 4k page size and
>>>> makes it fully flexible to dynamically create as many levels as
>>>> necessary for a map (including dynamic 1G/2M pages). It also adds
>>>> support to dynamically split a large map into smaller ones when
>>>> some code wants to set dcache attributes.
>>>>
>>>> With all this in place, there is very little reason to create your
>>>> own page tables in board specific files.
>>>>
>>>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>>> ---
>>>>   arch/arm/cpu/armv8/cache_v8.c      | 346 
>>>> +++++++++++++++++++++++++++++++------
>>>>   arch/arm/include/asm/armv8/mmu.h   |  68 ++++----
>>>>   arch/arm/include/asm/global_data.h |   4 +-
>>>>   arch/arm/include/asm/system.h      |   3 +-
>>>>   include/configs/thunderx_88xx.h    |  14 +-
>>>>   5 files changed, 332 insertions(+), 103 deletions(-)
>>>>
>>>
>>> Should the change to the thunderx file go in a separate patch?
>>
>> We're changing semantics for some defines from "this define acts in
>> L1/L2 page table entries" to "this define is for level/block type PTEs".
>> So it's tied to this patch :).
>>
>>>
>>>> diff --git a/arch/arm/cpu/armv8/cache_v8.c 
>>>> b/arch/arm/cpu/armv8/cache_v8.c
>>>> index 9229532..4369a83 100644
>>>> --- a/arch/arm/cpu/armv8/cache_v8.c
>>>> +++ b/arch/arm/cpu/armv8/cache_v8.c
>>>> @@ -2,6 +2,9 @@
>>>>    * (C) Copyright 2013
>>>>    * David Feng <fenghua@phytium.com.cn>
>>>>    *
>>>> + * (C) Copyright 2016
>>>> + * Alexander Graf <agraf@suse.de>
>>>> + *
>>>>    * SPDX-License-Identifier:    GPL-2.0+
>>>>    */
>>>>
>>>> @@ -9,35 +12,40 @@
>>>>   #include <asm/system.h>
>>>>   #include <asm/armv8/mmu.h>
>>>>
>>>> -DECLARE_GLOBAL_DATA_PTR;
>>>> -
>>>> -#ifndef CONFIG_SYS_DCACHE_OFF
>>>> +/* #define DEBUG_MMU */
>>>>
>>>> -#ifdef CONFIG_SYS_FULL_VA
>>>> -static void set_ptl1_entry(u64 index, u64 ptl2_entry)
>>>> -{
>>>> -       u64 *pgd = (u64 *)gd->arch.tlb_addr;
>>>> -       u64 value;
>>>> +#ifdef DEBUG_MMU
>>>> +#define DPRINTF(a, ...) printf("%s:%d: " a, __func__, __LINE__, 
>>>> __VA_ARGS__)
>>>> +#else
>>>> +#define DPRINTF(a, ...) do { } while(0)
>>>> +#endif
>>>
>>> Can you use the normal DEBUG and debug()?
>>
>> Uh, I guess so, yeah.
>>
>>>
>>>>
>>>> -       value = ptl2_entry | PTL1_TYPE_TABLE;
>>>> -       pgd[index] = value;
>>>> -}
>>>> +DECLARE_GLOBAL_DATA_PTR;
>>>>
>>>> -static void set_ptl2_block(u64 ptl1, u64 bfn, u64 address, u64 
>>>> memory_attrs)
>>>> -{
>>>> -       u64 *pmd = (u64 *)ptl1;
>>>> -       u64 value;
>>>> +#ifndef CONFIG_SYS_DCACHE_OFF
>>>>
>>>> -       value = address | PTL2_TYPE_BLOCK | PTL2_BLOCK_AF;
>>>> -       value |= memory_attrs;
>>>> -       pmd[bfn] = value;
>>>> -}
>>>> +/*
>>>> + *  With 4k page granule, a virtual address is split into 4 lookup 
>>>> parts
>>>> + *  spanning 9 bits each:
>>>> + *
>>>> + *    _______________________________________________
>>>> + *   |       |       |       |       |       |       |
>>>> + *   |   0   |  Lv0  |  Lv1  |  Lv2  |  Lv3  |  off  |
>>>> + *   |_______|_______|_______|_______|_______|_______|
>>>> + *     63-48   47-39   38-30   29-21   20-12   11-00
>>>> + *
>>>> + *             mask        page size
>>>> + *
>>>> + *    Lv0: FF8000000000       --
>>>> + *    Lv1:   7FC0000000       1G
>>>> + *    Lv2:     3FE00000       2M
>>>> + *    Lv3:       1FF000       4K
>>>> + *    off:          FFF
>>>> + */
>>>>
>>>> +#ifdef CONFIG_SYS_FULL_VA
>>>>   static struct mm_region mem_map[] = CONFIG_SYS_MEM_MAP;
>>>
>>> I am not ken on the idea of using a big #define table on these boards.
>>> Is there not a device-tree binding for this that we can use? It is
>>> just a data table, We are moving to Kconfig and eventually want to
>>> drop the config files.
>>
>> I'll move this into board files which then can do whatever they like
>> with it - take if from a #define in a header, populate it dynamically
>> from device tree, do something halfway in between, whatever fits your
>> needs best :).
>>
>> Btw, if you want to use dt for it, you don't need to add any new
>> bindings at all. Simply take all of your device regs/ranges and memory
>> ranges and gobble them into the memory map.
>
> That's only true if every single MMIO region that the code accesses is 
> already represented in DT already, or any DT conversion patches also 
> add any missing devices. It's quite unlikely that even on heavily 
> DT-dependant platforms that /all/ in-use MMIO regions are already 
> represented in DT. Such a conversion would need quite significant 
> testing.

Well, it's something I'd leave to the SoC / board maintainer really. 
With v2 you can now fiddle with the map as much as you like inside your 
code. The important bit to me is that we have a standardized path on how 
we map the mem_map table into the MMU. I don't care how we fetch the table.

Alex