Re: [PATCH v2 02/10] arm64/mm: add create_pgd_mapping() to create private page tables

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On 7 November 2014 16:08, Steve Capper <steve.capper@xxxxxxxxxx> wrote:
> On Thu, Nov 06, 2014 at 03:13:18PM +0100, Ard Biesheuvel wrote:
>
> Hi Ard,
> Some comments below:
>
>> For UEFI, we need to install the memory mappings used for Runtime Services
>> in a dedicated set of page tables. Add create_pgd_mapping(), which allows
>> us to allocate and install those page table entries early.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
>> ---
>>  arch/arm64/include/asm/mmu.h     |  3 +++
>>  arch/arm64/include/asm/pgtable.h |  5 +++++
>>  arch/arm64/mm/mmu.c              | 44 +++++++++++++++++++++-------------------
>>  3 files changed, 31 insertions(+), 21 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
>> index c2f006c48bdb..5fd40c43be80 100644
>> --- a/arch/arm64/include/asm/mmu.h
>> +++ b/arch/arm64/include/asm/mmu.h
>> @@ -33,5 +33,8 @@ extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
>>  extern void init_mem_pgprot(void);
>>  /* create an identity mapping for memory (or io if map_io is true) */
>>  extern void create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io);
>> +extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
>> +                            unsigned long virt, phys_addr_t size,
>> +                            pgprot_t prot);
>>
>>  #endif
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index 41a43bf26492..1abe4d08725b 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -264,6 +264,11 @@ static inline pmd_t pte_pmd(pte_t pte)
>>       return __pmd(pte_val(pte));
>>  }
>>
>> +static inline pgprot_t mk_sect_prot(pgprot_t prot)
>> +{
>> +     return __pgprot(pgprot_val(prot) & ~PTE_TABLE_BIT);
>> +}
>> +
>>  /*
>>   * THP definitions.
>>   */
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 83e6713143a3..b6dc2ce3991a 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -157,20 +157,10 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
>>
>>  static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>>                                 unsigned long addr, unsigned long end,
>> -                               phys_addr_t phys, int map_io)
>> +                               phys_addr_t phys, pgprot_t prot)
>>  {
>>       pmd_t *pmd;
>>       unsigned long next;
>> -     pmdval_t prot_sect;
>> -     pgprot_t prot_pte;
>> -
>> -     if (map_io) {
>> -             prot_sect = PROT_SECT_DEVICE_nGnRE;
>> -             prot_pte = __pgprot(PROT_DEVICE_nGnRE);
>> -     } else {
>> -             prot_sect = PROT_SECT_NORMAL_EXEC;
>> -             prot_pte = PAGE_KERNEL_EXEC;
>> -     }
>
> Thanks :-)
>
>>
>>       /*
>>        * Check for initial section mappings in the pgd/pud and remove them.
>> @@ -186,7 +176,8 @@ static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>>               /* try section mapping first */
>>               if (((addr | next | phys) & ~SECTION_MASK) == 0) {
>>                       pmd_t old_pmd =*pmd;
>> -                     set_pmd(pmd, __pmd(phys | prot_sect));
>> +                     set_pmd(pmd, __pmd(phys |
>> +                                        pgprot_val(mk_sect_prot(prot))));
>>                       /*
>>                        * Check for previous table entries created during
>>                        * boot (__create_page_tables) and flush them.
>> @@ -195,7 +186,7 @@ static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>>                               flush_tlb_all();
>>               } else {
>>                       alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
>> -                                    prot_pte);
>> +                                    prot);
>>               }
>>               phys += next - addr;
>>       } while (pmd++, addr = next, addr != end);
>> @@ -203,7 +194,7 @@ static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>>
>>  static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>>                                 unsigned long addr, unsigned long end,
>> -                               unsigned long phys, int map_io)
>> +                               unsigned long phys, pgprot_t prot)
>>  {
>>       pud_t *pud;
>>       unsigned long next;
>> @@ -221,10 +212,11 @@ static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>>               /*
>>                * For 4K granule only, attempt to put down a 1GB block
>>                */
>> -             if (!map_io && (PAGE_SHIFT == 12) &&
>> +             if ((PAGE_SHIFT == 12) &&
>>                   ((addr | next | phys) & ~PUD_MASK) == 0) {
>>                       pud_t old_pud = *pud;
>> -                     set_pud(pud, __pud(phys | PROT_SECT_NORMAL_EXEC));
>> +                     set_pud(pud, __pud(phys |
>> +                                        pgprot_val(mk_sect_prot(prot))));
>>
>>                       /*
>>                        * If we have an old value for a pud, it will
>> @@ -239,7 +231,7 @@ static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>>                               flush_tlb_all();
>>                       }
>>               } else {
>> -                     alloc_init_pmd(mm, pud, addr, next, phys, map_io);
>> +                     alloc_init_pmd(mm, pud, addr, next, phys, prot);
>>               }
>>               phys += next - addr;
>>       } while (pud++, addr = next, addr != end);
>> @@ -251,7 +243,7 @@ static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>>   */
>>  static void __init __create_mapping(struct mm_struct *mm, pgd_t *pgd,
>>                                   phys_addr_t phys, unsigned long virt,
>> -                                 phys_addr_t size, int map_io)
>> +                                 phys_addr_t size, pgprot_t prot)
>>  {
>>       unsigned long addr, length, end, next;
>>
>> @@ -261,7 +253,8 @@ static void __init __create_mapping(struct mm_struct *mm, pgd_t *pgd,
>>       end = addr + length;
>>       do {
>>               next = pgd_addr_end(addr, end);
>> -             alloc_init_pud(mm, pgd, addr, next, phys, map_io);
>> +             alloc_init_pud(mm, pgd, addr, next, phys, prot);
>> +
>>               phys += next - addr;
>>       } while (pgd++, addr = next, addr != end);
>>  }
>> @@ -275,7 +268,7 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt,
>>               return;
>>       }
>>       __create_mapping(&init_mm, pgd_offset_k(virt & PAGE_MASK), phys, virt,
>> -                      size, 0);
>> +                      size, PAGE_KERNEL_EXEC);
>>  }
>>
>>  void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io)
>> @@ -285,7 +278,16 @@ void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io)
>>               return;
>>       }
>>       __create_mapping(&init_mm, &idmap_pg_dir[pgd_index(addr)],
>> -                      addr, addr, size, map_io);
>> +                      addr, addr, size,
>> +                      map_io ? __pgprot(PROT_DEVICE_nGnRE)
>> +                             : PAGE_KERNEL_EXEC);
>> +}
>
> Could you please also change efi_setup_idmap (it's the only caller I
> can see for create_id_mapping)?
>
> That way the prototype for create_id_mapping would look like:
> void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, pgprot_t prot)
>

I didn't bother because a couple of patches later, this stuff is all
ripped out anyway
(7/10 arm64/efi: remove idmap manipulations from UEFI code), because
there is no longer a need for UEFI to switch to the ID map.

Do you feel I should still change it here, and then remove it later?

Thanks,
Ard.


>> +
>> +void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
>> +                            unsigned long virt, phys_addr_t size,
>> +                            pgprot_t prot)
>> +{
>> +     __create_mapping(mm, pgd_offset(mm, virt), phys, virt, size, prot);
>>  }
>>
>>  static void __init map_mem(void)
>> --
>> 1.8.3.2
>>
>
> Cheers,
> --
> Steve
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