arm64/mm: add create_pgd_mapping() to create private page tables

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.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

3 files changed, 30 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 210d632aa5ad..59079248529d 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 7d5dfe2d3de0..3f3d5aa4a8b1 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -158,20 +158,10 @@ 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;
-        }
 
         /*
          * Check for initial section mappings in the pgd/pud and remove them.
@@ -187,7 +177,8 @@ 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.
@@ -196,7 +187,7 @@ 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);
@@ -204,7 +195,7 @@ 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,
-                                  phys_addr_t phys, int map_io)
+                                  phys_addr_t phys, pgprot_t prot)
 {
         pud_t *pud;
         unsigned long next;
@@ -222,10 +213,11 @@ 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
@@ -240,7 +232,7 @@ 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);
@@ -252,7 +244,7 @@ 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;
 
@@ -262,7 +254,7 @@ 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);
 }
@@ -276,7 +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)
@@ -286,7 +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);
+}
+
+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)