[PATCHv2 04/10] arm64/mm: enable __create_pgd_mapping() to run across different pgtable

[Pingfan Liu]

__create_pgd_mapping() is planned not only to be used in boot process,
but also after fully bootup. The latter means several callers can run
__create_pgd_mapping() concurrenlty.

In this case, PUP/PMD/PTE fixmap should be not used, instead, the
virtual addresss owned by each pgtable is used.

Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Kristina Martsenko <kristina.martsenko at arm.com>
Cc: James Morse <james.morse at arm.com>
Cc: Steven Price <steven.price at arm.com>
Cc: Jonathan Cameron <Jonathan.Cameron at huawei.com>
Cc: Pavel Tatashin <pasha.tatashin at soleen.com>
Cc: Anshuman Khandual <anshuman.khandual at arm.com>
Cc: Atish Patra <atish.patra at wdc.com>
Cc: Mike Rapoport <rppt at kernel.org>
Cc: Logan Gunthorpe <logang at deltatee.com>
Cc: Mark Brown <broonie at kernel.org>
To: linux-arm-kernel at lists.infradead.org

---
rfc -> v2:
  change allocator return type back to phys_addr_t
---
 arch/arm64/mm/mmu_include.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/mm/mmu_include.c b/arch/arm64/mm/mmu_include.c
index 732e603fe3fc..ac8850fe6ce2 100644
--- a/arch/arm64/mm/mmu_include.c
+++ b/arch/arm64/mm/mmu_include.c
@@ -7,6 +7,7 @@
 
 #define NO_BLOCK_MAPPINGS	BIT(0)
 #define NO_CONT_MAPPINGS	BIT(1)
+#define NO_FIXMAP	BIT(2)
 
 static bool pgattr_change_is_safe(u64 old, u64 new)
 {
@@ -43,11 +44,14 @@ static bool pgattr_change_is_safe(u64 old, u64 new)
 }
 
 static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
-		     phys_addr_t phys, pgprot_t prot)
+		     phys_addr_t phys, pgprot_t prot, int flags)
 {
 	pte_t *ptep;
 
-	ptep = pte_set_fixmap_offset(pmdp, addr);
+	if (likely(!(flags & NO_FIXMAP)))
+		ptep = pte_set_fixmap_offset(pmdp, addr);
+	else
+		ptep = pte_offset_kernel(pmdp, addr);
 	do {
 		pte_t old_pte = READ_ONCE(*ptep);
 
@@ -63,7 +67,8 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
 		phys += PAGE_SIZE;
 	} while (ptep++, addr += PAGE_SIZE, addr != end);
 
-	pte_clear_fixmap();
+	if (likely(!(flags & NO_FIXMAP)))
+		pte_clear_fixmap();
 }
 
 static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
@@ -97,7 +102,7 @@ static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
 		    (flags & NO_CONT_MAPPINGS) == 0)
 			__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
 
-		init_pte(pmdp, addr, next, phys, __prot);
+		init_pte(pmdp, addr, next, phys, __prot, flags);
 
 		phys += next - addr;
 	} while (addr = next, addr != end);
@@ -112,7 +117,10 @@ static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
 	unsigned long next;
 	pmd_t *pmdp;
 
-	pmdp = pmd_set_fixmap_offset(pudp, addr);
+	if (likely(!(flags & NO_FIXMAP)))
+		pmdp = pmd_set_fixmap_offset(pudp, addr);
+	else
+		pmdp = pmd_offset(pudp, addr);
 	do {
 		pmd_t old_pmd = READ_ONCE(*pmdp);
 
@@ -139,7 +147,8 @@ static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
 		phys += next - addr;
 	} while (pmdp++, addr = next, addr != end);
 
-	pmd_clear_fixmap();
+	if (likely(!(flags & NO_FIXMAP)))
+		pmd_clear_fixmap();
 }
 
 static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
@@ -215,7 +224,10 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 	}
 	BUG_ON(p4d_bad(p4d));
 
-	pudp = pud_set_fixmap_offset(p4dp, addr);
+	if (likely(!(flags & NO_FIXMAP)))
+		pudp = pud_set_fixmap_offset(p4dp, addr);
+	else
+		pudp = pud_offset(p4dp, addr);
 	do {
 		pud_t old_pud = READ_ONCE(*pudp);
 
@@ -244,7 +256,8 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 		phys += next - addr;
 	} while (pudp++, addr = next, addr != end);
 
-	pud_clear_fixmap();
+	if (likely(!(flags & NO_FIXMAP)))
+		pud_clear_fixmap();
 }
 
 static void __create_pgd_mapping(pgd_t *pgdir, unsigned int entries_cnt, phys_addr_t phys,
-- 
2.29.2