1 files changed, 91 insertions, 46 deletions

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 05615a3fdc6f..17243e43184e 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -28,8 +28,6 @@
 #include <linux/memblock.h>
 #include <linux/fs.h>
 #include <linux/io.h>
-#include <linux/slab.h>
-#include <linux/stop_machine.h>
 
 #include <asm/barrier.h>
 #include <asm/cputype.h>
@@ -42,6 +40,7 @@
 #include <asm/tlb.h>
 #include <asm/memblock.h>
 #include <asm/mmu_context.h>
+#include <asm/ptdump.h>
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
 
@@ -95,11 +94,24 @@ static phys_addr_t __init early_pgtable_alloc(void)
 	return phys;
 }
 
+static bool pgattr_change_is_safe(u64 old, u64 new)
+{
+	/*
+	 * The following mapping attributes may be updated in live
+	 * kernel mappings without the need for break-before-make.
+	 */
+	static const pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE;
+
+	return old  == 0 || new  == 0 || ((old ^ new) & ~mask) == 0;
+}
+
 static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 				  unsigned long end, unsigned long pfn,
 				  pgprot_t prot,
-				  phys_addr_t (*pgtable_alloc)(void))
+				  phys_addr_t (*pgtable_alloc)(void),
+				  bool page_mappings_only)
 {
+	pgprot_t __prot = prot;
 	pte_t *pte;
 
 	BUG_ON(pmd_sect(*pmd));
@@ -115,8 +127,28 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 
 	pte = pte_set_fixmap_offset(pmd, addr);
 	do {
-		set_pte(pte, pfn_pte(pfn, prot));
+		pte_t old_pte = *pte;
+
+		/*
+		 * Set the contiguous bit for the subsequent group of PTEs if
+		 * its size and alignment are appropriate.
+		 */
+		if (((addr | PFN_PHYS(pfn)) & ~CONT_PTE_MASK) == 0) {
+			if (end - addr >= CONT_PTE_SIZE && !page_mappings_only)
+				__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
+			else
+				__prot = prot;
+		}
+
+		set_pte(pte, pfn_pte(pfn, __prot));
 		pfn++;
+
+		/*
+		 * After the PTE entry has been populated once, we
+		 * only allow updates to the permission attributes.
+		 */
+		BUG_ON(!pgattr_change_is_safe(pte_val(old_pte), pte_val(*pte)));
+
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 
 	pte_clear_fixmap();
@@ -125,8 +157,9 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 				  phys_addr_t phys, pgprot_t prot,
 				  phys_addr_t (*pgtable_alloc)(void),
-				  bool allow_block_mappings)
+				  bool page_mappings_only)
 {
+	pgprot_t __prot = prot;
 	pmd_t *pmd;
 	unsigned long next;
 
@@ -146,27 +179,39 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 
 	pmd = pmd_set_fixmap_offset(pud, addr);
 	do {
+		pmd_t old_pmd = *pmd;
+
 		next = pmd_addr_end(addr, end);
+
 		/* try section mapping first */
 		if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
-		      allow_block_mappings) {
-			pmd_t old_pmd =*pmd;
-			pmd_set_huge(pmd, phys, prot);
+		      !page_mappings_only) {
 			/*
-			 * Check for previous table entries created during
-			 * boot (__create_page_tables) and flush them.
+			 * Set the contiguous bit for the subsequent group of
+			 * PMDs if its size and alignment are appropriate.
 			 */
-			if (!pmd_none(old_pmd)) {
-				flush_tlb_all();
-				if (pmd_table(old_pmd)) {
-					phys_addr_t table = pmd_page_paddr(old_pmd);
-					if (!WARN_ON_ONCE(slab_is_available()))
-						memblock_free(table, PAGE_SIZE);
-				}
+			if (((addr | phys) & ~CONT_PMD_MASK) == 0) {
+				if (end - addr >= CONT_PMD_SIZE)
+					__prot = __pgprot(pgprot_val(prot) |
+							  PTE_CONT);
+				else
+					__prot = prot;
 			}
+			pmd_set_huge(pmd, phys, __prot);
+
+			/*
+			 * After the PMD entry has been populated once, we
+			 * only allow updates to the permission attributes.
+			 */
+			BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd),
+						      pmd_val(*pmd)));
 		} else {
 			alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
-				       prot, pgtable_alloc);
+				       prot, pgtable_alloc,
+				       page_mappings_only);
+
+			BUG_ON(pmd_val(old_pmd) != 0 &&
+			       pmd_val(old_pmd) != pmd_val(*pmd));
 		}
 		phys += next - addr;
 	} while (pmd++, addr = next, addr != end);
@@ -189,7 +234,7 @@ static inline bool use_1G_block(unsigned long addr, unsigned long next,
 static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
 				  phys_addr_t phys, pgprot_t prot,
 				  phys_addr_t (*pgtable_alloc)(void),
-				  bool allow_block_mappings)
+				  bool page_mappings_only)
 {
 	pud_t *pud;
 	unsigned long next;
@@ -204,33 +249,28 @@ static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
 
 	pud = pud_set_fixmap_offset(pgd, addr);
 	do {
+		pud_t old_pud = *pud;
+
 		next = pud_addr_end(addr, end);
 
 		/*
 		 * For 4K granule only, attempt to put down a 1GB block
 		 */
-		if (use_1G_block(addr, next, phys) && allow_block_mappings) {
-			pud_t old_pud = *pud;
+		if (use_1G_block(addr, next, phys) && !page_mappings_only) {
 			pud_set_huge(pud, phys, prot);
 
 			/*
-			 * If we have an old value for a pud, it will
-			 * be pointing to a pmd table that we no longer
-			 * need (from swapper_pg_dir).
-			 *
-			 * Look up the old pmd table and free it.
+			 * After the PUD entry has been populated once, we
+			 * only allow updates to the permission attributes.
 			 */
-			if (!pud_none(old_pud)) {
-				flush_tlb_all();
-				if (pud_table(old_pud)) {
-					phys_addr_t table = pud_page_paddr(old_pud);
-					if (!WARN_ON_ONCE(slab_is_available()))
-						memblock_free(table, PAGE_SIZE);
-				}
-			}
+			BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
+						      pud_val(*pud)));
 		} else {
 			alloc_init_pmd(pud, addr, next, phys, prot,
-				       pgtable_alloc, allow_block_mappings);
+				       pgtable_alloc, page_mappings_only);
+
+			BUG_ON(pud_val(old_pud) != 0 &&
+			       pud_val(old_pud) != pud_val(*pud));
 		}
 		phys += next - addr;
 	} while (pud++, addr = next, addr != end);
@@ -242,7 +282,7 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
 				 unsigned long virt, phys_addr_t size,
 				 pgprot_t prot,
 				 phys_addr_t (*pgtable_alloc)(void),
-				 bool allow_block_mappings)
+				 bool page_mappings_only)
 {
 	unsigned long addr, length, end, next;
 	pgd_t *pgd = pgd_offset_raw(pgdir, virt);
@@ -262,7 +302,7 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
 	do {
 		next = pgd_addr_end(addr, end);
 		alloc_init_pud(pgd, addr, next, phys, prot, pgtable_alloc,
-			       allow_block_mappings);
+			       page_mappings_only);
 		phys += next - addr;
 	} while (pgd++, addr = next, addr != end);
 }
@@ -291,17 +331,17 @@ static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
 			&phys, virt);
 		return;
 	}
-	__create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, true);
+	__create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, false);
 }
 
 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 			       unsigned long virt, phys_addr_t size,
-			       pgprot_t prot, bool allow_block_mappings)
+			       pgprot_t prot, bool page_mappings_only)
 {
 	BUG_ON(mm == &init_mm);
 
 	__create_pgd_mapping(mm->pgd, phys, virt, size, prot,
-			     pgd_pgtable_alloc, allow_block_mappings);
+			     pgd_pgtable_alloc, page_mappings_only);
 }
 
 static void create_mapping_late(phys_addr_t phys, unsigned long virt,
@@ -314,7 +354,7 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
 	}
 
 	__create_pgd_mapping(init_mm.pgd, phys, virt, size, prot,
-			     NULL, !debug_pagealloc_enabled());
+			     NULL, debug_pagealloc_enabled());
 }
 
 static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
@@ -332,7 +372,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
 		__create_pgd_mapping(pgd, start, __phys_to_virt(start),
 				     end - start, PAGE_KERNEL,
 				     early_pgtable_alloc,
-				     !debug_pagealloc_enabled());
+				     debug_pagealloc_enabled());
 		return;
 	}
 
@@ -345,13 +385,13 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
 				     __phys_to_virt(start),
 				     kernel_start - start, PAGE_KERNEL,
 				     early_pgtable_alloc,
-				     !debug_pagealloc_enabled());
+				     debug_pagealloc_enabled());
 	if (kernel_end < end)
 		__create_pgd_mapping(pgd, kernel_end,
 				     __phys_to_virt(kernel_end),
 				     end - kernel_end, PAGE_KERNEL,
 				     early_pgtable_alloc,
-				     !debug_pagealloc_enabled());
+				     debug_pagealloc_enabled());
 
 	/*
 	 * Map the linear alias of the [_text, __init_begin) interval as
@@ -361,7 +401,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
 	 */
 	__create_pgd_mapping(pgd, kernel_start, __phys_to_virt(kernel_start),
 			     kernel_end - kernel_start, PAGE_KERNEL_RO,
-			     early_pgtable_alloc, !debug_pagealloc_enabled());
+			     early_pgtable_alloc, debug_pagealloc_enabled());
 }
 
 static void __init map_mem(pgd_t *pgd)
@@ -396,6 +436,11 @@ void mark_rodata_ro(void)
 	section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
 	create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
 			    section_size, PAGE_KERNEL_RO);
+
+	/* flush the TLBs after updating live kernel mappings */
+	flush_tlb_all();
+
+	debug_checkwx();
 }
 
 static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
@@ -408,7 +453,7 @@ static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
 	BUG_ON(!PAGE_ALIGNED(size));
 
 	__create_pgd_mapping(pgd, pa_start, (unsigned long)va_start, size, prot,
-			     early_pgtable_alloc, !debug_pagealloc_enabled());
+			     early_pgtable_alloc, debug_pagealloc_enabled());
 
 	vma->addr	= va_start;
 	vma->phys_addr	= pa_start;