arm64: MMU initialisation

This patch contains the initialisation of the memory blocks, MMU
attributes and the memory map. Only five memory types are defined:
Device nGnRnE (equivalent to Strongly Ordered), Device nGnRE (classic
Device memory), Device GRE, Normal Non-cacheable and Normal Cacheable.
Cache policies are supported via the memory attributes register
(MAIR_EL1) and only affect the Normal Cacheable mappings.

This patch also adds the SPARSEMEM_VMEMMAP initialisation.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 395 insertions, 0 deletions

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
new file mode 100644
index 0000000..a6885d8
--- /dev/null
+++ b/arch/arm64/mm/mmu.c
@@ -0,0 +1,395 @@
+/*
+ * Based on arch/arm/mm/mmu.c
+ *
+ * Copyright (C) 1995-2005 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/mman.h>
+#include <linux/nodemask.h>
+#include <linux/memblock.h>
+#include <linux/fs.h>
+
+#include <asm/cputype.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/sizes.h>
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+
+#include "mm.h"
+
+/*
+ * Empty_zero_page is a special page that is used for zero-initialized data
+ * and COW.
+ */
+struct page *empty_zero_page;
+EXPORT_SYMBOL(empty_zero_page);
+
+pgprot_t pgprot_default;
+EXPORT_SYMBOL(pgprot_default);
+
+static pmdval_t prot_sect_kernel;
+
+struct cachepolicy {
+	const char	policy[16];
+	u64		mair;
+	u64		tcr;
+};
+
+static struct cachepolicy cache_policies[] __initdata = {
+	{
+		.policy		= "uncached",
+		.mair		= 0x44,			/* inner, outer non-cacheable */
+		.tcr		= TCR_IRGN_NC | TCR_ORGN_NC,
+	}, {
+		.policy		= "writethrough",
+		.mair		= 0xaa,			/* inner, outer write-through, read-allocate */
+		.tcr		= TCR_IRGN_WT | TCR_ORGN_WT,
+	}, {
+		.policy		= "writeback",
+		.mair		= 0xee,			/* inner, outer write-back, read-allocate */
+		.tcr		= TCR_IRGN_WBnWA | TCR_ORGN_WBnWA,
+	}
+};
+
+/*
+ * These are useful for identifying cache coherency problems by allowing the
+ * cache or the cache and writebuffer to be turned off. It changes the Normal
+ * memory caching attributes in the MAIR_EL1 register.
+ */
+static int __init early_cachepolicy(char *p)
+{
+	int i;
+	u64 tmp;
+
+	for (i = 0; i < ARRAY_SIZE(cache_policies); i++) {
+		int len = strlen(cache_policies[i].policy);
+
+		if (memcmp(p, cache_policies[i].policy, len) == 0)
+			break;
+	}
+	if (i == ARRAY_SIZE(cache_policies)) {
+		pr_err("ERROR: unknown or unsupported cache policy: %s\n", p);
+		return 0;
+	}
+
+	flush_cache_all();
+
+	/*
+	 * Modify MT_NORMAL attributes in MAIR_EL1.
+	 */
+	asm volatile(
+	"	mrs	%0, mair_el1\n"
+	"	bfi	%0, %1, #%2, #8\n"
+	"	msr	mair_el1, %0\n"
+	"	isb\n"
+	: "=&r" (tmp)
+	: "r" (cache_policies[i].mair), "i" (MT_NORMAL * 8));
+
+	/*
+	 * Modify TCR PTW cacheability attributes.
+	 */
+	asm volatile(
+	"	mrs	%0, tcr_el1\n"
+	"	bic	%0, %0, %2\n"
+	"	orr	%0, %0, %1\n"
+	"	msr	tcr_el1, %0\n"
+	"	isb\n"
+	: "=&r" (tmp)
+	: "r" (cache_policies[i].tcr), "r" (TCR_IRGN_MASK | TCR_ORGN_MASK));
+
+	flush_cache_all();
+
+	return 0;
+}
+early_param("cachepolicy", early_cachepolicy);
+
+/*
+ * Adjust the PMD section entries according to the CPU in use.
+ */
+static void __init init_mem_pgprot(void)
+{
+	pteval_t default_pgprot;
+	int i;
+
+	default_pgprot = PTE_ATTRINDX(MT_NORMAL);
+	prot_sect_kernel = PMD_TYPE_SECT | PMD_SECT_AF | PMD_ATTRINDX(MT_NORMAL);
+
+#ifdef CONFIG_SMP
+	/*
+	 * Mark memory with the "shared" attribute for SMP systems
+	 */
+	default_pgprot |= PTE_SHARED;
+	prot_sect_kernel |= PMD_SECT_S;
+#endif
+
+	for (i = 0; i < 16; i++) {
+		unsigned long v = pgprot_val(protection_map[i]);
+		protection_map[i] = __pgprot(v | default_pgprot);
+	}
+
+	pgprot_default = __pgprot(PTE_TYPE_PAGE | PTE_AF | default_pgprot);
+}
+
+pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
+			      unsigned long size, pgprot_t vma_prot)
+{
+	if (!pfn_valid(pfn))
+		return pgprot_noncached(vma_prot);
+	else if (file->f_flags & O_SYNC)
+		return pgprot_writecombine(vma_prot);
+	return vma_prot;
+}
+EXPORT_SYMBOL(phys_mem_access_prot);
+
+static void __init *early_alloc(unsigned long sz)
+{
+	void *ptr = __va(memblock_alloc(sz, sz));
+	memset(ptr, 0, sz);
+	return ptr;
+}
+
+static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
+				  unsigned long end, unsigned long pfn)
+{
+	pte_t *pte;
+
+	if (pmd_none(*pmd)) {
+		pte = early_alloc(PTRS_PER_PTE * sizeof(pte_t));
+		__pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE);
+	}
+	BUG_ON(pmd_bad(*pmd));
+
+	pte = pte_offset_kernel(pmd, addr);
+	do {
+		set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
+		pfn++;
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+}
+
+static void __init alloc_init_pmd(pud_t *pud, unsigned long addr,
+				  unsigned long end, phys_addr_t phys)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	/*
+	 * Check for initial section mappings in the pgd/pud and remove them.
+	 */
+	if (pud_none(*pud) || pud_bad(*pud)) {
+		pmd = early_alloc(PTRS_PER_PMD * sizeof(pmd_t));
+		pud_populate(&init_mm, pud, pmd);
+	}
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		/* try section mapping first */
+		if (((addr | next | phys) & ~SECTION_MASK) == 0)
+			set_pmd(pmd, __pmd(phys | prot_sect_kernel));
+		else
+			alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys));
+		phys += next - addr;
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
+				  unsigned long end, unsigned long phys)
+{
+	pud_t *pud = pud_offset(pgd, addr);
+	unsigned long next;
+
+	do {
+		next = pud_addr_end(addr, end);
+		alloc_init_pmd(pud, addr, next, phys);
+		phys += next - addr;
+	} while (pud++, addr = next, addr != end);
+}
+
+/*
+ * Create the page directory entries and any necessary page tables for the
+ * mapping specified by 'md'.
+ */
+static void __init create_mapping(phys_addr_t phys, unsigned long virt,
+				  phys_addr_t size)
+{
+	unsigned long addr, length, end, next;
+	pgd_t *pgd;
+
+	if (virt < VMALLOC_START) {
+		pr_warning("BUG: not creating mapping for 0x%016llx at 0x%016lx - outside kernel range\n",
+			   phys, virt);
+		return;
+	}
+
+	addr = virt & PAGE_MASK;
+	length = PAGE_ALIGN(size + (virt & ~PAGE_MASK));
+
+	pgd = pgd_offset_k(addr);
+	end = addr + length;
+	do {
+		next = pgd_addr_end(addr, end);
+		alloc_init_pud(pgd, addr, next, phys);
+		phys += next - addr;
+	} while (pgd++, addr = next, addr != end);
+}
+
+static void __init map_mem(void)
+{
+	struct memblock_region *reg;
+
+	/* map all the memory banks */
+	for_each_memblock(memory, reg) {
+		phys_addr_t start = reg->base;
+		phys_addr_t end = start + reg->size;
+
+		if (start >= end)
+			break;
+
+		create_mapping(start, __phys_to_virt(start), end - start);
+	}
+}
+
+/*
+ * paging_init() sets up the page tables, initialises the zone memory
+ * maps and sets up the zero page.
+ */
+void __init paging_init(void)
+{
+	void *zero_page;
+
+	/*
+	 * Maximum PGDIR_SIZE addressable via the initial direct kernel
+	 * mapping in swapper_pg_dir.
+	 */
+	memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);
+
+	init_mem_pgprot();
+	map_mem();
+
+	/*
+	 * Finally flush the caches and tlb to ensure that we're in a
+	 * consistent state.
+	 */
+	flush_cache_all();
+	flush_tlb_all();
+
+	/* allocate the zero page. */
+	zero_page = early_alloc(PAGE_SIZE);
+
+	bootmem_init();
+
+	empty_zero_page = virt_to_page(zero_page);
+	__flush_dcache_page(empty_zero_page);
+
+	/*
+	 * TTBR0 is only used for the identity mapping at this stage. Make it
+	 * point to zero page to avoid speculatively fetching new entries.
+	 */
+	cpu_set_reserved_ttbr0();
+	flush_tlb_all();
+}
+
+/*
+ * Enable the identity mapping to allow the MMU disabling.
+ */
+void setup_mm_for_reboot(void)
+{
+	cpu_switch_mm(idmap_pg_dir, &init_mm);
+	flush_tlb_all();
+}
+
+/*
+ * Check whether a kernel address is valid (derived from arch/x86/).
+ */
+int kern_addr_valid(unsigned long addr)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	if ((((long)addr) >> VA_BITS) != -1UL)
+		return 0;
+
+	pgd = pgd_offset_k(addr);
+	if (pgd_none(*pgd))
+		return 0;
+
+	pud = pud_offset(pgd, addr);
+	if (pud_none(*pud))
+		return 0;
+
+	pmd = pmd_offset(pud, addr);
+	if (pmd_none(*pmd))
+		return 0;
+
+	pte = pte_offset_kernel(pmd, addr);
+	if (pte_none(*pte))
+		return 0;
+
+	return pfn_valid(pte_pfn(*pte));
+}
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+#ifdef CONFIG_ARM64_64K_PAGES
+int __meminit vmemmap_populate(struct page *start_page,
+			       unsigned long size, int node)
+{
+	return vmemmap_populate_basepages(start_page, size, node);
+}
+#else	/* !CONFIG_ARM64_64K_PAGES */
+int __meminit vmemmap_populate(struct page *start_page,
+			       unsigned long size, int node)
+{
+	unsigned long addr = (unsigned long)start_page;
+	unsigned long end = (unsigned long)(start_page + size);
+	unsigned long next;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	do {
+		next = pmd_addr_end(addr, end);
+
+		pgd = vmemmap_pgd_populate(addr, node);
+		if (!pgd)
+			return -ENOMEM;
+
+		pud = vmemmap_pud_populate(pgd, addr, node);
+		if (!pud)
+			return -ENOMEM;
+
+		pmd = pmd_offset(pud, addr);
+		if (pmd_none(*pmd)) {
+			void *p = NULL;
+
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+			if (!p)
+				return -ENOMEM;
+
+			set_pmd(pmd, __pmd(__pa(p) | prot_sect_kernel));
+		} else
+			vmemmap_verify((pte_t *)pmd, node, addr, next);
+	} while (addr = next, addr != end);
+
+	return 0;
+}
+#endif	/* CONFIG_ARM64_64K_PAGES */
+#endif	/* CONFIG_SPARSEMEM_VMEMMAP */