1 files changed, 114 insertions, 0 deletions
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
new file mode 100644
index 00000000..ab88ed4f
--- /dev/null
+++ b/arch/arm/mm/idmap.c
@@ -0,0 +1,114 @@
+#include <linux/kernel.h>
+
+#include <asm/cputype.h>
+#include <asm/idmap.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/sections.h>
+#include <asm/system_info.h>
+
+pgd_t *idmap_pgd;
+
+#ifdef CONFIG_ARM_LPAE
+static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
+	unsigned long prot)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
+		pmd = pmd_alloc_one(&init_mm, addr);
+		if (!pmd) {
+			pr_warning("Failed to allocate identity pmd.\n");
+			return;
+		}
+		pud_populate(&init_mm, pud, pmd);
+		pmd += pmd_index(addr);
+	} else
+		pmd = pmd_offset(pud, addr);
+
+	do {
+		next = pmd_addr_end(addr, end);
+		*pmd = __pmd((addr & PMD_MASK) | prot);
+		flush_pmd_entry(pmd);
+	} while (pmd++, addr = next, addr != end);
+}
+#else	/* !CONFIG_ARM_LPAE */
+static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
+	unsigned long prot)
+{
+	pmd_t *pmd = pmd_offset(pud, addr);
+
+	addr = (addr & PMD_MASK) | prot;
+	pmd[0] = __pmd(addr);
+	addr += SECTION_SIZE;
+	pmd[1] = __pmd(addr);
+	flush_pmd_entry(pmd);
+}
+#endif	/* CONFIG_ARM_LPAE */
+
+static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
+	unsigned long prot)
+{
+	pud_t *pud = pud_offset(pgd, addr);
+	unsigned long next;
+
+	do {
+		next = pud_addr_end(addr, end);
+		idmap_add_pmd(pud, addr, next, prot);
+	} while (pud++, addr = next, addr != end);
+}
+
+static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+	unsigned long prot, next;
+
+	prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
+	if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
+		prot |= PMD_BIT4;
+
+	pgd += pgd_index(addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		idmap_add_pud(pgd, addr, next, prot);
+	} while (pgd++, addr = next, addr != end);
+}
+
+extern char  __idmap_text_start[], __idmap_text_end[];
+
+static int __init init_static_idmap(void)
+{
+	phys_addr_t idmap_start, idmap_end;
+
+	idmap_pgd = pgd_alloc(&init_mm);
+	if (!idmap_pgd)
+		return -ENOMEM;
+
+	/* Add an identity mapping for the physical address of the section. */
+	idmap_start = virt_to_phys((void *)__idmap_text_start);
+	idmap_end = virt_to_phys((void *)__idmap_text_end);
+
+	pr_info("Setting up static identity map for 0x%llx - 0x%llx\n",
+		(long long)idmap_start, (long long)idmap_end);
+	identity_mapping_add(idmap_pgd, idmap_start, idmap_end);
+
+	return 0;
+}
+early_initcall(init_static_idmap);
+
+/*
+ * In order to soft-boot, we need to switch to a 1:1 mapping for the
+ * cpu_reset functions. This will then ensure that we have predictable
+ * results when turning off the mmu.
+ */
+void setup_mm_for_reboot(void)
+{
+	/* Clean and invalidate L1. */
+	flush_cache_all();
+
+	/* Switch to the identity mapping. */
+	cpu_switch_mm(idmap_pgd, &init_mm);
+
+	/* Flush the TLB. */
+	local_flush_tlb_all();
+}