5 files changed, 51 insertions, 3 deletions

diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h
new file mode 100644
index 000000000000..62e3d19c9ad7
--- /dev/null
+++ b/arch/arm/include/asm/idmap.h
@@ -0,0 +1,17 @@
+#ifndef __ASM_IDMAP_H
+#define __ASM_IDMAP_H
+
+#include <linux/compiler.h>
+#include <asm/pgtable.h>
+
+/* Tag a function as requiring to be executed via an identity mapping. */
+#define __idmap __section(.idmap.text) noinline notrace
+
+extern pgd_t *idmap_pgd;
+
+void identity_mapping_add(pgd_t *, unsigned long, unsigned long);
+void identity_mapping_del(pgd_t *, unsigned long, unsigned long);
+
+void setup_mm_for_reboot(void);
+
+#endif  /* __ASM_IDMAP_H */
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9451dce3a553..03893a55e680 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -346,9 +346,6 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 
 #define pgtable_cache_init() do { } while (0)
 
-void identity_mapping_add(pgd_t *, unsigned long, unsigned long);
-void identity_mapping_del(pgd_t *, unsigned long, unsigned long);
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* CONFIG_MMU */
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index ef5640b9e218..8afadda37459 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -31,6 +31,7 @@
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 #include <asm/exception.h>
+#include <asm/idmap.h>
 #include <asm/topology.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 20b3041e0860..f76e75548670 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -13,6 +13,12 @@
         *(.proc.info.init)                                              \
         VMLINUX_SYMBOL(__proc_info_end) = .;
 
+#define IDMAP_TEXT                                                      \
+        ALIGN_FUNCTION();                                               \
+        VMLINUX_SYMBOL(__idmap_text_start) = .;                         \
+        *(.idmap.text)                                                  \
+        VMLINUX_SYMBOL(__idmap_text_end) = .;
+
 #ifdef CONFIG_HOTPLUG_CPU
 #define ARM_CPU_DISCARD(x)
 #define ARM_CPU_KEEP(x)         x
@@ -92,6 +98,7 @@ SECTIONS
                         SCHED_TEXT
                         LOCK_TEXT
                         KPROBES_TEXT
+                        IDMAP_TEXT
 #ifdef CONFIG_MMU
                         *(.fixup)
 #endif
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index 296ad2eaddb0..cda5ea3157a7 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -1,8 +1,12 @@
 #include <linux/kernel.h>
 
 #include <asm/cputype.h>
+#include <asm/idmap.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
+#include <asm/sections.h>
+
+pgd_t *idmap_pgd;
 
 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
         unsigned long prot)
@@ -73,6 +77,28 @@ void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
 }
 #endif
 
+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;
+}
+arch_initcall(init_static_idmap);
+
 /*
  * In order to soft-boot, we need to insert a 1:1 mapping in place of
  * the user-mode pages.  This will then ensure that we have predictable