ARM: Section based HYP idmap

Add a method (hyp_idmap_setup) to populate a hyp pgd with an
identity mapping of the code contained in the .hyp.idmap.text
section.

Offer a method to drop this identity mapping through
hyp_idmap_teardown.

Make all the above depend on CONFIG_ARM_VIRT_EXT and CONFIG_ARM_LPAE.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

1 files changed, 44 insertions, 11 deletions

diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index 99db769307ec..2dffc010cc41 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -1,4 +1,6 @@
+#include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/slab.h>
 
 #include <asm/cputype.h>
 #include <asm/idmap.h>
@@ -6,6 +8,7 @@
 #include <asm/pgtable.h>
 #include <asm/sections.h>
 #include <asm/system_info.h>
+#include <asm/virt.h>
 
 pgd_t *idmap_pgd;
 
@@ -59,11 +62,17 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
         } while (pud++, addr = next, addr != end);
 }
 
-static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
+static void identity_mapping_add(pgd_t *pgd, const char *text_start,
+                                 const char *text_end, unsigned long prot)
 {
-        unsigned long prot, next;
+        unsigned long addr, end;
+        unsigned long next;
+
+        addr = virt_to_phys(text_start);
+        end = virt_to_phys(text_end);
+
+        prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
 
-        prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
                 prot |= PMD_BIT4;
 
@@ -74,28 +83,52 @@ static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long e
         } while (pgd++, addr = next, addr != end);
 }
 
+#if defined(CONFIG_ARM_VIRT_EXT) && defined(CONFIG_ARM_LPAE)
+pgd_t *hyp_pgd;
+
+extern char  __hyp_idmap_text_start[], __hyp_idmap_text_end[];
+
+static int __init init_static_idmap_hyp(void)
+{
+        hyp_pgd = kzalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL);
+        if (!hyp_pgd)
+                return -ENOMEM;
+
+        pr_info("Setting up static HYP identity map for 0x%p - 0x%p\n",
+                __hyp_idmap_text_start, __hyp_idmap_text_end);
+        identity_mapping_add(hyp_pgd, __hyp_idmap_text_start,
+                             __hyp_idmap_text_end, PMD_SECT_AP1);
+
+        return 0;
+}
+#else
+static int __init init_static_idmap_hyp(void)
+{
+        return 0;
+}
+#endif
+
 extern char  __idmap_text_start[], __idmap_text_end[];
 
 static int __init init_static_idmap(void)
 {
-        phys_addr_t idmap_start, idmap_end;
+        int ret;
 
         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%p - 0x%p\n",
+                __idmap_text_start, __idmap_text_end);
+        identity_mapping_add(idmap_pgd, __idmap_text_start,
+                             __idmap_text_end, 0);
 
-        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);
+        ret = init_static_idmap_hyp();
 
         /* Flush L1 for the hardware to see this page table content */
         flush_cache_louis();
 
-        return 0;
+        return ret;
 }
 early_initcall(init_static_idmap);