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>

4 files changed, 51 insertions, 12 deletions

diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h
index bf863edb517d..1a66f907e5cc 100644
--- a/arch/arm/include/asm/idmap.h
+++ b/arch/arm/include/asm/idmap.h
@@ -8,6 +8,7 @@
 #define __idmap __section(.idmap.text) noinline notrace
 
 extern pgd_t *idmap_pgd;
+extern pgd_t *hyp_pgd;
 
 void setup_mm_for_reboot(void);
 
diff --git a/arch/arm/include/asm/pgtable-3level-hwdef.h b/arch/arm/include/asm/pgtable-3level-hwdef.h
index d7952824c5c4..a2d404ed1ade 100644
--- a/arch/arm/include/asm/pgtable-3level-hwdef.h
+++ b/arch/arm/include/asm/pgtable-3level-hwdef.h
@@ -44,6 +44,7 @@
 #define PMD_SECT_XN             (_AT(pmdval_t, 1) << 54)
 #define PMD_SECT_AP_WRITE       (_AT(pmdval_t, 0))
 #define PMD_SECT_AP_READ        (_AT(pmdval_t, 0))
+#define PMD_SECT_AP1            (_AT(pmdval_t, 1) << 6)
 #define PMD_SECT_TEX(x)         (_AT(pmdval_t, 0))
 
 /*
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 11c1785bf63e..b571484e9f03 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -19,7 +19,11 @@
         ALIGN_FUNCTION();                                               \
         VMLINUX_SYMBOL(__idmap_text_start) = .;                         \
         *(.idmap.text)                                                  \
-        VMLINUX_SYMBOL(__idmap_text_end) = .;
+        VMLINUX_SYMBOL(__idmap_text_end) = .;                           \
+        ALIGN_FUNCTION();                                               \
+        VMLINUX_SYMBOL(__hyp_idmap_text_start) = .;                     \
+        *(.hyp.idmap.text)                                              \
+        VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;
 
 #ifdef CONFIG_HOTPLUG_CPU
 #define ARM_CPU_DISCARD(x)
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);