x86: EFI runtime code mapping enhancement

This patch enhances EFI runtime code memory mapping as following:

- Move __supported_pte_mask & _PAGE_NX checking before invoking
  runtime_code_page_mkexec(). This makes it possible for compiler to
  eliminate runtime_code_page_mkexec() on machine without NX support.

- Use set_memory_x/nx in early_mapping_set_exec(). This eliminates the
  duplicated implementation.

This patch has been tested on Intel x86_64 platform with EFI64/32
firmware.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 15 insertions, 23 deletions

diff --git a/arch/x86/kernel/efi.c b/arch/x86/kernel/efi.c
index b4d523276f40..cbdf9bacc575 100644
--- a/arch/x86/kernel/efi.c
+++ b/arch/x86/kernel/efi.c
@@ -384,9 +384,6 @@ static void __init runtime_code_page_mkexec(void)
         efi_memory_desc_t *md;
         void *p;
 
-        if (!(__supported_pte_mask & _PAGE_NX))
-                return;
-
         /* Make EFI runtime service code area executable */
         for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                 md = p;
@@ -476,7 +473,8 @@ void __init efi_enter_virtual_mode(void)
         efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
         efi.reset_system = virt_efi_reset_system;
         efi.set_virtual_address_map = virt_efi_set_virtual_address_map;
-        runtime_code_page_mkexec();
+        if (__supported_pte_mask & _PAGE_NX)
+                runtime_code_page_mkexec();
         early_iounmap(memmap.map, memmap.nr_map * memmap.desc_size);
         memmap.map = NULL;
 }
diff --git a/arch/x86/kernel/efi_64.c b/arch/x86/kernel/efi_64.c
index 09d5c2330934..d143a1e76b30 100644
--- a/arch/x86/kernel/efi_64.c
+++ b/arch/x86/kernel/efi_64.c
@@ -35,6 +35,7 @@
 #include <asm/tlbflush.h>
 #include <asm/proto.h>
 #include <asm/efi.h>
+#include <asm/cacheflush.h>
 
 static pgd_t save_pgd __initdata;
 static unsigned long efi_flags __initdata;
@@ -43,22 +44,15 @@ static void __init early_mapping_set_exec(unsigned long start,
                                           unsigned long end,
                                           int executable)
 {
-        pte_t *kpte;
-        unsigned int level;
-
-        while (start < end) {
-                kpte = lookup_address((unsigned long)__va(start), &level);
-                BUG_ON(!kpte);
-                if (executable)
-                        set_pte(kpte, pte_mkexec(*kpte));
-                else
-                        set_pte(kpte, __pte((pte_val(*kpte) | _PAGE_NX) & \
-                                            __supported_pte_mask));
-                if (level == PG_LEVEL_4K)
-                        start = (start + PAGE_SIZE) & PAGE_MASK;
-                else
-                        start = (start + PMD_SIZE) & PMD_MASK;
-        }
+        unsigned long num_pages;
+
+        start &= PMD_MASK;
+        end = (end + PMD_SIZE - 1) & PMD_MASK;
+        num_pages = (end - start) >> PAGE_SHIFT;
+        if (executable)
+                set_memory_x((unsigned long)__va(start), num_pages);
+        else
+                set_memory_nx((unsigned long)__va(start), num_pages);
 }
 
 static void __init early_runtime_code_mapping_set_exec(int executable)
@@ -74,7 +68,7 @@ static void __init early_runtime_code_mapping_set_exec(int executable)
                 md = p;
                 if (md->type == EFI_RUNTIME_SERVICES_CODE) {
                         unsigned long end;
-                        end = md->phys_addr + (md->num_pages << PAGE_SHIFT);
+                        end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT);
                         early_mapping_set_exec(md->phys_addr, end, executable);
                 }
         }
@@ -84,8 +78,8 @@ void __init efi_call_phys_prelog(void)
 {
         unsigned long vaddress;
 
-        local_irq_save(efi_flags);
         early_runtime_code_mapping_set_exec(1);
+        local_irq_save(efi_flags);
         vaddress = (unsigned long)__va(0x0UL);
         save_pgd = *pgd_offset_k(0x0UL);
         set_pgd(pgd_offset_k(0x0UL), *pgd_offset_k(vaddress));
@@ -98,9 +92,9 @@ void __init efi_call_phys_epilog(void)
          * After the lock is released, the original page table is restored.
          */
         set_pgd(pgd_offset_k(0x0UL), save_pgd);
-        early_runtime_code_mapping_set_exec(0);
         __flush_tlb_all();
         local_irq_restore(efi_flags);
+        early_runtime_code_mapping_set_exec(0);
 }
 
 void __init efi_reserve_bootmem(void)