Revert "x86-64/efi: Use EFI to deal with platform wall clock (again)"

This reverts commit bd52276fa1d4 ("x86-64/efi: Use EFI to deal with
platform wall clock (again)"), and the two supporting commits:

  da5a108d05b4: "x86/kernel: remove tboot 1:1 page table creation code"

  185034e72d59: "x86, efi: 1:1 pagetable mapping for virtual EFI calls")

as they all depend semantically on commit 53b87cf088e2 ("x86, mm:
Include the entire kernel memory map in trampoline_pgd") that got
reverted earlier due to the problems it caused.

This was pointed out by Yinghai Lu, and verified by me on my Macbook Air
that uses EFI.

Pointed-out-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 26 insertions, 19 deletions

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0a34d9e9c263..ad4439145f85 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -239,7 +239,22 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
         return status;
 }
 
-static int efi_set_rtc_mmss(unsigned long nowtime)
+static efi_status_t __init phys_efi_get_time(efi_time_t *tm,
+                                             efi_time_cap_t *tc)
+{
+        unsigned long flags;
+        efi_status_t status;
+
+        spin_lock_irqsave(&rtc_lock, flags);
+        efi_call_phys_prelog();
+        status = efi_call_phys2(efi_phys.get_time, virt_to_phys(tm),
+                                virt_to_phys(tc));
+        efi_call_phys_epilog();
+        spin_unlock_irqrestore(&rtc_lock, flags);
+        return status;
+}
+
+int efi_set_rtc_mmss(unsigned long nowtime)
 {
         int real_seconds, real_minutes;
         efi_status_t    status;
@@ -268,7 +283,7 @@ static int efi_set_rtc_mmss(unsigned long nowtime)
         return 0;
 }
 
-static unsigned long efi_get_time(void)
+unsigned long efi_get_time(void)
 {
         efi_status_t status;
         efi_time_t eft;
@@ -624,13 +639,18 @@ static int __init efi_runtime_init(void)
         }
         /*
          * We will only need *early* access to the following
-         * EFI runtime service before set_virtual_address_map
+         * two EFI runtime services before set_virtual_address_map
          * is invoked.
          */
+        efi_phys.get_time = (efi_get_time_t *)runtime->get_time;
         efi_phys.set_virtual_address_map =
                 (efi_set_virtual_address_map_t *)
                 runtime->set_virtual_address_map;
-
+        /*
+         * Make efi_get_time can be called before entering
+         * virtual mode.
+         */
+        efi.get_time = phys_efi_get_time;
         early_iounmap(runtime, sizeof(efi_runtime_services_t));
 
         return 0;
@@ -716,10 +736,12 @@ void __init efi_init(void)
                 efi_enabled = 0;
                 return;
         }
+#ifdef CONFIG_X86_32
         if (efi_is_native()) {
                 x86_platform.get_wallclock = efi_get_time;
                 x86_platform.set_wallclock = efi_set_rtc_mmss;
         }
+#endif
 
 #if EFI_DEBUG
         print_efi_memmap();
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 06c8b2e662ab..95fd505dfeb6 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -58,21 +58,6 @@ static void __init early_code_mapping_set_exec(int executable)
         }
 }
 
-unsigned long efi_call_virt_prelog(void)
-{
-        unsigned long saved;
-
-        saved = read_cr3();
-        write_cr3(real_mode_header->trampoline_pgd);
-
-        return saved;
-}
-
-void efi_call_virt_epilog(unsigned long saved)
-{
-        write_cr3(saved);
-}
-
 void __init efi_call_phys_prelog(void)
 {
         unsigned long vaddress;