efi/x86: Split off some old memmap handling into separate routines

In a subsequent patch, we will fold the prolog/epilog routines that are
part of the support code to call SetVirtualAddressMap() with a 1:1
mapping into the callers. However, the 64-bit version mostly consists
of ugly mapping code that is only used when efi=old_map is in effect,
which is extremely rare. So let's move this code out of the way so it
does not clutter the common code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20200103113953.9571-7-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 03c2ed3c645cefe746fed8d5627c9a306977a9e8..a72bbabbc5953e1f588e931c209fb041a52a236c 100644 (file)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -72,7 +72,9 @@ static void __init early_code_mapping_set_exec(int executable)
        }
 }
 
-pgd_t * __init efi_call_phys_prolog(void)
+void __init efi_old_memmap_phys_epilog(pgd_t *save_pgd);
+
+pgd_t * __init efi_old_memmap_phys_prolog(void)
 {
        unsigned long vaddr, addr_pgd, addr_p4d, addr_pud;
        pgd_t *save_pgd, *pgd_k, *pgd_efi;
@@ -82,11 +84,6 @@ pgd_t * __init efi_call_phys_prolog(void)
        int pgd;
        int n_pgds, i, j;
 
-       if (!efi_enabled(EFI_OLD_MEMMAP)) {
-               efi_switch_mm(&efi_mm);
-               return efi_mm.pgd;
-       }
-
        early_code_mapping_set_exec(1);
 
        n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
@@ -143,11 +140,11 @@ pgd_t * __init efi_call_phys_prolog(void)
        __flush_tlb_all();
        return save_pgd;
 out:
-       efi_call_phys_epilog(save_pgd);
+       efi_old_memmap_phys_epilog(save_pgd);
        return NULL;
 }
 
-void __init efi_call_phys_epilog(pgd_t *save_pgd)
+void __init efi_old_memmap_phys_epilog(pgd_t *save_pgd)
 {
        /*
         * After the lock is released, the original page table is restored.
@@ -158,11 +155,6 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
        p4d_t *p4d;
        pud_t *pud;
 
-       if (!efi_enabled(EFI_OLD_MEMMAP)) {
-               efi_switch_mm(efi_scratch.prev_mm);
-               return;
-       }
-
        nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);
 
        for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++) {
@@ -193,6 +185,23 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
        early_code_mapping_set_exec(0);
 }
 
+pgd_t * __init efi_call_phys_prolog(void)
+{
+       if (efi_enabled(EFI_OLD_MEMMAP))
+               return efi_old_memmap_phys_prolog();
+
+       efi_switch_mm(&efi_mm);
+       return efi_mm.pgd;
+}
+
+void __init efi_call_phys_epilog(pgd_t *save_pgd)
+{
+       if (efi_enabled(EFI_OLD_MEMMAP))
+               efi_old_memmap_phys_epilog(save_pgd);
+       else
+               efi_switch_mm(efi_scratch.prev_mm);
+}
+
 EXPORT_SYMBOL_GPL(efi_mm);
 
 /*