linux-kernel - [PATCH 06/20] efi/x86: split off some old memmap handling into separate routines

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Message-Id: <20200103113953.9571-7-ardb@kernel.org>
Date:   Fri,  3 Jan 2020 12:39:39 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Matthew Garrett <mjg59@...gle.com>
Subject: [PATCH 06/20] 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@...nel.org>
---
 arch/x86/platform/efi/efi_64.c | 35 +++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 03c2ed3c645c..a72bbabbc595 100644
--- 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);
 
 /*
-- 
2.20.1