From: Joerg Roedel <jroedel@suse.de>
Date: Mon, 7 Sep 2020 15:15:19 +0200
Subject: x86/boot/compressed/64: Change add_identity_map() to take start and
 end
Git-commit: 21cf2372618ef167d8c4ae04880fb873b55b2daa
Patch-mainline: v5.10-rc1
References: jsc#SLE-14337

Changing the function to take start and end as parameters instead of
start and size simplifies the callers which don't need to calculate the
size if they already have start and end.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-19-joro@8bytes.org
---
 arch/x86/boot/compressed/ident_map_64.c |   15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -92,10 +92,8 @@ static struct x86_mapping_info mapping_i
 /*
  * Adds the specified range to the identity mappings.
  */
-static void add_identity_map(unsigned long start, unsigned long size)
+static void add_identity_map(unsigned long start, unsigned long end)
 {
-	unsigned long end = start + size;
-
 	/* Align boundary to 2M. */
 	start = round_down(start, PMD_SIZE);
 	end = round_up(end, PMD_SIZE);
@@ -110,8 +108,6 @@ static void add_identity_map(unsigned lo
 /* Locates and clears a region for a new top level page table. */
 void initialize_identity_maps(void)
 {
-	unsigned long start, size;
-
 	/* If running as an SEV guest, the encryption mask is required. */
 	set_sev_encryption_mask();
 
@@ -158,9 +154,7 @@ void initialize_identity_maps(void)
 	 * New page-table is set up - map the kernel image and load it
 	 * into cr3.
 	 */
-	start = (unsigned long)_head;
-	size  = _end - _head;
-	add_identity_map(start, size);
+	add_identity_map((unsigned long)_head, (unsigned long)_end);
 	write_cr3(top_level_pgt);
 }
 
@@ -192,7 +186,8 @@ static void do_pf_error(const char *msg,
 
 void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
 {
-	unsigned long address = native_read_cr2();
+	unsigned long address = native_read_cr2() & PMD_MASK;
+	unsigned long end = address + PMD_SIZE;
 
 	/*
 	 * Check for unexpected error codes. Unexpected are:
@@ -207,5 +202,5 @@ void do_boot_page_fault(struct pt_regs *
 	 * Error code is sane - now identity map the 2M region around
 	 * the faulting address.
 	 */
-	add_identity_map(address & PMD_MASK, PMD_SIZE);
+	add_identity_map(address, end);
 }