x86/compressed: Export and rename add_identity_map()

SEV-specific code will need to add some additional mappings, but doing
this within ident_map_64.c requires some SEV-specific helpers to be
exported and some SEV-specific struct definitions to be pulled into
ident_map_64.c. Instead, export add_identity_map() so SEV-specific (and
other subsystem-specific) code can be better contained outside of
ident_map_64.c.

While at it, rename the function to kernel_add_identity_map(), similar
to the kernel_ident_mapping_init() function it relies upon.

No functional changes.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-37-brijesh.singh@amd.com

2 files changed, 10 insertions, 9 deletions

diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index 613367e7e09e..99348ee7999b 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -90,7 +90,7 @@ static struct x86_mapping_info mapping_info;
 /*
  * Adds the specified range to the identity mappings.
  */
-static void add_identity_map(unsigned long start, unsigned long end)
+void kernel_add_identity_map(unsigned long start, unsigned long end)
 {
 	int ret;
 
@@ -157,11 +157,11 @@ void initialize_identity_maps(void *rmode)
 	 * explicitly here in case the compressed kernel does not touch them,
 	 * or does not touch all the pages covering them.
 	 */
-	add_identity_map((unsigned long)_head, (unsigned long)_end);
+	kernel_add_identity_map((unsigned long)_head, (unsigned long)_end);
 	boot_params = rmode;
-	add_identity_map((unsigned long)boot_params, (unsigned long)(boot_params + 1));
+	kernel_add_identity_map((unsigned long)boot_params, (unsigned long)(boot_params + 1));
 	cmdline = get_cmd_line_ptr();
-	add_identity_map(cmdline, cmdline + COMMAND_LINE_SIZE);
+	kernel_add_identity_map(cmdline, cmdline + COMMAND_LINE_SIZE);
 
 	/* Load the new page-table. */
 	sev_verify_cbit(top_level_pgt);
@@ -246,10 +246,10 @@ static int set_clr_page_flags(struct x86_mapping_info *info,
 	 * It should already exist, but keep things generic.
 	 *
 	 * To map the page just read from it and fault it in if there is no
-	 * mapping yet. add_identity_map() can't be called here because that
-	 * would unconditionally map the address on PMD level, destroying any
-	 * PTE-level mappings that might already exist. Use assembly here so
-	 * the access won't be optimized away.
+	 * mapping yet. kernel_add_identity_map() can't be called here because
+	 * that would unconditionally map the address on PMD level, destroying
+	 * any PTE-level mappings that might already exist. Use assembly here
+	 * so the access won't be optimized away.
 	 */
 	asm volatile("mov %[address], %%r9"
 		     :: [address] "g" (*(unsigned long *)address)
@@ -363,5 +363,5 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
 	 * Error code is sane - now identity map the 2M region around
 	 * the faulting address.
 	 */
-	add_identity_map(address, end);
+	kernel_add_identity_map(address, end);
 }
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index ba538af37e90..aae2722c6e9a 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -156,6 +156,7 @@ static inline int count_immovable_mem_regions(void) { return 0; }
 #ifdef CONFIG_X86_5LEVEL
 extern unsigned int __pgtable_l5_enabled, pgdir_shift, ptrs_per_p4d;
 #endif
+extern void kernel_add_identity_map(unsigned long start, unsigned long end);
 
 /* Used by PAGE_KERN* macros: */
 extern pteval_t __default_kernel_pte_mask;