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

diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index 613367e7e09e04f6d4bc85e0768c9582f703040a..99348ee7999b115ebe544ee00a275931bef9e8fe 100644 (file)
--- 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 ba538af37e90667ba4fcf6677801e6446816993e..aae2722c6e9abb915854107e95cbcc351cdd02f3 100644 (file)
--- 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;