x86/decompressor: Assign paging related global variables earlier

There is no need to defer the assignment of the paging related global
variables 'pgdir_shift' and 'ptrs_per_p4d' until after the trampoline is
cleaned up, so assign them as soon as it is clear that 5-level paging
will be enabled.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230807162720.545787-9-ardb@kernel.org

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 964fe90..cc70d3f 100644 (file)
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -179,9 +179,7 @@ static inline int count_immovable_mem_regions(void) { return 0; }
 #endif
 
 /* ident_map_64.c */
-#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: */

diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index 2ac12ff..f8092d3 100644 (file)
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -130,6 +130,11 @@ struct paging_config paging_prepare(void *rmode)
                        native_cpuid_eax(0) >= 7 &&
                        (native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) {
                paging_config.l5_required = 1;
+
+               /* Initialize variables for 5-level paging */
+               __pgtable_l5_enabled = 1;
+               pgdir_shift = 48;
+               ptrs_per_p4d = 512;
        }
 
        paging_config.trampoline_start = find_trampoline_placement();
@@ -206,13 +211,4 @@ void cleanup_trampoline(void *pgtable)
 
        /* Restore trampoline memory */
        memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE);
-
-       /* Initialize variables for 5-level paging */
-#ifdef CONFIG_X86_5LEVEL
-       if (__read_cr4() & X86_CR4_LA57) {
-               __pgtable_l5_enabled = 1;
-               pgdir_shift = 48;
-               ptrs_per_p4d = 512;
-       }
-#endif
 }