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x86/boot/64: Initialize 5-level paging variables earlier

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  ca0e22d4f0 ("x86/boot/compressed/64: Always switch to own page table")

started using a new set of pagetables even without KASLR.

After that commit, initialize_identity_maps() is called before the
5-level paging variables are setup in choose_random_location(), which
will not work if 5-level paging is actually enabled.

Fix this by moving the initialization of __pgtable_l5_enabled,
pgdir_shift and ptrs_per_p4d into cleanup_trampoline(), which is called
immediately after the finalization of whether the kernel is executing
with 4- or 5-level paging. This will be earlier than anything that might
require those variables, and keeps the 4- vs 5-level paging code all in
one place.

Fixes: ca0e22d4f0 ("x86/boot/compressed/64: Always switch to own page table")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20201010191110.4060905-1-nivedita@alum.mit.edu
This commit is contained in:
Arvind Sankar 2020-10-10 15:11:10 -04:00 committed by Borislav Petkov
parent da9803dfd3
commit e5ceb9a024
3 changed files with 16 additions and 14 deletions
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6
arch/x86/boot/compressed/ident_map_64.c
View File

@ -33,12 +33,6 @@
#define __PAGE_OFFSET __PAGE_OFFSET_BASE
#include "../../mm/ident_map.c"
#ifdef CONFIG_X86_5LEVEL
unsigned int __pgtable_l5_enabled;
unsigned int pgdir_shift = 39;
unsigned int ptrs_per_p4d = 1;
#endif
/* Used by PAGE_KERN* macros: */
pteval_t __default_kernel_pte_mask __read_mostly = ~0;

8
arch/x86/boot/compressed/kaslr.c
View File

@ -840,14 +840,6 @@ void choose_random_location(unsigned long input,
return;
}
#ifdef CONFIG_X86_5LEVEL
if (__read_cr4() & X86_CR4_LA57) {
__pgtable_l5_enabled = 1;
pgdir_shift = 48;
ptrs_per_p4d = 512;
}
#endif
boot_params->hdr.loadflags |= KASLR_FLAG;
if (IS_ENABLED(CONFIG_X86_32))

16
arch/x86/boot/compressed/pgtable_64.c
View File

@ -8,6 +8,13 @@
#define BIOS_START_MIN 0x20000U /* 128K, less than this is insane */
#define BIOS_START_MAX 0x9f000U /* 640K, absolute maximum */
#ifdef CONFIG_X86_5LEVEL
/* __pgtable_l5_enabled needs to be in .data to avoid being cleared along with .bss */
unsigned int __section(.data) __pgtable_l5_enabled;
unsigned int __section(.data) pgdir_shift = 39;
unsigned int __section(.data) ptrs_per_p4d = 1;
#endif
struct paging_config {
unsigned long trampoline_start;
unsigned long l5_required;
@ -198,4 +205,13 @@ 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
}