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Commit b16e770b authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Ingo Molnar
Browse files

x86/mm: Initialize 'pgdir_shift' and 'ptrs_per_p4d' at boot-time 



Switching between paging modes requires the folding of the p4d page table level
when we only have 4 paging levels, which means we need to adjust 'pgdir_shift'
and 'ptrs_per_p4d' during early boot according to paging mode.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214182542.69302-3-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4c2b4058

arch/x86/boot/compressed/kaslr.c

+4 −2
Original line number Diff line number Diff line
@@ -48,8 +48,8 @@ 


#ifdef CONFIG_X86_5LEVEL

unsigned int pgtable_l5_enabled __ro_after_init;

unsigned int pgdir_shift __ro_after_init = 48;

unsigned int ptrs_per_p4d __ro_after_init = 512;

unsigned int pgdir_shift __ro_after_init = 39;

unsigned int ptrs_per_p4d __ro_after_init = 1;

#endif



extern unsigned long get_cmd_line_ptr(void);
@@ -732,6 +732,8 @@ void choose_random_location(unsigned long input, 
#ifdef CONFIG_X86_5LEVEL

	if (__read_cr4() & X86_CR4_LA57) {

		pgtable_l5_enabled = 1;

		pgdir_shift = 48;

		ptrs_per_p4d = 512;

	}

#endif

arch/x86/kernel/head64.c

+4 −2
Original line number Diff line number Diff line
@@ -42,9 +42,9 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX); 
#ifdef CONFIG_X86_5LEVEL

unsigned int pgtable_l5_enabled __ro_after_init;

EXPORT_SYMBOL(pgtable_l5_enabled);

unsigned int pgdir_shift __ro_after_init = 48;

unsigned int pgdir_shift __ro_after_init = 39;

EXPORT_SYMBOL(pgdir_shift);

unsigned int ptrs_per_p4d __ro_after_init = 512;

unsigned int ptrs_per_p4d __ro_after_init = 1;

EXPORT_SYMBOL(ptrs_per_p4d);

#endif
@@ -79,6 +79,8 @@ static void __head check_la57_support(unsigned long physaddr) 
		return;



	*fixup_int(&pgtable_l5_enabled, physaddr) = 1;

	*fixup_int(&pgdir_shift, physaddr) = 48;

	*fixup_int(&ptrs_per_p4d, physaddr) = 512;

}

#else

static void __head check_la57_support(unsigned long physaddr) {}