Commit 8c5cc19e authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/tlb: Uninline __get_current_cr3_fast() 



cpu_tlbstate is exported because various TLB-related functions need
access to it, but cpu_tlbstate is sensitive information which should
only be accessed by well-contained kernel functions and not be directly
exposed to modules.

In preparation for unexporting cpu_tlbstate move __get_current_cr3_fast()
into the x86 TLB management code.

No functional change.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200421092558.848064318@linutronix.de
parent 325518e9

arch/x86/include/asm/mmu_context.h

+1 −18
Original line number Diff line number Diff line
@@ -225,24 +225,7 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, 
	return __pkru_allows_pkey(vma_pkey(vma), write);

}



/*

 * This can be used from process context to figure out what the value of

 * CR3 is without needing to do a (slow) __read_cr3().

 *

 * It's intended to be used for code like KVM that sneakily changes CR3

 * and needs to restore it.  It needs to be used very carefully.

 */

static inline unsigned long __get_current_cr3_fast(void)

{

	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,

		this_cpu_read(cpu_tlbstate.loaded_mm_asid));



	/* For now, be very restrictive about when this can be called. */

	VM_WARN_ON(in_nmi() || preemptible());



	VM_BUG_ON(cr3 != __read_cr3());

	return cr3;

}

unsigned long __get_current_cr3_fast(void);



typedef struct {

	struct mm_struct *mm;

arch/x86/mm/tlb.c

+20 −0
Original line number Diff line number Diff line
@@ -843,6 +843,26 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end) 
	}

}



/*

 * This can be used from process context to figure out what the value of

 * CR3 is without needing to do a (slow) __read_cr3().

 *

 * It's intended to be used for code like KVM that sneakily changes CR3

 * and needs to restore it.  It needs to be used very carefully.

 */

unsigned long __get_current_cr3_fast(void)

{

	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,

		this_cpu_read(cpu_tlbstate.loaded_mm_asid));



	/* For now, be very restrictive about when this can be called. */

	VM_WARN_ON(in_nmi() || preemptible());



	VM_BUG_ON(cr3 != __read_cr3());

	return cr3;

}

EXPORT_SYMBOL_GPL(__get_current_cr3_fast);



/*

 * arch_tlbbatch_flush() performs a full TLB flush regardless of the active mm.

 * This means that the 'struct flush_tlb_info' that describes which mappings to

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