Commit f7cfbee9 authored Dec 04, 2017 by Andy Lutomirski Committed by Ingo Molnar Dec 23, 2017

x86/mm/pti: Share cpu_entry_area with user space page tables

Share the cpu entry area so the user space and kernel space page tables
have the same P4D page.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 8d4b0678

arch/x86/mm/pti.c

+25 −0

Original line number	Diff line number	Diff line
		@@ -264,6 +264,29 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
		}
		}

		/*
		* Clone a single p4d (i.e. a top-level entry on 4-level systems and a
		* next-level entry on 5-level systems.
		*/
		static void __init pti_clone_p4d(unsigned long addr)
		{
		p4d_t kernel_p4d, user_p4d;
		pgd_t *kernel_pgd;

		user_p4d = pti_user_pagetable_walk_p4d(addr);
		kernel_pgd = pgd_offset_k(addr);
		kernel_p4d = p4d_offset(kernel_pgd, addr);
		user_p4d = kernel_p4d;
		}

		/*
		* Clone the CPU_ENTRY_AREA into the user space visible page table.
		*/
		static void __init pti_clone_user_shared(void)
		{
		pti_clone_p4d(CPU_ENTRY_AREA_BASE);
		}

		/*
		* Initialize kernel page table isolation
		*/
		@@ -273,4 +296,6 @@ void __init pti_init(void)
		return;

		pr_info("enabled\n");

		pti_clone_user_shared();
		}