Messages in this thread Patch in this message | | | Date | Sat, 16 Dec 2017 22:24:24 +0100 | From | Thomas Gleixner <> | Subject | [patch V149 30/50] x86/mm/pti: Share cpu_entry_area PMDs |
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From: Andy Lutomirski <luto@kernel.org>
Share the FIX_USR_SHARED PMDs so the user space and kernel space page tables have the same PMD page.
[ tglx: Made it use the FIX_USR_SHARED range so later additions are covered automatically ]
Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Ingo Molnar <mingo@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 --- arch/x86/mm/pti.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
--- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -187,6 +187,23 @@ pti_clone_pmds(unsigned long start, unsi } /* + * Clone the populated PMDs of the user shared fixmaps into the user space + * visible page table. + */ +static void __init pti_clone_user_shared(void) +{ + unsigned long bot, top; + + bot = __fix_to_virt(FIX_USR_SHARED_BOTTOM); + top = __fix_to_virt(FIX_USR_SHARED_TOP) + PAGE_SIZE; + + /* Top of the user shared block must be PMD-aligned. */ + WARN_ON(top & ~PMD_MASK); + + pti_clone_pmds(bot, top, 0); +} + +/* * Initialize kernel page table isolation */ void __init pti_init(void) @@ -195,4 +212,6 @@ void __init pti_init(void) return; pr_info("enabled\n"); + + pti_clone_user_shared(); }
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