From: Andy Lutomirski 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 Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Will Deacon 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 @@ -233,6 +233,23 @@ 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) @@ -241,4 +258,6 @@ void __init pti_init(void) return; pr_info("enabled\n"); + + pti_clone_user_shared(); }