From: Dave Hansen <[email protected]> Clone the ESPFIX alias mapping area so the entry/exit code has access to it even with the user space page tables.
[ tglx: Remove the per cpu user mapped oddity ] Signed-off-by: Dave Hansen <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/kernel/espfix_64.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) --- a/arch/x86/kernel/espfix_64.c +++ b/arch/x86/kernel/espfix_64.c @@ -129,6 +129,22 @@ void __init init_espfix_bsp(void) p4d = p4d_alloc(&init_mm, pgd, ESPFIX_BASE_ADDR); p4d_populate(&init_mm, p4d, espfix_pud_page); + /* + * Just copy the top-level PGD that is mapping the espfix area to + * ensure it is mapped into the user page tables. + * + * For 5-level paging, the espfix pgd was populated when + * kpti_init() pre-populated all the pgd entries. The above + * p4d_alloc() would never do anything and the p4d_populate() would + * be done to a p4d already mapped in the userspace pgd. + */ +#ifdef CONFIG_KERNEL_PAGE_TABLE_ISOLATION + if (CONFIG_PGTABLE_LEVELS <= 4) { + set_pgd(kernel_to_user_pgdp(pgd), + __pgd(_KERNPG_TABLE | (p4d_pfn(*p4d) << PAGE_SHIFT))); + } +#endif + /* Randomize the locations */ init_espfix_random();
