diff options
Diffstat (limited to 'arch/x86/mm/pti.c')
| -rw-r--r-- | arch/x86/mm/pti.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 631507f0c198..8082f8b0c10e 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -300,6 +300,27 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) return; /* + * Only clone present PMDs. This ensures only setting + * _PAGE_GLOBAL on present PMDs. This should only be + * called on well-known addresses anyway, so a non- + * present PMD would be a surprise. + */ + if (WARN_ON(!(pmd_flags(*pmd) & _PAGE_PRESENT))) + return; + + /* + * Setting 'target_pmd' below creates a mapping in both + * the user and kernel page tables. It is effectively + * global, so set it as global in both copies. Note: + * the X86_FEATURE_PGE check is not _required_ because + * the CPU ignores _PAGE_GLOBAL when PGE is not + * supported. The check keeps consistentency with + * code that only set this bit when supported. + */ + if (boot_cpu_has(X86_FEATURE_PGE)) + *pmd = pmd_set_flags(*pmd, _PAGE_GLOBAL); + + /* * Copy the PMD. That is, the kernelmode and usermode * tables will share the last-level page tables of this * address range @@ -348,7 +369,7 @@ static void __init pti_clone_entry_text(void) { pti_clone_pmds((unsigned long) __entry_text_start, (unsigned long) __irqentry_text_end, - _PAGE_RW | _PAGE_GLOBAL); + _PAGE_RW); } /* |