diff options
Diffstat (limited to 'arch/x86/include/asm/mmu_context.h')
| -rw-r--r-- | arch/x86/include/asm/mmu_context.h | 112 |
1 files changed, 6 insertions, 106 deletions
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 5f33924e200f..b538d9ddee9c 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -12,7 +12,6 @@ #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include <asm/paravirt.h> -#include <asm/mpx.h> #include <asm/debugreg.h> extern atomic64_t last_mm_ctx_id; @@ -69,14 +68,6 @@ struct ldt_struct { int slot; }; -/* This is a multiple of PAGE_SIZE. */ -#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE) - -static inline void *ldt_slot_va(int slot) -{ - return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot); -} - /* * Used for LDT copy/destruction. */ @@ -99,87 +90,21 @@ static inline void destroy_context_ldt(struct mm_struct *mm) { } static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { } #endif -static inline void load_mm_ldt(struct mm_struct *mm) -{ #ifdef CONFIG_MODIFY_LDT_SYSCALL - struct ldt_struct *ldt; - - /* READ_ONCE synchronizes with smp_store_release */ - ldt = READ_ONCE(mm->context.ldt); - - /* - * Any change to mm->context.ldt is followed by an IPI to all - * CPUs with the mm active. The LDT will not be freed until - * after the IPI is handled by all such CPUs. This means that, - * if the ldt_struct changes before we return, the values we see - * will be safe, and the new values will be loaded before we run - * any user code. - * - * NB: don't try to convert this to use RCU without extreme care. - * We would still need IRQs off, because we don't want to change - * the local LDT after an IPI loaded a newer value than the one - * that we can see. - */ - - if (unlikely(ldt)) { - if (static_cpu_has(X86_FEATURE_PTI)) { - if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) { - /* - * Whoops -- either the new LDT isn't mapped - * (if slot == -1) or is mapped into a bogus - * slot (if slot > 1). - */ - clear_LDT(); - return; - } - - /* - * If page table isolation is enabled, ldt->entries - * will not be mapped in the userspace pagetables. - * Tell the CPU to access the LDT through the alias - * at ldt_slot_va(ldt->slot). - */ - set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries); - } else { - set_ldt(ldt->entries, ldt->nr_entries); - } - } else { - clear_LDT(); - } +extern void load_mm_ldt(struct mm_struct *mm); +extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next); #else +static inline void load_mm_ldt(struct mm_struct *mm) +{ clear_LDT(); -#endif } - static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next) { -#ifdef CONFIG_MODIFY_LDT_SYSCALL - /* - * Load the LDT if either the old or new mm had an LDT. - * - * An mm will never go from having an LDT to not having an LDT. Two - * mms never share an LDT, so we don't gain anything by checking to - * see whether the LDT changed. There's also no guarantee that - * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL, - * then prev->context.ldt will also be non-NULL. - * - * If we really cared, we could optimize the case where prev == next - * and we're exiting lazy mode. Most of the time, if this happens, - * we don't actually need to reload LDTR, but modify_ldt() is mostly - * used by legacy code and emulators where we don't need this level of - * performance. - * - * This uses | instead of || because it generates better code. - */ - if (unlikely((unsigned long)prev->context.ldt | - (unsigned long)next->context.ldt)) - load_mm_ldt(next); -#endif - DEBUG_LOCKS_WARN_ON(preemptible()); } +#endif -void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk); +extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk); /* * Init a new mm. Used on mm copies, like at fork() @@ -274,34 +199,9 @@ static inline bool is_64bit_mm(struct mm_struct *mm) } #endif -static inline void arch_bprm_mm_init(struct mm_struct *mm, - struct vm_area_struct *vma) -{ - mpx_mm_init(mm); -} - static inline void arch_unmap(struct mm_struct *mm, unsigned long start, unsigned long end) { - /* - * mpx_notify_unmap() goes and reads a rarely-hot - * cacheline in the mm_struct. That can be expensive - * enough to be seen in profiles. - * - * The mpx_notify_unmap() call and its contents have been - * observed to affect munmap() performance on hardware - * where MPX is not present. - * - * The unlikely() optimizes for the fast case: no MPX - * in the CPU, or no MPX use in the process. Even if - * we get this wrong (in the unlikely event that MPX - * is widely enabled on some system) the overhead of - * MPX itself (reading bounds tables) is expected to - * overwhelm the overhead of getting this unlikely() - * consistently wrong. - */ - if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX))) - mpx_notify_unmap(mm, start, end); } /* |