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-rw-r--r--arch/x86/include/asm/mmu_context.h86
1 files changed, 6 insertions, 80 deletions
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 5f33924e200f..b243234e90cb 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -69,14 +69,6 @@ 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 +91,21 @@ 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()

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