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Diffstat (limited to 'arch/x86/include/asm/mmu_context.h')
-rw-r--r--arch/x86/include/asm/mmu_context.h113
1 files changed, 71 insertions, 42 deletions
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 6d16d15d09a0..c931b88982a0 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -50,22 +50,53 @@ struct ldt_struct {
* call gates. On native, we could merge the ldt_struct and LDT
* allocations, but it's not worth trying to optimize.
*/
- struct desc_struct *entries;
- unsigned int nr_entries;
+ struct desc_struct *entries;
+ unsigned int nr_entries;
+
+ /*
+ * If PTI is in use, then the entries array is not mapped while we're
+ * in user mode. The whole array will be aliased at the addressed
+ * given by ldt_slot_va(slot). We use two slots so that we can allocate
+ * and map, and enable a new LDT without invalidating the mapping
+ * of an older, still-in-use LDT.
+ *
+ * slot will be -1 if this LDT doesn't have an alias mapping.
+ */
+ 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)
+{
+#ifdef CONFIG_X86_64
+ return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot);
+#else
+ BUG();
+#endif
+}
+
/*
* Used for LDT copy/destruction.
*/
-int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm);
+static inline void init_new_context_ldt(struct mm_struct *mm)
+{
+ mm->context.ldt = NULL;
+ init_rwsem(&mm->context.ldt_usr_sem);
+}
+int ldt_dup_context(struct mm_struct *oldmm, struct mm_struct *mm);
void destroy_context_ldt(struct mm_struct *mm);
+void ldt_arch_exit_mmap(struct mm_struct *mm);
#else /* CONFIG_MODIFY_LDT_SYSCALL */
-static inline int init_new_context_ldt(struct task_struct *tsk,
- struct mm_struct *mm)
+static inline void init_new_context_ldt(struct mm_struct *mm) { }
+static inline int ldt_dup_context(struct mm_struct *oldmm,
+ struct mm_struct *mm)
{
return 0;
}
-static inline void destroy_context_ldt(struct mm_struct *mm) {}
+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)
@@ -90,10 +121,31 @@ static inline void load_mm_ldt(struct mm_struct *mm)
* that we can see.
*/
- if (unlikely(ldt))
- set_ldt(ldt->entries, ldt->nr_entries);
- else
+ 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();
+ }
#else
clear_LDT();
#endif
@@ -132,18 +184,21 @@ void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
+ mutex_init(&mm->context.lock);
+
mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
atomic64_set(&mm->context.tlb_gen, 0);
- #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
/* pkey 0 is the default and always allocated */
mm->context.pkey_allocation_map = 0x1;
/* -1 means unallocated or invalid */
mm->context.execute_only_pkey = -1;
}
- #endif
- return init_new_context_ldt(tsk, mm);
+#endif
+ init_new_context_ldt(mm);
+ return 0;
}
static inline void destroy_context(struct mm_struct *mm)
{
@@ -176,15 +231,16 @@ do { \
} while (0)
#endif
-static inline void arch_dup_mmap(struct mm_struct *oldmm,
- struct mm_struct *mm)
+static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
{
paravirt_arch_dup_mmap(oldmm, mm);
+ return ldt_dup_context(oldmm, mm);
}
static inline void arch_exit_mmap(struct mm_struct *mm)
{
paravirt_arch_exit_mmap(mm);
+ ldt_arch_exit_mmap(mm);
}
#ifdef CONFIG_X86_64
@@ -282,33 +338,6 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
}
/*
- * If PCID is on, ASID-aware code paths put the ASID+1 into the PCID
- * bits. This serves two purposes. It prevents a nasty situation in
- * which PCID-unaware code saves CR3, loads some other value (with PCID
- * == 0), and then restores CR3, thus corrupting the TLB for ASID 0 if
- * the saved ASID was nonzero. It also means that any bugs involving
- * loading a PCID-enabled CR3 with CR4.PCIDE off will trigger
- * deterministically.
- */
-
-static inline unsigned long build_cr3(struct mm_struct *mm, u16 asid)
-{
- if (static_cpu_has(X86_FEATURE_PCID)) {
- VM_WARN_ON_ONCE(asid > 4094);
- return __sme_pa(mm->pgd) | (asid + 1);
- } else {
- VM_WARN_ON_ONCE(asid != 0);
- return __sme_pa(mm->pgd);
- }
-}
-
-static inline unsigned long build_cr3_noflush(struct mm_struct *mm, u16 asid)
-{
- VM_WARN_ON_ONCE(asid > 4094);
- return __sme_pa(mm->pgd) | (asid + 1) | CR3_NOFLUSH;
-}
-
-/*
* This can be used from process context to figure out what the value of
* CR3 is without needing to do a (slow) __read_cr3().
*
@@ -317,7 +346,7 @@ static inline unsigned long build_cr3_noflush(struct mm_struct *mm, u16 asid)
*/
static inline unsigned long __get_current_cr3_fast(void)
{
- unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm),
+ unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
this_cpu_read(cpu_tlbstate.loaded_mm_asid));
/* For now, be very restrictive about when this can be called. */