include/asm/mmu_context.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _ASM_X86_MMU_CONTEXT_H
0003 #define _ASM_X86_MMU_CONTEXT_H
0004
0005 #include <asm/desc.h>
0006 #include <linux/atomic.h>
0007 #include <linux/mm_types.h>
0008 #include <linux/pkeys.h>
0009
0010 #include <trace/events/tlb.h>
0011
0012 #include <asm/tlbflush.h>
0013 #include <asm/paravirt.h>
0014 #include <asm/debugreg.h>
0015
0016 extern atomic64_t last_mm_ctx_id;
0017
0018 #ifndef CONFIG_PARAVIRT_XXL
0019 static inline void paravirt_activate_mm(struct mm_struct *prev,
0020                     struct mm_struct *next)
0021 {
0022 }
0023 #endif  /* !CONFIG_PARAVIRT_XXL */
0024
0025 #ifdef CONFIG_PERF_EVENTS
0026 DECLARE_STATIC_KEY_FALSE(rdpmc_never_available_key);
0027 DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key);
0028 void cr4_update_pce(void *ignored);
0029 #endif
0030
0031 #ifdef CONFIG_MODIFY_LDT_SYSCALL
0032 /*
0033  * ldt_structs can be allocated, used, and freed, but they are never
0034  * modified while live.
0035  */
0036 struct ldt_struct {
0037     /*
0038      * Xen requires page-aligned LDTs with special permissions.  This is
0039      * needed to prevent us from installing evil descriptors such as
0040      * call gates.  On native, we could merge the ldt_struct and LDT
0041      * allocations, but it's not worth trying to optimize.
0042      */
0043     struct desc_struct  *entries;
0044     unsigned int        nr_entries;
0045
0046     /*
0047      * If PTI is in use, then the entries array is not mapped while we're
0048      * in user mode.  The whole array will be aliased at the addressed
0049      * given by ldt_slot_va(slot).  We use two slots so that we can allocate
0050      * and map, and enable a new LDT without invalidating the mapping
0051      * of an older, still-in-use LDT.
0052      *
0053      * slot will be -1 if this LDT doesn't have an alias mapping.
0054      */
0055     int         slot;
0056 };
0057
0058 /*
0059  * Used for LDT copy/destruction.
0060  */
0061 static inline void init_new_context_ldt(struct mm_struct *mm)
0062 {
0063     mm->context.ldt = NULL;
0064     init_rwsem(&mm->context.ldt_usr_sem);
0065 }
0066 int ldt_dup_context(struct mm_struct *oldmm, struct mm_struct *mm);
0067 void destroy_context_ldt(struct mm_struct *mm);
0068 void ldt_arch_exit_mmap(struct mm_struct *mm);
0069 #else   /* CONFIG_MODIFY_LDT_SYSCALL */
0070 static inline void init_new_context_ldt(struct mm_struct *mm) { }
0071 static inline int ldt_dup_context(struct mm_struct *oldmm,
0072                   struct mm_struct *mm)
0073 {
0074     return 0;
0075 }
0076 static inline void destroy_context_ldt(struct mm_struct *mm) { }
0077 static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
0078 #endif
0079
0080 #ifdef CONFIG_MODIFY_LDT_SYSCALL
0081 extern void load_mm_ldt(struct mm_struct *mm);
0082 extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next);
0083 #else
0084 static inline void load_mm_ldt(struct mm_struct *mm)
0085 {
0086     clear_LDT();
0087 }
0088 static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
0089 {
0090     DEBUG_LOCKS_WARN_ON(preemptible());
0091 }
0092 #endif
0093
0094 #define enter_lazy_tlb enter_lazy_tlb
0095 extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
0096
0097 /*
0098  * Init a new mm.  Used on mm copies, like at fork()
0099  * and on mm's that are brand-new, like at execve().
0100  */
0101 #define init_new_context init_new_context
0102 static inline int init_new_context(struct task_struct *tsk,
0103                    struct mm_struct *mm)
0104 {
0105     mutex_init(&mm->context.lock);
0106
0107     mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
0108     atomic64_set(&mm->context.tlb_gen, 0);
0109
0110 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
0111     if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
0112         /* pkey 0 is the default and allocated implicitly */
0113         mm->context.pkey_allocation_map = 0x1;
0114         /* -1 means unallocated or invalid */
0115         mm->context.execute_only_pkey = -1;
0116     }
0117 #endif
0118     init_new_context_ldt(mm);
0119     return 0;
0120 }
0121
0122 #define destroy_context destroy_context
0123 static inline void destroy_context(struct mm_struct *mm)
0124 {
0125     destroy_context_ldt(mm);
0126 }
0127
0128 extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
0129               struct task_struct *tsk);
0130
0131 extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
0132                    struct task_struct *tsk);
0133 #define switch_mm_irqs_off switch_mm_irqs_off
0134
0135 #define activate_mm(prev, next)         \
0136 do {                        \
0137     paravirt_activate_mm((prev), (next));   \
0138     switch_mm((prev), (next), NULL);    \
0139 } while (0);
0140
0141 #ifdef CONFIG_X86_32
0142 #define deactivate_mm(tsk, mm)          \
0143 do {                        \
0144     loadsegment(gs, 0);         \
0145 } while (0)
0146 #else
0147 #define deactivate_mm(tsk, mm)          \
0148 do {                        \
0149     load_gs_index(0);           \
0150     loadsegment(fs, 0);         \
0151 } while (0)
0152 #endif
0153
0154 static inline void arch_dup_pkeys(struct mm_struct *oldmm,
0155                   struct mm_struct *mm)
0156 {
0157 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
0158     if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
0159         return;
0160
0161     /* Duplicate the oldmm pkey state in mm: */
0162     mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
0163     mm->context.execute_only_pkey   = oldmm->context.execute_only_pkey;
0164 #endif
0165 }
0166
0167 static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
0168 {
0169     arch_dup_pkeys(oldmm, mm);
0170     paravirt_arch_dup_mmap(oldmm, mm);
0171     return ldt_dup_context(oldmm, mm);
0172 }
0173
0174 static inline void arch_exit_mmap(struct mm_struct *mm)
0175 {
0176     paravirt_arch_exit_mmap(mm);
0177     ldt_arch_exit_mmap(mm);
0178 }
0179
0180 #ifdef CONFIG_X86_64
0181 static inline bool is_64bit_mm(struct mm_struct *mm)
0182 {
0183     return  !IS_ENABLED(CONFIG_IA32_EMULATION) ||
0184         !(mm->context.flags & MM_CONTEXT_UPROBE_IA32);
0185 }
0186 #else
0187 static inline bool is_64bit_mm(struct mm_struct *mm)
0188 {
0189     return false;
0190 }
0191 #endif
0192
0193 static inline void arch_unmap(struct mm_struct *mm, unsigned long start,
0194                   unsigned long end)
0195 {
0196 }
0197
0198 /*
0199  * We only want to enforce protection keys on the current process
0200  * because we effectively have no access to PKRU for other
0201  * processes or any way to tell *which * PKRU in a threaded
0202  * process we could use.
0203  *
0204  * So do not enforce things if the VMA is not from the current
0205  * mm, or if we are in a kernel thread.
0206  */
0207 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
0208         bool write, bool execute, bool foreign)
0209 {
0210     /* pkeys never affect instruction fetches */
0211     if (execute)
0212         return true;
0213     /* allow access if the VMA is not one from this process */
0214     if (foreign || vma_is_foreign(vma))
0215         return true;
0216     return __pkru_allows_pkey(vma_pkey(vma), write);
0217 }
0218
0219 unsigned long __get_current_cr3_fast(void);
0220
0221 #include <asm-generic/mmu_context.h>
0222
0223 #endif /* _ASM_X86_MMU_CONTEXT_H */