mmu_context.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef _ASM_X86_MMU_CONTEXT_H
  3#define _ASM_X86_MMU_CONTEXT_H
  4
  5#include <linux/atomic.h>
  6#include <linux/mm_types.h>
  7#include <linux/pkeys.h>
  8
  9#include <trace/events/tlb.h>
 10
 11#include <asm/tlbflush.h>
 12#include <asm/paravirt.h>
 13#include <asm/debugreg.h>
 14#include <asm/gsseg.h>
 15#include <asm/desc.h>
 16
 17extern atomic64_t last_mm_ctx_id;
 18
 19#ifdef CONFIG_PERF_EVENTS
 20DECLARE_STATIC_KEY_FALSE(rdpmc_never_available_key);
 21DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key);
 22void cr4_update_pce(void *ignored);
 23#endif
 24
 25#ifdef CONFIG_MODIFY_LDT_SYSCALL
 26/*
 27 * ldt_structs can be allocated, used, and freed, but they are never
 28 * modified while live.
 29 */
 30struct ldt_struct {
 31	/*
 32	 * Xen requires page-aligned LDTs with special permissions.  This is
 33	 * needed to prevent us from installing evil descriptors such as
 34	 * call gates.  On native, we could merge the ldt_struct and LDT
 35	 * allocations, but it's not worth trying to optimize.
 36	 */
 37	struct desc_struct	*entries;
 38	unsigned int		nr_entries;
 39
 40	/*
 41	 * If PTI is in use, then the entries array is not mapped while we're
 42	 * in user mode.  The whole array will be aliased at the addressed
 43	 * given by ldt_slot_va(slot).  We use two slots so that we can allocate
 44	 * and map, and enable a new LDT without invalidating the mapping
 45	 * of an older, still-in-use LDT.
 46	 *
 47	 * slot will be -1 if this LDT doesn't have an alias mapping.
 48	 */
 49	int			slot;
 50};
 51
 52/*
 53 * Used for LDT copy/destruction.
 54 */
 55static inline void init_new_context_ldt(struct mm_struct *mm)
 56{
 57	mm->context.ldt = NULL;
 58	init_rwsem(&mm->context.ldt_usr_sem);
 59}
 60int ldt_dup_context(struct mm_struct *oldmm, struct mm_struct *mm);
 61void destroy_context_ldt(struct mm_struct *mm);
 62void ldt_arch_exit_mmap(struct mm_struct *mm);
 63#else	/* CONFIG_MODIFY_LDT_SYSCALL */
 64static inline void init_new_context_ldt(struct mm_struct *mm) { }
 65static inline int ldt_dup_context(struct mm_struct *oldmm,
 66				  struct mm_struct *mm)
 67{
 68	return 0;
 69}
 70static inline void destroy_context_ldt(struct mm_struct *mm) { }
 71static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
 72#endif
 73
 74#ifdef CONFIG_MODIFY_LDT_SYSCALL
 75extern void load_mm_ldt(struct mm_struct *mm);
 76extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next);
 77#else
 78static inline void load_mm_ldt(struct mm_struct *mm)
 79{
 80	clear_LDT();
 81}
 82static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
 83{
 84	DEBUG_LOCKS_WARN_ON(preemptible());
 85}
 86#endif
 87
 88#ifdef CONFIG_ADDRESS_MASKING
 89static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm)
 90{
 91	/*
 92	 * When switch_mm_irqs_off() is called for a kthread, it may race with
 93	 * LAM enablement. switch_mm_irqs_off() uses the LAM mask to do two
 94	 * things: populate CR3 and populate 'cpu_tlbstate.lam'. Make sure it
 95	 * reads a single value for both.
 96	 */
 97	return READ_ONCE(mm->context.lam_cr3_mask);
 98}
 99
100static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
101{
102	mm->context.lam_cr3_mask = oldmm->context.lam_cr3_mask;
103	mm->context.untag_mask = oldmm->context.untag_mask;
104}
105
106#define mm_untag_mask mm_untag_mask
107static inline unsigned long mm_untag_mask(struct mm_struct *mm)
108{
109	return mm->context.untag_mask;
110}
111
112static inline void mm_reset_untag_mask(struct mm_struct *mm)
113{
114	mm->context.untag_mask = -1UL;
115}
116
117#define arch_pgtable_dma_compat arch_pgtable_dma_compat
118static inline bool arch_pgtable_dma_compat(struct mm_struct *mm)
119{
120	return !mm_lam_cr3_mask(mm) ||
121		test_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &mm->context.flags);
122}
123#else
124
125static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm)
126{
127	return 0;
128}
129
130static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
131{
132}
133
134static inline void mm_reset_untag_mask(struct mm_struct *mm)
135{
136}
137#endif
138
139#define enter_lazy_tlb enter_lazy_tlb
140extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
141
142#define mm_init_global_asid mm_init_global_asid
143extern void mm_init_global_asid(struct mm_struct *mm);
144
145extern void mm_free_global_asid(struct mm_struct *mm);
146
147/*
148 * Init a new mm.  Used on mm copies, like at fork()
149 * and on mm's that are brand-new, like at execve().
150 */
151#define init_new_context init_new_context
152static inline int init_new_context(struct task_struct *tsk,
153				   struct mm_struct *mm)
154{
155	mutex_init(&mm->context.lock);
156
157	mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
158	atomic64_set(&mm->context.tlb_gen, 0);
159	mm->context.next_trim_cpumask = jiffies + HZ;
160
161#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
162	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
163		/* pkey 0 is the default and allocated implicitly */
164		mm->context.pkey_allocation_map = 0x1;
165		/* -1 means unallocated or invalid */
166		mm->context.execute_only_pkey = -1;
167	}
168#endif
169
170	mm_init_global_asid(mm);
171	mm_reset_untag_mask(mm);
172	init_new_context_ldt(mm);
173	return 0;
174}
175
176#define destroy_context destroy_context
177static inline void destroy_context(struct mm_struct *mm)
178{
179	destroy_context_ldt(mm);
180	mm_free_global_asid(mm);
181}
182
183extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
184		      struct task_struct *tsk);
185
186extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
187			       struct task_struct *tsk);
188#define switch_mm_irqs_off switch_mm_irqs_off
189
190#define activate_mm(prev, next)			\
191do {						\
192	paravirt_enter_mmap(next);		\
193	switch_mm_irqs_off((prev), (next), NULL);	\
194} while (0);
195
196#ifdef CONFIG_X86_32
197#define deactivate_mm(tsk, mm)			\
198do {						\
199	loadsegment(gs, 0);			\
200} while (0)
201#else
202#define deactivate_mm(tsk, mm)			\
203do {						\
204	shstk_free(tsk);			\
205	load_gs_index(0);			\
206	loadsegment(fs, 0);			\
207} while (0)
208#endif
209
210static inline void arch_dup_pkeys(struct mm_struct *oldmm,
211				  struct mm_struct *mm)
212{
213#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
214	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
215		return;
216
217	/* Duplicate the oldmm pkey state in mm: */
218	mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
219	mm->context.execute_only_pkey   = oldmm->context.execute_only_pkey;
220#endif
221}
222
223static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
224{
225	arch_dup_pkeys(oldmm, mm);
226	paravirt_enter_mmap(mm);
227	dup_lam(oldmm, mm);
228	return ldt_dup_context(oldmm, mm);
229}
230
231static inline void arch_exit_mmap(struct mm_struct *mm)
232{
233	paravirt_arch_exit_mmap(mm);
234	ldt_arch_exit_mmap(mm);
235}
236
237#ifdef CONFIG_X86_64
238static inline bool is_64bit_mm(struct mm_struct *mm)
239{
240	return	!IS_ENABLED(CONFIG_IA32_EMULATION) ||
241		!test_bit(MM_CONTEXT_UPROBE_IA32, &mm->context.flags);
242}
243#else
244static inline bool is_64bit_mm(struct mm_struct *mm)
245{
246	return false;
247}
248#endif
249
250static inline bool is_notrack_mm(struct mm_struct *mm)
251{
252	return test_bit(MM_CONTEXT_NOTRACK, &mm->context.flags);
253}
254
255static inline void set_notrack_mm(struct mm_struct *mm)
256{
257	set_bit(MM_CONTEXT_NOTRACK, &mm->context.flags);
258}
259
260/*
261 * We only want to enforce protection keys on the current process
262 * because we effectively have no access to PKRU for other
263 * processes or any way to tell *which * PKRU in a threaded
264 * process we could use.
265 *
266 * So do not enforce things if the VMA is not from the current
267 * mm, or if we are in a kernel thread.
268 */
269static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
270		bool write, bool execute, bool foreign)
271{
272	/* pkeys never affect instruction fetches */
273	if (execute)
274		return true;
275	/* allow access if the VMA is not one from this process */
276	if (foreign || vma_is_foreign(vma))
277		return true;
278	return __pkru_allows_pkey(vma_pkey(vma), write);
279}
280
281unsigned long __get_current_cr3_fast(void);
282
283#include <asm-generic/mmu_context.h>
284
285extern struct mm_struct *use_temporary_mm(struct mm_struct *temp_mm);
286extern void unuse_temporary_mm(struct mm_struct *prev_mm);
287
288#endif /* _ASM_X86_MMU_CONTEXT_H */