[mirror_ubuntu-artful-kernel.git] / arch / x86 / include / asm / mmu_context.h

#ifndef _ASM_X86_MMU_CONTEXT_H
#define _ASM_X86_MMU_CONTEXT_H

#include <asm/desc.h>
#include <linux/atomic.h>
#include <linux/mm_types.h>
#include <linux/pkeys.h>

#include <trace/events/tlb.h>

#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#include <asm/mpx.h>

extern atomic64_t last_mm_ctx_id;

#ifndef CONFIG_PARAVIRT
static inline void paravirt_activate_mm(struct mm_struct *prev,
					struct mm_struct *next)
{
}
#endif	/* !CONFIG_PARAVIRT */

#ifdef CONFIG_PERF_EVENTS
extern struct static_key rdpmc_always_available;

static inline void load_mm_cr4(struct mm_struct *mm)
{
	if (static_key_false(&rdpmc_always_available) ||
	    atomic_read(&mm->context.perf_rdpmc_allowed))
		cr4_set_bits(X86_CR4_PCE);
	else
		cr4_clear_bits(X86_CR4_PCE);
}
#else
static inline void load_mm_cr4(struct mm_struct *mm) {}
#endif

#ifdef CONFIG_MODIFY_LDT_SYSCALL
/*
 * ldt_structs can be allocated, used, and freed, but they are never
 * modified while live.
 */
struct ldt_struct {
	/*
	 * Xen requires page-aligned LDTs with special permissions.  This is
	 * needed to prevent us from installing evil descriptors such as
	 * 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;

	/*
	 * 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.
 */
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 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 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();
	}
#else
	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());
}

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
	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
	init_new_context_ldt(mm);
	return 0;
}
static inline void destroy_context(struct mm_struct *mm)
{
	destroy_context_ldt(mm);
}

extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
		      struct task_struct *tsk);

extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
			       struct task_struct *tsk);
#define switch_mm_irqs_off switch_mm_irqs_off

#define activate_mm(prev, next)			\
do {						\
	paravirt_activate_mm((prev), (next));	\
	switch_mm((prev), (next), NULL);	\
} while (0);

#ifdef CONFIG_X86_32
#define deactivate_mm(tsk, mm)			\
do {						\
	lazy_load_gs(0);			\
} while (0)
#else
#define deactivate_mm(tsk, mm)			\
do {						\
	load_gs_index(0);			\
	loadsegment(fs, 0);			\
} while (0)
#endif

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
static inline bool is_64bit_mm(struct mm_struct *mm)
{
	return	!IS_ENABLED(CONFIG_IA32_EMULATION) ||
		!(mm->context.ia32_compat == TIF_IA32);
}
#else
static inline bool is_64bit_mm(struct mm_struct *mm)
{
	return false;
}
#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, struct vm_area_struct *vma,
			      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, vma, start, end);
}

#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
static inline int vma_pkey(struct vm_area_struct *vma)
{
	unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
				      VM_PKEY_BIT2 | VM_PKEY_BIT3;

	return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
}
#else
static inline int vma_pkey(struct vm_area_struct *vma)
{
	return 0;
}
#endif

/*
 * We only want to enforce protection keys on the current process
 * because we effectively have no access to PKRU for other
 * processes or any way to tell *which * PKRU in a threaded
 * process we could use.
 *
 * So do not enforce things if the VMA is not from the current
 * mm, or if we are in a kernel thread.
 */
static inline bool vma_is_foreign(struct vm_area_struct *vma)
{
	if (!current->mm)
		return true;
	/*
	 * Should PKRU be enforced on the access to this VMA?  If
	 * the VMA is from another process, then PKRU has no
	 * relevance and should not be enforced.
	 */
	if (current->mm != vma->vm_mm)
		return true;

	return false;
}

static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
		bool write, bool execute, bool foreign)
{
	/* pkeys never affect instruction fetches */
	if (execute)
		return true;
	/* allow access if the VMA is not one from this process */
	if (foreign || vma_is_foreign(vma))
		return true;
	return __pkru_allows_pkey(vma_pkey(vma), write);
}

/*
 * This can be used from process context to figure out what the value of
 * CR3 is without needing to do a (slow) __read_cr3().
 *
 * It's intended to be used for code like KVM that sneakily changes CR3
 * and needs to restore it.  It needs to be used very carefully.
 */
static inline unsigned long __get_current_cr3_fast(void)
{
	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. */
	VM_WARN_ON(in_nmi() || preemptible());

	VM_BUG_ON(cr3 != __read_cr3());
	return cr3;
}

#endif /* _ASM_X86_MMU_CONTEXT_H */
Commit	Line	Data
1965aae3 PA	1	#ifndef _ASM_X86_MMU_CONTEXT_H
1965aae3 PA	2	#define _ASM_X86_MMU_CONTEXT_H
c3c2fee3 JF	3
c3c2fee3 JF	4	#include <asm/desc.h>
60063497	5	#include <linux/atomic.h>
d17d8f9d	6	#include <linux/mm_types.h>
7d06d9c9	7	#include <linux/pkeys.h>
d17d8f9d DH	8
	9	#include <trace/events/tlb.h>
	10
c3c2fee3 JF	11	#include <asm/pgalloc.h>
	12	#include <asm/tlbflush.h>
	13	#include <asm/paravirt.h>
fe3d197f	14	#include <asm/mpx.h>
e566a0df AL	15
	16	extern atomic64_t last_mm_ctx_id;
	17
c3c2fee3	18	#ifndef CONFIG_PARAVIRT
c3c2fee3 JF	19	static inline void paravirt_activate_mm(struct mm_struct *prev,
	20	struct mm_struct *next)
	21	{
	22	}
	23	#endif /* !CONFIG_PARAVIRT */
	24
7911d3f7	25	#ifdef CONFIG_PERF_EVENTS
a6673429 AL	26	extern struct static_key rdpmc_always_available;
a6673429 AL	27
7911d3f7 AL	28	static inline void load_mm_cr4(struct mm_struct *mm)
7911d3f7 AL	29	{
a833581e	30	if (static_key_false(&rdpmc_always_available) \|\|
a6673429	31	atomic_read(&mm->context.perf_rdpmc_allowed))
7911d3f7 AL	32	cr4_set_bits(X86_CR4_PCE);
	33	else
	34	cr4_clear_bits(X86_CR4_PCE);
	35	}
	36	#else
	37	static inline void load_mm_cr4(struct mm_struct *mm) {}
	38	#endif
	39
a5b9e5a2	40	#ifdef CONFIG_MODIFY_LDT_SYSCALL
37868fe1 AL	41	/*
	42	* ldt_structs can be allocated, used, and freed, but they are never
	43	* modified while live.
	44	*/
	45	struct ldt_struct {
	46	/*
	47	* Xen requires page-aligned LDTs with special permissions. This is
	48	* needed to prevent us from installing evil descriptors such as
	49	* call gates. On native, we could merge the ldt_struct and LDT
	50	* allocations, but it's not worth trying to optimize.
	51	*/
c2506438 AL	52	struct desc_struct *entries;
	53	unsigned int nr_entries;
	54
	55	/*
	56	* If PTI is in use, then the entries array is not mapped while we're
	57	* in user mode. The whole array will be aliased at the addressed
	58	* given by ldt_slot_va(slot). We use two slots so that we can allocate
	59	* and map, and enable a new LDT without invalidating the mapping
	60	* of an older, still-in-use LDT.
	61	*
	62	* slot will be -1 if this LDT doesn't have an alias mapping.
	63	*/
	64	int slot;
37868fe1 AL	65	};
37868fe1 AL	66
c2506438 AL	67	/* This is a multiple of PAGE_SIZE. */
	68	#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE)
	69
	70	static inline void *ldt_slot_va(int slot)
	71	{
	72	#ifdef CONFIG_X86_64
	73	return (void )(LDT_BASE_ADDR + LDT_SLOT_STRIDE slot);
	74	#else
	75	BUG();
	76	#endif
	77	}
	78
a5b9e5a2 AL	79	/*
	80	* Used for LDT copy/destruction.
	81	*/
f90d2542 TG	82	static inline void init_new_context_ldt(struct mm_struct *mm)
	83	{
	84	mm->context.ldt = NULL;
	85	init_rwsem(&mm->context.ldt_usr_sem);
	86	}
	87	int ldt_dup_context(struct mm_struct oldmm, struct mm_struct mm);
39a0526f	88	void destroy_context_ldt(struct mm_struct *mm);
c2506438	89	void ldt_arch_exit_mmap(struct mm_struct *mm);
a5b9e5a2	90	#else /* CONFIG_MODIFY_LDT_SYSCALL */
f90d2542 TG	91	static inline void init_new_context_ldt(struct mm_struct *mm) { }
	92	static inline int ldt_dup_context(struct mm_struct *oldmm,
	93	struct mm_struct *mm)
a5b9e5a2 AL	94	{
	95	return 0;
	96	}
c2506438 AL	97	static inline void destroy_context_ldt(struct mm_struct *mm) { }
c2506438 AL	98	static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
a5b9e5a2 AL	99	#endif
a5b9e5a2 AL	100
37868fe1 AL	101	static inline void load_mm_ldt(struct mm_struct *mm)
37868fe1 AL	102	{
a5b9e5a2	103	#ifdef CONFIG_MODIFY_LDT_SYSCALL
37868fe1 AL	104	struct ldt_struct *ldt;
37868fe1 AL	105
7252704b WD	106	/* READ_ONCE synchronizes with smp_store_release */
7252704b WD	107	ldt = READ_ONCE(mm->context.ldt);
37868fe1 AL	108
	109	/*
	110	* Any change to mm->context.ldt is followed by an IPI to all
	111	* CPUs with the mm active. The LDT will not be freed until
	112	* after the IPI is handled by all such CPUs. This means that,
	113	* if the ldt_struct changes before we return, the values we see
	114	* will be safe, and the new values will be loaded before we run
	115	* any user code.
	116	*
	117	* NB: don't try to convert this to use RCU without extreme care.
	118	* We would still need IRQs off, because we don't want to change
	119	* the local LDT after an IPI loaded a newer value than the one
	120	* that we can see.
	121	*/
	122
c2506438 AL	123	if (unlikely(ldt)) {
	124	if (static_cpu_has(X86_FEATURE_PTI)) {
	125	if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) {
	126	/*
	127	* Whoops -- either the new LDT isn't mapped
	128	* (if slot == -1) or is mapped into a bogus
	129	* slot (if slot > 1).
	130	*/
	131	clear_LDT();
	132	return;
	133	}
	134
	135	/*
	136	* If page table isolation is enabled, ldt->entries
	137	* will not be mapped in the userspace pagetables.
	138	* Tell the CPU to access the LDT through the alias
	139	* at ldt_slot_va(ldt->slot).
	140	*/
	141	set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries);
	142	} else {
	143	set_ldt(ldt->entries, ldt->nr_entries);
	144	}
	145	} else {
37868fe1	146	clear_LDT();
c2506438	147	}
a5b9e5a2 AL	148	#else
	149	clear_LDT();
	150	#endif
73534258 AL	151	}
	152
	153	static inline void switch_ldt(struct mm_struct prev, struct mm_struct next)
	154	{
	155	#ifdef CONFIG_MODIFY_LDT_SYSCALL
	156	/*
	157	* Load the LDT if either the old or new mm had an LDT.
	158	*
	159	* An mm will never go from having an LDT to not having an LDT. Two
	160	* mms never share an LDT, so we don't gain anything by checking to
	161	* see whether the LDT changed. There's also no guarantee that
	162	* prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
	163	* then prev->context.ldt will also be non-NULL.
	164	*
	165	* If we really cared, we could optimize the case where prev == next
	166	* and we're exiting lazy mode. Most of the time, if this happens,
	167	* we don't actually need to reload LDTR, but modify_ldt() is mostly
	168	* used by legacy code and emulators where we don't need this level of
	169	* performance.
	170	*
	171	* This uses \| instead of \|\| because it generates better code.
	172	*/
	173	if (unlikely((unsigned long)prev->context.ldt \|
	174	(unsigned long)next->context.ldt))
	175	load_mm_ldt(next);
	176	#endif
37868fe1 AL	177
	178	DEBUG_LOCKS_WARN_ON(preemptible());
	179	}
	180
a4bb9409	181	void enter_lazy_tlb(struct mm_struct mm, struct task_struct tsk);
6826c8ff	182
39a0526f DH	183	static inline int init_new_context(struct task_struct *tsk,
	184	struct mm_struct *mm)
	185	{
bf7ee649 PZ	186	mutex_init(&mm->context.lock);
bf7ee649 PZ	187
e566a0df AL	188	mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
	189	atomic64_set(&mm->context.tlb_gen, 0);
	190
f90d2542	191	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
e8c24d3a DH	192	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
	193	/* pkey 0 is the default and always allocated */
	194	mm->context.pkey_allocation_map = 0x1;
	195	/* -1 means unallocated or invalid */
	196	mm->context.execute_only_pkey = -1;
	197	}
f90d2542 TG	198	#endif
	199	init_new_context_ldt(mm);
	200	return 0;
39a0526f DH	201	}
	202	static inline void destroy_context(struct mm_struct *mm)
	203	{
	204	destroy_context_ldt(mm);
	205	}
	206
69c0319a AL	207	extern void switch_mm(struct mm_struct prev, struct mm_struct next,
69c0319a AL	208	struct task_struct *tsk);
6826c8ff	209
078194f8 AL	210	extern void switch_mm_irqs_off(struct mm_struct prev, struct mm_struct next,
	211	struct task_struct *tsk);
	212	#define switch_mm_irqs_off switch_mm_irqs_off
c3c2fee3 JF	213
	214	#define activate_mm(prev, next) \
	215	do { \
	216	paravirt_activate_mm((prev), (next)); \
	217	switch_mm((prev), (next), NULL); \
	218	} while (0);
	219
6826c8ff BG	220	#ifdef CONFIG_X86_32
	221	#define deactivate_mm(tsk, mm) \
	222	do { \
ccbeed3a	223	lazy_load_gs(0); \
6826c8ff BG	224	} while (0)
	225	#else
	226	#define deactivate_mm(tsk, mm) \
	227	do { \
	228	load_gs_index(0); \
	229	loadsegment(fs, 0); \
	230	} while (0)
	231	#endif
c3c2fee3	232
b812abb6	233	static inline int arch_dup_mmap(struct mm_struct oldmm, struct mm_struct mm)
a1ea1c03 DH	234	{
a1ea1c03 DH	235	paravirt_arch_dup_mmap(oldmm, mm);
f90d2542	236	return ldt_dup_context(oldmm, mm);
a1ea1c03 DH	237	}
	238
	239	static inline void arch_exit_mmap(struct mm_struct *mm)
	240	{
	241	paravirt_arch_exit_mmap(mm);
c2506438	242	ldt_arch_exit_mmap(mm);
a1ea1c03 DH	243	}
a1ea1c03 DH	244
b0e9b09b DH	245	#ifdef CONFIG_X86_64
	246	static inline bool is_64bit_mm(struct mm_struct *mm)
	247	{
97f2645f	248	return !IS_ENABLED(CONFIG_IA32_EMULATION) \|\|
b0e9b09b DH	249	!(mm->context.ia32_compat == TIF_IA32);
	250	}
	251	#else
	252	static inline bool is_64bit_mm(struct mm_struct *mm)
	253	{
	254	return false;
	255	}
	256	#endif
	257
fe3d197f DH	258	static inline void arch_bprm_mm_init(struct mm_struct *mm,
	259	struct vm_area_struct *vma)
	260	{
	261	mpx_mm_init(mm);
	262	}
	263
1de4fa14 DH	264	static inline void arch_unmap(struct mm_struct mm, struct vm_area_struct vma,
	265	unsigned long start, unsigned long end)
	266	{
c922228e DH	267	/*
	268	* mpx_notify_unmap() goes and reads a rarely-hot
	269	* cacheline in the mm_struct. That can be expensive
	270	* enough to be seen in profiles.
	271	*
	272	* The mpx_notify_unmap() call and its contents have been
	273	* observed to affect munmap() performance on hardware
	274	* where MPX is not present.
	275	*
	276	* The unlikely() optimizes for the fast case: no MPX
	277	* in the CPU, or no MPX use in the process. Even if
	278	* we get this wrong (in the unlikely event that MPX
	279	* is widely enabled on some system) the overhead of
	280	* MPX itself (reading bounds tables) is expected to
	281	* overwhelm the overhead of getting this unlikely()
	282	* consistently wrong.
	283	*/
	284	if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
	285	mpx_notify_unmap(mm, vma, start, end);
1de4fa14 DH	286	}
1de4fa14 DH	287
7d06d9c9	288	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
8f62c883 DH	289	static inline int vma_pkey(struct vm_area_struct *vma)
8f62c883 DH	290	{
8f62c883 DH	291	unsigned long vma_pkey_mask = VM_PKEY_BIT0 \| VM_PKEY_BIT1 \|
8f62c883 DH	292	VM_PKEY_BIT2 \| VM_PKEY_BIT3;
7d06d9c9 DH	293
	294	return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
	295	}
	296	#else
	297	static inline int vma_pkey(struct vm_area_struct *vma)
	298	{
	299	return 0;
8f62c883	300	}
7d06d9c9	301	#endif
8f62c883	302
33a709b2 DH	303	/*
	304	* We only want to enforce protection keys on the current process
	305	* because we effectively have no access to PKRU for other
	306	* processes or any way to tell which PKRU in a threaded
	307	* process we could use.
	308	*
	309	* So do not enforce things if the VMA is not from the current
	310	* mm, or if we are in a kernel thread.
	311	*/
	312	static inline bool vma_is_foreign(struct vm_area_struct *vma)
	313	{
	314	if (!current->mm)
	315	return true;
	316	/*
	317	* Should PKRU be enforced on the access to this VMA? If
	318	* the VMA is from another process, then PKRU has no
	319	* relevance and should not be enforced.
	320	*/
	321	if (current->mm != vma->vm_mm)
	322	return true;
	323
	324	return false;
	325	}
	326
1b2ee126	327	static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
d61172b4	328	bool write, bool execute, bool foreign)
33a709b2	329	{
d61172b4 DH	330	/* pkeys never affect instruction fetches */
	331	if (execute)
	332	return true;
33a709b2	333	/* allow access if the VMA is not one from this process */
1b2ee126	334	if (foreign \|\| vma_is_foreign(vma))
33a709b2 DH	335	return true;
	336	return __pkru_allows_pkey(vma_pkey(vma), write);
	337	}
	338
d6e41f11 AL	339	/*
d6e41f11 AL	340	* This can be used from process context to figure out what the value of
6c690ee1	341	* CR3 is without needing to do a (slow) __read_cr3().
d6e41f11 AL	342	*
	343	* It's intended to be used for code like KVM that sneakily changes CR3
	344	* and needs to restore it. It needs to be used very carefully.
	345	*/
	346	static inline unsigned long __get_current_cr3_fast(void)
	347	{
f741923a	348	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
72be211b	349	this_cpu_read(cpu_tlbstate.loaded_mm_asid));
d833a976	350
d6e41f11	351	/* For now, be very restrictive about when this can be called. */
4c07f904	352	VM_WARN_ON(in_nmi() \|\| preemptible());
d6e41f11	353
6c690ee1	354	VM_BUG_ON(cr3 != __read_cr3());
d6e41f11 AL	355	return cr3;
	356	}
	357
1965aae3	358	#endif /* _ASM_X86_MMU_CONTEXT_H */