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

/* SPDX-License-Identifier: GPL-2.0 */
#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_XXL
static inline void paravirt_activate_mm(struct mm_struct *prev,
					struct mm_struct *next)
{
}
#endif	/* !CONFIG_PARAVIRT_XXL */

#ifdef CONFIG_PERF_EVENTS

DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key);

static inline void load_mm_cr4(struct mm_struct *mm)
{
	if (static_branch_unlikely(&rdpmc_always_available_key) ||
	    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)
{
	return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot);
}

/*
 * 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);

/*
 * Init a new mm.  Used on mm copies, like at fork()
 * and on mm's that are brand-new, like at execve().
 */
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 allocated implicitly */
		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 void arch_dup_pkeys(struct mm_struct *oldmm,
				  struct mm_struct *mm)
{
#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
		return;

	/* Duplicate the oldmm pkey state in mm: */
	mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
	mm->context.execute_only_pkey   = oldmm->context.execute_only_pkey;
#endif
}

static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
{
	arch_dup_pkeys(oldmm, 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);
}

/*
 * 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
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1965aae3 PA	2	#ifndef _ASM_X86_MMU_CONTEXT_H
1965aae3 PA	3	#define _ASM_X86_MMU_CONTEXT_H
c3c2fee3 JF	4
c3c2fee3 JF	5	#include <asm/desc.h>
60063497	6	#include <linux/atomic.h>
d17d8f9d	7	#include <linux/mm_types.h>
7d06d9c9	8	#include <linux/pkeys.h>
d17d8f9d DH	9
	10	#include <trace/events/tlb.h>
	11
c3c2fee3 JF	12	#include <asm/pgalloc.h>
	13	#include <asm/tlbflush.h>
	14	#include <asm/paravirt.h>
fe3d197f	15	#include <asm/mpx.h>
f39681ed AL	16
	17	extern atomic64_t last_mm_ctx_id;
	18
fdc0269e	19	#ifndef CONFIG_PARAVIRT_XXL
c3c2fee3 JF	20	static inline void paravirt_activate_mm(struct mm_struct *prev,
	21	struct mm_struct *next)
	22	{
	23	}
fdc0269e	24	#endif /* !CONFIG_PARAVIRT_XXL */
c3c2fee3	25
7911d3f7	26	#ifdef CONFIG_PERF_EVENTS
631fe154 DB	27
631fe154 DB	28	DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key);
a6673429	29
7911d3f7 AL	30	static inline void load_mm_cr4(struct mm_struct *mm)
7911d3f7 AL	31	{
631fe154	32	if (static_branch_unlikely(&rdpmc_always_available_key) \|\|
a6673429	33	atomic_read(&mm->context.perf_rdpmc_allowed))
7911d3f7 AL	34	cr4_set_bits(X86_CR4_PCE);
	35	else
	36	cr4_clear_bits(X86_CR4_PCE);
	37	}
	38	#else
	39	static inline void load_mm_cr4(struct mm_struct *mm) {}
	40	#endif
	41
a5b9e5a2	42	#ifdef CONFIG_MODIFY_LDT_SYSCALL
37868fe1 AL	43	/*
	44	* ldt_structs can be allocated, used, and freed, but they are never
	45	* modified while live.
	46	*/
	47	struct ldt_struct {
	48	/*
	49	* Xen requires page-aligned LDTs with special permissions. This is
	50	* needed to prevent us from installing evil descriptors such as
	51	* call gates. On native, we could merge the ldt_struct and LDT
	52	* allocations, but it's not worth trying to optimize.
	53	*/
f55f0501 AL	54	struct desc_struct *entries;
	55	unsigned int nr_entries;
	56
	57	/*
	58	* If PTI is in use, then the entries array is not mapped while we're
	59	* in user mode. The whole array will be aliased at the addressed
	60	* given by ldt_slot_va(slot). We use two slots so that we can allocate
	61	* and map, and enable a new LDT without invalidating the mapping
	62	* of an older, still-in-use LDT.
	63	*
	64	* slot will be -1 if this LDT doesn't have an alias mapping.
	65	*/
	66	int slot;
37868fe1 AL	67	};
37868fe1 AL	68
f55f0501 AL	69	/* This is a multiple of PAGE_SIZE. */
	70	#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE)
	71
	72	static inline void *ldt_slot_va(int slot)
	73	{
f55f0501	74	return (void )(LDT_BASE_ADDR + LDT_SLOT_STRIDE slot);
f55f0501 AL	75	}
f55f0501 AL	76
a5b9e5a2 AL	77	/*
	78	* Used for LDT copy/destruction.
	79	*/
a4828f81 TG	80	static inline void init_new_context_ldt(struct mm_struct *mm)
	81	{
	82	mm->context.ldt = NULL;
	83	init_rwsem(&mm->context.ldt_usr_sem);
	84	}
	85	int ldt_dup_context(struct mm_struct oldmm, struct mm_struct mm);
39a0526f	86	void destroy_context_ldt(struct mm_struct *mm);
f55f0501	87	void ldt_arch_exit_mmap(struct mm_struct *mm);
a5b9e5a2	88	#else /* CONFIG_MODIFY_LDT_SYSCALL */
a4828f81 TG	89	static inline void init_new_context_ldt(struct mm_struct *mm) { }
	90	static inline int ldt_dup_context(struct mm_struct *oldmm,
	91	struct mm_struct *mm)
a5b9e5a2 AL	92	{
	93	return 0;
	94	}
f55f0501 AL	95	static inline void destroy_context_ldt(struct mm_struct *mm) { }
f55f0501 AL	96	static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
a5b9e5a2 AL	97	#endif
a5b9e5a2 AL	98
37868fe1 AL	99	static inline void load_mm_ldt(struct mm_struct *mm)
37868fe1 AL	100	{
a5b9e5a2	101	#ifdef CONFIG_MODIFY_LDT_SYSCALL
37868fe1 AL	102	struct ldt_struct *ldt;
37868fe1 AL	103
3382290e WD	104	/* READ_ONCE synchronizes with smp_store_release */
3382290e WD	105	ldt = READ_ONCE(mm->context.ldt);
37868fe1 AL	106
	107	/*
	108	* Any change to mm->context.ldt is followed by an IPI to all
	109	* CPUs with the mm active. The LDT will not be freed until
	110	* after the IPI is handled by all such CPUs. This means that,
	111	* if the ldt_struct changes before we return, the values we see
	112	* will be safe, and the new values will be loaded before we run
	113	* any user code.
	114	*
	115	* NB: don't try to convert this to use RCU without extreme care.
	116	* We would still need IRQs off, because we don't want to change
	117	* the local LDT after an IPI loaded a newer value than the one
	118	* that we can see.
	119	*/
	120
f55f0501 AL	121	if (unlikely(ldt)) {
	122	if (static_cpu_has(X86_FEATURE_PTI)) {
	123	if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) {
	124	/*
	125	* Whoops -- either the new LDT isn't mapped
	126	* (if slot == -1) or is mapped into a bogus
	127	* slot (if slot > 1).
	128	*/
	129	clear_LDT();
	130	return;
	131	}
	132
	133	/*
	134	* If page table isolation is enabled, ldt->entries
	135	* will not be mapped in the userspace pagetables.
	136	* Tell the CPU to access the LDT through the alias
	137	* at ldt_slot_va(ldt->slot).
	138	*/
	139	set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries);
	140	} else {
	141	set_ldt(ldt->entries, ldt->nr_entries);
	142	}
	143	} else {
37868fe1	144	clear_LDT();
f55f0501	145	}
a5b9e5a2 AL	146	#else
	147	clear_LDT();
	148	#endif
73534258 AL	149	}
	150
	151	static inline void switch_ldt(struct mm_struct prev, struct mm_struct next)
	152	{
	153	#ifdef CONFIG_MODIFY_LDT_SYSCALL
	154	/*
	155	* Load the LDT if either the old or new mm had an LDT.
	156	*
	157	* An mm will never go from having an LDT to not having an LDT. Two
	158	* mms never share an LDT, so we don't gain anything by checking to
	159	* see whether the LDT changed. There's also no guarantee that
	160	* prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
	161	* then prev->context.ldt will also be non-NULL.
	162	*
	163	* If we really cared, we could optimize the case where prev == next
	164	* and we're exiting lazy mode. Most of the time, if this happens,
	165	* we don't actually need to reload LDTR, but modify_ldt() is mostly
	166	* used by legacy code and emulators where we don't need this level of
	167	* performance.
	168	*
	169	* This uses \| instead of \|\| because it generates better code.
	170	*/
	171	if (unlikely((unsigned long)prev->context.ldt \|
	172	(unsigned long)next->context.ldt))
	173	load_mm_ldt(next);
	174	#endif
37868fe1 AL	175
	176	DEBUG_LOCKS_WARN_ON(preemptible());
	177	}
	178
b956575b	179	void enter_lazy_tlb(struct mm_struct mm, struct task_struct tsk);
6826c8ff	180
a31e184e DH	181	/*
	182	* Init a new mm. Used on mm copies, like at fork()
	183	* and on mm's that are brand-new, like at execve().
	184	*/
39a0526f DH	185	static inline int init_new_context(struct task_struct *tsk,
	186	struct mm_struct *mm)
	187	{
c2b3496b PZ	188	mutex_init(&mm->context.lock);
c2b3496b PZ	189
f39681ed AL	190	mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
	191	atomic64_set(&mm->context.tlb_gen, 0);
	192
a4828f81	193	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
e8c24d3a	194	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
2fa9d1cf	195	/* pkey 0 is the default and allocated implicitly */
e8c24d3a DH	196	mm->context.pkey_allocation_map = 0x1;
	197	/* -1 means unallocated or invalid */
	198	mm->context.execute_only_pkey = -1;
	199	}
a4828f81 TG	200	#endif
	201	init_new_context_ldt(mm);
	202	return 0;
39a0526f DH	203	}
	204	static inline void destroy_context(struct mm_struct *mm)
	205	{
	206	destroy_context_ldt(mm);
	207	}
	208
69c0319a AL	209	extern void switch_mm(struct mm_struct prev, struct mm_struct next,
69c0319a AL	210	struct task_struct *tsk);
6826c8ff	211
078194f8 AL	212	extern void switch_mm_irqs_off(struct mm_struct prev, struct mm_struct next,
	213	struct task_struct *tsk);
	214	#define switch_mm_irqs_off switch_mm_irqs_off
c3c2fee3 JF	215
	216	#define activate_mm(prev, next) \
	217	do { \
	218	paravirt_activate_mm((prev), (next)); \
	219	switch_mm((prev), (next), NULL); \
	220	} while (0);
	221
6826c8ff BG	222	#ifdef CONFIG_X86_32
	223	#define deactivate_mm(tsk, mm) \
	224	do { \
ccbeed3a	225	lazy_load_gs(0); \
6826c8ff BG	226	} while (0)
	227	#else
	228	#define deactivate_mm(tsk, mm) \
	229	do { \
	230	load_gs_index(0); \
	231	loadsegment(fs, 0); \
	232	} while (0)
	233	#endif
c3c2fee3	234
a31e184e DH	235	static inline void arch_dup_pkeys(struct mm_struct *oldmm,
	236	struct mm_struct *mm)
	237	{
	238	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
	239	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
	240	return;
	241
	242	/* Duplicate the oldmm pkey state in mm: */
	243	mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
	244	mm->context.execute_only_pkey = oldmm->context.execute_only_pkey;
	245	#endif
	246	}
	247
c10e83f5	248	static inline int arch_dup_mmap(struct mm_struct oldmm, struct mm_struct mm)
a1ea1c03	249	{
a31e184e	250	arch_dup_pkeys(oldmm, mm);
a1ea1c03	251	paravirt_arch_dup_mmap(oldmm, mm);
a4828f81	252	return ldt_dup_context(oldmm, mm);
a1ea1c03 DH	253	}
	254
	255	static inline void arch_exit_mmap(struct mm_struct *mm)
	256	{
	257	paravirt_arch_exit_mmap(mm);
f55f0501	258	ldt_arch_exit_mmap(mm);
a1ea1c03 DH	259	}
a1ea1c03 DH	260
b0e9b09b DH	261	#ifdef CONFIG_X86_64
	262	static inline bool is_64bit_mm(struct mm_struct *mm)
	263	{
97f2645f	264	return !IS_ENABLED(CONFIG_IA32_EMULATION) \|\|
b0e9b09b DH	265	!(mm->context.ia32_compat == TIF_IA32);
	266	}
	267	#else
	268	static inline bool is_64bit_mm(struct mm_struct *mm)
	269	{
	270	return false;
	271	}
	272	#endif
	273
fe3d197f DH	274	static inline void arch_bprm_mm_init(struct mm_struct *mm,
	275	struct vm_area_struct *vma)
	276	{
	277	mpx_mm_init(mm);
	278	}
	279
1de4fa14 DH	280	static inline void arch_unmap(struct mm_struct mm, struct vm_area_struct vma,
	281	unsigned long start, unsigned long end)
	282	{
c922228e DH	283	/*
	284	* mpx_notify_unmap() goes and reads a rarely-hot
	285	* cacheline in the mm_struct. That can be expensive
	286	* enough to be seen in profiles.
	287	*
	288	* The mpx_notify_unmap() call and its contents have been
	289	* observed to affect munmap() performance on hardware
	290	* where MPX is not present.
	291	*
	292	* The unlikely() optimizes for the fast case: no MPX
	293	* in the CPU, or no MPX use in the process. Even if
	294	* we get this wrong (in the unlikely event that MPX
	295	* is widely enabled on some system) the overhead of
	296	* MPX itself (reading bounds tables) is expected to
	297	* overwhelm the overhead of getting this unlikely()
	298	* consistently wrong.
	299	*/
	300	if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
	301	mpx_notify_unmap(mm, vma, start, end);
1de4fa14 DH	302	}
1de4fa14 DH	303
33a709b2 DH	304	/*
	305	* We only want to enforce protection keys on the current process
	306	* because we effectively have no access to PKRU for other
	307	* processes or any way to tell which PKRU in a threaded
	308	* process we could use.
	309	*
	310	* So do not enforce things if the VMA is not from the current
	311	* mm, or if we are in a kernel thread.
	312	*/
	313	static inline bool vma_is_foreign(struct vm_area_struct *vma)
	314	{
	315	if (!current->mm)
	316	return true;
	317	/*
	318	* Should PKRU be enforced on the access to this VMA? If
	319	* the VMA is from another process, then PKRU has no
	320	* relevance and should not be enforced.
	321	*/
	322	if (current->mm != vma->vm_mm)
	323	return true;
	324
	325	return false;
	326	}
	327
1b2ee126	328	static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
d61172b4	329	bool write, bool execute, bool foreign)
33a709b2	330	{
d61172b4 DH	331	/* pkeys never affect instruction fetches */
	332	if (execute)
	333	return true;
33a709b2	334	/* allow access if the VMA is not one from this process */
1b2ee126	335	if (foreign \|\| vma_is_foreign(vma))
33a709b2 DH	336	return true;
	337	return __pkru_allows_pkey(vma_pkey(vma), write);
	338	}
	339
d6e41f11 AL	340	/*
d6e41f11 AL	341	* This can be used from process context to figure out what the value of
6c690ee1	342	* CR3 is without needing to do a (slow) __read_cr3().
d6e41f11 AL	343	*
	344	* It's intended to be used for code like KVM that sneakily changes CR3
	345	* and needs to restore it. It needs to be used very carefully.
	346	*/
	347	static inline unsigned long __get_current_cr3_fast(void)
	348	{
50fb83a6	349	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
47061a24	350	this_cpu_read(cpu_tlbstate.loaded_mm_asid));
10af6235	351
d6e41f11	352	/* For now, be very restrictive about when this can be called. */
4c07f904	353	VM_WARN_ON(in_nmi() \|\| preemptible());
d6e41f11	354
6c690ee1	355	VM_BUG_ON(cr3 != __read_cr3());
d6e41f11 AL	356	return cr3;
	357	}
	358
1965aae3	359	#endif /* _ASM_X86_MMU_CONTEXT_H */