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#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 <trace/events/tlb.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#include <asm/mpx.h>
#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;
int size;
};
/*
* Used for LDT copy/destruction.
*/
int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm);
void destroy_context_ldt(struct mm_struct *mm);
#else /* CONFIG_MODIFY_LDT_SYSCALL */
static inline int init_new_context_ldt(struct task_struct *tsk,
struct mm_struct *mm)
{
return 0;
}
static inline void destroy_context_ldt(struct mm_struct *mm) {}
#endif
static inline void load_mm_ldt(struct mm_struct *mm)
{
#ifdef CONFIG_MODIFY_LDT_SYSCALL
struct ldt_struct *ldt;
/* lockless_dereference synchronizes with smp_store_release */
ldt = lockless_dereference(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))
set_ldt(ldt->entries, ldt->size);
else
clear_LDT();
#else
clear_LDT();
#endif
DEBUG_LOCKS_WARN_ON(preemptible());
}
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
#ifdef CONFIG_SMP
if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
#endif
}
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
init_new_context_ldt(tsk, 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_mmap(struct mm_struct *oldmm,
struct mm_struct *mm)
{
paravirt_arch_dup_mmap(oldmm, mm);
}
static inline void arch_exit_mmap(struct mm_struct *mm)
{
paravirt_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);
}
static inline int vma_pkey(struct vm_area_struct *vma)
{
u16 pkey = 0;
#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
VM_PKEY_BIT2 | VM_PKEY_BIT3;
pkey = (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
#endif
return pkey;
}
static inline bool __pkru_allows_pkey(u16 pkey, bool write)
{
u32 pkru = read_pkru();
if (!__pkru_allows_read(pkru, pkey))
return false;
if (write && !__pkru_allows_write(pkru, pkey))
return false;
return true;
}
/*
* 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);
}
static inline bool arch_pte_access_permitted(pte_t pte, bool write)
{
return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write);
}
#endif /* _ASM_X86_MMU_CONTEXT_H */
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