1b2441318SGreg Kroah-Hartman /* SPDX-License-Identifier: GPL-2.0 */ 21965aae3SH. Peter Anvin #ifndef _ASM_X86_MMU_CONTEXT_H 31965aae3SH. Peter Anvin #define _ASM_X86_MMU_CONTEXT_H 4bb898558SAl Viro 5bb898558SAl Viro #include <asm/desc.h> 660063497SArun Sharma #include <linux/atomic.h> 7d17d8f9dSDave Hansen #include <linux/mm_types.h> 87d06d9c9SDave Hansen #include <linux/pkeys.h> 9d17d8f9dSDave Hansen 10d17d8f9dSDave Hansen #include <trace/events/tlb.h> 11d17d8f9dSDave Hansen 12bb898558SAl Viro #include <asm/pgalloc.h> 13bb898558SAl Viro #include <asm/tlbflush.h> 14bb898558SAl Viro #include <asm/paravirt.h> 15fe3d197fSDave Hansen #include <asm/mpx.h> 16f39681edSAndy Lutomirski 17f39681edSAndy Lutomirski extern atomic64_t last_mm_ctx_id; 18f39681edSAndy Lutomirski 19bb898558SAl Viro #ifndef CONFIG_PARAVIRT 20bb898558SAl Viro static inline void paravirt_activate_mm(struct mm_struct *prev, 21bb898558SAl Viro struct mm_struct *next) 22bb898558SAl Viro { 23bb898558SAl Viro } 24bb898558SAl Viro #endif /* !CONFIG_PARAVIRT */ 25bb898558SAl Viro 267911d3f7SAndy Lutomirski #ifdef CONFIG_PERF_EVENTS 27a6673429SAndy Lutomirski extern struct static_key rdpmc_always_available; 28a6673429SAndy Lutomirski 297911d3f7SAndy Lutomirski static inline void load_mm_cr4(struct mm_struct *mm) 307911d3f7SAndy Lutomirski { 31a833581eSPeter Zijlstra if (static_key_false(&rdpmc_always_available) || 32a6673429SAndy Lutomirski atomic_read(&mm->context.perf_rdpmc_allowed)) 337911d3f7SAndy Lutomirski cr4_set_bits(X86_CR4_PCE); 347911d3f7SAndy Lutomirski else 357911d3f7SAndy Lutomirski cr4_clear_bits(X86_CR4_PCE); 367911d3f7SAndy Lutomirski } 377911d3f7SAndy Lutomirski #else 387911d3f7SAndy Lutomirski static inline void load_mm_cr4(struct mm_struct *mm) {} 397911d3f7SAndy Lutomirski #endif 407911d3f7SAndy Lutomirski 41a5b9e5a2SAndy Lutomirski #ifdef CONFIG_MODIFY_LDT_SYSCALL 42bb898558SAl Viro /* 4337868fe1SAndy Lutomirski * ldt_structs can be allocated, used, and freed, but they are never 4437868fe1SAndy Lutomirski * modified while live. 4537868fe1SAndy Lutomirski */ 4637868fe1SAndy Lutomirski struct ldt_struct { 4737868fe1SAndy Lutomirski /* 4837868fe1SAndy Lutomirski * Xen requires page-aligned LDTs with special permissions. This is 4937868fe1SAndy Lutomirski * needed to prevent us from installing evil descriptors such as 5037868fe1SAndy Lutomirski * call gates. On native, we could merge the ldt_struct and LDT 5137868fe1SAndy Lutomirski * allocations, but it's not worth trying to optimize. 5237868fe1SAndy Lutomirski */ 5337868fe1SAndy Lutomirski struct desc_struct *entries; 54bbf79d21SBorislav Petkov unsigned int nr_entries; 5537868fe1SAndy Lutomirski }; 5637868fe1SAndy Lutomirski 57a5b9e5a2SAndy Lutomirski /* 58a5b9e5a2SAndy Lutomirski * Used for LDT copy/destruction. 59a5b9e5a2SAndy Lutomirski */ 6039a0526fSDave Hansen int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm); 6139a0526fSDave Hansen void destroy_context_ldt(struct mm_struct *mm); 62a5b9e5a2SAndy Lutomirski #else /* CONFIG_MODIFY_LDT_SYSCALL */ 6339a0526fSDave Hansen static inline int init_new_context_ldt(struct task_struct *tsk, 64a5b9e5a2SAndy Lutomirski struct mm_struct *mm) 65a5b9e5a2SAndy Lutomirski { 66a5b9e5a2SAndy Lutomirski return 0; 67a5b9e5a2SAndy Lutomirski } 6839a0526fSDave Hansen static inline void destroy_context_ldt(struct mm_struct *mm) {} 69a5b9e5a2SAndy Lutomirski #endif 70a5b9e5a2SAndy Lutomirski 7137868fe1SAndy Lutomirski static inline void load_mm_ldt(struct mm_struct *mm) 7237868fe1SAndy Lutomirski { 73a5b9e5a2SAndy Lutomirski #ifdef CONFIG_MODIFY_LDT_SYSCALL 7437868fe1SAndy Lutomirski struct ldt_struct *ldt; 7537868fe1SAndy Lutomirski 763382290eSWill Deacon /* READ_ONCE synchronizes with smp_store_release */ 773382290eSWill Deacon ldt = READ_ONCE(mm->context.ldt); 7837868fe1SAndy Lutomirski 7937868fe1SAndy Lutomirski /* 8037868fe1SAndy Lutomirski * Any change to mm->context.ldt is followed by an IPI to all 8137868fe1SAndy Lutomirski * CPUs with the mm active. The LDT will not be freed until 8237868fe1SAndy Lutomirski * after the IPI is handled by all such CPUs. This means that, 8337868fe1SAndy Lutomirski * if the ldt_struct changes before we return, the values we see 8437868fe1SAndy Lutomirski * will be safe, and the new values will be loaded before we run 8537868fe1SAndy Lutomirski * any user code. 8637868fe1SAndy Lutomirski * 8737868fe1SAndy Lutomirski * NB: don't try to convert this to use RCU without extreme care. 8837868fe1SAndy Lutomirski * We would still need IRQs off, because we don't want to change 8937868fe1SAndy Lutomirski * the local LDT after an IPI loaded a newer value than the one 9037868fe1SAndy Lutomirski * that we can see. 9137868fe1SAndy Lutomirski */ 9237868fe1SAndy Lutomirski 9337868fe1SAndy Lutomirski if (unlikely(ldt)) 94bbf79d21SBorislav Petkov set_ldt(ldt->entries, ldt->nr_entries); 9537868fe1SAndy Lutomirski else 9637868fe1SAndy Lutomirski clear_LDT(); 97a5b9e5a2SAndy Lutomirski #else 98a5b9e5a2SAndy Lutomirski clear_LDT(); 99a5b9e5a2SAndy Lutomirski #endif 10073534258SAndy Lutomirski } 10173534258SAndy Lutomirski 10273534258SAndy Lutomirski static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next) 10373534258SAndy Lutomirski { 10473534258SAndy Lutomirski #ifdef CONFIG_MODIFY_LDT_SYSCALL 10573534258SAndy Lutomirski /* 10673534258SAndy Lutomirski * Load the LDT if either the old or new mm had an LDT. 10773534258SAndy Lutomirski * 10873534258SAndy Lutomirski * An mm will never go from having an LDT to not having an LDT. Two 10973534258SAndy Lutomirski * mms never share an LDT, so we don't gain anything by checking to 11073534258SAndy Lutomirski * see whether the LDT changed. There's also no guarantee that 11173534258SAndy Lutomirski * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL, 11273534258SAndy Lutomirski * then prev->context.ldt will also be non-NULL. 11373534258SAndy Lutomirski * 11473534258SAndy Lutomirski * If we really cared, we could optimize the case where prev == next 11573534258SAndy Lutomirski * and we're exiting lazy mode. Most of the time, if this happens, 11673534258SAndy Lutomirski * we don't actually need to reload LDTR, but modify_ldt() is mostly 11773534258SAndy Lutomirski * used by legacy code and emulators where we don't need this level of 11873534258SAndy Lutomirski * performance. 11973534258SAndy Lutomirski * 12073534258SAndy Lutomirski * This uses | instead of || because it generates better code. 12173534258SAndy Lutomirski */ 12273534258SAndy Lutomirski if (unlikely((unsigned long)prev->context.ldt | 12373534258SAndy Lutomirski (unsigned long)next->context.ldt)) 12473534258SAndy Lutomirski load_mm_ldt(next); 12573534258SAndy Lutomirski #endif 12637868fe1SAndy Lutomirski 12737868fe1SAndy Lutomirski DEBUG_LOCKS_WARN_ON(preemptible()); 12837868fe1SAndy Lutomirski } 12937868fe1SAndy Lutomirski 130b956575bSAndy Lutomirski void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk); 1316826c8ffSBrian Gerst 13239a0526fSDave Hansen static inline int init_new_context(struct task_struct *tsk, 13339a0526fSDave Hansen struct mm_struct *mm) 13439a0526fSDave Hansen { 135f39681edSAndy Lutomirski mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id); 136f39681edSAndy Lutomirski atomic64_set(&mm->context.tlb_gen, 0); 137f39681edSAndy Lutomirski 138e8c24d3aSDave Hansen #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS 139e8c24d3aSDave Hansen if (cpu_feature_enabled(X86_FEATURE_OSPKE)) { 140e8c24d3aSDave Hansen /* pkey 0 is the default and always allocated */ 141e8c24d3aSDave Hansen mm->context.pkey_allocation_map = 0x1; 142e8c24d3aSDave Hansen /* -1 means unallocated or invalid */ 143e8c24d3aSDave Hansen mm->context.execute_only_pkey = -1; 144e8c24d3aSDave Hansen } 145e8c24d3aSDave Hansen #endif 146ccd5b323SEric Biggers return init_new_context_ldt(tsk, mm); 14739a0526fSDave Hansen } 14839a0526fSDave Hansen static inline void destroy_context(struct mm_struct *mm) 14939a0526fSDave Hansen { 15039a0526fSDave Hansen destroy_context_ldt(mm); 15139a0526fSDave Hansen } 15239a0526fSDave Hansen 15369c0319aSAndy Lutomirski extern void switch_mm(struct mm_struct *prev, struct mm_struct *next, 15469c0319aSAndy Lutomirski struct task_struct *tsk); 1556826c8ffSBrian Gerst 156078194f8SAndy Lutomirski extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, 157078194f8SAndy Lutomirski struct task_struct *tsk); 158078194f8SAndy Lutomirski #define switch_mm_irqs_off switch_mm_irqs_off 159bb898558SAl Viro 160bb898558SAl Viro #define activate_mm(prev, next) \ 161bb898558SAl Viro do { \ 162bb898558SAl Viro paravirt_activate_mm((prev), (next)); \ 163bb898558SAl Viro switch_mm((prev), (next), NULL); \ 164bb898558SAl Viro } while (0); 165bb898558SAl Viro 1666826c8ffSBrian Gerst #ifdef CONFIG_X86_32 1676826c8ffSBrian Gerst #define deactivate_mm(tsk, mm) \ 1686826c8ffSBrian Gerst do { \ 169ccbeed3aSTejun Heo lazy_load_gs(0); \ 1706826c8ffSBrian Gerst } while (0) 1716826c8ffSBrian Gerst #else 1726826c8ffSBrian Gerst #define deactivate_mm(tsk, mm) \ 1736826c8ffSBrian Gerst do { \ 1746826c8ffSBrian Gerst load_gs_index(0); \ 1756826c8ffSBrian Gerst loadsegment(fs, 0); \ 1766826c8ffSBrian Gerst } while (0) 1776826c8ffSBrian Gerst #endif 178bb898558SAl Viro 179a1ea1c03SDave Hansen static inline void arch_dup_mmap(struct mm_struct *oldmm, 180a1ea1c03SDave Hansen struct mm_struct *mm) 181a1ea1c03SDave Hansen { 182a1ea1c03SDave Hansen paravirt_arch_dup_mmap(oldmm, mm); 183a1ea1c03SDave Hansen } 184a1ea1c03SDave Hansen 185a1ea1c03SDave Hansen static inline void arch_exit_mmap(struct mm_struct *mm) 186a1ea1c03SDave Hansen { 187a1ea1c03SDave Hansen paravirt_arch_exit_mmap(mm); 188a1ea1c03SDave Hansen } 189a1ea1c03SDave Hansen 190b0e9b09bSDave Hansen #ifdef CONFIG_X86_64 191b0e9b09bSDave Hansen static inline bool is_64bit_mm(struct mm_struct *mm) 192b0e9b09bSDave Hansen { 19397f2645fSMasahiro Yamada return !IS_ENABLED(CONFIG_IA32_EMULATION) || 194b0e9b09bSDave Hansen !(mm->context.ia32_compat == TIF_IA32); 195b0e9b09bSDave Hansen } 196b0e9b09bSDave Hansen #else 197b0e9b09bSDave Hansen static inline bool is_64bit_mm(struct mm_struct *mm) 198b0e9b09bSDave Hansen { 199b0e9b09bSDave Hansen return false; 200b0e9b09bSDave Hansen } 201b0e9b09bSDave Hansen #endif 202b0e9b09bSDave Hansen 203fe3d197fSDave Hansen static inline void arch_bprm_mm_init(struct mm_struct *mm, 204fe3d197fSDave Hansen struct vm_area_struct *vma) 205fe3d197fSDave Hansen { 206fe3d197fSDave Hansen mpx_mm_init(mm); 207fe3d197fSDave Hansen } 208fe3d197fSDave Hansen 2091de4fa14SDave Hansen static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma, 2101de4fa14SDave Hansen unsigned long start, unsigned long end) 2111de4fa14SDave Hansen { 212c922228eSDave Hansen /* 213c922228eSDave Hansen * mpx_notify_unmap() goes and reads a rarely-hot 214c922228eSDave Hansen * cacheline in the mm_struct. That can be expensive 215c922228eSDave Hansen * enough to be seen in profiles. 216c922228eSDave Hansen * 217c922228eSDave Hansen * The mpx_notify_unmap() call and its contents have been 218c922228eSDave Hansen * observed to affect munmap() performance on hardware 219c922228eSDave Hansen * where MPX is not present. 220c922228eSDave Hansen * 221c922228eSDave Hansen * The unlikely() optimizes for the fast case: no MPX 222c922228eSDave Hansen * in the CPU, or no MPX use in the process. Even if 223c922228eSDave Hansen * we get this wrong (in the unlikely event that MPX 224c922228eSDave Hansen * is widely enabled on some system) the overhead of 225c922228eSDave Hansen * MPX itself (reading bounds tables) is expected to 226c922228eSDave Hansen * overwhelm the overhead of getting this unlikely() 227c922228eSDave Hansen * consistently wrong. 228c922228eSDave Hansen */ 229c922228eSDave Hansen if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX))) 2301de4fa14SDave Hansen mpx_notify_unmap(mm, vma, start, end); 2311de4fa14SDave Hansen } 2321de4fa14SDave Hansen 2337d06d9c9SDave Hansen #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS 2348f62c883SDave Hansen static inline int vma_pkey(struct vm_area_struct *vma) 2358f62c883SDave Hansen { 2368f62c883SDave Hansen unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 | 2378f62c883SDave Hansen VM_PKEY_BIT2 | VM_PKEY_BIT3; 2387d06d9c9SDave Hansen 2397d06d9c9SDave Hansen return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT; 2408f62c883SDave Hansen } 2417d06d9c9SDave Hansen #else 2427d06d9c9SDave Hansen static inline int vma_pkey(struct vm_area_struct *vma) 2437d06d9c9SDave Hansen { 2447d06d9c9SDave Hansen return 0; 2457d06d9c9SDave Hansen } 2467d06d9c9SDave Hansen #endif 2478f62c883SDave Hansen 24833a709b2SDave Hansen /* 24933a709b2SDave Hansen * We only want to enforce protection keys on the current process 25033a709b2SDave Hansen * because we effectively have no access to PKRU for other 25133a709b2SDave Hansen * processes or any way to tell *which * PKRU in a threaded 25233a709b2SDave Hansen * process we could use. 25333a709b2SDave Hansen * 25433a709b2SDave Hansen * So do not enforce things if the VMA is not from the current 25533a709b2SDave Hansen * mm, or if we are in a kernel thread. 25633a709b2SDave Hansen */ 25733a709b2SDave Hansen static inline bool vma_is_foreign(struct vm_area_struct *vma) 25833a709b2SDave Hansen { 25933a709b2SDave Hansen if (!current->mm) 26033a709b2SDave Hansen return true; 26133a709b2SDave Hansen /* 26233a709b2SDave Hansen * Should PKRU be enforced on the access to this VMA? If 26333a709b2SDave Hansen * the VMA is from another process, then PKRU has no 26433a709b2SDave Hansen * relevance and should not be enforced. 26533a709b2SDave Hansen */ 26633a709b2SDave Hansen if (current->mm != vma->vm_mm) 26733a709b2SDave Hansen return true; 26833a709b2SDave Hansen 26933a709b2SDave Hansen return false; 27033a709b2SDave Hansen } 27133a709b2SDave Hansen 2721b2ee126SDave Hansen static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, 273d61172b4SDave Hansen bool write, bool execute, bool foreign) 27433a709b2SDave Hansen { 275d61172b4SDave Hansen /* pkeys never affect instruction fetches */ 276d61172b4SDave Hansen if (execute) 277d61172b4SDave Hansen return true; 27833a709b2SDave Hansen /* allow access if the VMA is not one from this process */ 2791b2ee126SDave Hansen if (foreign || vma_is_foreign(vma)) 28033a709b2SDave Hansen return true; 28133a709b2SDave Hansen return __pkru_allows_pkey(vma_pkey(vma), write); 28233a709b2SDave Hansen } 28333a709b2SDave Hansen 28452a2af40SAndy Lutomirski /* 28552a2af40SAndy Lutomirski * If PCID is on, ASID-aware code paths put the ASID+1 into the PCID 28652a2af40SAndy Lutomirski * bits. This serves two purposes. It prevents a nasty situation in 28752a2af40SAndy Lutomirski * which PCID-unaware code saves CR3, loads some other value (with PCID 28852a2af40SAndy Lutomirski * == 0), and then restores CR3, thus corrupting the TLB for ASID 0 if 28952a2af40SAndy Lutomirski * the saved ASID was nonzero. It also means that any bugs involving 29052a2af40SAndy Lutomirski * loading a PCID-enabled CR3 with CR4.PCIDE off will trigger 29152a2af40SAndy Lutomirski * deterministically. 29252a2af40SAndy Lutomirski */ 29352a2af40SAndy Lutomirski 29447061a24SAndy Lutomirski static inline unsigned long build_cr3(struct mm_struct *mm, u16 asid) 29547061a24SAndy Lutomirski { 29652a2af40SAndy Lutomirski if (static_cpu_has(X86_FEATURE_PCID)) { 29752a2af40SAndy Lutomirski VM_WARN_ON_ONCE(asid > 4094); 29852a2af40SAndy Lutomirski return __sme_pa(mm->pgd) | (asid + 1); 29952a2af40SAndy Lutomirski } else { 30052a2af40SAndy Lutomirski VM_WARN_ON_ONCE(asid != 0); 30152a2af40SAndy Lutomirski return __sme_pa(mm->pgd); 30252a2af40SAndy Lutomirski } 30347061a24SAndy Lutomirski } 30447061a24SAndy Lutomirski 30547061a24SAndy Lutomirski static inline unsigned long build_cr3_noflush(struct mm_struct *mm, u16 asid) 30647061a24SAndy Lutomirski { 30752a2af40SAndy Lutomirski VM_WARN_ON_ONCE(asid > 4094); 30852a2af40SAndy Lutomirski return __sme_pa(mm->pgd) | (asid + 1) | CR3_NOFLUSH; 30947061a24SAndy Lutomirski } 310d6e41f11SAndy Lutomirski 311d6e41f11SAndy Lutomirski /* 312d6e41f11SAndy Lutomirski * This can be used from process context to figure out what the value of 3136c690ee1SAndy Lutomirski * CR3 is without needing to do a (slow) __read_cr3(). 314d6e41f11SAndy Lutomirski * 315d6e41f11SAndy Lutomirski * It's intended to be used for code like KVM that sneakily changes CR3 316d6e41f11SAndy Lutomirski * and needs to restore it. It needs to be used very carefully. 317d6e41f11SAndy Lutomirski */ 318d6e41f11SAndy Lutomirski static inline unsigned long __get_current_cr3_fast(void) 319d6e41f11SAndy Lutomirski { 32047061a24SAndy Lutomirski unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm), 32147061a24SAndy Lutomirski this_cpu_read(cpu_tlbstate.loaded_mm_asid)); 32210af6235SAndy Lutomirski 323d6e41f11SAndy Lutomirski /* For now, be very restrictive about when this can be called. */ 3244c07f904SRoman Kagan VM_WARN_ON(in_nmi() || preemptible()); 325d6e41f11SAndy Lutomirski 3266c690ee1SAndy Lutomirski VM_BUG_ON(cr3 != __read_cr3()); 327d6e41f11SAndy Lutomirski return cr3; 328d6e41f11SAndy Lutomirski } 329d6e41f11SAndy Lutomirski 3301965aae3SH. Peter Anvin #endif /* _ASM_X86_MMU_CONTEXT_H */ 331