#include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * TLB flushing, formerly SMP-only * c/o Linus Torvalds. * * These mean you can really definitely utterly forget about * writing to user space from interrupts. (Its not allowed anyway). * * Optimizations Manfred Spraul * * More scalable flush, from Andi Kleen * * Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi */ /* * Use bit 0 to mangle the TIF_SPEC_IB state into the mm pointer which is * stored in cpu_tlb_state.last_user_mm_ibpb. */ #define LAST_USER_MM_IBPB 0x1UL /* * We get here when we do something requiring a TLB invalidation * but could not go invalidate all of the contexts. We do the * necessary invalidation by clearing out the 'ctx_id' which * forces a TLB flush when the context is loaded. */ static void clear_asid_other(void) { u16 asid; /* * This is only expected to be set if we have disabled * kernel _PAGE_GLOBAL pages. */ if (!static_cpu_has(X86_FEATURE_PTI)) { WARN_ON_ONCE(1); return; } for (asid = 0; asid < TLB_NR_DYN_ASIDS; asid++) { /* Do not need to flush the current asid */ if (asid == this_cpu_read(cpu_tlbstate.loaded_mm_asid)) continue; /* * Make sure the next time we go to switch to * this asid, we do a flush: */ this_cpu_write(cpu_tlbstate.ctxs[asid].ctx_id, 0); } this_cpu_write(cpu_tlbstate.invalidate_other, false); } atomic64_t last_mm_ctx_id = ATOMIC64_INIT(1); static void choose_new_asid(struct mm_struct *next, u64 next_tlb_gen, u16 *new_asid, bool *need_flush) { u16 asid; if (!static_cpu_has(X86_FEATURE_PCID)) { *new_asid = 0; *need_flush = true; return; } if (this_cpu_read(cpu_tlbstate.invalidate_other)) clear_asid_other(); for (asid = 0; asid < TLB_NR_DYN_ASIDS; asid++) { if (this_cpu_read(cpu_tlbstate.ctxs[asid].ctx_id) != next->context.ctx_id) continue; *new_asid = asid; *need_flush = (this_cpu_read(cpu_tlbstate.ctxs[asid].tlb_gen) < next_tlb_gen); return; } /* * We don't currently own an ASID slot on this CPU. * Allocate a slot. */ *new_asid = this_cpu_add_return(cpu_tlbstate.next_asid, 1) - 1; if (*new_asid >= TLB_NR_DYN_ASIDS) { *new_asid = 0; this_cpu_write(cpu_tlbstate.next_asid, 1); } *need_flush = true; } static void load_new_mm_cr3(pgd_t *pgdir, u16 new_asid, bool need_flush) { unsigned long new_mm_cr3; if (need_flush) { invalidate_user_asid(new_asid); new_mm_cr3 = build_cr3(pgdir, new_asid); } else { new_mm_cr3 = build_cr3_noflush(pgdir, new_asid); } /* * Caution: many callers of this function expect * that load_cr3() is serializing and orders TLB * fills with respect to the mm_cpumask writes. */ write_cr3(new_mm_cr3); } void leave_mm(int cpu) { struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm); /* * It's plausible that we're in lazy TLB mode while our mm is init_mm. * If so, our callers still expect us to flush the TLB, but there * aren't any user TLB entries in init_mm to worry about. * * This needs to happen before any other sanity checks due to * intel_idle's shenanigans. */ if (loaded_mm == &init_mm) return; /* Warn if we're not lazy. */ WARN_ON(!this_cpu_read(cpu_tlbstate.is_lazy)); switch_mm(NULL, &init_mm, NULL); } EXPORT_SYMBOL_GPL(leave_mm); void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk) { unsigned long flags; local_irq_save(flags); switch_mm_irqs_off(prev, next, tsk); local_irq_restore(flags); } static void sync_current_stack_to_mm(struct mm_struct *mm) { unsigned long sp = current_stack_pointer; pgd_t *pgd = pgd_offset(mm, sp); if (pgtable_l5_enabled()) { if (unlikely(pgd_none(*pgd))) { pgd_t *pgd_ref = pgd_offset_k(sp); set_pgd(pgd, *pgd_ref); } } else { /* * "pgd" is faked. The top level entries are "p4d"s, so sync * the p4d. This compiles to approximately the same code as * the 5-level case. */ p4d_t *p4d = p4d_offset(pgd, sp); if (unlikely(p4d_none(*p4d))) { pgd_t *pgd_ref = pgd_offset_k(sp); p4d_t *p4d_ref = p4d_offset(pgd_ref, sp); set_p4d(p4d, *p4d_ref); } } } static inline unsigned long mm_mangle_tif_spec_ib(struct task_struct *next) { unsigned long next_tif = task_thread_info(next)->flags; unsigned long ibpb = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_IBPB; return (unsigned long)next->mm | ibpb; } static void cond_ibpb(struct task_struct *next) { if (!next || !next->mm) return; /* * Both, the conditional and the always IBPB mode use the mm * pointer to avoid the IBPB when switching between tasks of the * same process. Using the mm pointer instead of mm->context.ctx_id * opens a hypothetical hole vs. mm_struct reuse, which is more or * less impossible to control by an attacker. Aside of that it * would only affect the first schedule so the theoretically * exposed data is not really interesting. */ if (static_branch_likely(&switch_mm_cond_ibpb)) { unsigned long prev_mm, next_mm; /* * This is a bit more complex than the always mode because * it has to handle two cases: * * 1) Switch from a user space task (potential attacker) * which has TIF_SPEC_IB set to a user space task * (potential victim) which has TIF_SPEC_IB not set. * * 2) Switch from a user space task (potential attacker) * which has TIF_SPEC_IB not set to a user space task * (potential victim) which has TIF_SPEC_IB set. * * This could be done by unconditionally issuing IBPB when * a task which has TIF_SPEC_IB set is either scheduled in * or out. Though that results in two flushes when: * * - the same user space task is scheduled out and later * scheduled in again and only a kernel thread ran in * between. * * - a user space task belonging to the same process is * scheduled in after a kernel thread ran in between * * - a user space task belonging to the same process is * scheduled in immediately. * * Optimize this with reasonably small overhead for the * above cases. Mangle the TIF_SPEC_IB bit into the mm * pointer of the incoming task which is stored in * cpu_tlbstate.last_user_mm_ibpb for comparison. */ next_mm = mm_mangle_tif_spec_ib(next); prev_mm = this_cpu_read(cpu_tlbstate.last_user_mm_ibpb); /* * Issue IBPB only if the mm's are different and one or * both have the IBPB bit set. */ if (next_mm != prev_mm && (next_mm | prev_mm) & LAST_USER_MM_IBPB) indirect_branch_prediction_barrier(); this_cpu_write(cpu_tlbstate.last_user_mm_ibpb, next_mm); } if (static_branch_unlikely(&switch_mm_always_ibpb)) { /* * Only flush when switching to a user space task with a * different context than the user space task which ran * last on this CPU. */ if (this_cpu_read(cpu_tlbstate.last_user_mm) != next->mm) { indirect_branch_prediction_barrier(); this_cpu_write(cpu_tlbstate.last_user_mm, next->mm); } } } void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk) { struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm); u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid); unsigned cpu = smp_processor_id(); u64 next_tlb_gen; /* * NB: The scheduler will call us with prev == next when switching * from lazy TLB mode to normal mode if active_mm isn't changing. * When this happens, we don't assume that CR3 (and hence * cpu_tlbstate.loaded_mm) matches next. * * NB: leave_mm() calls us with prev == NULL and tsk == NULL. */ /* We don't want flush_tlb_func_* to run concurrently with us. */ if (IS_ENABLED(CONFIG_PROVE_LOCKING)) WARN_ON_ONCE(!irqs_disabled()); /* * Verify that CR3 is what we think it is. This will catch * hypothetical buggy code that directly switches to swapper_pg_dir * without going through leave_mm() / switch_mm_irqs_off() or that * does something like write_cr3(read_cr3_pa()). * * Only do this check if CONFIG_DEBUG_VM=y because __read_cr3() * isn't free. */ #ifdef CONFIG_DEBUG_VM if (WARN_ON_ONCE(__read_cr3() != build_cr3(real_prev->pgd, prev_asid))) { /* * If we were to BUG here, we'd be very likely to kill * the system so hard that we don't see the call trace. * Try to recover instead by ignoring the error and doing * a global flush to minimize the chance of corruption. * * (This is far from being a fully correct recovery. * Architecturally, the CPU could prefetch something * back into an incorrect ASID slot and leave it there * to cause trouble down the road. It's better than * nothing, though.) */ __flush_tlb_all(); } #endif this_cpu_write(cpu_tlbstate.is_lazy, false); /* * The membarrier system call requires a full memory barrier and * core serialization before returning to user-space, after * storing to rq->curr. Writing to CR3 provides that full * memory barrier and core serializing instruction. */ if (real_prev == next) { VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) != next->context.ctx_id); /* * We don't currently support having a real mm loaded without * our cpu set in mm_cpumask(). We have all the bookkeeping * in place to figure out whether we would need to flush * if our cpu were cleared in mm_cpumask(), but we don't * currently use it. */ if (WARN_ON_ONCE(real_prev != &init_mm && !cpumask_test_cpu(cpu, mm_cpumask(next)))) cpumask_set_cpu(cpu, mm_cpumask(next)); return; } else { u16 new_asid; bool need_flush; /* * Avoid user/user BTB poisoning by flushing the branch * predictor when switching between processes. This stops * one process from doing Spectre-v2 attacks on another. */ cond_ibpb(tsk); if (IS_ENABLED(CONFIG_VMAP_STACK)) { /* * If our current stack is in vmalloc space and isn't * mapped in the new pgd, we'll double-fault. Forcibly * map it. */ sync_current_stack_to_mm(next); } /* * Stop remote flushes for the previous mm. * Skip kernel threads; we never send init_mm TLB flushing IPIs, * but the bitmap manipulation can cause cache line contention. */ if (real_prev != &init_mm) { VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, mm_cpumask(real_prev))); cpumask_clear_cpu(cpu, mm_cpumask(real_prev)); } /* * Start remote flushes and then read tlb_gen. */ if (next != &init_mm) cpumask_set_cpu(cpu, mm_cpumask(next)); next_tlb_gen = atomic64_read(&next->context.tlb_gen); choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush); /* Let nmi_uaccess_okay() know that we're changing CR3. */ this_cpu_write(cpu_tlbstate.loaded_mm, LOADED_MM_SWITCHING); barrier(); if (need_flush) { this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id); this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen); load_new_mm_cr3(next->pgd, new_asid, true); /* * NB: This gets called via leave_mm() in the idle path * where RCU functions differently. Tracing normally * uses RCU, so we need to use the _rcuidle variant. * * (There is no good reason for this. The idle code should * be rearranged to call this before rcu_idle_enter().) */ trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); } else { /* The new ASID is already up to date. */ load_new_mm_cr3(next->pgd, new_asid, false); /* See above wrt _rcuidle. */ trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0); } /* Make sure we write CR3 before loaded_mm. */ barrier(); this_cpu_write(cpu_tlbstate.loaded_mm, next); this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid); } load_mm_cr4(next); switch_ldt(real_prev, next); } /* * Please ignore the name of this function. It should be called * switch_to_kernel_thread(). * * enter_lazy_tlb() is a hint from the scheduler that we are entering a * kernel thread or other context without an mm. Acceptable implementations * include doing nothing whatsoever, switching to init_mm, or various clever * lazy tricks to try to minimize TLB flushes. * * The scheduler reserves the right to call enter_lazy_tlb() several times * in a row. It will notify us that we're going back to a real mm by * calling switch_mm_irqs_off(). */ void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) { if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm) return; if (tlb_defer_switch_to_init_mm()) { /* * There's a significant optimization that may be possible * here. We have accurate enough TLB flush tracking that we * don't need to maintain coherence of TLB per se when we're * lazy. We do, however, need to maintain coherence of * paging-structure caches. We could, in principle, leave our * old mm loaded and only switch to init_mm when * tlb_remove_page() happens. */ this_cpu_write(cpu_tlbstate.is_lazy, true); } else { switch_mm(NULL, &init_mm, NULL); } } /* * Call this when reinitializing a CPU. It fixes the following potential * problems: * * - The ASID changed from what cpu_tlbstate thinks it is (most likely * because the CPU was taken down and came back up with CR3's PCID * bits clear. CPU hotplug can do this. * * - The TLB contains junk in slots corresponding to inactive ASIDs. * * - The CPU went so far out to lunch that it may have missed a TLB * flush. */ void initialize_tlbstate_and_flush(void) { int i; struct mm_struct *mm = this_cpu_read(cpu_tlbstate.loaded_mm); u64 tlb_gen = atomic64_read(&init_mm.context.tlb_gen); unsigned long cr3 = __read_cr3(); /* Assert that CR3 already references the right mm. */ WARN_ON((cr3 & CR3_ADDR_MASK) != __pa(mm->pgd)); /* * Assert that CR4.PCIDE is set if needed. (CR4.PCIDE initialization * doesn't work like other CR4 bits because it can only be set from * long mode.) */ WARN_ON(boot_cpu_has(X86_FEATURE_PCID) && !(cr4_read_shadow() & X86_CR4_PCIDE)); /* Force ASID 0 and force a TLB flush. */ write_cr3(build_cr3(mm->pgd, 0)); /* Reinitialize tlbstate. */ this_cpu_write(cpu_tlbstate.last_user_mm_ibpb, LAST_USER_MM_IBPB); this_cpu_write(cpu_tlbstate.loaded_mm_asid, 0); this_cpu_write(cpu_tlbstate.next_asid, 1); this_cpu_write(cpu_tlbstate.ctxs[0].ctx_id, mm->context.ctx_id); this_cpu_write(cpu_tlbstate.ctxs[0].tlb_gen, tlb_gen); for (i = 1; i < TLB_NR_DYN_ASIDS; i++) this_cpu_write(cpu_tlbstate.ctxs[i].ctx_id, 0); } /* * flush_tlb_func_common()'s memory ordering requirement is that any * TLB fills that happen after we flush the TLB are ordered after we * read active_mm's tlb_gen. We don't need any explicit barriers * because all x86 flush operations are serializing and the * atomic64_read operation won't be reordered by the compiler. */ static void flush_tlb_func_common(const struct flush_tlb_info *f, bool local, enum tlb_flush_reason reason) { /* * We have three different tlb_gen values in here. They are: * * - mm_tlb_gen: the latest generation. * - local_tlb_gen: the generation that this CPU has already caught * up to. * - f->new_tlb_gen: the generation that the requester of the flush * wants us to catch up to. */ struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm); u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid); u64 mm_tlb_gen = atomic64_read(&loaded_mm->context.tlb_gen); u64 local_tlb_gen = this_cpu_read(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen); /* This code cannot presently handle being reentered. */ VM_WARN_ON(!irqs_disabled()); if (unlikely(loaded_mm == &init_mm)) return; VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[loaded_mm_asid].ctx_id) != loaded_mm->context.ctx_id); if (this_cpu_read(cpu_tlbstate.is_lazy)) { /* * We're in lazy mode. We need to at least flush our * paging-structure cache to avoid speculatively reading * garbage into our TLB. Since switching to init_mm is barely * slower than a minimal flush, just switch to init_mm. */ switch_mm_irqs_off(NULL, &init_mm, NULL); return; } if (unlikely(local_tlb_gen == mm_tlb_gen)) { /* * There's nothing to do: we're already up to date. This can * happen if two concurrent flushes happen -- the first flush to * be handled can catch us all the way up, leaving no work for * the second flush. */ trace_tlb_flush(reason, 0); return; } WARN_ON_ONCE(local_tlb_gen > mm_tlb_gen); WARN_ON_ONCE(f->new_tlb_gen > mm_tlb_gen); /* * If we get to this point, we know that our TLB is out of date. * This does not strictly imply that we need to flush (it's * possible that f->new_tlb_gen <= local_tlb_gen), but we're * going to need to flush in the very near future, so we might * as well get it over with. * * The only question is whether to do a full or partial flush. * * We do a partial flush if requested and two extra conditions * are met: * * 1. f->new_tlb_gen == local_tlb_gen + 1. We have an invariant that * we've always done all needed flushes to catch up to * local_tlb_gen. If, for example, local_tlb_gen == 2 and * f->new_tlb_gen == 3, then we know that the flush needed to bring * us up to date for tlb_gen 3 is the partial flush we're * processing. * * As an example of why this check is needed, suppose that there * are two concurrent flushes. The first is a full flush that * changes context.tlb_gen from 1 to 2. The second is a partial * flush that changes context.tlb_gen from 2 to 3. If they get * processed on this CPU in reverse order, we'll see * local_tlb_gen == 1, mm_tlb_gen == 3, and end != TLB_FLUSH_ALL. * If we were to use __flush_tlb_one_user() and set local_tlb_gen to * 3, we'd be break the invariant: we'd update local_tlb_gen above * 1 without the full flush that's needed for tlb_gen 2. * * 2. f->new_tlb_gen == mm_tlb_gen. This is purely an optimiation. * Partial TLB flushes are not all that much cheaper than full TLB * flushes, so it seems unlikely that it would be a performance win * to do a partial flush if that won't bring our TLB fully up to * date. By doing a full flush instead, we can increase * local_tlb_gen all the way to mm_tlb_gen and we can probably * avoid another flush in the very near future. */ if (f->end != TLB_FLUSH_ALL && f->new_tlb_gen == local_tlb_gen + 1 && f->new_tlb_gen == mm_tlb_gen) { /* Partial flush */ unsigned long addr; unsigned long nr_pages = (f->end - f->start) >> PAGE_SHIFT; addr = f->start; while (addr < f->end) { __flush_tlb_one_user(addr); addr += PAGE_SIZE; } if (local) count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_pages); trace_tlb_flush(reason, nr_pages); } else { /* Full flush. */ local_flush_tlb(); if (local) count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); trace_tlb_flush(reason, TLB_FLUSH_ALL); } /* Both paths above update our state to mm_tlb_gen. */ this_cpu_write(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen, mm_tlb_gen); } static void flush_tlb_func_local(void *info, enum tlb_flush_reason reason) { const struct flush_tlb_info *f = info; flush_tlb_func_common(f, true, reason); } static void flush_tlb_func_remote(void *info) { const struct flush_tlb_info *f = info; inc_irq_stat(irq_tlb_count); if (f->mm && f->mm != this_cpu_read(cpu_tlbstate.loaded_mm)) return; count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED); flush_tlb_func_common(f, false, TLB_REMOTE_SHOOTDOWN); } void native_flush_tlb_others(const struct cpumask *cpumask, const struct flush_tlb_info *info) { count_vm_tlb_event(NR_TLB_REMOTE_FLUSH); if (info->end == TLB_FLUSH_ALL) trace_tlb_flush(TLB_REMOTE_SEND_IPI, TLB_FLUSH_ALL); else trace_tlb_flush(TLB_REMOTE_SEND_IPI, (info->end - info->start) >> PAGE_SHIFT); if (is_uv_system()) { /* * This whole special case is confused. UV has a "Broadcast * Assist Unit", which seems to be a fancy way to send IPIs. * Back when x86 used an explicit TLB flush IPI, UV was * optimized to use its own mechanism. These days, x86 uses * smp_call_function_many(), but UV still uses a manual IPI, * and that IPI's action is out of date -- it does a manual * flush instead of calling flush_tlb_func_remote(). This * means that the percpu tlb_gen variables won't be updated * and we'll do pointless flushes on future context switches. * * Rather than hooking native_flush_tlb_others() here, I think * that UV should be updated so that smp_call_function_many(), * etc, are optimal on UV. */ unsigned int cpu; cpu = smp_processor_id(); cpumask = uv_flush_tlb_others(cpumask, info); if (cpumask) smp_call_function_many(cpumask, flush_tlb_func_remote, (void *)info, 1); return; } smp_call_function_many(cpumask, flush_tlb_func_remote, (void *)info, 1); } /* * See Documentation/x86/tlb.txt for details. We choose 33 * because it is large enough to cover the vast majority (at * least 95%) of allocations, and is small enough that we are * confident it will not cause too much overhead. Each single * flush is about 100 ns, so this caps the maximum overhead at * _about_ 3,000 ns. * * This is in units of pages. */ static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33; void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, unsigned long end, unsigned long vmflag) { int cpu; struct flush_tlb_info info = { .mm = mm, }; cpu = get_cpu(); /* This is also a barrier that synchronizes with switch_mm(). */ info.new_tlb_gen = inc_mm_tlb_gen(mm); /* Should we flush just the requested range? */ if ((end != TLB_FLUSH_ALL) && !(vmflag & VM_HUGETLB) && ((end - start) >> PAGE_SHIFT) <= tlb_single_page_flush_ceiling) { info.start = start; info.end = end; } else { info.start = 0UL; info.end = TLB_FLUSH_ALL; } if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) { VM_WARN_ON(irqs_disabled()); local_irq_disable(); flush_tlb_func_local(&info, TLB_LOCAL_MM_SHOOTDOWN); local_irq_enable(); } if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids) flush_tlb_others(mm_cpumask(mm), &info); put_cpu(); } static void do_flush_tlb_all(void *info) { count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED); __flush_tlb_all(); } void flush_tlb_all(void) { count_vm_tlb_event(NR_TLB_REMOTE_FLUSH); on_each_cpu(do_flush_tlb_all, NULL, 1); } static void do_kernel_range_flush(void *info) { struct flush_tlb_info *f = info; unsigned long addr; /* flush range by one by one 'invlpg' */ for (addr = f->start; addr < f->end; addr += PAGE_SIZE) __flush_tlb_one_kernel(addr); } void flush_tlb_kernel_range(unsigned long start, unsigned long end) { /* Balance as user space task's flush, a bit conservative */ if (end == TLB_FLUSH_ALL || (end - start) > tlb_single_page_flush_ceiling << PAGE_SHIFT) { on_each_cpu(do_flush_tlb_all, NULL, 1); } else { struct flush_tlb_info info; info.start = start; info.end = end; on_each_cpu(do_kernel_range_flush, &info, 1); } } void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch) { struct flush_tlb_info info = { .mm = NULL, .start = 0UL, .end = TLB_FLUSH_ALL, }; int cpu = get_cpu(); if (cpumask_test_cpu(cpu, &batch->cpumask)) { VM_WARN_ON(irqs_disabled()); local_irq_disable(); flush_tlb_func_local(&info, TLB_LOCAL_SHOOTDOWN); local_irq_enable(); } if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids) flush_tlb_others(&batch->cpumask, &info); cpumask_clear(&batch->cpumask); put_cpu(); } static ssize_t tlbflush_read_file(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { char buf[32]; unsigned int len; len = sprintf(buf, "%ld\n", tlb_single_page_flush_ceiling); return simple_read_from_buffer(user_buf, count, ppos, buf, len); } static ssize_t tlbflush_write_file(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) { char buf[32]; ssize_t len; int ceiling; len = min(count, sizeof(buf) - 1); if (copy_from_user(buf, user_buf, len)) return -EFAULT; buf[len] = '\0'; if (kstrtoint(buf, 0, &ceiling)) return -EINVAL; if (ceiling < 0) return -EINVAL; tlb_single_page_flush_ceiling = ceiling; return count; } static const struct file_operations fops_tlbflush = { .read = tlbflush_read_file, .write = tlbflush_write_file, .llseek = default_llseek, }; static int __init create_tlb_single_page_flush_ceiling(void) { debugfs_create_file("tlb_single_page_flush_ceiling", S_IRUSR | S_IWUSR, arch_debugfs_dir, NULL, &fops_tlbflush); return 0; } late_initcall(create_tlb_single_page_flush_ceiling);