/* * Intel SMP support routines. * * (c) 1995 Alan Cox, Building #3 * (c) 1998-99, 2000 Ingo Molnar * (c) 2002,2003 Andi Kleen, SuSE Labs. * * This code is released under the GNU General Public License version 2 or * later. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Smarter SMP flushing macros. * 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 * * To avoid global state use 8 different call vectors. * Each CPU uses a specific vector to trigger flushes on other * CPUs. Depending on the received vector the target CPUs look into * the right per cpu variable for the flush data. * * With more than 8 CPUs they are hashed to the 8 available * vectors. The limited global vector space forces us to this right now. * In future when interrupts are split into per CPU domains this could be * fixed, at the cost of triggering multiple IPIs in some cases. */ union smp_flush_state { struct { cpumask_t flush_cpumask; struct mm_struct *flush_mm; unsigned long flush_va; #define FLUSH_ALL -1ULL spinlock_t tlbstate_lock; }; char pad[SMP_CACHE_BYTES]; } ____cacheline_aligned; /* State is put into the per CPU data section, but padded to a full cache line because other CPUs can access it and we don't want false sharing in the per cpu data segment. */ static DEFINE_PER_CPU(union smp_flush_state, flush_state); /* * We cannot call mmdrop() because we are in interrupt context, * instead update mm->cpu_vm_mask. */ static inline void leave_mm(int cpu) { if (read_pda(mmu_state) == TLBSTATE_OK) BUG(); cpu_clear(cpu, read_pda(active_mm)->cpu_vm_mask); load_cr3(swapper_pg_dir); } /* * * The flush IPI assumes that a thread switch happens in this order: * [cpu0: the cpu that switches] * 1) switch_mm() either 1a) or 1b) * 1a) thread switch to a different mm * 1a1) cpu_clear(cpu, old_mm->cpu_vm_mask); * Stop ipi delivery for the old mm. This is not synchronized with * the other cpus, but smp_invalidate_interrupt ignore flush ipis * for the wrong mm, and in the worst case we perform a superfluous * tlb flush. * 1a2) set cpu mmu_state to TLBSTATE_OK * Now the smp_invalidate_interrupt won't call leave_mm if cpu0 * was in lazy tlb mode. * 1a3) update cpu active_mm * Now cpu0 accepts tlb flushes for the new mm. * 1a4) cpu_set(cpu, new_mm->cpu_vm_mask); * Now the other cpus will send tlb flush ipis. * 1a4) change cr3. * 1b) thread switch without mm change * cpu active_mm is correct, cpu0 already handles * flush ipis. * 1b1) set cpu mmu_state to TLBSTATE_OK * 1b2) test_and_set the cpu bit in cpu_vm_mask. * Atomically set the bit [other cpus will start sending flush ipis], * and test the bit. * 1b3) if the bit was 0: leave_mm was called, flush the tlb. * 2) switch %%esp, ie current * * The interrupt must handle 2 special cases: * - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm. * - the cpu performs speculative tlb reads, i.e. even if the cpu only * runs in kernel space, the cpu could load tlb entries for user space * pages. * * The good news is that cpu mmu_state is local to each cpu, no * write/read ordering problems. */ /* * TLB flush IPI: * * 1) Flush the tlb entries if the cpu uses the mm that's being flushed. * 2) Leave the mm if we are in the lazy tlb mode. * * Interrupts are disabled. */ asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs) { int cpu; int sender; union smp_flush_state *f; cpu = smp_processor_id(); /* * orig_rax contains the interrupt vector - 256. * Use that to determine where the sender put the data. */ sender = regs->orig_rax + 256 - INVALIDATE_TLB_VECTOR_START; f = &per_cpu(flush_state, sender); if (!cpu_isset(cpu, f->flush_cpumask)) goto out; /* * This was a BUG() but until someone can quote me the * line from the intel manual that guarantees an IPI to * multiple CPUs is retried _only_ on the erroring CPUs * its staying as a return * * BUG(); */ if (f->flush_mm == read_pda(active_mm)) { if (read_pda(mmu_state) == TLBSTATE_OK) { if (f->flush_va == FLUSH_ALL) local_flush_tlb(); else __flush_tlb_one(f->flush_va); } else leave_mm(cpu); } out: ack_APIC_irq(); cpu_clear(cpu, f->flush_cpumask); } static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm, unsigned long va) { int sender; union smp_flush_state *f; /* Caller has disabled preemption */ sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS; f = &per_cpu(flush_state, sender); /* Could avoid this lock when num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is probably not worth checking this for a cache-hot lock. */ spin_lock(&f->tlbstate_lock); f->flush_mm = mm; f->flush_va = va; cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask); /* * We have to send the IPI only to * CPUs affected. */ send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender); while (!cpus_empty(f->flush_cpumask)) cpu_relax(); f->flush_mm = NULL; f->flush_va = 0; spin_unlock(&f->tlbstate_lock); } int __cpuinit init_smp_flush(void) { int i; for_each_cpu_mask(i, cpu_possible_map) { spin_lock_init(&per_cpu(flush_state.tlbstate_lock, i)); } return 0; } core_initcall(init_smp_flush); void flush_tlb_current_task(void) { struct mm_struct *mm = current->mm; cpumask_t cpu_mask; preempt_disable(); cpu_mask = mm->cpu_vm_mask; cpu_clear(smp_processor_id(), cpu_mask); local_flush_tlb(); if (!cpus_empty(cpu_mask)) flush_tlb_others(cpu_mask, mm, FLUSH_ALL); preempt_enable(); } void flush_tlb_mm (struct mm_struct * mm) { cpumask_t cpu_mask; preempt_disable(); cpu_mask = mm->cpu_vm_mask; cpu_clear(smp_processor_id(), cpu_mask); if (current->active_mm == mm) { if (current->mm) local_flush_tlb(); else leave_mm(smp_processor_id()); } if (!cpus_empty(cpu_mask)) flush_tlb_others(cpu_mask, mm, FLUSH_ALL); preempt_enable(); } void flush_tlb_page(struct vm_area_struct * vma, unsigned long va) { struct mm_struct *mm = vma->vm_mm; cpumask_t cpu_mask; preempt_disable(); cpu_mask = mm->cpu_vm_mask; cpu_clear(smp_processor_id(), cpu_mask); if (current->active_mm == mm) { if(current->mm) __flush_tlb_one(va); else leave_mm(smp_processor_id()); } if (!cpus_empty(cpu_mask)) flush_tlb_others(cpu_mask, mm, va); preempt_enable(); } static void do_flush_tlb_all(void* info) { unsigned long cpu = smp_processor_id(); __flush_tlb_all(); if (read_pda(mmu_state) == TLBSTATE_LAZY) leave_mm(cpu); } void flush_tlb_all(void) { on_each_cpu(do_flush_tlb_all, NULL, 1, 1); } /* * this function sends a 'reschedule' IPI to another CPU. * it goes straight through and wastes no time serializing * anything. Worst case is that we lose a reschedule ... */ void smp_send_reschedule(int cpu) { send_IPI_mask(cpumask_of_cpu(cpu), RESCHEDULE_VECTOR); } /* * Structure and data for smp_call_function(). This is designed to minimise * static memory requirements. It also looks cleaner. */ static DEFINE_SPINLOCK(call_lock); struct call_data_struct { void (*func) (void *info); void *info; atomic_t started; atomic_t finished; int wait; }; static struct call_data_struct * call_data; void lock_ipi_call_lock(void) { spin_lock_irq(&call_lock); } void unlock_ipi_call_lock(void) { spin_unlock_irq(&call_lock); } /* * this function sends a 'generic call function' IPI to one other CPU * in the system. * * cpu is a standard Linux logical CPU number. */ static void __smp_call_function_single(int cpu, void (*func) (void *info), void *info, int nonatomic, int wait) { struct call_data_struct data; int cpus = 1; data.func = func; data.info = info; atomic_set(&data.started, 0); data.wait = wait; if (wait) atomic_set(&data.finished, 0); call_data = &data; wmb(); /* Send a message to all other CPUs and wait for them to respond */ send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR); /* Wait for response */ while (atomic_read(&data.started) != cpus) cpu_relax(); if (!wait) return; while (atomic_read(&data.finished) != cpus) cpu_relax(); } /* * smp_call_function_single - Run a function on another CPU * @func: The function to run. This must be fast and non-blocking. * @info: An arbitrary pointer to pass to the function. * @nonatomic: Currently unused. * @wait: If true, wait until function has completed on other CPUs. * * Retrurns 0 on success, else a negative status code. * * Does not return until the remote CPU is nearly ready to execute * or is or has executed. */ int smp_call_function_single (int cpu, void (*func) (void *info), void *info, int nonatomic, int wait) { /* prevent preemption and reschedule on another processor */ int me = get_cpu(); if (cpu == me) { WARN_ON(1); put_cpu(); return -EBUSY; } spin_lock_bh(&call_lock); __smp_call_function_single(cpu, func, info, nonatomic, wait); spin_unlock_bh(&call_lock); put_cpu(); return 0; } /* * this function sends a 'generic call function' IPI to all other CPUs * in the system. */ static void __smp_call_function (void (*func) (void *info), void *info, int nonatomic, int wait) { struct call_data_struct data; int cpus = num_online_cpus()-1; if (!cpus) return; data.func = func; data.info = info; atomic_set(&data.started, 0); data.wait = wait; if (wait) atomic_set(&data.finished, 0); call_data = &data; wmb(); /* Send a message to all other CPUs and wait for them to respond */ send_IPI_allbutself(CALL_FUNCTION_VECTOR); /* Wait for response */ while (atomic_read(&data.started) != cpus) cpu_relax(); if (!wait) return; while (atomic_read(&data.finished) != cpus) cpu_relax(); } /* * smp_call_function - run a function on all other CPUs. * @func: The function to run. This must be fast and non-blocking. * @info: An arbitrary pointer to pass to the function. * @nonatomic: currently unused. * @wait: If true, wait (atomically) until function has completed on other * CPUs. * * Returns 0 on success, else a negative status code. Does not return until * remote CPUs are nearly ready to execute func or are or have executed. * * You must not call this function with disabled interrupts or from a * hardware interrupt handler or from a bottom half handler. * Actually there are a few legal cases, like panic. */ int smp_call_function (void (*func) (void *info), void *info, int nonatomic, int wait) { spin_lock(&call_lock); __smp_call_function(func,info,nonatomic,wait); spin_unlock(&call_lock); return 0; } void smp_stop_cpu(void) { unsigned long flags; /* * Remove this CPU: */ cpu_clear(smp_processor_id(), cpu_online_map); local_irq_save(flags); disable_local_APIC(); local_irq_restore(flags); } static void smp_really_stop_cpu(void *dummy) { smp_stop_cpu(); for (;;) halt(); } void smp_send_stop(void) { int nolock = 0; if (reboot_force) return; /* Don't deadlock on the call lock in panic */ if (!spin_trylock(&call_lock)) { /* ignore locking because we have paniced anyways */ nolock = 1; } __smp_call_function(smp_really_stop_cpu, NULL, 0, 0); if (!nolock) spin_unlock(&call_lock); local_irq_disable(); disable_local_APIC(); local_irq_enable(); } /* * Reschedule call back. Nothing to do, * all the work is done automatically when * we return from the interrupt. */ asmlinkage void smp_reschedule_interrupt(void) { ack_APIC_irq(); } asmlinkage void smp_call_function_interrupt(void) { void (*func) (void *info) = call_data->func; void *info = call_data->info; int wait = call_data->wait; ack_APIC_irq(); /* * Notify initiating CPU that I've grabbed the data and am * about to execute the function */ mb(); atomic_inc(&call_data->started); /* * At this point the info structure may be out of scope unless wait==1 */ exit_idle(); irq_enter(); (*func)(info); irq_exit(); if (wait) { mb(); atomic_inc(&call_data->finished); } } int safe_smp_processor_id(void) { unsigned apicid, i; if (disable_apic) return 0; apicid = hard_smp_processor_id(); if (apicid < NR_CPUS && x86_cpu_to_apicid[apicid] == apicid) return apicid; for (i = 0; i < NR_CPUS; ++i) { if (x86_cpu_to_apicid[i] == apicid) return i; } /* No entries in x86_cpu_to_apicid? Either no MPS|ACPI, * or called too early. Either way, we must be CPU 0. */ if (x86_cpu_to_apicid[0] == BAD_APICID) return 0; return 0; /* Should not happen */ }