arch/x86/kernel/smp.c

   1 /*
   2  *      Intel SMP support routines.
   3  *
   4  *      (c) 1995 Alan Cox, Building #3 <alan@redhat.com>
   5  *      (c) 1998-99, 2000 Ingo Molnar <mingo@redhat.com>
   6  *      (c) 2002,2003 Andi Kleen, SuSE Labs.
   7  *
   8  *      i386 and x86_64 integration by Glauber Costa <gcosta@redhat.com>
   9  *
  10  *      This code is released under the GNU General Public License version 2 or
  11  *      later.
  12  */
  13
  14 #include <linux/init.h>
  15
  16 #include <linux/mm.h>
  17 #include <linux/delay.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/mc146818rtc.h>
  21 #include <linux/cache.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/cpu.h>
  24
  25 #include <asm/mtrr.h>
  26 #include <asm/tlbflush.h>
  27 #include <asm/mmu_context.h>
  28 #include <asm/proto.h>
  29 #include <mach_ipi.h>
  30 #include <mach_apic.h>
  31 /*
  32  *      Some notes on x86 processor bugs affecting SMP operation:
  33  *
  34  *      Pentium, Pentium Pro, II, III (and all CPUs) have bugs.
  35  *      The Linux implications for SMP are handled as follows:
  36  *
  37  *      Pentium III / [Xeon]
  38  *              None of the E1AP-E3AP errata are visible to the user.
  39  *
  40  *      E1AP.   see PII A1AP
  41  *      E2AP.   see PII A2AP
  42  *      E3AP.   see PII A3AP
  43  *
  44  *      Pentium II / [Xeon]
  45  *              None of the A1AP-A3AP errata are visible to the user.
  46  *
  47  *      A1AP.   see PPro 1AP
  48  *      A2AP.   see PPro 2AP
  49  *      A3AP.   see PPro 7AP
  50  *
  51  *      Pentium Pro
  52  *              None of 1AP-9AP errata are visible to the normal user,
  53  *      except occasional delivery of 'spurious interrupt' as trap #15.
  54  *      This is very rare and a non-problem.
  55  *
  56  *      1AP.    Linux maps APIC as non-cacheable
  57  *      2AP.    worked around in hardware
  58  *      3AP.    fixed in C0 and above steppings microcode update.
  59  *              Linux does not use excessive STARTUP_IPIs.
  60  *      4AP.    worked around in hardware
  61  *      5AP.    symmetric IO mode (normal Linux operation) not affected.
  62  *              'noapic' mode has vector 0xf filled out properly.
  63  *      6AP.    'noapic' mode might be affected - fixed in later steppings
  64  *      7AP.    We do not assume writes to the LVT deassering IRQs
  65  *      8AP.    We do not enable low power mode (deep sleep) during MP bootup
  66  *      9AP.    We do not use mixed mode
  67  *
  68  *      Pentium
  69  *              There is a marginal case where REP MOVS on 100MHz SMP
  70  *      machines with B stepping processors can fail. XXX should provide
  71  *      an L1cache=Writethrough or L1cache=off option.
  72  *
  73  *              B stepping CPUs may hang. There are hardware work arounds
  74  *      for this. We warn about it in case your board doesn't have the work
  75  *      arounds. Basically that's so I can tell anyone with a B stepping
  76  *      CPU and SMP problems "tough".
  77  *
  78  *      Specific items [From Pentium Processor Specification Update]
  79  *
  80  *      1AP.    Linux doesn't use remote read
  81  *      2AP.    Linux doesn't trust APIC errors
  82  *      3AP.    We work around this
  83  *      4AP.    Linux never generated 3 interrupts of the same priority
  84  *              to cause a lost local interrupt.
  85  *      5AP.    Remote read is never used
  86  *      6AP.    not affected - worked around in hardware
  87  *      7AP.    not affected - worked around in hardware
  88  *      8AP.    worked around in hardware - we get explicit CS errors if not
  89  *      9AP.    only 'noapic' mode affected. Might generate spurious
  90  *              interrupts, we log only the first one and count the
  91  *              rest silently.
  92  *      10AP.   not affected - worked around in hardware
  93  *      11AP.   Linux reads the APIC between writes to avoid this, as per
  94  *              the documentation. Make sure you preserve this as it affects
  95  *              the C stepping chips too.
  96  *      12AP.   not affected - worked around in hardware
  97  *      13AP.   not affected - worked around in hardware
  98  *      14AP.   we always deassert INIT during bootup
  99  *      15AP.   not affected - worked around in hardware
 100  *      16AP.   not affected - worked around in hardware
 101  *      17AP.   not affected - worked around in hardware
 102  *      18AP.   not affected - worked around in hardware
 103  *      19AP.   not affected - worked around in BIOS
 104  *
 105  *      If this sounds worrying believe me these bugs are either ___RARE___,
 106  *      or are signal timing bugs worked around in hardware and there's
 107  *      about nothing of note with C stepping upwards.
 108  */
 109
 110 /*
 111  * this function sends a 'reschedule' IPI to another CPU.
 112  * it goes straight through and wastes no time serializing
 113  * anything. Worst case is that we lose a reschedule ...
 114  */
 115 static void native_smp_send_reschedule(int cpu)
 116 {
 117         if (unlikely(cpu_is_offline(cpu))) {
 118                 WARN_ON(1);
 119                 return;
 120         }
 121         send_IPI_mask(cpumask_of_cpu(cpu), RESCHEDULE_VECTOR);
 122 }
 123
 124 /*
 125  * Structure and data for smp_call_function(). This is designed to minimise
 126  * static memory requirements. It also looks cleaner.
 127  */
 128 static DEFINE_SPINLOCK(call_lock);
 129
 130 struct call_data_struct {
 131         void (*func) (void *info);
 132         void *info;
 133         atomic_t started;
 134         atomic_t finished;
 135         int wait;
 136 };
 137
 138 void lock_ipi_call_lock(void)
 139 {
 140         spin_lock_irq(&call_lock);
 141 }
 142
 143 void unlock_ipi_call_lock(void)
 144 {
 145         spin_unlock_irq(&call_lock);
 146 }
 147
 148 static struct call_data_struct *call_data;
 149
 150 static void __smp_call_function(void (*func) (void *info), void *info,
 151                                 int nonatomic, int wait)
 152 {
 153         struct call_data_struct data;
 154         int cpus = num_online_cpus() - 1;
 155
 156         if (!cpus)
 157                 return;
 158
 159         data.func = func;
 160         data.info = info;
 161         atomic_set(&data.started, 0);
 162         data.wait = wait;
 163         if (wait)
 164                 atomic_set(&data.finished, 0);
 165
 166         call_data = &data;
 167         mb();
 168
 169         /* Send a message to all other CPUs and wait for them to respond */
 170         send_IPI_allbutself(CALL_FUNCTION_VECTOR);
 171
 172         /* Wait for response */
 173         while (atomic_read(&data.started) != cpus)
 174                 cpu_relax();
 175
 176         if (wait)
 177                 while (atomic_read(&data.finished) != cpus)
 178                         cpu_relax();
 179 }
 180
 181
 182 /**
 183  * smp_call_function_mask(): Run a function on a set of other CPUs.
 184  * @mask: The set of cpus to run on.  Must not include the current cpu.
 185  * @func: The function to run. This must be fast and non-blocking.
 186  * @info: An arbitrary pointer to pass to the function.
 187  * @wait: If true, wait (atomically) until function has completed on other CPUs.
 188  *
 189   * Returns 0 on success, else a negative status code.
 190  *
 191  * If @wait is true, then returns once @func has returned; otherwise
 192  * it returns just before the target cpu calls @func.
 193  *
 194  * You must not call this function with disabled interrupts or from a
 195  * hardware interrupt handler or from a bottom half handler.
 196  */
 197 static int
 198 native_smp_call_function_mask(cpumask_t mask,
 199                               void (*func)(void *), void *info,
 200                               int wait)
 201 {
 202         struct call_data_struct data;
 203         cpumask_t allbutself;
 204         int cpus;
 205
 206         /* Can deadlock when called with interrupts disabled */
 207         WARN_ON(irqs_disabled());
 208
 209         /* Holding any lock stops cpus from going down. */
 210         spin_lock(&call_lock);
 211
 212         allbutself = cpu_online_map;
 213         cpu_clear(smp_processor_id(), allbutself);
 214
 215         cpus_and(mask, mask, allbutself);
 216         cpus = cpus_weight(mask);
 217
 218         if (!cpus) {
 219                 spin_unlock(&call_lock);
 220                 return 0;
 221         }
 222
 223         data.func = func;
 224         data.info = info;
 225         atomic_set(&data.started, 0);
 226         data.wait = wait;
 227         if (wait)
 228                 atomic_set(&data.finished, 0);
 229
 230         call_data = &data;
 231         wmb();
 232
 233         /* Send a message to other CPUs */
 234         if (cpus_equal(mask, allbutself) &&
 235             cpus_equal(cpu_online_map, cpu_callout_map))
 236                 send_IPI_allbutself(CALL_FUNCTION_VECTOR);
 237         else
 238                 send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
 239
 240         /* Wait for response */
 241         while (atomic_read(&data.started) != cpus)
 242                 cpu_relax();
 243
 244         if (wait)
 245                 while (atomic_read(&data.finished) != cpus)
 246                         cpu_relax();
 247         spin_unlock(&call_lock);
 248
 249         return 0;
 250 }
 251
 252 static void stop_this_cpu(void *dummy)
 253 {
 254         local_irq_disable();
 255         /*
 256          * Remove this CPU:
 257          */
 258         cpu_clear(smp_processor_id(), cpu_online_map);
 259         disable_local_APIC();
 260         if (hlt_works(smp_processor_id()))
 261                 for (;;) halt();
 262         for (;;);
 263 }
 264
 265 /*
 266  * this function calls the 'stop' function on all other CPUs in the system.
 267  */
 268
 269 static void native_smp_send_stop(void)
 270 {
 271         int nolock;
 272         unsigned long flags;
 273
 274         if (reboot_force)
 275                 return;
 276
 277         /* Don't deadlock on the call lock in panic */
 278         nolock = !spin_trylock(&call_lock);
 279         local_irq_save(flags);
 280         __smp_call_function(stop_this_cpu, NULL, 0, 0);
 281         if (!nolock)
 282                 spin_unlock(&call_lock);
 283         disable_local_APIC();
 284         local_irq_restore(flags);
 285 }
 286
 287 /*
 288  * Reschedule call back. Nothing to do,
 289  * all the work is done automatically when
 290  * we return from the interrupt.
 291  */
 292 void smp_reschedule_interrupt(struct pt_regs *regs)
 293 {
 294         ack_APIC_irq();
 295 #ifdef CONFIG_X86_32
 296         __get_cpu_var(irq_stat).irq_resched_count++;
 297 #else
 298         add_pda(irq_resched_count, 1);
 299 #endif
 300 }
 301
 302 void smp_call_function_interrupt(struct pt_regs *regs)
 303 {
 304         void (*func) (void *info) = call_data->func;
 305         void *info = call_data->info;
 306         int wait = call_data->wait;
 307
 308         ack_APIC_irq();
 309         /*
 310          * Notify initiating CPU that I've grabbed the data and am
 311          * about to execute the function
 312          */
 313         mb();
 314         atomic_inc(&call_data->started);
 315         /*
 316          * At this point the info structure may be out of scope unless wait==1
 317          */
 318         irq_enter();
 319         (*func)(info);
 320 #ifdef CONFIG_X86_32
 321         __get_cpu_var(irq_stat).irq_call_count++;
 322 #else
 323         add_pda(irq_call_count, 1);
 324 #endif
 325         irq_exit();
 326
 327         if (wait) {
 328                 mb();
 329                 atomic_inc(&call_data->finished);
 330         }
 331 }
 332
 333 struct smp_ops smp_ops = {
 334         .smp_prepare_boot_cpu = native_smp_prepare_boot_cpu,
 335         .smp_prepare_cpus = native_smp_prepare_cpus,
 336         .cpu_up = native_cpu_up,
 337         .smp_cpus_done = native_smp_cpus_done,
 338
 339         .smp_send_stop = native_smp_send_stop,
 340         .smp_send_reschedule = native_smp_send_reschedule,
 341         .smp_call_function_mask = native_smp_call_function_mask,
 342 };
 343 EXPORT_SYMBOL_GPL(smp_ops);
 344