2 * SMP boot-related support
4 * Copyright (C) 1998-2003 Hewlett-Packard Co
5 * David Mosberger-Tang <davidm@hpl.hp.com>
7 * 01/05/16 Rohit Seth <rohit.seth@intel.com> Moved SMP booting functions from smp.c to here.
8 * 01/04/27 David Mosberger <davidm@hpl.hp.com> Added ITC synching code.
9 * 02/07/31 David Mosberger <davidm@hpl.hp.com> Switch over to hotplug-CPU boot-sequence.
10 * smp_boot_cpus()/smp_commence() is replaced by
11 * smp_prepare_cpus()/__cpu_up()/smp_cpus_done().
13 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/acpi.h>
17 #include <linux/bootmem.h>
18 #include <linux/cpu.h>
19 #include <linux/delay.h>
20 #include <linux/init.h>
21 #include <linux/interrupt.h>
22 #include <linux/irq.h>
23 #include <linux/kernel.h>
24 #include <linux/kernel_stat.h>
26 #include <linux/notifier.h>
27 #include <linux/smp.h>
28 #include <linux/smp_lock.h>
29 #include <linux/spinlock.h>
30 #include <linux/efi.h>
31 #include <linux/percpu.h>
33 #include <asm/atomic.h>
34 #include <asm/bitops.h>
35 #include <asm/cache.h>
36 #include <asm/current.h>
37 #include <asm/delay.h>
41 #include <asm/machvec.h>
44 #include <asm/pgalloc.h>
45 #include <asm/pgtable.h>
46 #include <asm/processor.h>
47 #include <asm/ptrace.h>
49 #include <asm/system.h>
50 #include <asm/tlbflush.h>
51 #include <asm/unistd.h>
56 #define Dprintk(x...) printk(x)
63 * ITC synchronization related stuff:
66 #define SLAVE (SMP_CACHE_BYTES/8)
68 #define NUM_ROUNDS 64 /* magic value */
69 #define NUM_ITERS 5 /* likewise */
71 static spinlock_t itc_sync_lock
= SPIN_LOCK_UNLOCKED
;
72 static volatile unsigned long go
[SLAVE
+ 1];
74 #define DEBUG_ITC_SYNC 0
76 extern void __devinit
calibrate_delay (void);
77 extern void start_ap (void);
78 extern unsigned long ia64_iobase
;
80 task_t
*task_for_booting_cpu
;
85 DEFINE_PER_CPU(int, cpu_state
);
87 /* Bitmasks of currently online, and possible CPUs */
88 cpumask_t cpu_online_map
;
89 EXPORT_SYMBOL(cpu_online_map
);
90 cpumask_t cpu_possible_map
;
91 EXPORT_SYMBOL(cpu_possible_map
);
93 /* which logical CPU number maps to which CPU (physical APIC ID) */
94 volatile int ia64_cpu_to_sapicid
[NR_CPUS
];
95 EXPORT_SYMBOL(ia64_cpu_to_sapicid
);
97 static volatile cpumask_t cpu_callin_map
;
99 struct smp_boot_data smp_boot_data __initdata
;
101 unsigned long ap_wakeup_vector
= -1; /* External Int use to wakeup APs */
103 char __initdata no_int_routing
;
105 unsigned char smp_int_redirect
; /* are INT and IPI redirectable by the chipset? */
108 nointroute (char *str
)
111 printk ("no_int_routing on\n");
115 __setup("nointroute", nointroute
);
118 sync_master (void *arg
)
120 unsigned long flags
, i
;
124 local_irq_save(flags
);
126 for (i
= 0; i
< NUM_ROUNDS
*NUM_ITERS
; ++i
) {
129 go
[SLAVE
] = ia64_get_itc();
132 local_irq_restore(flags
);
136 * Return the number of cycles by which our itc differs from the itc on the master
137 * (time-keeper) CPU. A positive number indicates our itc is ahead of the master,
138 * negative that it is behind.
141 get_delta (long *rt
, long *master
)
143 unsigned long best_t0
= 0, best_t1
= ~0UL, best_tm
= 0;
144 unsigned long tcenter
, t0
, t1
, tm
;
147 for (i
= 0; i
< NUM_ITERS
; ++i
) {
150 while (!(tm
= go
[SLAVE
]));
154 if (t1
- t0
< best_t1
- best_t0
)
155 best_t0
= t0
, best_t1
= t1
, best_tm
= tm
;
158 *rt
= best_t1
- best_t0
;
159 *master
= best_tm
- best_t0
;
161 /* average best_t0 and best_t1 without overflow: */
162 tcenter
= (best_t0
/2 + best_t1
/2);
163 if (best_t0
% 2 + best_t1
% 2 == 2)
165 return tcenter
- best_tm
;
169 * Synchronize ar.itc of the current (slave) CPU with the ar.itc of the MASTER CPU
170 * (normally the time-keeper CPU). We use a closed loop to eliminate the possibility of
171 * unaccounted-for errors (such as getting a machine check in the middle of a calibration
172 * step). The basic idea is for the slave to ask the master what itc value it has and to
173 * read its own itc before and after the master responds. Each iteration gives us three
187 * The goal is to adjust the slave's ar.itc such that tm falls exactly half-way between t0
188 * and t1. If we achieve this, the clocks are synchronized provided the interconnect
189 * between the slave and the master is symmetric. Even if the interconnect were
190 * asymmetric, we would still know that the synchronization error is smaller than the
191 * roundtrip latency (t0 - t1).
193 * When the interconnect is quiet and symmetric, this lets us synchronize the itc to
194 * within one or two cycles. However, we can only *guarantee* that the synchronization is
195 * accurate to within a round-trip time, which is typically in the range of several
196 * hundred cycles (e.g., ~500 cycles). In practice, this means that the itc's are usually
197 * almost perfectly synchronized, but we shouldn't assume that the accuracy is much better
198 * than half a micro second or so.
201 ia64_sync_itc (unsigned int master
)
203 long i
, delta
, adj
, adjust_latency
= 0, done
= 0;
204 unsigned long flags
, rt
, master_time_stamp
, bound
;
207 long rt
; /* roundtrip time */
208 long master
; /* master's timestamp */
209 long diff
; /* difference between midpoint and master's timestamp */
210 long lat
; /* estimate of itc adjustment latency */
215 * Make sure local timer ticks are disabled while we sync. If
216 * they were enabled, we'd have to worry about nasty issues
217 * like setting the ITC ahead of (or a long time before) the
218 * next scheduled tick.
220 BUG_ON((ia64_get_itv() & (1 << 16)) == 0);
224 if (smp_call_function_single(master
, sync_master
, NULL
, 1, 0) < 0) {
225 printk(KERN_ERR
"sync_itc: failed to get attention of CPU %u!\n", master
);
229 while (go
[MASTER
]); /* wait for master to be ready */
231 spin_lock_irqsave(&itc_sync_lock
, flags
);
233 for (i
= 0; i
< NUM_ROUNDS
; ++i
) {
234 delta
= get_delta(&rt
, &master_time_stamp
);
236 done
= 1; /* let's lock on to this... */
242 adjust_latency
+= -delta
;
243 adj
= -delta
+ adjust_latency
/4;
247 ia64_set_itc(ia64_get_itc() + adj
);
251 t
[i
].master
= master_time_stamp
;
253 t
[i
].lat
= adjust_latency
/4;
257 spin_unlock_irqrestore(&itc_sync_lock
, flags
);
260 for (i
= 0; i
< NUM_ROUNDS
; ++i
)
261 printk("rt=%5ld master=%5ld diff=%5ld adjlat=%5ld\n",
262 t
[i
].rt
, t
[i
].master
, t
[i
].diff
, t
[i
].lat
);
265 printk(KERN_INFO
"CPU %d: synchronized ITC with CPU %u (last diff %ld cycles, "
266 "maxerr %lu cycles)\n", smp_processor_id(), master
, delta
, rt
);
270 * Ideally sets up per-cpu profiling hooks. Doesn't do much now...
272 static inline void __devinit
273 smp_setup_percpu_timer (void)
277 static void __devinit
281 extern void ia64_init_itm(void);
283 #ifdef CONFIG_PERFMON
284 extern void pfm_init_percpu(void);
287 cpuid
= smp_processor_id();
288 phys_id
= hard_smp_processor_id();
290 if (cpu_online(cpuid
)) {
291 printk(KERN_ERR
"huh, phys CPU#0x%x, CPU#0x%x already present??\n",
297 cpu_set(cpuid
, cpu_online_map
);
298 unlock_ipi_calllock();
300 smp_setup_percpu_timer();
302 ia64_mca_cmc_vector_setup(); /* Setup vector on AP */
304 #ifdef CONFIG_PERFMON
310 if (!(sal_platform_features
& IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT
)) {
312 * Synchronize the ITC with the BP. Need to do this after irqs are
313 * enabled because ia64_sync_itc() calls smp_call_function_single(), which
314 * calls spin_unlock_bh(), which calls spin_unlock_bh(), which calls
315 * local_bh_enable(), which bugs out if irqs are not enabled...
317 Dprintk("Going to syncup ITC with BP.\n");
326 local_cpu_data
->loops_per_jiffy
= loops_per_jiffy
;
328 #ifdef CONFIG_IA32_SUPPORT
333 * Allow the master to continue.
335 cpu_set(cpuid
, cpu_callin_map
);
336 Dprintk("Stack on CPU %d at about %p\n",cpuid
, &cpuid
);
341 * Activate a secondary processor. head.S calls this.
344 start_secondary (void *unused
)
346 extern int cpu_idle (void);
348 /* Early console may use I/O ports */
349 ia64_set_kr(IA64_KR_IO_BASE
, __pa(ia64_iobase
));
351 Dprintk("start_secondary: starting CPU 0x%x\n", hard_smp_processor_id());
359 struct pt_regs
* __devinit
idle_regs(struct pt_regs
*regs
)
365 struct task_struct
*idle
;
366 struct completion done
;
371 do_fork_idle(void *_c_idle
)
373 struct create_idle
*c_idle
= _c_idle
;
375 c_idle
->idle
= fork_idle(c_idle
->cpu
);
376 complete(&c_idle
->done
);
380 do_boot_cpu (int sapicid
, int cpu
)
383 struct create_idle c_idle
= {
385 .done
= COMPLETION_INITIALIZER(c_idle
.done
),
387 DECLARE_WORK(work
, do_fork_idle
, &c_idle
);
389 * We can't use kernel_thread since we must avoid to reschedule the child.
391 if (!keventd_up() || current_is_keventd())
392 work
.func(work
.data
);
394 schedule_work(&work
);
395 wait_for_completion(&c_idle
.done
);
398 if (IS_ERR(c_idle
.idle
))
399 panic("failed fork for CPU %d", cpu
);
400 task_for_booting_cpu
= c_idle
.idle
;
402 Dprintk("Sending wakeup vector %lu to AP 0x%x/0x%x.\n", ap_wakeup_vector
, cpu
, sapicid
);
404 platform_send_ipi(cpu
, ap_wakeup_vector
, IA64_IPI_DM_INT
, 0);
407 * Wait 10s total for the AP to start
409 Dprintk("Waiting on callin_map ...");
410 for (timeout
= 0; timeout
< 100000; timeout
++) {
411 if (cpu_isset(cpu
, cpu_callin_map
))
412 break; /* It has booted */
417 if (!cpu_isset(cpu
, cpu_callin_map
)) {
418 printk(KERN_ERR
"Processor 0x%x/0x%x is stuck.\n", cpu
, sapicid
);
419 ia64_cpu_to_sapicid
[cpu
] = -1;
420 cpu_clear(cpu
, cpu_online_map
); /* was set in smp_callin() */
430 get_option (&str
, &ticks
);
431 cache_decay_ticks
= ticks
;
435 __setup("decay=", decay
);
438 * # of ticks an idle task is considered cache-hot. Highly application-dependent. There
439 * are apps out there which are known to suffer significantly with values >= 4.
441 unsigned long cache_decay_ticks
= 10; /* equal to MIN_TIMESLICE */
444 smp_tune_scheduling (void)
446 printk(KERN_INFO
"task migration cache decay timeout: %ld msecs.\n",
447 (cache_decay_ticks
+ 1) * 1000 / HZ
);
451 * Initialize the logical CPU number to SAPICID mapping
454 smp_build_cpu_map (void)
457 int boot_cpu_id
= hard_smp_processor_id();
459 for (cpu
= 0; cpu
< NR_CPUS
; cpu
++) {
460 ia64_cpu_to_sapicid
[cpu
] = -1;
461 #ifdef CONFIG_HOTPLUG_CPU
462 cpu_set(cpu
, cpu_possible_map
);
466 ia64_cpu_to_sapicid
[0] = boot_cpu_id
;
467 cpus_clear(cpu_present_map
);
468 cpu_set(0, cpu_present_map
);
469 cpu_set(0, cpu_possible_map
);
470 for (cpu
= 1, i
= 0; i
< smp_boot_data
.cpu_count
; i
++) {
471 sapicid
= smp_boot_data
.cpu_phys_id
[i
];
472 if (sapicid
== boot_cpu_id
)
474 cpu_set(cpu
, cpu_present_map
);
475 cpu_set(cpu
, cpu_possible_map
);
476 ia64_cpu_to_sapicid
[cpu
] = sapicid
;
483 /* on which node is each logical CPU (one cacheline even for 64 CPUs) */
484 u8 cpu_to_node_map
[NR_CPUS
] __cacheline_aligned
;
485 EXPORT_SYMBOL(cpu_to_node_map
);
486 /* which logical CPUs are on which nodes */
487 cpumask_t node_to_cpu_mask
[MAX_NUMNODES
] __cacheline_aligned
;
490 * Build cpu to node mapping and initialize the per node cpu masks.
493 build_cpu_to_node_map (void)
497 for(node
=0; node
<MAX_NUMNODES
; node
++)
498 cpus_clear(node_to_cpu_mask
[node
]);
499 for(cpu
= 0; cpu
< NR_CPUS
; ++cpu
) {
501 * All Itanium NUMA platforms I know use ACPI, so maybe we
502 * can drop this ifdef completely. [EF]
504 #ifdef CONFIG_ACPI_NUMA
506 for (i
= 0; i
< NR_CPUS
; ++i
)
507 if (cpu_physical_id(cpu
) == node_cpuid
[i
].phys_id
) {
508 node
= node_cpuid
[i
].nid
;
512 # error Fixme: Dunno how to build CPU-to-node map.
514 cpu_to_node_map
[cpu
] = (node
>= 0) ? node
: 0;
516 cpu_set(cpu
, node_to_cpu_mask
[node
]);
520 #endif /* CONFIG_NUMA */
523 * Cycle through the APs sending Wakeup IPIs to boot each.
526 smp_prepare_cpus (unsigned int max_cpus
)
528 int boot_cpu_id
= hard_smp_processor_id();
531 * Initialize the per-CPU profiling counter/multiplier
534 smp_setup_percpu_timer();
537 * We have the boot CPU online for sure.
539 cpu_set(0, cpu_online_map
);
540 cpu_set(0, cpu_callin_map
);
542 local_cpu_data
->loops_per_jiffy
= loops_per_jiffy
;
543 ia64_cpu_to_sapicid
[0] = boot_cpu_id
;
545 printk(KERN_INFO
"Boot processor id 0x%x/0x%x\n", 0, boot_cpu_id
);
547 current_thread_info()->cpu
= 0;
548 smp_tune_scheduling();
551 * If SMP should be disabled, then really disable it!
554 printk(KERN_INFO
"SMP mode deactivated.\n");
555 cpus_clear(cpu_online_map
);
556 cpus_clear(cpu_present_map
);
557 cpus_clear(cpu_possible_map
);
558 cpu_set(0, cpu_online_map
);
559 cpu_set(0, cpu_present_map
);
560 cpu_set(0, cpu_possible_map
);
565 void __devinit
smp_prepare_boot_cpu(void)
567 cpu_set(smp_processor_id(), cpu_online_map
);
568 cpu_set(smp_processor_id(), cpu_callin_map
);
571 #ifdef CONFIG_HOTPLUG_CPU
572 extern void fixup_irqs(void);
573 /* must be called with cpucontrol mutex held */
574 static int __devinit
cpu_enable(unsigned int cpu
)
576 per_cpu(cpu_state
,cpu
) = CPU_UP_PREPARE
;
579 while (!cpu_online(cpu
))
584 int __cpu_disable(void)
586 int cpu
= smp_processor_id();
589 * dont permit boot processor for now
595 local_flush_tlb_all();
596 printk ("Disabled cpu %u\n", smp_processor_id());
600 void __cpu_die(unsigned int cpu
)
604 for (i
= 0; i
< 100; i
++) {
605 /* They ack this in play_dead by setting CPU_DEAD */
606 if (per_cpu(cpu_state
, cpu
) == CPU_DEAD
)
609 * TBD: Enable this when physical removal
610 * or when we put the processor is put in
611 * SAL_BOOT_RENDEZ mode
612 * cpu_clear(cpu, cpu_callin_map);
616 current
->state
= TASK_UNINTERRUPTIBLE
;
617 schedule_timeout(HZ
/10);
619 printk(KERN_ERR
"CPU %u didn't die...\n", cpu
);
621 #else /* !CONFIG_HOTPLUG_CPU */
622 static int __devinit
cpu_enable(unsigned int cpu
)
627 int __cpu_disable(void)
632 void __cpu_die(unsigned int cpu
)
634 /* We said "no" in __cpu_disable */
637 #endif /* CONFIG_HOTPLUG_CPU */
640 smp_cpus_done (unsigned int dummy
)
643 unsigned long bogosum
= 0;
646 * Allow the user to impress friends.
649 for (cpu
= 0; cpu
< NR_CPUS
; cpu
++)
651 bogosum
+= cpu_data(cpu
)->loops_per_jiffy
;
653 printk(KERN_INFO
"Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
654 (int)num_online_cpus(), bogosum
/(500000/HZ
), (bogosum
/(5000/HZ
))%100);
658 __cpu_up (unsigned int cpu
)
663 sapicid
= ia64_cpu_to_sapicid
[cpu
];
668 * Already booted.. just enable and get outa idle lool
670 if (cpu_isset(cpu
, cpu_callin_map
))
674 while (!cpu_isset(cpu
, cpu_online_map
))
678 /* Processor goes to start_secondary(), sets online flag */
679 ret
= do_boot_cpu(sapicid
, cpu
);
687 * Assume that CPU's have been discovered by some platform-dependent interface. For
688 * SoftSDV/Lion, that would be ACPI.
690 * Setup of the IPI irq handler is done in irq.c:init_IRQ_SMP().
693 init_smp_config(void)
701 /* Tell SAL where to drop the AP's. */
702 ap_startup
= (struct fptr
*) start_ap
;
703 sal_ret
= ia64_sal_set_vectors(SAL_VECTOR_OS_BOOT_RENDEZ
,
704 ia64_tpa(ap_startup
->fp
), ia64_tpa(ap_startup
->gp
), 0, 0, 0, 0);
706 printk(KERN_ERR
"SMP: Can't set SAL AP Boot Rendezvous: %s\n",
707 ia64_sal_strerror(sal_ret
));