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/*
* Intel SMP support routines.
*
* (c) 1995 Alan Cox, Building #3 <alan@redhat.com>
* (c) 1998-99, 2000 Ingo Molnar <mingo@redhat.com>
*
* This code is released under the GNU General Public License version 2 or
* later.
*/
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/smp_lock.h>
#include <linux/kernel_stat.h>
#include <linux/mc146818rtc.h>
#include <linux/cache.h>
#include <asm/mtrr.h>
#include <asm/pgalloc.h>
#include <asm/smpboot.h>
/*
* Some notes on x86 processor bugs affecting SMP operation:
*
* Pentium, Pentium Pro, II, III (and all CPUs) have bugs.
* The Linux implications for SMP are handled as follows:
*
* Pentium III / [Xeon]
* None of the E1AP-E3AP errata are visible to the user.
*
* E1AP. see PII A1AP
* E2AP. see PII A2AP
* E3AP. see PII A3AP
*
* Pentium II / [Xeon]
* None of the A1AP-A3AP errata are visible to the user.
*
* A1AP. see PPro 1AP
* A2AP. see PPro 2AP
* A3AP. see PPro 7AP
*
* Pentium Pro
* None of 1AP-9AP errata are visible to the normal user,
* except occasional delivery of 'spurious interrupt' as trap #15.
* This is very rare and a non-problem.
*
* 1AP. Linux maps APIC as non-cacheable
* 2AP. worked around in hardware
* 3AP. fixed in C0 and above steppings microcode update.
* Linux does not use excessive STARTUP_IPIs.
* 4AP. worked around in hardware
* 5AP. symmetric IO mode (normal Linux operation) not affected.
* 'noapic' mode has vector 0xf filled out properly.
* 6AP. 'noapic' mode might be affected - fixed in later steppings
* 7AP. We do not assume writes to the LVT deassering IRQs
* 8AP. We do not enable low power mode (deep sleep) during MP bootup
* 9AP. We do not use mixed mode
*
* Pentium
* There is a marginal case where REP MOVS on 100MHz SMP
* machines with B stepping processors can fail. XXX should provide
* an L1cache=Writethrough or L1cache=off option.
*
* B stepping CPUs may hang. There are hardware work arounds
* for this. We warn about it in case your board doesnt have the work
* arounds. Basically thats so I can tell anyone with a B stepping
* CPU and SMP problems "tough".
*
* Specific items [From Pentium Processor Specification Update]
*
* 1AP. Linux doesn't use remote read
* 2AP. Linux doesn't trust APIC errors
* 3AP. We work around this
* 4AP. Linux never generated 3 interrupts of the same priority
* to cause a lost local interrupt.
* 5AP. Remote read is never used
* 6AP. not affected - worked around in hardware
* 7AP. not affected - worked around in hardware
* 8AP. worked around in hardware - we get explicit CS errors if not
* 9AP. only 'noapic' mode affected. Might generate spurious
* interrupts, we log only the first one and count the
* rest silently.
* 10AP. not affected - worked around in hardware
* 11AP. Linux reads the APIC between writes to avoid this, as per
* the documentation. Make sure you preserve this as it affects
* the C stepping chips too.
* 12AP. not affected - worked around in hardware
* 13AP. not affected - worked around in hardware
* 14AP. we always deassert INIT during bootup
* 15AP. not affected - worked around in hardware
* 16AP. not affected - worked around in hardware
* 17AP. not affected - worked around in hardware
* 18AP. not affected - worked around in hardware
* 19AP. not affected - worked around in BIOS
*
* If this sounds worrying believe me these bugs are either ___RARE___,
* or are signal timing bugs worked around in hardware and there's
* about nothing of note with C stepping upwards.
*/
/* The 'big kernel lock' */
spinlock_t kernel_flag __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
struct tlb_state cpu_tlbstate[NR_CPUS] = {[0 ... NR_CPUS-1] = { &init_mm, 0 }};
/*
* the following functions deal with sending IPIs between CPUs.
*
* We use 'broadcast', CPU->CPU IPIs and self-IPIs too.
*/
static inline int __prepare_ICR (unsigned int shortcut, int vector)
{
return APIC_DM_FIXED | shortcut | vector | APIC_DEST_LOGICAL;
}
static inline int __prepare_ICR2 (unsigned int mask)
{
return SET_APIC_DEST_FIELD(mask);
}
static inline void __send_IPI_shortcut(unsigned int shortcut, int vector)
{
/*
* Subtle. In the case of the 'never do double writes' workaround
* we have to lock out interrupts to be safe. As we don't care
* of the value read we use an atomic rmw access to avoid costly
* cli/sti. Otherwise we use an even cheaper single atomic write
* to the APIC.
*/
unsigned int cfg;
/*
* Wait for idle.
*/
apic_wait_icr_idle();
/*
* No need to touch the target chip field
*/
cfg = __prepare_ICR(shortcut, vector);
/*
* Send the IPI. The write to APIC_ICR fires this off.
*/
apic_write_around(APIC_ICR, cfg);
}
void send_IPI_self(int vector)
{
__send_IPI_shortcut(APIC_DEST_SELF, vector);
}
static inline void send_IPI_mask_bitmask(int mask, int vector)
{
unsigned long cfg;
unsigned long flags;
__save_flags(flags);
__cli();
/*
* Wait for idle.
*/
apic_wait_icr_idle();
/*
* prepare target chip field
*/
cfg = __prepare_ICR2(mask);
apic_write_around(APIC_ICR2, cfg);
/*
* program the ICR
*/
cfg = __prepare_ICR(0, vector);
/*
* Send the IPI. The write to APIC_ICR fires this off.
*/
apic_write_around(APIC_ICR, cfg);
__restore_flags(flags);
}
static inline void send_IPI_mask_sequence(int mask, int vector)
{
unsigned long cfg, flags;
unsigned int query_cpu, query_mask;
/*
* Hack. The clustered APIC addressing mode doesn't allow us to send
* to an arbitrary mask, so I do a unicasts to each CPU instead. This
* should be modified to do 1 message per cluster ID - mbligh
*/
__save_flags(flags);
__cli();
for (query_cpu = 0; query_cpu < NR_CPUS; ++query_cpu) {
query_mask = 1 << query_cpu;
if (query_mask & mask) {
/*
* Wait for idle.
*/
apic_wait_icr_idle();
/*
* prepare target chip field
*/
cfg = __prepare_ICR2(cpu_to_logical_apicid(query_cpu));
apic_write_around(APIC_ICR2, cfg);
/*
* program the ICR
*/
cfg = __prepare_ICR(0, vector);
/*
* Send the IPI. The write to APIC_ICR fires this off.
*/
apic_write_around(APIC_ICR, cfg);
}
}
__restore_flags(flags);
}
static inline void send_IPI_mask(int mask, int vector)
{
if (clustered_apic_mode)
send_IPI_mask_sequence(mask, vector);
else
send_IPI_mask_bitmask(mask, vector);
}
static inline void send_IPI_allbutself(int vector)
{
/*
* if there are no other CPUs in the system then
* we get an APIC send error if we try to broadcast.
* thus we have to avoid sending IPIs in this case.
*/
if (!(smp_num_cpus > 1))
return;
if (clustered_apic_mode) {
// Pointless. Use send_IPI_mask to do this instead
int cpu;
if (smp_num_cpus > 1) {
for (cpu = 0; cpu < smp_num_cpus; ++cpu) {
if (cpu != smp_processor_id())
send_IPI_mask(1 << cpu, vector);
}
}
} else {
__send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
return;
}
}
static inline void send_IPI_all(int vector)
{
if (clustered_apic_mode) {
// Pointless. Use send_IPI_mask to do this instead
int cpu;
for (cpu = 0; cpu < smp_num_cpus; ++cpu) {
send_IPI_mask(1 << cpu, vector);
}
} else {
__send_IPI_shortcut(APIC_DEST_ALLINC, vector);
}
}
/*
* 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 <manfred@colorfullife.com>
*/
static volatile unsigned long flush_cpumask;
static struct mm_struct * flush_mm;
static unsigned long flush_va;
static spinlock_t tlbstate_lock = SPIN_LOCK_UNLOCKED;
#define FLUSH_ALL 0xffffffff
/*
* We cannot call mmdrop() because we are in interrupt context,
* instead update mm->cpu_vm_mask.
*/
static void inline leave_mm (unsigned long cpu)
{
if (cpu_tlbstate[cpu].state == TLBSTATE_OK)
BUG();
clear_bit(cpu, &cpu_tlbstate[cpu].active_mm->cpu_vm_mask);
}
/*
*
* 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) clear_bit(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 superflous
* tlb flush.
* 1a2) set cpu_tlbstate to TLBSTATE_OK
* Now the smp_invalidate_interrupt won't call leave_mm if cpu0
* was in lazy tlb mode.
* 1a3) update cpu_tlbstate[].active_mm
* Now cpu0 accepts tlb flushes for the new mm.
* 1a4) set_bit(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_tlbstate[].active_mm is correct, cpu0 already handles
* flush ipis.
* 1b1) set cpu_tlbstate 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_tlbstate 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.
*/
asmlinkage void smp_invalidate_interrupt (void)
{
unsigned long cpu = smp_processor_id();
if (!test_bit(cpu, &flush_cpumask))
return;
/*
* 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 (flush_mm == cpu_tlbstate[cpu].active_mm) {
if (cpu_tlbstate[cpu].state == TLBSTATE_OK) {
if (flush_va == FLUSH_ALL)
local_flush_tlb();
else
__flush_tlb_one(flush_va);
} else
leave_mm(cpu);
}
ack_APIC_irq();
clear_bit(cpu, &flush_cpumask);
}
static void flush_tlb_others (unsigned long cpumask, struct mm_struct *mm,
unsigned long va)
{
/*
* A couple of (to be removed) sanity checks:
*
* - we do not send IPIs to not-yet booted CPUs.
* - current CPU must not be in mask
* - mask must exist :)
*/
if (!cpumask)
BUG();
if ((cpumask & cpu_online_map) != cpumask)
BUG();
if (cpumask & (1 << smp_processor_id()))
BUG();
if (!mm)
BUG();
/*
* i'm not happy about this global shared spinlock in the
* MM hot path, but we'll see how contended it is.
* Temporarily this turns IRQs off, so that lockups are
* detected by the NMI watchdog.
*/
spin_lock(&tlbstate_lock);
flush_mm = mm;
flush_va = va;
atomic_set_mask(cpumask, &flush_cpumask);
/*
* We have to send the IPI only to
* CPUs affected.
*/
send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR);
while (flush_cpumask)
/* nothing. lockup detection does not belong here */;
flush_mm = NULL;
flush_va = 0;
spin_unlock(&tlbstate_lock);
}
void flush_tlb_current_task(void)
{
struct mm_struct *mm = current->mm;
unsigned long cpu_mask = mm->cpu_vm_mask & ~(1 << smp_processor_id());
local_flush_tlb();
if (cpu_mask)
flush_tlb_others(cpu_mask, mm, FLUSH_ALL);
}
void flush_tlb_mm (struct mm_struct * mm)
{
unsigned long cpu_mask = mm->cpu_vm_mask & ~(1 << smp_processor_id());
if (current->active_mm == mm) {
if (current->mm)
local_flush_tlb();
else
leave_mm(smp_processor_id());
}
if (cpu_mask)
flush_tlb_others(cpu_mask, mm, FLUSH_ALL);
}
void flush_tlb_page(struct vm_area_struct * vma, unsigned long va)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long cpu_mask = mm->cpu_vm_mask & ~(1 << smp_processor_id());
if (current->active_mm == mm) {
if(current->mm)
__flush_tlb_one(va);
else
leave_mm(smp_processor_id());
}
if (cpu_mask)
flush_tlb_others(cpu_mask, mm, va);
}
static inline void do_flush_tlb_all_local(void)
{
unsigned long cpu = smp_processor_id();
__flush_tlb_all();
if (cpu_tlbstate[cpu].state == TLBSTATE_LAZY)
leave_mm(cpu);
}
static void flush_tlb_all_ipi(void* info)
{
do_flush_tlb_all_local();
}
void flush_tlb_all(void)
{
smp_call_function (flush_tlb_all_ipi,0,1,1);
do_flush_tlb_all_local();
}
/*
* 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(1 << cpu, RESCHEDULE_VECTOR);
}
/*
* Structure and data for smp_call_function(). This is designed to minimise
* static memory requirements. It also looks cleaner.
*/
static spinlock_t call_lock = SPIN_LOCK_UNLOCKED;
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;
/*
* this function sends a 'generic call function' IPI to all other CPUs
* in the system.
*/
int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
int wait)
/*
* [SUMMARY] 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, you may call it from a bottom half handler.
*/
{
struct call_data_struct data;
int cpus = smp_num_cpus-1;
if (!cpus)
return 0;
data.func = func;
data.info = info;
atomic_set(&data.started, 0);
data.wait = wait;
if (wait)
atomic_set(&data.finished, 0);
spin_lock_bh(&call_lock);
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)
barrier();
if (wait)
while (atomic_read(&data.finished) != cpus)
barrier();
spin_unlock_bh(&call_lock);
return 0;
}
static void stop_this_cpu (void * dummy)
{
/*
* Remove this CPU:
*/
clear_bit(smp_processor_id(), &cpu_online_map);
__cli();
disable_local_APIC();
if (cpu_data[smp_processor_id()].hlt_works_ok)
for(;;) __asm__("hlt");
for (;;);
}
/*
* this function calls the 'stop' function on all other CPUs in the system.
*/
void smp_send_stop(void)
{
smp_call_function(stop_this_cpu, NULL, 1, 0);
smp_num_cpus = 1;
__cli();
disable_local_APIC();
__sti();
}
/*
* 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
*/
(*func)(info);
if (wait) {
mb();
atomic_inc(&call_data->finished);
}
}
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