/*
* Intel SMP support routines.
*
* (c) 1995 Alan Cox, Building #3 <alan@redhat.com>
* (c) 1998-99, 2000 Ingo Molnar <mingo@redhat.com>
* (c) 2002,2003 Andi Kleen, SuSE Labs.
*
* This code is released under the GNU General Public License version 2 or
* later.
*/
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/smp_lock.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/mc146818rtc.h>
#include <linux/interrupt.h>
#include <asm/mtrr.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/mach_apic.h>
#include <asm/mmu_context.h>
#include <asm/proto.h>
#include <asm/apicdef.h>
/*
* 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>
*
* 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();
clear_bit(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) 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 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) 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 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);
}
void smp_kdb_stop(void)
{
send_IPI_allbutself(KDB_VECTOR);
}
/*
* 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 <func>
* 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 (;;)
asm("hlt");
}
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
*/
irq_enter();
(*func)(info);
irq_exit();
if (wait) {
mb();
atomic_inc(&call_data->finished);
}
}
int safe_smp_processor_id(void)
{
int apicid, i;
if (disable_apic)
return 0;
apicid = hard_smp_processor_id();
if (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 */
}
