https://github.com/torvalds/linux
Tip revision: 7d132055814ef17a6c7b69f342244c410a5e000f authored by Linus Torvalds on 15 June 2013, 21:51:07 UTC
Linux 3.10-rc6
Linux 3.10-rc6
Tip revision: 7d13205
tlb.c
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/cache.h>
#include <asm/apic.h>
#include <asm/uv/uv.h>
#include <linux/debugfs.h>
DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate)
= { &init_mm, 0, };
/*
* 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
*
* Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi
*/
struct flush_tlb_info {
struct mm_struct *flush_mm;
unsigned long flush_start;
unsigned long flush_end;
};
/*
* We cannot call mmdrop() because we are in interrupt context,
* instead update mm->cpu_vm_mask.
*/
void leave_mm(int cpu)
{
struct mm_struct *active_mm = this_cpu_read(cpu_tlbstate.active_mm);
if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
BUG();
if (cpumask_test_cpu(cpu, mm_cpumask(active_mm))) {
cpumask_clear_cpu(cpu, mm_cpumask(active_mm));
load_cr3(swapper_pg_dir);
}
}
EXPORT_SYMBOL_GPL(leave_mm);
/*
* 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) set cpu_tlbstate to TLBSTATE_OK
* Now the tlb flush NMI handler flush_tlb_func won't call leave_mm
* if cpu0 was in lazy tlb mode.
* 1a2) update cpu active_mm
* Now cpu0 accepts tlb flushes for the new mm.
* 1a3) cpu_set(cpu, new_mm->cpu_vm_mask);
* Now the other cpus will send tlb flush ipis.
* 1a4) change cr3.
* 1a5) cpu_clear(cpu, old_mm->cpu_vm_mask);
* Stop ipi delivery for the old mm. This is not synchronized with
* the other cpus, but flush_tlb_func ignore flush ipis for the wrong
* mm, and in the worst case we perform a superfluous tlb flush.
* 1b) thread switch without mm change
* cpu 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 funcation:
* 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.
*/
static void flush_tlb_func(void *info)
{
struct flush_tlb_info *f = info;
inc_irq_stat(irq_tlb_count);
if (f->flush_mm != this_cpu_read(cpu_tlbstate.active_mm))
return;
if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
if (f->flush_end == TLB_FLUSH_ALL)
local_flush_tlb();
else if (!f->flush_end)
__flush_tlb_single(f->flush_start);
else {
unsigned long addr;
addr = f->flush_start;
while (addr < f->flush_end) {
__flush_tlb_single(addr);
addr += PAGE_SIZE;
}
}
} else
leave_mm(smp_processor_id());
}
void native_flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm, unsigned long start,
unsigned long end)
{
struct flush_tlb_info info;
info.flush_mm = mm;
info.flush_start = start;
info.flush_end = end;
if (is_uv_system()) {
unsigned int cpu;
cpu = smp_processor_id();
cpumask = uv_flush_tlb_others(cpumask, mm, start, end, cpu);
if (cpumask)
smp_call_function_many(cpumask, flush_tlb_func,
&info, 1);
return;
}
smp_call_function_many(cpumask, flush_tlb_func, &info, 1);
}
void flush_tlb_current_task(void)
{
struct mm_struct *mm = current->mm;
preempt_disable();
local_flush_tlb();
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, 0UL, TLB_FLUSH_ALL);
preempt_enable();
}
/*
* It can find out the THP large page, or
* HUGETLB page in tlb_flush when THP disabled
*/
static inline unsigned long has_large_page(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
unsigned long addr = ALIGN(start, HPAGE_SIZE);
for (; addr < end; addr += HPAGE_SIZE) {
pgd = pgd_offset(mm, addr);
if (likely(!pgd_none(*pgd))) {
pud = pud_offset(pgd, addr);
if (likely(!pud_none(*pud))) {
pmd = pmd_offset(pud, addr);
if (likely(!pmd_none(*pmd)))
if (pmd_large(*pmd))
return addr;
}
}
}
return 0;
}
void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long vmflag)
{
unsigned long addr;
unsigned act_entries, tlb_entries = 0;
preempt_disable();
if (current->active_mm != mm)
goto flush_all;
if (!current->mm) {
leave_mm(smp_processor_id());
goto flush_all;
}
if (end == TLB_FLUSH_ALL || tlb_flushall_shift == -1
|| vmflag & VM_HUGETLB) {
local_flush_tlb();
goto flush_all;
}
/* In modern CPU, last level tlb used for both data/ins */
if (vmflag & VM_EXEC)
tlb_entries = tlb_lli_4k[ENTRIES];
else
tlb_entries = tlb_lld_4k[ENTRIES];
/* Assume all of TLB entries was occupied by this task */
act_entries = mm->total_vm > tlb_entries ? tlb_entries : mm->total_vm;
/* tlb_flushall_shift is on balance point, details in commit log */
if ((end - start) >> PAGE_SHIFT > act_entries >> tlb_flushall_shift)
local_flush_tlb();
else {
if (has_large_page(mm, start, end)) {
local_flush_tlb();
goto flush_all;
}
/* flush range by one by one 'invlpg' */
for (addr = start; addr < end; addr += PAGE_SIZE)
__flush_tlb_single(addr);
if (cpumask_any_but(mm_cpumask(mm),
smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, start, end);
preempt_enable();
return;
}
flush_all:
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, 0UL, TLB_FLUSH_ALL);
preempt_enable();
}
void flush_tlb_page(struct vm_area_struct *vma, unsigned long start)
{
struct mm_struct *mm = vma->vm_mm;
preempt_disable();
if (current->active_mm == mm) {
if (current->mm)
__flush_tlb_one(start);
else
leave_mm(smp_processor_id());
}
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, start, 0UL);
preempt_enable();
}
static void do_flush_tlb_all(void *info)
{
__flush_tlb_all();
if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_LAZY)
leave_mm(smp_processor_id());
}
void flush_tlb_all(void)
{
on_each_cpu(do_flush_tlb_all, NULL, 1);
}
static void do_kernel_range_flush(void *info)
{
struct flush_tlb_info *f = info;
unsigned long addr;
/* flush range by one by one 'invlpg' */
for (addr = f->flush_start; addr < f->flush_end; addr += PAGE_SIZE)
__flush_tlb_single(addr);
}
void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
unsigned act_entries;
struct flush_tlb_info info;
/* In modern CPU, last level tlb used for both data/ins */
act_entries = tlb_lld_4k[ENTRIES];
/* Balance as user space task's flush, a bit conservative */
if (end == TLB_FLUSH_ALL || tlb_flushall_shift == -1 ||
(end - start) >> PAGE_SHIFT > act_entries >> tlb_flushall_shift)
on_each_cpu(do_flush_tlb_all, NULL, 1);
else {
info.flush_start = start;
info.flush_end = end;
on_each_cpu(do_kernel_range_flush, &info, 1);
}
}
#ifdef CONFIG_DEBUG_TLBFLUSH
static ssize_t tlbflush_read_file(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[32];
unsigned int len;
len = sprintf(buf, "%hd\n", tlb_flushall_shift);
return simple_read_from_buffer(user_buf, count, ppos, buf, len);
}
static ssize_t tlbflush_write_file(struct file *file,
const char __user *user_buf, size_t count, loff_t *ppos)
{
char buf[32];
ssize_t len;
s8 shift;
len = min(count, sizeof(buf) - 1);
if (copy_from_user(buf, user_buf, len))
return -EFAULT;
buf[len] = '\0';
if (kstrtos8(buf, 0, &shift))
return -EINVAL;
if (shift < -1 || shift >= BITS_PER_LONG)
return -EINVAL;
tlb_flushall_shift = shift;
return count;
}
static const struct file_operations fops_tlbflush = {
.read = tlbflush_read_file,
.write = tlbflush_write_file,
.llseek = default_llseek,
};
static int __init create_tlb_flushall_shift(void)
{
debugfs_create_file("tlb_flushall_shift", S_IRUSR | S_IWUSR,
arch_debugfs_dir, NULL, &fops_tlbflush);
return 0;
}
late_initcall(create_tlb_flushall_shift);
#endif