void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_vma = vma;
ta.ta_start = uaddr;
on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_page,
&ta, 1);
} else
local_flush_tlb_page(vma, uaddr);
broadcast_tlb_mm_a15_erratum(vma->vm_mm);
}
void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_vma = vma;
ta.ta_start = start;
ta.ta_end = end;
on_each_cpu_mask(ipi_flush_tlb_range, &ta, 1, mm_cpumask(vma->vm_mm));
} else
local_flush_tlb_range(vma, start, end);
}
void smp_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
struct mm_struct *mm = vma->vm_mm;
if(mm->context != NO_CONTEXT) {
cpumask_t cpu_mask = *mm_cpumask(mm);
cpu_clear(smp_processor_id(), cpu_mask);
if (!cpus_empty(cpu_mask))
xc2((smpfunc_t) BTFIXUP_CALL(local_flush_tlb_page), (unsigned long) vma, page);
local_flush_tlb_page(vma, page);
}
}
void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
unsigned long uaddr, void *kaddr,
unsigned long len, int write)
{
/* VIPT non-aliasing cache */
if (cpumask_test_cpu(smp_processor_id(), mm_cpumask(vma->vm_mm)) &&
vma->vm_flags & VM_EXEC) {
unsigned long addr = (unsigned long)kaddr;
/* only flushing the kernel mapping on non-aliasing VIPT */
__cpuc_coherent_kern_range(addr, addr + len);
}
}
/*
* We cannot call mmdrop() because we are in interrupt context,
* instead update mm->cpu_vm_mask.
*/
void leave_mm(int cpu)
{
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
BUG();
cpumask_clear_cpu(cpu,
mm_cpumask(percpu_read(cpu_tlbstate.active_mm)));
#ifndef CONFIG_PAX_PER_CPU_PGD
load_cr3(swapper_pg_dir);
#endif
}
/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
asmlinkage void __cpuinit secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
/*
* All kernel threads share the same mm context; grab a
* reference and switch to it.
*/
atomic_inc(&mm->mm_count);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
printk("CPU%u: Booted secondary processor\n", cpu);
/*
* TTBR0 is only used for the identity mapping at this stage. Make it
* point to zero page to avoid speculatively fetching new entries.
*/
cpu_set_reserved_ttbr0();
flush_tlb_all();
preempt_disable();
trace_hardirqs_off();
if (cpu_ops[cpu]->cpu_postboot)
cpu_ops[cpu]->cpu_postboot();
/*
* Enable GIC and timers.
*/
notify_cpu_starting(cpu);
smp_store_cpu_info(cpu);
/*
* OK, now it's safe to let the boot CPU continue. Wait for
* the CPU migration code to notice that the CPU is online
* before we continue.
*/
set_cpu_online(cpu, true);
complete(&cpu_running);
local_dbg_enable();
local_irq_enable();
local_fiq_enable();
/*
* OK, it's off to the idle thread for us
*/
cpu_startup_entry(CPUHP_ONLINE);
}
void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long vmflag)
{
unsigned long addr;
/* do a global flush by default */
unsigned long base_pages_to_flush = TLB_FLUSH_ALL;
preempt_disable();
if (current->active_mm != mm)
goto out;
if (!current->mm) {
leave_mm(smp_processor_id());
goto out;
}
if ((end != TLB_FLUSH_ALL) && !(vmflag & VM_HUGETLB))
base_pages_to_flush = (end - start) >> PAGE_SHIFT;
if (base_pages_to_flush > tlb_single_page_flush_ceiling) {
base_pages_to_flush = TLB_FLUSH_ALL;
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
local_flush_tlb();
} else {
/* flush range by one by one 'invlpg' */
for (addr = start; addr < end; addr += PAGE_SIZE) {
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
__flush_tlb_single(addr);
}
}
trace_tlb_flush(TLB_LOCAL_MM_SHOOTDOWN, base_pages_to_flush);
out:
if (base_pages_to_flush == TLB_FLUSH_ALL) {
start = 0UL;
end = TLB_FLUSH_ALL;
}
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, start, end);
preempt_enable();
}
static unsigned int steal_context_smp(unsigned int id)
{
struct mm_struct *mm;
unsigned int cpu, max, i;
max = last_context - first_context;
/* Attempt to free next_context first and then loop until we manage */
while (max--) {
/* Pick up the victim mm */
mm = context_mm[id];
/* We have a candidate victim, check if it's active, on SMP
* we cannot steal active contexts
*/
if (mm->context.active) {
id++;
if (id > last_context)
id = first_context;
continue;
}
pr_hardcont(" | steal %d from 0x%p", id, mm);
/* Mark this mm has having no context anymore */
mm->context.id = MMU_NO_CONTEXT;
/* Mark it stale on all CPUs that used this mm. For threaded
* implementations, we set it on all threads on each core
* represented in the mask. A future implementation will use
* a core map instead but this will do for now.
*/
for_each_cpu(cpu, mm_cpumask(mm)) {
for (i = cpu_first_thread_sibling(cpu);
i <= cpu_last_thread_sibling(cpu); i++) {
if (stale_map[i])
__set_bit(id, stale_map[i]);
}
cpu = i - 1;
}
return id;
}
/* This will happen if you have more CPUs than available contexts,
* all we can do here is wait a bit and try again
*/
raw_spin_unlock(&context_lock);
cpu_relax();
raw_spin_lock(&context_lock);
/* This will cause the caller to try again */
return MMU_NO_CONTEXT;
}
static void exit_flush_lazy_tlbs(struct mm_struct *mm)
{
/*
* Would be nice if this was async so it could be run in
* parallel with our local flush, but generic code does not
* give a good API for it. Could extend the generic code or
* make a special powerpc IPI for flushing TLBs.
* For now it's not too performance critical.
*/
smp_call_function_many(mm_cpumask(mm), do_exit_flush_lazy_tlb,
(void *)mm, 1);
mm_reset_thread_local(mm);
}
void flush_tlb_mm(struct mm_struct *mm)
{
if (IS_ENABLED(CONFIG_L4)) {
l4x_unmap_sync_mm(mm);
l4x_del_task(mm);
return;
}
if (tlb_ops_need_broadcast())
on_each_cpu_mask(mm_cpumask(mm), ipi_flush_tlb_mm, mm, 1);
else
local_flush_tlb_mm(mm);
broadcast_tlb_mm_a15_erratum(mm);
}
/* context.lock is held */
static void install_ldt(struct mm_struct *current_mm,
struct ldt_struct *ldt)
{
/* Synchronizes with smp_read_barrier_depends in load_mm_ldt. */
barrier();
ACCESS_ONCE(current_mm->context.ldt) = ldt;
/* Activate the LDT for all CPUs using current_mm. */
smp_call_function_many(mm_cpumask(current_mm), flush_ldt, current_mm,
true);
local_irq_disable();
flush_ldt(current_mm);
local_irq_enable();
}
/**
* flush_tlb_mm - Invalidate TLB of specified VM context
* @mm: The VM context to invalidate.
*/
void flush_tlb_mm(struct mm_struct *mm)
{
cpumask_t cpu_mask;
preempt_disable();
cpumask_copy(&cpu_mask, mm_cpumask(mm));
cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
local_flush_tlb();
if (!cpumask_empty(&cpu_mask))
flush_tlb_others(cpu_mask, mm, FLUSH_ALL);
preempt_enable();
}
void smp_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
if (mm->context != NO_CONTEXT) {
cpumask_t cpu_mask;
cpumask_copy(&cpu_mask, mm_cpumask(mm));
cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
if (!cpumask_empty(&cpu_mask))
xc3((smpfunc_t) BTFIXUP_CALL(local_flush_tlb_range), (unsigned long) vma, start, end);
local_flush_tlb_range(vma, start, end);
}
}
/**
* flush_tlb_page - Invalidate TLB of page
* @vma: The VM context to invalidate the page for.
* @va: The virtual address of the page to invalidate.
*/
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();
cpumask_copy(&cpu_mask, mm_cpumask(mm));
cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
local_flush_tlb_page(mm, va);
if (!cpumask_empty(&cpu_mask))
flush_tlb_others(cpu_mask, mm, va);
preempt_enable();
}
void secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
init_mmu();
#ifdef CONFIG_DEBUG_KERNEL
if (boot_secondary_processors == 0) {
pr_debug("%s: boot_secondary_processors:%d; Hanging cpu:%d\n",
__func__, boot_secondary_processors, cpu);
for (;;)
__asm__ __volatile__ ("waiti " __stringify(LOCKLEVEL));
}
pr_debug("%s: boot_secondary_processors:%d; Booting cpu:%d\n",
__func__, boot_secondary_processors, cpu);
#endif
/* Init EXCSAVE1 */
secondary_trap_init();
/* All kernel threads share the same mm context. */
mmget(mm);
mmgrab(mm);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
enter_lazy_tlb(mm, current);
preempt_disable();
trace_hardirqs_off();
calibrate_delay();
notify_cpu_starting(cpu);
secondary_init_irq();
local_timer_setup(cpu);
set_cpu_online(cpu, true);
local_irq_enable();
complete(&cpu_running);
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}
/*
* This function is called when terminating an mmu batch or when a batch
* is full. It will perform the flush of all the entries currently stored
* in a batch.
*
* Must be called from within some kind of spinlock/non-preempt region...
*/
void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
{
const struct cpumask *tmp;
int i, local = 0;
i = batch->index;
tmp = cpumask_of(smp_processor_id());
if (cpumask_equal(mm_cpumask(batch->mm), tmp))
local = 1;
if (i == 1)
flush_hash_page(batch->vpn[0], batch->pte[0],
batch->psize, batch->ssize, local);
else
flush_hash_range(i, local);
batch->index = 0;
}
void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
if (IS_ENABLED(CONFIG_L4)) {
l4x_unmap_sync_mm(vma->vm_mm);
l4x_unmap_page(vma->vm_mm, uaddr);
return;
}
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_vma = vma;
ta.ta_start = uaddr;
on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_page,
&ta, 1);
} else
local_flush_tlb_page(vma, uaddr);
broadcast_tlb_mm_a15_erratum(vma->vm_mm);
}
void __init mem_init(void)
{
cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
cpumask_set_cpu(0, mm_cpumask(&init_mm));
set_max_mapnr(max_low_pfn);
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
/* Setup guest page hinting */
cmma_init();
/* this will put all low memory onto the freelists */
free_all_bootmem();
setup_zero_pages(); /* Setup zeroed pages. */
cmma_init_nodat();
mem_init_print_info(NULL);
}
static unsigned int steal_context_smp(unsigned int id)
{
struct mm_struct *mm;
unsigned int cpu, max;
max = last_context - first_context;
/* Attempt to free next_context first and then loop until we manage */
while (max--) {
/* Pick up the victim mm */
mm = context_mm[id];
/* We have a candidate victim, check if it's active, on SMP
* we cannot steal active contexts
*/
if (mm->context.active) {
id++;
if (id > last_context)
id = first_context;
continue;
}
pr_devel("[%d] steal context %d from mm @%p\n",
smp_processor_id(), id, mm);
/* Mark this mm has having no context anymore */
mm->context.id = MMU_NO_CONTEXT;
/* Mark it stale on all CPUs that used this mm */
for_each_cpu(cpu, mm_cpumask(mm))
__set_bit(id, stale_map[cpu]);
return id;
}
/* This will happen if you have more CPUs than available contexts,
* all we can do here is wait a bit and try again
*/
atomic_spin_unlock(&context_lock);
cpu_relax();
atomic_spin_lock(&context_lock);
/* This will cause the caller to try again */
return MMU_NO_CONTEXT;
}
void leave_mm(int cpu)
{
struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
/*
* It's plausible that we're in lazy TLB mode while our mm is init_mm.
* If so, our callers still expect us to flush the TLB, but there
* aren't any user TLB entries in init_mm to worry about.
*
* This needs to happen before any other sanity checks due to
* intel_idle's shenanigans.
*/
if (loaded_mm == &init_mm)
return;
/* Warn if we're not lazy. */
WARN_ON(cpumask_test_cpu(smp_processor_id(), mm_cpumask(loaded_mm)));
switch_mm(NULL, &init_mm, NULL);
}
int __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
struct task_struct *p;
int ret;
ret = mp_ops->cpu_disable(cpu);
if (ret)
return ret;
/*
* Take this CPU offline. Once we clear this, we can't return,
* and we must not schedule until we're ready to give up the cpu.
*/
set_cpu_online(cpu, false);
/*
* OK - migrate IRQs away from this CPU
*/
migrate_irqs();
/*
* Stop the local timer for this CPU.
*/
local_timer_stop(cpu);
/*
* Flush user cache and TLB mappings, and then remove this CPU
* from the vm mask set of all processes.
*/
flush_cache_all();
local_flush_tlb_all();
read_lock(&tasklist_lock);
for_each_process(p)
if (p->mm)
cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
read_unlock(&tasklist_lock);
return 0;
}
static int __cpuinit mmu_context_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned int)(long)hcpu;
#ifdef CONFIG_HOTPLUG_CPU
struct task_struct *p;
#endif
/* We don't touch CPU 0 map, it's allocated at aboot and kept
* around forever
*/
if (cpu == boot_cpuid)
return NOTIFY_OK;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
pr_devel("MMU: Allocating stale context map for CPU %d\n", cpu);
stale_map[cpu] = kzalloc(CTX_MAP_SIZE, GFP_KERNEL);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
pr_devel("MMU: Freeing stale context map for CPU %d\n", cpu);
kfree(stale_map[cpu]);
stale_map[cpu] = NULL;
/* We also clear the cpu_vm_mask bits of CPUs going away */
read_lock(&tasklist_lock);
for_each_process(p) {
if (p->mm)
cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
}
read_unlock(&tasklist_lock);
break;
#endif /* CONFIG_HOTPLUG_CPU */
}
return NOTIFY_OK;
}
void __init mem_init(void)
{
if (MACHINE_HAS_TLB_LC)
cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
cpumask_set_cpu(0, mm_cpumask(&init_mm));
atomic_set(&init_mm.context.attach_count, 1);
max_mapnr = max_low_pfn;
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
/* Setup guest page hinting */
cmma_init();
/* this will put all low memory onto the freelists */
free_all_bootmem();
setup_zero_pages(); /* Setup zeroed pages. */
mem_init_print_info(NULL);
printk("Write protected kernel read-only data: %#lx - %#lx\n",
(unsigned long)&_stext,
PFN_ALIGN((unsigned long)&_eshared) - 1);
}
static unsigned int steal_context_smp(unsigned int id)
{
struct mm_struct *mm;
unsigned int cpu, max, i;
max = last_context - first_context;
while (max--) {
mm = context_mm[id];
if (mm->context.active) {
id++;
if (id > last_context)
id = first_context;
continue;
}
pr_hardcont(" | steal %d from 0x%p", id, mm);
mm->context.id = MMU_NO_CONTEXT;
for_each_cpu(cpu, mm_cpumask(mm)) {
for (i = cpu_first_thread_sibling(cpu);
i <= cpu_last_thread_sibling(cpu); i++)
__set_bit(id, stale_map[i]);
cpu = i - 1;
}
return id;
}
raw_spin_unlock(&context_lock);
cpu_relax();
raw_spin_lock(&context_lock);
return MMU_NO_CONTEXT;
}
* so that when we are unmapping an executable page, we also flush it.
* Combined with flushing the L1I at context switch time, this means
* we don't have to do any other icache flushes.
*/
void flush_tlb_mm(struct mm_struct *mm)
{
HV_Remote_ASID asids[NR_CPUS];
int i = 0, cpu;
for_each_cpu(cpu, mm_cpumask(mm)) {
HV_Remote_ASID *asid = &asids[i++];
asid->y = cpu / smp_topology.width;
asid->x = cpu % smp_topology.width;
asid->asid = per_cpu(current_asid, cpu);
}
flush_remote(0, HV_FLUSH_EVICT_L1I, mm_cpumask(mm),
0, 0, 0, NULL, asids, i);
}
void flush_tlb_current_task(void)
{
flush_tlb_mm(current->mm);
}
void flush_tlb_page_mm(struct vm_area_struct *vma, struct mm_struct *mm,
unsigned long va)
{
unsigned long size = vma_kernel_pagesize(vma);
int cache = (vma->vm_flags & VM_EXEC) ? HV_FLUSH_EVICT_L1I : 0;
flush_remote(0, cache, mm_cpumask(mm),
va, size, size, mm_cpumask(mm), NULL, 0);
void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm);
u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
unsigned cpu = smp_processor_id();
u64 next_tlb_gen;
/*
* NB: The scheduler will call us with prev == next when switching
* from lazy TLB mode to normal mode if active_mm isn't changing.
* When this happens, we don't assume that CR3 (and hence
* cpu_tlbstate.loaded_mm) matches next.
*
* NB: leave_mm() calls us with prev == NULL and tsk == NULL.
*/
/* We don't want flush_tlb_func_* to run concurrently with us. */
if (IS_ENABLED(CONFIG_PROVE_LOCKING))
WARN_ON_ONCE(!irqs_disabled());
/*
* Verify that CR3 is what we think it is. This will catch
* hypothetical buggy code that directly switches to swapper_pg_dir
* without going through leave_mm() / switch_mm_irqs_off() or that
* does something like write_cr3(read_cr3_pa()).
*
* Only do this check if CONFIG_DEBUG_VM=y because __read_cr3()
* isn't free.
*/
#ifdef CONFIG_DEBUG_VM
if (WARN_ON_ONCE(__read_cr3() != build_cr3(real_prev, prev_asid))) {
/*
* If we were to BUG here, we'd be very likely to kill
* the system so hard that we don't see the call trace.
* Try to recover instead by ignoring the error and doing
* a global flush to minimize the chance of corruption.
*
* (This is far from being a fully correct recovery.
* Architecturally, the CPU could prefetch something
* back into an incorrect ASID slot and leave it there
* to cause trouble down the road. It's better than
* nothing, though.)
*/
__flush_tlb_all();
}
#endif
this_cpu_write(cpu_tlbstate.is_lazy, false);
if (real_prev == next) {
VM_BUG_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) !=
next->context.ctx_id);
/*
* We don't currently support having a real mm loaded without
* our cpu set in mm_cpumask(). We have all the bookkeeping
* in place to figure out whether we would need to flush
* if our cpu were cleared in mm_cpumask(), but we don't
* currently use it.
*/
if (WARN_ON_ONCE(real_prev != &init_mm &&
!cpumask_test_cpu(cpu, mm_cpumask(next))))
cpumask_set_cpu(cpu, mm_cpumask(next));
return;
} else {
u16 new_asid;
bool need_flush;
if (IS_ENABLED(CONFIG_VMAP_STACK)) {
/*
* If our current stack is in vmalloc space and isn't
* mapped in the new pgd, we'll double-fault. Forcibly
* map it.
*/
unsigned int index = pgd_index(current_stack_pointer);
pgd_t *pgd = next->pgd + index;
if (unlikely(pgd_none(*pgd)))
set_pgd(pgd, init_mm.pgd[index]);
}
/* Stop remote flushes for the previous mm */
VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, mm_cpumask(real_prev)) &&
real_prev != &init_mm);
cpumask_clear_cpu(cpu, mm_cpumask(real_prev));
/*
* Start remote flushes and then read tlb_gen.
*/
cpumask_set_cpu(cpu, mm_cpumask(next));
next_tlb_gen = atomic64_read(&next->context.tlb_gen);
choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush);
if (need_flush) {
this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
write_cr3(build_cr3(next, new_asid));
trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH,
TLB_FLUSH_ALL);
} else {
/* The new ASID is already up to date. */
write_cr3(build_cr3_noflush(next, new_asid));
trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, 0);
}
this_cpu_write(cpu_tlbstate.loaded_mm, next);
this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid);
}
load_mm_cr4(next);
switch_ldt(real_prev, next);
}
static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
{
struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
struct rb_node **rb_link, *rb_parent;
int retval;
unsigned long charge;
uprobe_start_dup_mmap();
down_write(&oldmm->mmap_sem);
flush_cache_dup_mm(oldmm);
uprobe_dup_mmap(oldmm, mm);
/*
* Not linked in yet - no deadlock potential:
*/
down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
mm->locked_vm = 0;
mm->mmap = NULL;
mm->mmap_cache = NULL;
mm->map_count = 0;
cpumask_clear(mm_cpumask(mm));
mm->mm_rb = RB_ROOT;
rb_link = &mm->mm_rb.rb_node;
rb_parent = NULL;
pprev = &mm->mmap;
retval = ksm_fork(mm, oldmm);
if (retval)
goto out;
retval = khugepaged_fork(mm, oldmm);
if (retval)
goto out;
prev = NULL;
for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
struct file *file;
if (mpnt->vm_flags & VM_DONTCOPY) {
vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
-vma_pages(mpnt));
continue;
}
charge = 0;
if (mpnt->vm_flags & VM_ACCOUNT) {
unsigned long len = vma_pages(mpnt);
if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
goto fail_nomem;
charge = len;
}
tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!tmp)
goto fail_nomem;
*tmp = *mpnt;
INIT_LIST_HEAD(&tmp->anon_vma_chain);
retval = vma_dup_policy(mpnt, tmp);
if (retval)
goto fail_nomem_policy;
tmp->vm_mm = mm;
if (anon_vma_fork(tmp, mpnt))
goto fail_nomem_anon_vma_fork;
tmp->vm_flags &= ~VM_LOCKED;
tmp->vm_next = tmp->vm_prev = NULL;
file = tmp->vm_file;
if (file) {
struct inode *inode = file_inode(file);
struct address_space *mapping = file->f_mapping;
get_file(file);
if (tmp->vm_flags & VM_DENYWRITE)
atomic_dec(&inode->i_writecount);
mutex_lock(&mapping->i_mmap_mutex);
if (tmp->vm_flags & VM_SHARED)
mapping->i_mmap_writable++;
flush_dcache_mmap_lock(mapping);
/* insert tmp into the share list, just after mpnt */
if (unlikely(tmp->vm_flags & VM_NONLINEAR))
vma_nonlinear_insert(tmp,
&mapping->i_mmap_nonlinear);
else
vma_interval_tree_insert_after(tmp, mpnt,
&mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
mutex_unlock(&mapping->i_mmap_mutex);
}
/*
* Clear hugetlb-related page reserves for children. This only
* affects MAP_PRIVATE mappings. Faults generated by the child
* are not guaranteed to succeed, even if read-only
*/
if (is_vm_hugetlb_page(tmp))
reset_vma_resv_huge_pages(tmp);
/*
* Link in the new vma and copy the page table entries.
*/
*pprev = tmp;
pprev = &tmp->vm_next;
tmp->vm_prev = prev;
prev = tmp;
__vma_link_rb(mm, tmp, rb_link, rb_parent);
rb_link = &tmp->vm_rb.rb_right;
rb_parent = &tmp->vm_rb;
mm->map_count++;
retval = copy_page_range(mm, oldmm, mpnt);
if (tmp->vm_ops && tmp->vm_ops->open)
tmp->vm_ops->open(tmp);
if (retval)
goto out;
}
/* a new mm has just been created */
arch_dup_mmap(oldmm, mm);
retval = 0;
out:
up_write(&mm->mmap_sem);
flush_tlb_mm(oldmm);
up_write(&oldmm->mmap_sem);
uprobe_end_dup_mmap();
return retval;
fail_nomem_anon_vma_fork:
mpol_put(vma_policy(tmp));
fail_nomem_policy:
kmem_cache_free(vm_area_cachep, tmp);
fail_nomem:
retval = -ENOMEM;
vm_unacct_memory(charge);
goto out;
}
void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
unsigned cpu = smp_processor_id();
if (likely(prev != next)) {
#ifdef CONFIG_SMP
this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
this_cpu_write(cpu_tlbstate.active_mm, next);
#endif
cpumask_set_cpu(cpu, mm_cpumask(next));
/*
* Re-load page tables.
*
* This logic has an ordering constraint:
*
* CPU 0: Write to a PTE for 'next'
* CPU 0: load bit 1 in mm_cpumask. if nonzero, send IPI.
* CPU 1: set bit 1 in next's mm_cpumask
* CPU 1: load from the PTE that CPU 0 writes (implicit)
*
* We need to prevent an outcome in which CPU 1 observes
* the new PTE value and CPU 0 observes bit 1 clear in
* mm_cpumask. (If that occurs, then the IPI will never
* be sent, and CPU 0's TLB will contain a stale entry.)
*
* The bad outcome can occur if either CPU's load is
* reordered before that CPU's store, so both CPUs must
* execute full barriers to prevent this from happening.
*
* Thus, switch_mm needs a full barrier between the
* store to mm_cpumask and any operation that could load
* from next->pgd. TLB fills are special and can happen
* due to instruction fetches or for no reason at all,
* and neither LOCK nor MFENCE orders them.
* Fortunately, load_cr3() is serializing and gives the
* ordering guarantee we need.
*
*/
load_cr3(next->pgd);
trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
/* Stop flush ipis for the previous mm */
cpumask_clear_cpu(cpu, mm_cpumask(prev));
/* Load per-mm CR4 state */
load_mm_cr4(next);
#ifdef CONFIG_MODIFY_LDT_SYSCALL
/*
* Load the LDT, if the LDT is different.
*
* It's possible that prev->context.ldt doesn't match
* the LDT register. This can happen if leave_mm(prev)
* was called and then modify_ldt changed
* prev->context.ldt but suppressed an IPI to this CPU.
* In this case, prev->context.ldt != NULL, because we
* never set context.ldt to NULL while the mm still
* exists. That means that next->context.ldt !=
* prev->context.ldt, because mms never share an LDT.
*/
if (unlikely(prev->context.ldt != next->context.ldt))
load_mm_ldt(next);
#endif
}
#ifdef CONFIG_SMP
else {
this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
BUG_ON(this_cpu_read(cpu_tlbstate.active_mm) != next);
if (!cpumask_test_cpu(cpu, mm_cpumask(next))) {
/*
* On established mms, the mm_cpumask is only changed
* from irq context, from ptep_clear_flush() while in
* lazy tlb mode, and here. Irqs are blocked during
* schedule, protecting us from simultaneous changes.
*/
cpumask_set_cpu(cpu, mm_cpumask(next));
/*
* We were in lazy tlb mode and leave_mm disabled
* tlb flush IPI delivery. We must reload CR3
* to make sure to use no freed page tables.
*
* As above, load_cr3() is serializing and orders TLB
* fills with respect to the mm_cpumask write.
*/
load_cr3(next->pgd);
trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
load_mm_cr4(next);
load_mm_ldt(next);
}
}
#endif
}
static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
{
struct vm_area_struct *mpnt, *tmp, **pprev;
struct rb_node **rb_link, *rb_parent;
int retval;
unsigned long charge;
struct mempolicy *pol;
down_write(&oldmm->mmap_sem);
flush_cache_dup_mm(oldmm);
/*
* Not linked in yet - no deadlock potential:
*/
down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
mm->locked_vm = 0;
mm->mmap = NULL;
mm->mmap_cache = NULL;
mm->free_area_cache = oldmm->mmap_base;
mm->cached_hole_size = ~0UL;
mm->map_count = 0;
cpumask_clear(mm_cpumask(mm));
mm->mm_rb = RB_ROOT;
rb_link = &mm->mm_rb.rb_node;
rb_parent = NULL;
pprev = &mm->mmap;
retval = ksm_fork(mm, oldmm);
if (retval)
goto out;
for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
struct file *file;
if (mpnt->vm_flags & VM_DONTCOPY) {
long pages = vma_pages(mpnt);
mm->total_vm -= pages;
vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
-pages);
continue;
}
charge = 0;
if (mpnt->vm_flags & VM_ACCOUNT) {
unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
if (security_vm_enough_memory(len))
goto fail_nomem;
charge = len;
}
tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!tmp)
goto fail_nomem;
*tmp = *mpnt;
pol = mpol_dup(vma_policy(mpnt));
retval = PTR_ERR(pol);
if (IS_ERR(pol))
goto fail_nomem_policy;
vma_set_policy(tmp, pol);
tmp->vm_flags &= ~VM_LOCKED;
tmp->vm_mm = mm;
tmp->vm_next = NULL;
anon_vma_link(tmp);
file = tmp->vm_file;
if (file) {
struct inode *inode = file->f_path.dentry->d_inode;
struct address_space *mapping = file->f_mapping;
get_file(file);
if (tmp->vm_flags & VM_DENYWRITE)
atomic_dec(&inode->i_writecount);
spin_lock(&mapping->i_mmap_lock);
if (tmp->vm_flags & VM_SHARED)
mapping->i_mmap_writable++;
tmp->vm_truncate_count = mpnt->vm_truncate_count;
flush_dcache_mmap_lock(mapping);
/* insert tmp into the share list, just after mpnt */
vma_prio_tree_add(tmp, mpnt);
flush_dcache_mmap_unlock(mapping);
spin_unlock(&mapping->i_mmap_lock);
}
/*
* Clear hugetlb-related page reserves for children. This only
* affects MAP_PRIVATE mappings. Faults generated by the child
* are not guaranteed to succeed, even if read-only
*/
if (is_vm_hugetlb_page(tmp))
reset_vma_resv_huge_pages(tmp);
/*
* Link in the new vma and copy the page table entries.
*/
*pprev = tmp;
pprev = &tmp->vm_next;
__vma_link_rb(mm, tmp, rb_link, rb_parent);
rb_link = &tmp->vm_rb.rb_right;
rb_parent = &tmp->vm_rb;
mm->map_count++;
retval = copy_page_range(mm, oldmm, mpnt);
if (tmp->vm_ops && tmp->vm_ops->open)
tmp->vm_ops->open(tmp);
if (retval)
goto out;
}
void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm);
u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
bool was_lazy = this_cpu_read(cpu_tlbstate.is_lazy);
unsigned cpu = smp_processor_id();
u64 next_tlb_gen;
bool need_flush;
u16 new_asid;
/*
* NB: The scheduler will call us with prev == next when switching
* from lazy TLB mode to normal mode if active_mm isn't changing.
* When this happens, we don't assume that CR3 (and hence
* cpu_tlbstate.loaded_mm) matches next.
*
* NB: leave_mm() calls us with prev == NULL and tsk == NULL.
*/
/* We don't want flush_tlb_func_* to run concurrently with us. */
if (IS_ENABLED(CONFIG_PROVE_LOCKING))
WARN_ON_ONCE(!irqs_disabled());
/*
* Verify that CR3 is what we think it is. This will catch
* hypothetical buggy code that directly switches to swapper_pg_dir
* without going through leave_mm() / switch_mm_irqs_off() or that
* does something like write_cr3(read_cr3_pa()).
*
* Only do this check if CONFIG_DEBUG_VM=y because __read_cr3()
* isn't free.
*/
#ifdef CONFIG_DEBUG_VM
if (WARN_ON_ONCE(__read_cr3() != build_cr3(real_prev->pgd, prev_asid))) {
/*
* If we were to BUG here, we'd be very likely to kill
* the system so hard that we don't see the call trace.
* Try to recover instead by ignoring the error and doing
* a global flush to minimize the chance of corruption.
*
* (This is far from being a fully correct recovery.
* Architecturally, the CPU could prefetch something
* back into an incorrect ASID slot and leave it there
* to cause trouble down the road. It's better than
* nothing, though.)
*/
__flush_tlb_all();
}
#endif
this_cpu_write(cpu_tlbstate.is_lazy, false);
/*
* The membarrier system call requires a full memory barrier and
* core serialization before returning to user-space, after
* storing to rq->curr. Writing to CR3 provides that full
* memory barrier and core serializing instruction.
*/
if (real_prev == next) {
VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) !=
next->context.ctx_id);
/*
* Even in lazy TLB mode, the CPU should stay set in the
* mm_cpumask. The TLB shootdown code can figure out from
* from cpu_tlbstate.is_lazy whether or not to send an IPI.
*/
if (WARN_ON_ONCE(real_prev != &init_mm &&
!cpumask_test_cpu(cpu, mm_cpumask(next))))
cpumask_set_cpu(cpu, mm_cpumask(next));
/*
* If the CPU is not in lazy TLB mode, we are just switching
* from one thread in a process to another thread in the same
* process. No TLB flush required.
*/
if (!was_lazy)
return;
/*
* Read the tlb_gen to check whether a flush is needed.
* If the TLB is up to date, just use it.
* The barrier synchronizes with the tlb_gen increment in
* the TLB shootdown code.
*/
smp_mb();
next_tlb_gen = atomic64_read(&next->context.tlb_gen);
if (this_cpu_read(cpu_tlbstate.ctxs[prev_asid].tlb_gen) ==
next_tlb_gen)
return;
/*
* TLB contents went out of date while we were in lazy
* mode. Fall through to the TLB switching code below.
*/
new_asid = prev_asid;
need_flush = true;
} else {
/*
* Avoid user/user BTB poisoning by flushing the branch
* predictor when switching between processes. This stops
* one process from doing Spectre-v2 attacks on another.
*/
cond_ibpb(tsk);
if (IS_ENABLED(CONFIG_VMAP_STACK)) {
/*
* If our current stack is in vmalloc space and isn't
* mapped in the new pgd, we'll double-fault. Forcibly
* map it.
*/
sync_current_stack_to_mm(next);
}
/*
* Stop remote flushes for the previous mm.
* Skip kernel threads; we never send init_mm TLB flushing IPIs,
* but the bitmap manipulation can cause cache line contention.
*/
if (real_prev != &init_mm) {
VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu,
mm_cpumask(real_prev)));
cpumask_clear_cpu(cpu, mm_cpumask(real_prev));
}
/*
* Start remote flushes and then read tlb_gen.
*/
if (next != &init_mm)
cpumask_set_cpu(cpu, mm_cpumask(next));
next_tlb_gen = atomic64_read(&next->context.tlb_gen);
choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush);
/* Let nmi_uaccess_okay() know that we're changing CR3. */
this_cpu_write(cpu_tlbstate.loaded_mm, LOADED_MM_SWITCHING);
barrier();
}
if (need_flush) {
this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
load_new_mm_cr3(next->pgd, new_asid, true);
/*
* NB: This gets called via leave_mm() in the idle path
* where RCU functions differently. Tracing normally
* uses RCU, so we need to use the _rcuidle variant.
*
* (There is no good reason for this. The idle code should
* be rearranged to call this before rcu_idle_enter().)
*/
trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
} else {
/* The new ASID is already up to date. */
load_new_mm_cr3(next->pgd, new_asid, false);
/* See above wrt _rcuidle. */
trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
}
/* Make sure we write CR3 before loaded_mm. */
barrier();
this_cpu_write(cpu_tlbstate.loaded_mm, next);
this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid);
if (next != real_prev) {
load_mm_cr4(next);
switch_ldt(real_prev, next);
}
}
