291 lines
8.3 KiB
C
291 lines
8.3 KiB
C
/*
|
|
* Copyright 2010 Tilera Corporation. All Rights Reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation, version 2.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
|
|
* NON INFRINGEMENT. See the GNU General Public License for
|
|
* more details.
|
|
*/
|
|
|
|
#include <linux/highmem.h>
|
|
#include <linux/module.h>
|
|
#include <linux/pagemap.h>
|
|
#include <asm/homecache.h>
|
|
|
|
#define kmap_get_pte(vaddr) \
|
|
pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)),\
|
|
(vaddr)), (vaddr))
|
|
|
|
|
|
void *kmap(struct page *page)
|
|
{
|
|
void *kva;
|
|
unsigned long flags;
|
|
pte_t *ptep;
|
|
|
|
might_sleep();
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
kva = kmap_high(page);
|
|
|
|
/*
|
|
* Rewrite the PTE under the lock. This ensures that the page
|
|
* is not currently migrating.
|
|
*/
|
|
ptep = kmap_get_pte((unsigned long)kva);
|
|
flags = homecache_kpte_lock();
|
|
set_pte_at(&init_mm, kva, ptep, mk_pte(page, page_to_kpgprot(page)));
|
|
homecache_kpte_unlock(flags);
|
|
|
|
return kva;
|
|
}
|
|
EXPORT_SYMBOL(kmap);
|
|
|
|
void kunmap(struct page *page)
|
|
{
|
|
if (in_interrupt())
|
|
BUG();
|
|
if (!PageHighMem(page))
|
|
return;
|
|
kunmap_high(page);
|
|
}
|
|
EXPORT_SYMBOL(kunmap);
|
|
|
|
/*
|
|
* Describe a single atomic mapping of a page on a given cpu at a
|
|
* given address, and allow it to be linked into a list.
|
|
*/
|
|
struct atomic_mapped_page {
|
|
struct list_head list;
|
|
struct page *page;
|
|
int cpu;
|
|
unsigned long va;
|
|
};
|
|
|
|
static spinlock_t amp_lock = __SPIN_LOCK_UNLOCKED(&_lock);
|
|
static struct list_head amp_list = LIST_HEAD_INIT(amp_list);
|
|
|
|
/*
|
|
* Combining this structure with a per-cpu declaration lets us give
|
|
* each cpu an atomic_mapped_page structure per type.
|
|
*/
|
|
struct kmap_amps {
|
|
struct atomic_mapped_page per_type[KM_TYPE_NR];
|
|
};
|
|
static DEFINE_PER_CPU(struct kmap_amps, amps);
|
|
|
|
/*
|
|
* Add a page and va, on this cpu, to the list of kmap_atomic pages,
|
|
* and write the new pte to memory. Writing the new PTE under the
|
|
* lock guarantees that it is either on the list before migration starts
|
|
* (if we won the race), or set_pte() sets the migrating bit in the PTE
|
|
* (if we lost the race). And doing it under the lock guarantees
|
|
* that when kmap_atomic_fix_one_pte() comes along, it finds a valid
|
|
* PTE in memory, iff the mapping is still on the amp_list.
|
|
*
|
|
* Finally, doing it under the lock lets us safely examine the page
|
|
* to see if it is immutable or not, for the generic kmap_atomic() case.
|
|
* If we examine it earlier we are exposed to a race where it looks
|
|
* writable earlier, but becomes immutable before we write the PTE.
|
|
*/
|
|
static void kmap_atomic_register(struct page *page, int type,
|
|
unsigned long va, pte_t *ptep, pte_t pteval)
|
|
{
|
|
unsigned long flags;
|
|
struct atomic_mapped_page *amp;
|
|
|
|
flags = homecache_kpte_lock();
|
|
spin_lock(&_lock);
|
|
|
|
/* With interrupts disabled, now fill in the per-cpu info. */
|
|
amp = &__get_cpu_var(amps).per_type[type];
|
|
amp->page = page;
|
|
amp->cpu = smp_processor_id();
|
|
amp->va = va;
|
|
|
|
/* For generic kmap_atomic(), choose the PTE writability now. */
|
|
if (!pte_read(pteval))
|
|
pteval = mk_pte(page, page_to_kpgprot(page));
|
|
|
|
list_add(&->list, &_list);
|
|
set_pte(ptep, pteval);
|
|
arch_flush_lazy_mmu_mode();
|
|
|
|
spin_unlock(&_lock);
|
|
homecache_kpte_unlock(flags);
|
|
}
|
|
|
|
/*
|
|
* Remove a page and va, on this cpu, from the list of kmap_atomic pages.
|
|
* Linear-time search, but we count on the lists being short.
|
|
* We don't need to adjust the PTE under the lock (as opposed to the
|
|
* kmap_atomic_register() case), since we're just unconditionally
|
|
* zeroing the PTE after it's off the list.
|
|
*/
|
|
static void kmap_atomic_unregister(struct page *page, unsigned long va)
|
|
{
|
|
unsigned long flags;
|
|
struct atomic_mapped_page *amp;
|
|
int cpu = smp_processor_id();
|
|
spin_lock_irqsave(&_lock, flags);
|
|
list_for_each_entry(amp, &_list, list) {
|
|
if (amp->page == page && amp->cpu == cpu && amp->va == va)
|
|
break;
|
|
}
|
|
BUG_ON(&->list == &_list);
|
|
list_del(&->list);
|
|
spin_unlock_irqrestore(&_lock, flags);
|
|
}
|
|
|
|
/* Helper routine for kmap_atomic_fix_kpte(), below. */
|
|
static void kmap_atomic_fix_one_kpte(struct atomic_mapped_page *amp,
|
|
int finished)
|
|
{
|
|
pte_t *ptep = kmap_get_pte(amp->va);
|
|
if (!finished) {
|
|
set_pte(ptep, pte_mkmigrate(*ptep));
|
|
flush_remote(0, 0, NULL, amp->va, PAGE_SIZE, PAGE_SIZE,
|
|
cpumask_of(amp->cpu), NULL, 0);
|
|
} else {
|
|
/*
|
|
* Rewrite a default kernel PTE for this page.
|
|
* We rely on the fact that set_pte() writes the
|
|
* present+migrating bits last.
|
|
*/
|
|
pte_t pte = mk_pte(amp->page, page_to_kpgprot(amp->page));
|
|
set_pte(ptep, pte);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This routine is a helper function for homecache_fix_kpte(); see
|
|
* its comments for more information on the "finished" argument here.
|
|
*
|
|
* Note that we hold the lock while doing the remote flushes, which
|
|
* will stall any unrelated cpus trying to do kmap_atomic operations.
|
|
* We could just update the PTEs under the lock, and save away copies
|
|
* of the structs (or just the va+cpu), then flush them after we
|
|
* release the lock, but it seems easier just to do it all under the lock.
|
|
*/
|
|
void kmap_atomic_fix_kpte(struct page *page, int finished)
|
|
{
|
|
struct atomic_mapped_page *amp;
|
|
unsigned long flags;
|
|
spin_lock_irqsave(&_lock, flags);
|
|
list_for_each_entry(amp, &_list, list) {
|
|
if (amp->page == page)
|
|
kmap_atomic_fix_one_kpte(amp, finished);
|
|
}
|
|
spin_unlock_irqrestore(&_lock, flags);
|
|
}
|
|
|
|
/*
|
|
* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap
|
|
* because the kmap code must perform a global TLB invalidation when
|
|
* the kmap pool wraps.
|
|
*
|
|
* Note that they may be slower than on x86 (etc.) because unlike on
|
|
* those platforms, we do have to take a global lock to map and unmap
|
|
* pages on Tile (see above).
|
|
*
|
|
* When holding an atomic kmap is is not legal to sleep, so atomic
|
|
* kmaps are appropriate for short, tight code paths only.
|
|
*/
|
|
void *kmap_atomic_prot(struct page *page, pgprot_t prot)
|
|
{
|
|
unsigned long vaddr;
|
|
int idx, type;
|
|
pte_t *pte;
|
|
|
|
/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
|
|
pagefault_disable();
|
|
|
|
/* Avoid icache flushes by disallowing atomic executable mappings. */
|
|
BUG_ON(pte_exec(prot));
|
|
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
|
|
type = kmap_atomic_idx_push();
|
|
idx = type + KM_TYPE_NR*smp_processor_id();
|
|
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
pte = kmap_get_pte(vaddr);
|
|
BUG_ON(!pte_none(*pte));
|
|
|
|
/* Register that this page is mapped atomically on this cpu. */
|
|
kmap_atomic_register(page, type, vaddr, pte, mk_pte(page, prot));
|
|
|
|
return (void *)vaddr;
|
|
}
|
|
EXPORT_SYMBOL(kmap_atomic_prot);
|
|
|
|
void *kmap_atomic(struct page *page)
|
|
{
|
|
/* PAGE_NONE is a magic value that tells us to check immutability. */
|
|
return kmap_atomic_prot(page, PAGE_NONE);
|
|
}
|
|
EXPORT_SYMBOL(kmap_atomic);
|
|
|
|
void __kunmap_atomic(void *kvaddr)
|
|
{
|
|
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
|
|
|
|
if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
|
|
vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
|
|
pte_t *pte = kmap_get_pte(vaddr);
|
|
pte_t pteval = *pte;
|
|
int idx, type;
|
|
|
|
type = kmap_atomic_idx();
|
|
idx = type + KM_TYPE_NR*smp_processor_id();
|
|
|
|
/*
|
|
* Force other mappings to Oops if they try to access this pte
|
|
* without first remapping it. Keeping stale mappings around
|
|
* is a bad idea.
|
|
*/
|
|
BUG_ON(!pte_present(pteval) && !pte_migrating(pteval));
|
|
kmap_atomic_unregister(pte_page(pteval), vaddr);
|
|
kpte_clear_flush(pte, vaddr);
|
|
kmap_atomic_idx_pop();
|
|
} else {
|
|
/* Must be a lowmem page */
|
|
BUG_ON(vaddr < PAGE_OFFSET);
|
|
BUG_ON(vaddr >= (unsigned long)high_memory);
|
|
}
|
|
|
|
arch_flush_lazy_mmu_mode();
|
|
pagefault_enable();
|
|
}
|
|
EXPORT_SYMBOL(__kunmap_atomic);
|
|
|
|
/*
|
|
* This API is supposed to allow us to map memory without a "struct page".
|
|
* Currently we don't support this, though this may change in the future.
|
|
*/
|
|
void *kmap_atomic_pfn(unsigned long pfn)
|
|
{
|
|
return kmap_atomic(pfn_to_page(pfn));
|
|
}
|
|
void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
|
|
{
|
|
return kmap_atomic_prot(pfn_to_page(pfn), prot);
|
|
}
|
|
|
|
struct page *kmap_atomic_to_page(void *ptr)
|
|
{
|
|
pte_t *pte;
|
|
unsigned long vaddr = (unsigned long)ptr;
|
|
|
|
if (vaddr < FIXADDR_START)
|
|
return virt_to_page(ptr);
|
|
|
|
pte = kmap_get_pte(vaddr);
|
|
return pte_page(*pte);
|
|
}
|