23002d88be
Create a new PTE function which combines clearing a kernel PTE with the subsequent flush. This allows the two to be easily combined into a single hypercall or paravirt-op. More subtly, reverse the order of the flush for kmap_atomic. Instead of flushing on establishing a mapping, flush on clearing a mapping. This eliminates the possibility of leaving stale kmap entries which may still have valid TLB mappings. This is required for direct mode hypervisors, which need to reprotect all mappings of a given page when changing the page type from a normal page to a protected page (such as a page table or descriptor table page). But it also provides some nicer semantics for real hardware, by providing extra debug-proofing against using stale mappings, as well as ensuring that no stale mappings exist when changing the cacheability attributes of a page, which could lead to cache conflicts when two different types of mappings exist for the same page. Signed-off-by: Zachary Amsden <zach@vmware.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
#include <linux/highmem.h>
|
|
#include <linux/module.h>
|
|
|
|
void *kmap(struct page *page)
|
|
{
|
|
might_sleep();
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
return kmap_high(page);
|
|
}
|
|
|
|
void kunmap(struct page *page)
|
|
{
|
|
if (in_interrupt())
|
|
BUG();
|
|
if (!PageHighMem(page))
|
|
return;
|
|
kunmap_high(page);
|
|
}
|
|
|
|
/*
|
|
* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
|
|
* no global lock is needed and because the kmap code must perform a global TLB
|
|
* invalidation when the kmap pool wraps.
|
|
*
|
|
* However 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(struct page *page, enum km_type type)
|
|
{
|
|
enum fixed_addresses idx;
|
|
unsigned long vaddr;
|
|
|
|
/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
|
|
inc_preempt_count();
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
|
|
idx = type + KM_TYPE_NR*smp_processor_id();
|
|
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
if (!pte_none(*(kmap_pte-idx)))
|
|
BUG();
|
|
set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
|
|
|
|
return (void*) vaddr;
|
|
}
|
|
|
|
void kunmap_atomic(void *kvaddr, enum km_type type)
|
|
{
|
|
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
|
|
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
|
|
|
|
#ifdef CONFIG_DEBUG_HIGHMEM
|
|
if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
|
|
dec_preempt_count();
|
|
preempt_check_resched();
|
|
return;
|
|
}
|
|
|
|
if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
|
|
BUG();
|
|
#endif
|
|
/*
|
|
* Force other mappings to Oops if they'll try to access this pte
|
|
* without first remap it. Keeping stale mappings around is a bad idea
|
|
* also, in case the page changes cacheability attributes or becomes
|
|
* a protected page in a hypervisor.
|
|
*/
|
|
kpte_clear_flush(kmap_pte-idx, vaddr);
|
|
|
|
dec_preempt_count();
|
|
preempt_check_resched();
|
|
}
|
|
|
|
/* This is the same as kmap_atomic() but can map memory that doesn't
|
|
* have a struct page associated with it.
|
|
*/
|
|
void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
|
|
{
|
|
enum fixed_addresses idx;
|
|
unsigned long vaddr;
|
|
|
|
inc_preempt_count();
|
|
|
|
idx = type + KM_TYPE_NR*smp_processor_id();
|
|
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
|
|
|
|
return (void*) vaddr;
|
|
}
|
|
|
|
struct page *kmap_atomic_to_page(void *ptr)
|
|
{
|
|
unsigned long idx, vaddr = (unsigned long)ptr;
|
|
pte_t *pte;
|
|
|
|
if (vaddr < FIXADDR_START)
|
|
return virt_to_page(ptr);
|
|
|
|
idx = virt_to_fix(vaddr);
|
|
pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
|
|
return pte_page(*pte);
|
|
}
|
|
|
|
EXPORT_SYMBOL(kmap);
|
|
EXPORT_SYMBOL(kunmap);
|
|
EXPORT_SYMBOL(kmap_atomic);
|
|
EXPORT_SYMBOL(kunmap_atomic);
|
|
EXPORT_SYMBOL(kmap_atomic_to_page);
|