kernel/arch/x86/mm/iomap_32.c

   1 /*
   2  * Copyright © 2008 Ingo Molnar
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #include <asm/iomap.h>
  20 #include <asm/pat.h>
  21 #include <linux/module.h>
  22 #include <linux/highmem.h>
  23
  24 static int is_io_mapping_possible(resource_size_t base, unsigned long size)
  25 {
  26 #if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
  27         /* There is no way to map greater than 1 << 32 address without PAE */
  28         if (base + size > 0x100000000ULL)
  29                 return 0;
  30 #endif
  31         return 1;
  32 }
  33
  34 int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
  35 {
  36         enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
  37         int ret;
  38
  39         if (!is_io_mapping_possible(base, size))
  40                 return -EINVAL;
  41
  42         ret = io_reserve_memtype(base, base + size, &pcm);
  43         if (ret)
  44                 return ret;
  45
  46         *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
  47         return 0;
  48 }
  49 EXPORT_SYMBOL_GPL(iomap_create_wc);
  50
  51 void iomap_free(resource_size_t base, unsigned long size)
  52 {
  53         io_free_memtype(base, base + size);
  54 }
  55 EXPORT_SYMBOL_GPL(iomap_free);
  56
  57 void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  58 {
  59         pte_t pte = pfn_pte(pfn, prot);
  60         unsigned long vaddr;
  61         int idx, type;
  62
  63         preempt_disable();
  64         pagefault_disable();
  65
  66         type = kmap_atomic_idx_push();
  67         idx = type + KM_TYPE_NR * smp_processor_id();
  68         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  69         WARN_ON(!pte_none(*(kmap_pte - idx)));
  70
  71 #ifdef CONFIG_PREEMPT_RT_FULL
  72         current->kmap_pte[type] = pte;
  73 #endif
  74         set_pte(kmap_pte - idx, pte);
  75         arch_flush_lazy_mmu_mode();
  76
  77         return (void *)vaddr;
  78 }
  79
  80 /*
  81  * Map 'pfn' using protections 'prot'
  82  */
  83 void __iomem *
  84 iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  85 {
  86         /*
  87          * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
  88          * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
  89          * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
  90          * user, which is "WC if the MTRR is WC, UC if you can't do that."
  91          */
  92         if (!pat_enabled && pgprot_val(prot) ==
  93             (__PAGE_KERNEL | cachemode2protval(_PAGE_CACHE_MODE_WC)))
  94                 prot = __pgprot(__PAGE_KERNEL |
  95                                 cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
  96
  97         return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot);
  98 }
  99 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
 100
 101 void
 102 iounmap_atomic(void __iomem *kvaddr)
 103 {
 104         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 105
 106         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
 107             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
 108                 int idx, type;
 109
 110                 type = kmap_atomic_idx();
 111                 idx = type + KM_TYPE_NR * smp_processor_id();
 112
 113 #ifdef CONFIG_DEBUG_HIGHMEM
 114                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 115 #endif
 116                 /*
 117                  * Force other mappings to Oops if they'll try to access this
 118                  * pte without first remap it.  Keeping stale mappings around
 119                  * is a bad idea also, in case the page changes cacheability
 120                  * attributes or becomes a protected page in a hypervisor.
 121                  */
 122 #ifdef CONFIG_PREEMPT_RT_FULL
 123                 current->kmap_pte[type] = __pte(0);
 124 #endif
 125                 kpte_clear_flush(kmap_pte-idx, vaddr);
 126                 kmap_atomic_idx_pop();
 127         }
 128
 129         pagefault_enable();
 130         preempt_enable();
 131 }
 132 EXPORT_SYMBOL_GPL(iounmap_atomic);