arch/x86/mm/iomap_32.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright © 2008 Ingo Molnar
   4  */
   5
   6 #include <asm/iomap.h>
   7 #include <asm/pat.h>
   8 #include <linux/export.h>
   9 #include <linux/highmem.h>
  10
  11 static int is_io_mapping_possible(resource_size_t base, unsigned long size)
  12 {
  13 #if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
  14         /* There is no way to map greater than 1 << 32 address without PAE */
  15         if (base + size > 0x100000000ULL)
  16                 return 0;
  17 #endif
  18         return 1;
  19 }
  20
  21 int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
  22 {
  23         enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
  24         int ret;
  25
  26         if (!is_io_mapping_possible(base, size))
  27                 return -EINVAL;
  28
  29         ret = io_reserve_memtype(base, base + size, &pcm);
  30         if (ret)
  31                 return ret;
  32
  33         *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
  34         /* Filter out unsupported __PAGE_KERNEL* bits: */
  35         pgprot_val(*prot) &= __default_kernel_pte_mask;
  36
  37         return 0;
  38 }
  39 EXPORT_SYMBOL_GPL(iomap_create_wc);
  40
  41 void iomap_free(resource_size_t base, unsigned long size)
  42 {
  43         io_free_memtype(base, base + size);
  44 }
  45 EXPORT_SYMBOL_GPL(iomap_free);
  46
  47 void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  48 {
  49         unsigned long vaddr;
  50         int idx, type;
  51
  52         preempt_disable();
  53         pagefault_disable();
  54
  55         type = kmap_atomic_idx_push();
  56         idx = type + KM_TYPE_NR * smp_processor_id();
  57         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  58         set_pte(kmap_pte - idx, pfn_pte(pfn, prot));
  59         arch_flush_lazy_mmu_mode();
  60
  61         return (void *)vaddr;
  62 }
  63
  64 /*
  65  * Map 'pfn' using protections 'prot'
  66  */
  67 void __iomem *
  68 iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  69 {
  70         /*
  71          * For non-PAT systems, translate non-WB request to UC- just in
  72          * case the caller set the PWT bit to prot directly without using
  73          * pgprot_writecombine(). UC- translates to uncached if the MTRR
  74          * is UC or WC. UC- gets the real intention, of the user, which is
  75          * "WC if the MTRR is WC, UC if you can't do that."
  76          */
  77         if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
  78                 prot = __pgprot(__PAGE_KERNEL |
  79                                 cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
  80
  81         /* Filter out unsupported __PAGE_KERNEL* bits: */
  82         pgprot_val(prot) &= __default_kernel_pte_mask;
  83
  84         return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot);
  85 }
  86 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
  87
  88 void
  89 iounmap_atomic(void __iomem *kvaddr)
  90 {
  91         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  92
  93         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  94             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  95                 int idx, type;
  96
  97                 type = kmap_atomic_idx();
  98                 idx = type + KM_TYPE_NR * smp_processor_id();
  99
 100 #ifdef CONFIG_DEBUG_HIGHMEM
 101                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 102 #endif
 103                 /*
 104                  * Force other mappings to Oops if they'll try to access this
 105                  * pte without first remap it.  Keeping stale mappings around
 106                  * is a bad idea also, in case the page changes cacheability
 107                  * attributes or becomes a protected page in a hypervisor.
 108                  */
 109                 kpte_clear_flush(kmap_pte-idx, vaddr);
 110                 kmap_atomic_idx_pop();
 111         }
 112
 113         pagefault_enable();
 114         preempt_enable();
 115 }
 116 EXPORT_SYMBOL_GPL(iounmap_atomic);