arch/x86/mm/pgtable_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/sched.h>
   3 #include <linux/kernel.h>
   4 #include <linux/errno.h>
   5 #include <linux/mm.h>
   6 #include <linux/nmi.h>
   7 #include <linux/swap.h>
   8 #include <linux/smp.h>
   9 #include <linux/highmem.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/spinlock.h>
  12
  13 #include <asm/cpu_entry_area.h>
  14 #include <asm/fixmap.h>
  15 #include <asm/e820/api.h>
  16 #include <asm/tlb.h>
  17 #include <asm/tlbflush.h>
  18 #include <asm/io.h>
  19 #include <linux/vmalloc.h>
  20
  21 unsigned int __VMALLOC_RESERVE = 128 << 20;
  22
  23 /*
  24  * Associate a virtual page frame with a given physical page frame
  25  * and protection flags for that frame.
  26  */
  27 void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
  28 {
  29         pgd_t *pgd;
  30         p4d_t *p4d;
  31         pud_t *pud;
  32         pmd_t *pmd;
  33         pte_t *pte;
  34
  35         pgd = swapper_pg_dir + pgd_index(vaddr);
  36         if (pgd_none(*pgd)) {
  37                 BUG();
  38                 return;
  39         }
  40         p4d = p4d_offset(pgd, vaddr);
  41         if (p4d_none(*p4d)) {
  42                 BUG();
  43                 return;
  44         }
  45         pud = pud_offset(p4d, vaddr);
  46         if (pud_none(*pud)) {
  47                 BUG();
  48                 return;
  49         }
  50         pmd = pmd_offset(pud, vaddr);
  51         if (pmd_none(*pmd)) {
  52                 BUG();
  53                 return;
  54         }
  55         pte = pte_offset_kernel(pmd, vaddr);
  56         if (!pte_none(pteval))
  57                 set_pte_at(&init_mm, vaddr, pte, pteval);
  58         else
  59                 pte_clear(&init_mm, vaddr, pte);
  60
  61         /*
  62          * It's enough to flush this one mapping.
  63          * (PGE mappings get flushed as well)
  64          */
  65         flush_tlb_one_kernel(vaddr);
  66 }
  67
  68 unsigned long __FIXADDR_TOP = 0xfffff000;
  69 EXPORT_SYMBOL(__FIXADDR_TOP);
  70
  71 /*
  72  * vmalloc=size forces the vmalloc area to be exactly 'size'
  73  * bytes. This can be used to increase (or decrease) the
  74  * vmalloc area - the default is 128m.
  75  */
  76 static int __init parse_vmalloc(char *arg)
  77 {
  78         if (!arg)
  79                 return -EINVAL;
  80
  81         /* Add VMALLOC_OFFSET to the parsed value due to vm area guard hole*/
  82         __VMALLOC_RESERVE = memparse(arg, &arg) + VMALLOC_OFFSET;
  83         return 0;
  84 }
  85 early_param("vmalloc", parse_vmalloc);
  86
  87 /*
  88  * reservetop=size reserves a hole at the top of the kernel address space which
  89  * a hypervisor can load into later.  Needed for dynamically loaded hypervisors,
  90  * so relocating the fixmap can be done before paging initialization.
  91  */
  92 static int __init parse_reservetop(char *arg)
  93 {
  94         unsigned long address;
  95
  96         if (!arg)
  97                 return -EINVAL;
  98
  99         address = memparse(arg, &arg);
 100         reserve_top_address(address);
 101         early_ioremap_init();
 102         return 0;
 103 }
 104 early_param("reservetop", parse_reservetop);