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/pgtable.h>
  15 #include <asm/pgalloc.h>
  16 #include <asm/fixmap.h>
  17 #include <asm/e820/api.h>
  18 #include <asm/tlb.h>
  19 #include <asm/tlbflush.h>
  20 #include <asm/io.h>
  21 #include <linux/vmalloc.h>
  22
  23 unsigned int __VMALLOC_RESERVE = 128 << 20;
  24
  25 /*
  26  * Associate a virtual page frame with a given physical page frame
  27  * and protection flags for that frame.
  28  */
  29 void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
  30 {
  31         pgd_t *pgd;
  32         p4d_t *p4d;
  33         pud_t *pud;
  34         pmd_t *pmd;
  35         pte_t *pte;
  36
  37         pgd = swapper_pg_dir + pgd_index(vaddr);
  38         if (pgd_none(*pgd)) {
  39                 BUG();
  40                 return;
  41         }
  42         p4d = p4d_offset(pgd, vaddr);
  43         if (p4d_none(*p4d)) {
  44                 BUG();
  45                 return;
  46         }
  47         pud = pud_offset(p4d, vaddr);
  48         if (pud_none(*pud)) {
  49                 BUG();
  50                 return;
  51         }
  52         pmd = pmd_offset(pud, vaddr);
  53         if (pmd_none(*pmd)) {
  54                 BUG();
  55                 return;
  56         }
  57         pte = pte_offset_kernel(pmd, vaddr);
  58         if (!pte_none(pteval))
  59                 set_pte_at(&init_mm, vaddr, pte, pteval);
  60         else
  61                 pte_clear(&init_mm, vaddr, pte);
  62
  63         /*
  64          * It's enough to flush this one mapping.
  65          * (PGE mappings get flushed as well)
  66          */
  67         __flush_tlb_one_kernel(vaddr);
  68 }
  69
  70 unsigned long __FIXADDR_TOP = 0xfffff000;
  71 EXPORT_SYMBOL(__FIXADDR_TOP);
  72
  73 /*
  74  * vmalloc=size forces the vmalloc area to be exactly 'size'
  75  * bytes. This can be used to increase (or decrease) the
  76  * vmalloc area - the default is 128m.
  77  */
  78 static int __init parse_vmalloc(char *arg)
  79 {
  80         if (!arg)
  81                 return -EINVAL;
  82
  83         /* Add VMALLOC_OFFSET to the parsed value due to vm area guard hole*/
  84         __VMALLOC_RESERVE = memparse(arg, &arg) + VMALLOC_OFFSET;
  85         return 0;
  86 }
  87 early_param("vmalloc", parse_vmalloc);
  88
  89 /*
  90  * reservetop=size reserves a hole at the top of the kernel address space which
  91  * a hypervisor can load into later.  Needed for dynamically loaded hypervisors,
  92  * so relocating the fixmap can be done before paging initialization.
  93  */
  94 static int __init parse_reservetop(char *arg)
  95 {
  96         unsigned long address;
  97
  98         if (!arg)
  99                 return -EINVAL;
 100
 101         address = memparse(arg, &arg);
 102         reserve_top_address(address);
 103         early_ioremap_init();
 104         return 0;
 105 }
 106 early_param("reservetop", parse_reservetop);