root/arch/x86/mm/pgtable_32.c

DEFINITIONS

1. set_pte_vaddr
2. parse_vmalloc
3. parse_reservetop

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