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
21unsigned 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 */
27void 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: *pgd)) {
37 BUG();
38 return;
39 }
40 p4d = p4d_offset(pgd, address: vaddr);
41 if (p4d_none(p4d: *p4d)) {
42 BUG();
43 return;
44 }
45 pud = pud_offset(p4d, address: vaddr);
46 if (pud_none(pud: *pud)) {
47 BUG();
48 return;
49 }
50 pmd = pmd_offset(pud, address: vaddr);
51 if (pmd_none(pmd: *pmd)) {
52 BUG();
53 return;
54 }
55 pte = pte_offset_kernel(pmd, address: vaddr);
56 if (!pte_none(pte: pteval))
57 set_pte_at(&init_mm, vaddr, pte, pteval);
58 else
59 pte_clear(mm: &init_mm, addr: vaddr, ptep: 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(addr: vaddr);
66}
67
68unsigned long __FIXADDR_TOP = 0xfffff000;
69EXPORT_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 */
76static 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(ptr: arg, retptr: &arg) + VMALLOC_OFFSET;
83 return 0;
84}
85early_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 */
92static int __init parse_reservetop(char *arg)
93{
94 unsigned long address;
95
96 if (!arg)
97 return -EINVAL;
98
99 address = memparse(ptr: arg, retptr: &arg);
100 reserve_top_address(reserve: address);
101 early_ioremap_init();
102 return 0;
103}
104early_param("reservetop", parse_reservetop);
105

source code of linux/arch/x86/mm/pgtable_32.c