1 .. SPDX-License-Identifier: GPL-2.0
2
3 =================
4 Memory Management
5 =================
6
7 Virtual memory layout
8 =====================
9
10 .. note::
11
12 - Some aspects of the virtual memory layout s
13 clarified (number of page levels, alignment
14
15 - Unused gaps in the virtual memory layout co
16 or not - depending on how partucular system
17 No page tables are created for the unused g
18
19 - The virtual memory regions are tracked or u
20 instrumentation, as well as the KASAN shado
21 created only when CONFIG_KASAN configuratio
22
23 ::
24
25 ============================================
26 | Physical | Virtual | VM a
27 ============================================
28 +- 0 --------------+- 0 --------------+
29 | | S390_lowcore | Low-
30 | +- 8 KB -----------+
31 | | |
32 | | |
33 | | ... unused gap | KASA
34 | | |
35 +- AMODE31_START --+- AMODE31_START --+ .amo
36 |.amode31 text/data|.amode31 text/data| KASA
37 +- AMODE31_END ----+- AMODE31_END ----+ .amo
38 | | |
39 | | |
40 +- __kaslr_offset_phys | kern
41 | | |
42 | kernel text/data | |
43 | | |
44 +------------------+ | kern
45 | | |
46 | | |
47 | | |
48 | | |
49 +- ident_map_size -+ |
50 | |
51 | ... unused gap | KASA
52 | |
53 +- __identity_base + iden
54 | |
55 | identity | phys
56 | mapping | virt
57 | |
58 | | KASA
59 | |
60 | |
61 | |
62 | |
63 | |
64 | |
65 | |
66 | |
67 | |
68 | |
69 | |
70 | |
71 | |
72 | |
73 | |
74 +---- vmemmap -----+ 'str
75 | |
76 | virtually mapped |
77 | memory map | KASA
78 | |
79 +- __abs_lowcore --+
80 | |
81 | Absolute Lowcore | KASA
82 | |
83 +- __memcpy_real_area
84 | |
85 | Real Memory Copy| KASA
86 | |
87 +- VMALLOC_START --+ vmal
88 | | KASA
89 | vmalloc area | KASA
90 | |
91 +- MODULES_VADDR --+ modu
92 | | KASA
93 | modules area | KASA
94 | |
95 +- __kaslr_offset -+ kern
96 | | KASA
97 | kernel text/data | phys
98 | |
99 +- kernel .bss end + kern
100 | |
101 | ... unused gap | KASA
102 | |
103 +------------------+ Ultr
104 | |
105 | ... unused gap | KASA
106 | |
107 +KASAN_SHADOW_START+ KASA
108 | |
109 | KASAN shadow | KASA
110 | |
111 +------------------+ ASCE
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