1 KASAN is supported on powerpc on 32-bit and Ra
2
3 32 bit support
4 ==============
5
6 KASAN is supported on both hash and nohash MMU
7
8 The shadow area sits at the top of the kernel
9 fixmap area and occupies one eighth of the tot
10
11 Instrumentation of the vmalloc area is optiona
12 in which case it is required.
13
14 64 bit support
15 ==============
16
17 Currently, only the radix MMU is supported. Th
18 and Book3E processors floating around on the m
19 merged.
20
21 KASAN support on Book3S is a bit tricky to get
22
23 - It would be good to support inline instrume
24 stack issues that cannot be caught with out
25
26 - Inline instrumentation requires a fixed off
27
28 - Book3S runs code with translations off ("re
29 lot of generic device-tree parsing code whi
30 features.
31
32 - Some code - most notably a lot of KVM code
33 after boot.
34
35 - Therefore any offset has to point to memory
36 translations on or off.
37
38 One approach is just to give up on inline inst
39 checks can be delayed until after the MMU is s
40 instrument any code that runs with translation
41 current approach.
42
43 To avoid this limitation, the KASAN shadow wou
44 linear mapping, using the same high-bits trick
45 mapping. This is tricky:
46
47 - We'd like to place it near the start of phy
48 this at run-time based on how much physical
49 being able to arbitrarily relocate the kern
50 part of KASLR. Not being game to implement
51 is hopefully something we can revisit once
52
53 - Alternatively, we can place the shadow at t
54 requires knowing how much contiguous physic
55 time_. This is a big hammer, and has some u
56 to handle discontiguous physical memory, to
57 with less memory than specified, and that m
58 specified can't use it. This was deemed una
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