/[packages]/updates/8/kernel/current/SOURCES/arm64-entry-make-the-kpti-trampoline-s-kpti-sequence-optional.patch
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Contents of /updates/8/kernel/current/SOURCES/arm64-entry-make-the-kpti-trampoline-s-kpti-sequence-optional.patch

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Revision 1789982 - (show annotations) (download)
Tue Mar 8 23:11:59 2022 UTC (2 years ago) by tmb
File size: 2442 byte(s)
add current -stable queue
1 From foo@baz Tue Mar 8 08:47:19 PM CET 2022
2 From: James Morse <james.morse@arm.com>
3 Date: Thu, 18 Nov 2021 13:16:23 +0000
4 Subject: arm64: entry: Make the kpti trampoline's kpti sequence optional
5
6 From: James Morse <james.morse@arm.com>
7
8 commit c47e4d04ba0f1ea17353d85d45f611277507e07a upstream.
9
10 Spectre-BHB needs to add sequences to the vectors. Having one global
11 set of vectors is a problem for big/little systems where the sequence
12 is costly on cpus that are not vulnerable.
13
14 Making the vectors per-cpu in the style of KVM's bh_harden_hyp_vecs
15 requires the vectors to be generated by macros.
16
17 Make the kpti re-mapping of the kernel optional, so the macros can be
18 used without kpti.
19
20 Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
21 Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
22 Signed-off-by: James Morse <james.morse@arm.com>
23 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
24 ---
25 arch/arm64/kernel/entry.S | 18 ++++++++++++------
26 1 file changed, 12 insertions(+), 6 deletions(-)
27
28 --- a/arch/arm64/kernel/entry.S
29 +++ b/arch/arm64/kernel/entry.S
30 @@ -646,9 +646,10 @@ alternative_else_nop_endif
31 sub \dst, \dst, PAGE_SIZE
32 .endm
33
34 - .macro tramp_ventry, vector_start, regsize
35 + .macro tramp_ventry, vector_start, regsize, kpti
36 .align 7
37 1:
38 + .if \kpti == 1
39 .if \regsize == 64
40 msr tpidrro_el0, x30 // Restored in kernel_ventry
41 .endif
42 @@ -671,9 +672,14 @@ alternative_insn isb, nop, ARM64_WORKARO
43 alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM
44 prfm plil1strm, [x30, #(1b - \vector_start)]
45 alternative_else_nop_endif
46 +
47 msr vbar_el1, x30
48 - add x30, x30, #(1b - \vector_start + 4)
49 isb
50 + .else
51 + ldr x30, =vectors
52 + .endif // \kpti == 1
53 +
54 + add x30, x30, #(1b - \vector_start + 4)
55 ret
56 .org 1b + 128 // Did we overflow the ventry slot?
57 .endm
58 @@ -691,15 +697,15 @@ alternative_else_nop_endif
59 sb
60 .endm
61
62 - .macro generate_tramp_vector
63 + .macro generate_tramp_vector, kpti
64 .Lvector_start\@:
65 .space 0x400
66
67 .rept 4
68 - tramp_ventry .Lvector_start\@, 64
69 + tramp_ventry .Lvector_start\@, 64, \kpti
70 .endr
71 .rept 4
72 - tramp_ventry .Lvector_start\@, 32
73 + tramp_ventry .Lvector_start\@, 32, \kpti
74 .endr
75 .endm
76
77 @@ -710,7 +716,7 @@ alternative_else_nop_endif
78 .pushsection ".entry.tramp.text", "ax"
79 .align 11
80 SYM_CODE_START_NOALIGN(tramp_vectors)
81 - generate_tramp_vector
82 + generate_tramp_vector kpti=1
83 SYM_CODE_END(tramp_vectors)
84
85 SYM_CODE_START(tramp_exit_native)

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