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Commit 1f7da613 authored by James Morse's avatar James Morse Committed by Greg Kroah-Hartman
Browse files

arm64: entry: Make the kpti trampoline's kpti sequence optional 



commit c47e4d04ba0f1ea17353d85d45f611277507e07a upstream.

Spectre-BHB needs to add sequences to the vectors. Having one global
set of vectors is a problem for big/little systems where the sequence
is costly on cpus that are not vulnerable.

Making the vectors per-cpu in the style of KVM's bh_harden_hyp_vecs
requires the vectors to be generated by macros.

Make the kpti re-mapping of the kernel optional, so the macros can be
used without kpti.

Reviewed-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 283bcb8f

arch/arm64/kernel/entry.S

+11 −6
Original line number Diff line number Diff line
@@ -921,9 +921,10 @@ __ni_sys_trace: 
	sub	\dst, \dst, PAGE_SIZE

	.endm



	.macro tramp_ventry, vector_start, regsize

	.macro tramp_ventry, vector_start, regsize, kpti

	.align	7

1:

	.if	\kpti == 1

	.if	\regsize == 64

	msr	tpidrro_el0, x30	// Restored in kernel_ventry

	.endif
@@ -945,8 +946,12 @@ __ni_sys_trace: 
#endif

	prfm	plil1strm, [x30, #(1b - \vector_start)]

	msr	vbar_el1, x30

	add	x30, x30, #(1b - \vector_start + 4)

	isb

	.else

	ldr	x30, =vectors

	.endif // \kpti == 1



	add	x30, x30, #(1b - \vector_start + 4)

	ret

.org 1b + 128	// Did we overflow the ventry slot?

	.endm
@@ -963,15 +968,15 @@ __ni_sys_trace: 
	eret

	.endm



	.macro	generate_tramp_vector

	.macro	generate_tramp_vector,	kpti

.Lvector_start\@:

	.space	0x400



	.rept	4

	tramp_ventry	.Lvector_start\@, 64

	tramp_ventry	.Lvector_start\@, 64, \kpti

	.endr

	.rept	4

	tramp_ventry	.Lvector_start\@, 32

	tramp_ventry	.Lvector_start\@, 32, \kpti

	.endr

	.endm
@@ -982,7 +987,7 @@ __ni_sys_trace: 
	.pushsection ".entry.tramp.text", "ax"

	.align	11

ENTRY(tramp_vectors)

	generate_tramp_vector

	generate_tramp_vector	kpti=1

END(tramp_vectors)



ENTRY(tramp_exit_native)