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Commit 00a44cda authored by James Morse's avatar James Morse Committed by Will Deacon
Browse files

arm64: kvm: Move lr save/restore from do_el2_call into EL1 



Today the 'hvc' calling KVM or the hyp-stub is expected to preserve all
registers. KVM saves/restores the registers it needs on the EL2 stack using
do_el2_call(). The hyp-stub has no stack, later patches need to be able to
be able to clobber the link register.

Move the link register save/restore to the the call sites.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent e7227d0e

arch/arm64/kernel/hyp-stub.S

+8 −2
Original line number Diff line number Diff line
@@ -101,10 +101,16 @@ ENDPROC(\label) 
 */



ENTRY(__hyp_get_vectors)

	str	lr, [sp, #-16]!

	mov	x0, xzr

	// fall through

ENTRY(__hyp_set_vectors)

	hvc	#0

	ldr	lr, [sp], #16

	ret

ENDPROC(__hyp_get_vectors)



ENTRY(__hyp_set_vectors)

	str	lr, [sp, #-16]!

	hvc	#0

	ldr	lr, [sp], #16

	ret

ENDPROC(__hyp_set_vectors)

arch/arm64/kvm/hyp.S

+6 −1
Original line number Diff line number Diff line
@@ -38,13 +38,18 @@ 
 * A function pointer with a value of 0 has a special meaning, and is

 * used to implement __hyp_get_vectors in the same way as in

 * arch/arm64/kernel/hyp_stub.S.

 * HVC behaves as a 'bl' call and will clobber lr.

 */

ENTRY(__kvm_call_hyp)

alternative_if_not ARM64_HAS_VIRT_HOST_EXTN

	str     lr, [sp, #-16]!

	hvc	#0

	ldr     lr, [sp], #16

	ret

alternative_else

	b	__vhe_hyp_call

	nop

	nop

	nop

alternative_endif

ENDPROC(__kvm_call_hyp)

arch/arm64/kvm/hyp/hyp-entry.S

+2 −4
Original line number Diff line number Diff line
@@ -42,19 +42,17 @@ 
	 * Shuffle the parameters before calling the function

	 * pointed to in x0. Assumes parameters in x[1,2,3].

	 */

	sub	sp, sp, #16

	str	lr, [sp]

	mov	lr, x0

	mov	x0, x1

	mov	x1, x2

	mov	x2, x3

	blr	lr

	ldr	lr, [sp]

	add	sp, sp, #16

.endm



ENTRY(__vhe_hyp_call)

	str	lr, [sp, #-16]!

	do_el2_call

	ldr	lr, [sp], #16

	/*

	 * We used to rely on having an exception return to get

	 * an implicit isb. In the E2H case, we don't have it anymore.