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f99e406491
commit b4f18c063a upstream.
In order to forward the guest's ARCH_WORKAROUND_2 calls to EL3,
add a small(-ish) sequence to handle it at EL2. Special care must
be taken to track the state of the guest itself by updating the
workaround flags. We also rely on patching to enable calls into
the firmware.
Note that since we need to execute branches, this always executes
after the Spectre-v2 mitigation has been applied.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
260 lines
6.1 KiB
ArmAsm
260 lines
6.1 KiB
ArmAsm
/*
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* Copyright (C) 2015 - ARM Ltd
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* Author: Marc Zyngier <marc.zyngier@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/arm-smccc.h>
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#include <linux/linkage.h>
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#include <asm/alternative.h>
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#include <asm/assembler.h>
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#include <asm/cpufeature.h>
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#include <asm/kvm_arm.h>
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#include <asm/kvm_asm.h>
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#include <asm/kvm_mmu.h>
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.text
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.pushsection .hyp.text, "ax"
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.macro do_el2_call
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/*
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* Shuffle the parameters before calling the function
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* pointed to in x0. Assumes parameters in x[1,2,3].
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*/
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mov lr, x0
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mov x0, x1
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mov x1, x2
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mov x2, x3
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blr lr
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.endm
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ENTRY(__vhe_hyp_call)
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str lr, [sp, #-16]!
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do_el2_call
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ldr lr, [sp], #16
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/*
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* We used to rely on having an exception return to get
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* an implicit isb. In the E2H case, we don't have it anymore.
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* rather than changing all the leaf functions, just do it here
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* before returning to the rest of the kernel.
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*/
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isb
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ret
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ENDPROC(__vhe_hyp_call)
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/*
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* Compute the idmap address of __kvm_hyp_reset based on the idmap
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* start passed as a parameter, and jump there.
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*
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* x0: HYP phys_idmap_start
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*/
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ENTRY(__kvm_hyp_teardown)
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mov x4, x0
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adr_l x3, __kvm_hyp_reset
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/* insert __kvm_hyp_reset()s offset into phys_idmap_start */
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bfi x4, x3, #0, #PAGE_SHIFT
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br x4
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ENDPROC(__kvm_hyp_teardown)
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el1_sync: // Guest trapped into EL2
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stp x0, x1, [sp, #-16]!
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mrs x0, esr_el2
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lsr x0, x0, #ESR_ELx_EC_SHIFT
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cmp x0, #ESR_ELx_EC_HVC64
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ccmp x0, #ESR_ELx_EC_HVC32, #4, ne
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b.ne el1_trap
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mrs x1, vttbr_el2 // If vttbr is valid, the guest
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cbnz x1, el1_hvc_guest // called HVC
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/* Here, we're pretty sure the host called HVC. */
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ldp x0, x1, [sp], #16
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cmp x0, #HVC_GET_VECTORS
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b.ne 1f
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mrs x0, vbar_el2
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b 2f
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1:
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/*
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* Perform the EL2 call
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*/
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kern_hyp_va x0
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do_el2_call
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2: eret
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el1_hvc_guest:
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/*
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* Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1.
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* The workaround has already been applied on the host,
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* so let's quickly get back to the guest. We don't bother
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* restoring x1, as it can be clobbered anyway.
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*/
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ldr x1, [sp] // Guest's x0
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eor w1, w1, #ARM_SMCCC_ARCH_WORKAROUND_1
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cbz w1, wa_epilogue
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/* ARM_SMCCC_ARCH_WORKAROUND_2 handling */
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eor w1, w1, #(ARM_SMCCC_ARCH_WORKAROUND_1 ^ \
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ARM_SMCCC_ARCH_WORKAROUND_2)
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cbnz w1, el1_trap
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#ifdef CONFIG_ARM64_SSBD
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alternative_cb arm64_enable_wa2_handling
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b wa2_end
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alternative_cb_end
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get_vcpu_ptr x2, x0
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ldr x0, [x2, #VCPU_WORKAROUND_FLAGS]
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// Sanitize the argument and update the guest flags
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ldr x1, [sp, #8] // Guest's x1
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clz w1, w1 // Murphy's device:
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lsr w1, w1, #5 // w1 = !!w1 without using
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eor w1, w1, #1 // the flags...
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bfi x0, x1, #VCPU_WORKAROUND_2_FLAG_SHIFT, #1
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str x0, [x2, #VCPU_WORKAROUND_FLAGS]
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/* Check that we actually need to perform the call */
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hyp_ldr_this_cpu x0, arm64_ssbd_callback_required, x2
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cbz x0, wa2_end
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mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
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smc #0
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/* Don't leak data from the SMC call */
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mov x3, xzr
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wa2_end:
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mov x2, xzr
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mov x1, xzr
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#endif
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wa_epilogue:
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mov x0, xzr
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add sp, sp, #16
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eret
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el1_trap:
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get_vcpu_ptr x1, x0
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mrs x0, esr_el2
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lsr x0, x0, #ESR_ELx_EC_SHIFT
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/*
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* x0: ESR_EC
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* x1: vcpu pointer
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*/
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/* Guest accessed VFP/SIMD registers, save host, restore Guest */
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cmp x0, #ESR_ELx_EC_FP_ASIMD
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b.eq __fpsimd_guest_restore
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mov x0, #ARM_EXCEPTION_TRAP
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b __guest_exit
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el1_irq:
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stp x0, x1, [sp, #-16]!
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get_vcpu_ptr x1, x0
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mov x0, #ARM_EXCEPTION_IRQ
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b __guest_exit
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el1_error:
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stp x0, x1, [sp, #-16]!
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get_vcpu_ptr x1, x0
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mov x0, #ARM_EXCEPTION_EL1_SERROR
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b __guest_exit
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el2_error:
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/*
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* Only two possibilities:
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* 1) Either we come from the exit path, having just unmasked
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* PSTATE.A: change the return code to an EL2 fault, and
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* carry on, as we're already in a sane state to handle it.
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* 2) Or we come from anywhere else, and that's a bug: we panic.
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*
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* For (1), x0 contains the original return code and x1 doesn't
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* contain anything meaningful at that stage. We can reuse them
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* as temp registers.
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* For (2), who cares?
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*/
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mrs x0, elr_el2
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adr x1, abort_guest_exit_start
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cmp x0, x1
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adr x1, abort_guest_exit_end
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ccmp x0, x1, #4, ne
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b.ne __hyp_panic
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mov x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
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eret
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ENTRY(__hyp_do_panic)
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mov lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
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PSR_MODE_EL1h)
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msr spsr_el2, lr
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ldr lr, =panic
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msr elr_el2, lr
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eret
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ENDPROC(__hyp_do_panic)
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ENTRY(__hyp_panic)
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get_host_ctxt x0, x1
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b hyp_panic
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ENDPROC(__hyp_panic)
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.macro invalid_vector label, target = __hyp_panic
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.align 2
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\label:
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b \target
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ENDPROC(\label)
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.endm
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/* None of these should ever happen */
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invalid_vector el2t_sync_invalid
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invalid_vector el2t_irq_invalid
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invalid_vector el2t_fiq_invalid
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invalid_vector el2t_error_invalid
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invalid_vector el2h_sync_invalid
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invalid_vector el2h_irq_invalid
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invalid_vector el2h_fiq_invalid
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invalid_vector el1_sync_invalid
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invalid_vector el1_irq_invalid
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invalid_vector el1_fiq_invalid
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.ltorg
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.align 11
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ENTRY(__kvm_hyp_vector)
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ventry el2t_sync_invalid // Synchronous EL2t
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ventry el2t_irq_invalid // IRQ EL2t
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ventry el2t_fiq_invalid // FIQ EL2t
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ventry el2t_error_invalid // Error EL2t
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ventry el2h_sync_invalid // Synchronous EL2h
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ventry el2h_irq_invalid // IRQ EL2h
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ventry el2h_fiq_invalid // FIQ EL2h
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ventry el2_error // Error EL2h
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ventry el1_sync // Synchronous 64-bit EL1
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ventry el1_irq // IRQ 64-bit EL1
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ventry el1_fiq_invalid // FIQ 64-bit EL1
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ventry el1_error // Error 64-bit EL1
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ventry el1_sync // Synchronous 32-bit EL1
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ventry el1_irq // IRQ 32-bit EL1
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ventry el1_fiq_invalid // FIQ 32-bit EL1
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ventry el1_error // Error 32-bit EL1
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ENDPROC(__kvm_hyp_vector)
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