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/*
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/linkage.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
.arch_extension virt
.text
.pushsection .hyp.text, "ax"
.macro load_vcpu reg
mrc p15, 4, \reg, c13, c0, 2 @ HTPIDR
.endm
/********************************************************************
* Hypervisor exception vector and handlers
*
*
* The KVM/ARM Hypervisor ABI is defined as follows:
*
* Entry to Hyp mode from the host kernel will happen _only_ when an HVC
* instruction is issued since all traps are disabled when running the host
* kernel as per the Hyp-mode initialization at boot time.
*
* HVC instructions cause a trap to the vector page + offset 0x14 (see hyp_hvc
* below) when the HVC instruction is called from SVC mode (i.e. a guest or the
* host kernel) and they cause a trap to the vector page + offset 0x8 when HVC
* instructions are called from within Hyp-mode.
*
* Hyp-ABI: Calling HYP-mode functions from host (in SVC mode):
* Switching to Hyp mode is done through a simple HVC #0 instruction. The
* exception vector code will check that the HVC comes from VMID==0.
* - r0 contains a pointer to a HYP function
* - r1, r2, and r3 contain arguments to the above function.
* - The HYP function will be called with its arguments in r0, r1 and r2.
* On HYP function return, we return directly to SVC.
*
* Note that the above is used to execute code in Hyp-mode from a host-kernel
* point of view, and is a different concept from performing a world-switch and
* executing guest code SVC mode (with a VMID != 0).
*/
.align 5
__kvm_hyp_vector:
.global __kvm_hyp_vector
@ Hyp-mode exception vector
W(b) hyp_reset
W(b) hyp_undef
W(b) hyp_svc
W(b) hyp_pabt
W(b) hyp_dabt
W(b) hyp_hvc
W(b) hyp_irq
W(b) hyp_fiq
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
.align 5
__kvm_hyp_vector_bp_inv:
.global __kvm_hyp_vector_bp_inv
/*
* We encode the exception entry in the bottom 3 bits of
* SP, and we have to guarantee to be 8 bytes aligned.
*/
W(add) sp, sp, #1 /* Reset 7 */
W(add) sp, sp, #1 /* Undef 6 */
W(add) sp, sp, #1 /* Syscall 5 */
W(add) sp, sp, #1 /* Prefetch abort 4 */
W(add) sp, sp, #1 /* Data abort 3 */
W(add) sp, sp, #1 /* HVC 2 */
W(add) sp, sp, #1 /* IRQ 1 */
W(nop) /* FIQ 0 */
mcr p15, 0, r0, c7, c5, 6 /* BPIALL */
isb
#ifdef CONFIG_THUMB2_KERNEL
/*
* Yet another silly hack: Use VPIDR as a temp register.
* Thumb2 is really a pain, as SP cannot be used with most
* of the bitwise instructions. The vect_br macro ensures
* things gets cleaned-up.
*/
mcr p15, 4, r0, c0, c0, 0 /* VPIDR */
mov r0, sp
and r0, r0, #7
sub sp, sp, r0
push {r1, r2}
mov r1, r0
mrc p15, 4, r0, c0, c0, 0 /* VPIDR */
mrc p15, 0, r2, c0, c0, 0 /* MIDR */
mcr p15, 4, r2, c0, c0, 0 /* VPIDR */
#endif
.macro vect_br val, targ
ARM( eor sp, sp, #\val )
ARM( tst sp, #7 )
ARM( eorne sp, sp, #\val )
THUMB( cmp r1, #\val )
THUMB( popeq {r1, r2} )
beq \targ
.endm
vect_br 0, hyp_fiq
vect_br 1, hyp_irq
vect_br 2, hyp_hvc
vect_br 3, hyp_dabt
vect_br 4, hyp_pabt
vect_br 5, hyp_svc
vect_br 6, hyp_undef
vect_br 7, hyp_reset
#endif
.macro invalid_vector label, cause
.align
\label: mov r0, #\cause
b __hyp_panic
.endm
invalid_vector hyp_reset ARM_EXCEPTION_RESET
invalid_vector hyp_undef ARM_EXCEPTION_UNDEFINED
invalid_vector hyp_svc ARM_EXCEPTION_SOFTWARE
invalid_vector hyp_pabt ARM_EXCEPTION_PREF_ABORT
invalid_vector hyp_fiq ARM_EXCEPTION_FIQ
ENTRY(__hyp_do_panic)
mrs lr, cpsr
bic lr, lr, #MODE_MASK
orr lr, lr, #SVC_MODE
THUMB( orr lr, lr, #PSR_T_BIT )
msr spsr_cxsf, lr
ldr lr, =panic
msr ELR_hyp, lr
ldr lr, =kvm_call_hyp
clrex
eret
ENDPROC(__hyp_do_panic)
hyp_hvc:
/*
* Getting here is either because of a trap from a guest,
* or from executing HVC from the host kernel, which means
* "do something in Hyp mode".
*/
push {r0, r1, r2}
@ Check syndrome register
mrc p15, 4, r1, c5, c2, 0 @ HSR
lsr r0, r1, #HSR_EC_SHIFT
cmp r0, #HSR_EC_HVC
bne guest_trap @ Not HVC instr.
/*
* Let's check if the HVC came from VMID 0 and allow simple
* switch to Hyp mode
*/
mrrc p15, 6, r0, r2, c2
lsr r2, r2, #16
and r2, r2, #0xff
cmp r2, #0
bne guest_trap @ Guest called HVC
/*
* Getting here means host called HVC, we shift parameters and branch
* to Hyp function.
*/
pop {r0, r1, r2}
/*
* Check if we have a kernel function, which is guaranteed to be
* bigger than the maximum hyp stub hypercall
*/
cmp r0, #HVC_STUB_HCALL_NR
bhs 1f
/*
* Not a kernel function, treat it as a stub hypercall.
* Compute the physical address for __kvm_handle_stub_hvc
* (as the code lives in the idmaped page) and branch there.
* We hijack ip (r12) as a tmp register.
*/
push {r1}
ldr r1, =kimage_voffset
ldr r1, [r1]
ldr ip, =__kvm_handle_stub_hvc
sub ip, ip, r1
pop {r1}
bx ip
1:
/*
* Pushing r2 here is just a way of keeping the stack aligned to
* 8 bytes on any path that can trigger a HYP exception. Here,
* we may well be about to jump into the guest, and the guest
* exit would otherwise be badly decoded by our fancy
* "decode-exception-without-a-branch" code...
*/
push {r2, lr}
mov lr, r0
mov r0, r1
mov r1, r2
mov r2, r3
THUMB( orr lr, #1)
blx lr @ Call the HYP function
pop {r2, lr}
eret
guest_trap:
load_vcpu r0 @ Load VCPU pointer to r0
#ifdef CONFIG_VFPv3
@ Check for a VFP access
lsr r1, r1, #HSR_EC_SHIFT
cmp r1, #HSR_EC_CP_0_13
beq __vfp_guest_restore
#endif
mov r1, #ARM_EXCEPTION_HVC
b __guest_exit
hyp_irq:
push {r0, r1, r2}
mov r1, #ARM_EXCEPTION_IRQ
load_vcpu r0 @ Load VCPU pointer to r0
b __guest_exit
hyp_dabt:
push {r0, r1}
mrs r0, ELR_hyp
ldr r1, =abort_guest_exit_start
THUMB( add r1, r1, #1)
cmp r0, r1
ldrne r1, =abort_guest_exit_end
THUMB( addne r1, r1, #1)
cmpne r0, r1
pop {r0, r1}
bne __hyp_panic
orr r0, r0, #(1 << ARM_EXIT_WITH_ABORT_BIT)
eret
.ltorg
.popsection
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