2 * (not much of an) Emulation layer for 32bit guests.
4 * Copyright (C) 2012,2013 - ARM Ltd
5 * Author: Marc Zyngier <marc.zyngier@arm.com>
7 * based on arch/arm/kvm/emulate.c
8 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
9 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
11 * This program is free software: you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program. If not, see <http://www.gnu.org/licenses/>.
24 #include <linux/kvm_host.h>
25 #include <asm/kvm_emulate.h>
28 #define COMPAT_PSR_T_BIT PSR_T_BIT
29 #define COMPAT_PSR_IT_MASK PSR_IT_MASK
33 * stolen from arch/arm/kernel/opcodes.c
35 * condition code lookup table
36 * index into the table is test code: EQ, NE, ... LT, GT, AL, NV
38 * bit position in short is condition code: NZCV
40 static const unsigned short cc_map[16] = {
41 0xF0F0, /* EQ == Z set */
43 0xCCCC, /* CS == C set */
45 0xFF00, /* MI == N set */
47 0xAAAA, /* VS == V set */
49 0x0C0C, /* HI == C set && Z clear */
50 0xF3F3, /* LS == C clear || Z set */
51 0xAA55, /* GE == (N==V) */
52 0x55AA, /* LT == (N!=V) */
53 0x0A05, /* GT == (!Z && (N==V)) */
54 0xF5FA, /* LE == (Z || (N!=V)) */
55 0xFFFF, /* AL always */
60 * Check if a trapped instruction should have been executed or not.
62 bool kvm_condition_valid32(const struct kvm_vcpu *vcpu)
68 /* Top two bits non-zero? Unconditional. */
69 if (kvm_vcpu_get_hsr(vcpu) >> 30)
72 /* Is condition field valid? */
73 cond = kvm_vcpu_get_condition(vcpu);
77 cpsr = *vcpu_cpsr(vcpu);
80 /* This can happen in Thumb mode: examine IT state. */
83 it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3);
85 /* it == 0 => unconditional. */
89 /* The cond for this insn works out as the top 4 bits. */
93 cpsr_cond = cpsr >> 28;
95 if (!((cc_map[cond] >> cpsr_cond) & 1))
102 * adjust_itstate - adjust ITSTATE when emulating instructions in IT-block
103 * @vcpu: The VCPU pointer
105 * When exceptions occur while instructions are executed in Thumb IF-THEN
106 * blocks, the ITSTATE field of the CPSR is not advanced (updated), so we have
107 * to do this little bit of work manually. The fields map like this:
109 * IT[7:0] -> CPSR[26:25],CPSR[15:10]
111 static void kvm_adjust_itstate(struct kvm_vcpu *vcpu)
113 unsigned long itbits, cond;
114 unsigned long cpsr = *vcpu_cpsr(vcpu);
115 bool is_arm = !(cpsr & COMPAT_PSR_T_BIT);
117 if (is_arm || !(cpsr & COMPAT_PSR_IT_MASK))
120 cond = (cpsr & 0xe000) >> 13;
121 itbits = (cpsr & 0x1c00) >> (10 - 2);
122 itbits |= (cpsr & (0x3 << 25)) >> 25;
124 /* Perform ITAdvance (see page A2-52 in ARM DDI 0406C) */
125 if ((itbits & 0x7) == 0)
128 itbits = (itbits << 1) & 0x1f;
130 cpsr &= ~COMPAT_PSR_IT_MASK;
132 cpsr |= (itbits & 0x1c) << (10 - 2);
133 cpsr |= (itbits & 0x3) << 25;
134 *vcpu_cpsr(vcpu) = cpsr;
138 * kvm_skip_instr - skip a trapped instruction and proceed to the next
139 * @vcpu: The vcpu pointer
141 void kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr)
145 is_thumb = !!(*vcpu_cpsr(vcpu) & COMPAT_PSR_T_BIT);
146 if (is_thumb && !is_wide_instr)
150 kvm_adjust_itstate(vcpu);