1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Hyp portion of the (not much of an) Emulation layer for 32bit guests. 4 * 5 * Copyright (C) 2012,2013 - ARM Ltd 6 * Author: Marc Zyngier <marc.zyngier@arm.com> 7 * 8 * based on arch/arm/kvm/emulate.c 9 * Copyright (C) 2012 - Virtual Open Systems and Columbia University 10 * Author: Christoffer Dall <c.dall@virtualopensystems.com> 11 */ 12 13 #include <linux/kvm_host.h> 14 #include <asm/kvm_emulate.h> 15 #include <asm/kvm_hyp.h> 16 17 /* 18 * stolen from arch/arm/kernel/opcodes.c 19 * 20 * condition code lookup table 21 * index into the table is test code: EQ, NE, ... LT, GT, AL, NV 22 * 23 * bit position in short is condition code: NZCV 24 */ 25 static const unsigned short cc_map[16] = { 26 0xF0F0, /* EQ == Z set */ 27 0x0F0F, /* NE */ 28 0xCCCC, /* CS == C set */ 29 0x3333, /* CC */ 30 0xFF00, /* MI == N set */ 31 0x00FF, /* PL */ 32 0xAAAA, /* VS == V set */ 33 0x5555, /* VC */ 34 0x0C0C, /* HI == C set && Z clear */ 35 0xF3F3, /* LS == C clear || Z set */ 36 0xAA55, /* GE == (N==V) */ 37 0x55AA, /* LT == (N!=V) */ 38 0x0A05, /* GT == (!Z && (N==V)) */ 39 0xF5FA, /* LE == (Z || (N!=V)) */ 40 0xFFFF, /* AL always */ 41 0 /* NV */ 42 }; 43 44 /* 45 * Check if a trapped instruction should have been executed or not. 46 */ 47 bool kvm_condition_valid32(const struct kvm_vcpu *vcpu) 48 { 49 unsigned long cpsr; 50 u32 cpsr_cond; 51 int cond; 52 53 /* Top two bits non-zero? Unconditional. */ 54 if (kvm_vcpu_get_esr(vcpu) >> 30) 55 return true; 56 57 /* Is condition field valid? */ 58 cond = kvm_vcpu_get_condition(vcpu); 59 if (cond == 0xE) 60 return true; 61 62 cpsr = *vcpu_cpsr(vcpu); 63 64 if (cond < 0) { 65 /* This can happen in Thumb mode: examine IT state. */ 66 unsigned long it; 67 68 it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3); 69 70 /* it == 0 => unconditional. */ 71 if (it == 0) 72 return true; 73 74 /* The cond for this insn works out as the top 4 bits. */ 75 cond = (it >> 4); 76 } 77 78 cpsr_cond = cpsr >> 28; 79 80 if (!((cc_map[cond] >> cpsr_cond) & 1)) 81 return false; 82 83 return true; 84 } 85 86 /** 87 * adjust_itstate - adjust ITSTATE when emulating instructions in IT-block 88 * @vcpu: The VCPU pointer 89 * 90 * When exceptions occur while instructions are executed in Thumb IF-THEN 91 * blocks, the ITSTATE field of the CPSR is not advanced (updated), so we have 92 * to do this little bit of work manually. The fields map like this: 93 * 94 * IT[7:0] -> CPSR[26:25],CPSR[15:10] 95 */ 96 static void kvm_adjust_itstate(struct kvm_vcpu *vcpu) 97 { 98 unsigned long itbits, cond; 99 unsigned long cpsr = *vcpu_cpsr(vcpu); 100 bool is_arm = !(cpsr & PSR_AA32_T_BIT); 101 102 if (is_arm || !(cpsr & PSR_AA32_IT_MASK)) 103 return; 104 105 cond = (cpsr & 0xe000) >> 13; 106 itbits = (cpsr & 0x1c00) >> (10 - 2); 107 itbits |= (cpsr & (0x3 << 25)) >> 25; 108 109 /* Perform ITAdvance (see page A2-52 in ARM DDI 0406C) */ 110 if ((itbits & 0x7) == 0) 111 itbits = cond = 0; 112 else 113 itbits = (itbits << 1) & 0x1f; 114 115 cpsr &= ~PSR_AA32_IT_MASK; 116 cpsr |= cond << 13; 117 cpsr |= (itbits & 0x1c) << (10 - 2); 118 cpsr |= (itbits & 0x3) << 25; 119 *vcpu_cpsr(vcpu) = cpsr; 120 } 121 122 /** 123 * kvm_skip_instr - skip a trapped instruction and proceed to the next 124 * @vcpu: The vcpu pointer 125 */ 126 void kvm_skip_instr32(struct kvm_vcpu *vcpu) 127 { 128 u32 pc = *vcpu_pc(vcpu); 129 bool is_thumb; 130 131 is_thumb = !!(*vcpu_cpsr(vcpu) & PSR_AA32_T_BIT); 132 if (is_thumb && !kvm_vcpu_trap_il_is32bit(vcpu)) 133 pc += 2; 134 else 135 pc += 4; 136 137 *vcpu_pc(vcpu) = pc; 138 139 kvm_adjust_itstate(vcpu); 140 } 141