linux-stable/virt/kvm/arm/aarch32.c
Marc Zyngier 021234ef37 KVM: arm64: Make kvm_condition_valid32() accessible from EL2
As we're about to trap CP15 accesses and handle them at EL2, we
need to evaluate whether or not the condition flags are valid,
as an implementation is allowed to trap despite the condition
not being met.

Tagging the function as __hyp_text allows this. We still rely on
the cc_map array to be mapped at EL2 by virtue of being "const",
and the linker to only emit relative references.

Tested-by: Alexander Graf <agraf@suse.de>
Acked-by: David Daney <david.daney@cavium.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
2017-06-15 09:44:58 +01:00

152 lines
4.1 KiB
C

/*
* (not much of an) Emulation layer for 32bit guests.
*
* Copyright (C) 2012,2013 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* based on arch/arm/kvm/emulate.c
* 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, see <http://www.gnu.org/licenses/>.
*/
#include <linux/kvm_host.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#ifndef CONFIG_ARM64
#define COMPAT_PSR_T_BIT PSR_T_BIT
#define COMPAT_PSR_IT_MASK PSR_IT_MASK
#endif
/*
* stolen from arch/arm/kernel/opcodes.c
*
* condition code lookup table
* index into the table is test code: EQ, NE, ... LT, GT, AL, NV
*
* bit position in short is condition code: NZCV
*/
static const unsigned short cc_map[16] = {
0xF0F0, /* EQ == Z set */
0x0F0F, /* NE */
0xCCCC, /* CS == C set */
0x3333, /* CC */
0xFF00, /* MI == N set */
0x00FF, /* PL */
0xAAAA, /* VS == V set */
0x5555, /* VC */
0x0C0C, /* HI == C set && Z clear */
0xF3F3, /* LS == C clear || Z set */
0xAA55, /* GE == (N==V) */
0x55AA, /* LT == (N!=V) */
0x0A05, /* GT == (!Z && (N==V)) */
0xF5FA, /* LE == (Z || (N!=V)) */
0xFFFF, /* AL always */
0 /* NV */
};
/*
* Check if a trapped instruction should have been executed or not.
*/
bool __hyp_text kvm_condition_valid32(const struct kvm_vcpu *vcpu)
{
unsigned long cpsr;
u32 cpsr_cond;
int cond;
/* Top two bits non-zero? Unconditional. */
if (kvm_vcpu_get_hsr(vcpu) >> 30)
return true;
/* Is condition field valid? */
cond = kvm_vcpu_get_condition(vcpu);
if (cond == 0xE)
return true;
cpsr = *vcpu_cpsr(vcpu);
if (cond < 0) {
/* This can happen in Thumb mode: examine IT state. */
unsigned long it;
it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3);
/* it == 0 => unconditional. */
if (it == 0)
return true;
/* The cond for this insn works out as the top 4 bits. */
cond = (it >> 4);
}
cpsr_cond = cpsr >> 28;
if (!((cc_map[cond] >> cpsr_cond) & 1))
return false;
return true;
}
/**
* adjust_itstate - adjust ITSTATE when emulating instructions in IT-block
* @vcpu: The VCPU pointer
*
* When exceptions occur while instructions are executed in Thumb IF-THEN
* blocks, the ITSTATE field of the CPSR is not advanced (updated), so we have
* to do this little bit of work manually. The fields map like this:
*
* IT[7:0] -> CPSR[26:25],CPSR[15:10]
*/
static void __hyp_text kvm_adjust_itstate(struct kvm_vcpu *vcpu)
{
unsigned long itbits, cond;
unsigned long cpsr = *vcpu_cpsr(vcpu);
bool is_arm = !(cpsr & COMPAT_PSR_T_BIT);
if (is_arm || !(cpsr & COMPAT_PSR_IT_MASK))
return;
cond = (cpsr & 0xe000) >> 13;
itbits = (cpsr & 0x1c00) >> (10 - 2);
itbits |= (cpsr & (0x3 << 25)) >> 25;
/* Perform ITAdvance (see page A2-52 in ARM DDI 0406C) */
if ((itbits & 0x7) == 0)
itbits = cond = 0;
else
itbits = (itbits << 1) & 0x1f;
cpsr &= ~COMPAT_PSR_IT_MASK;
cpsr |= cond << 13;
cpsr |= (itbits & 0x1c) << (10 - 2);
cpsr |= (itbits & 0x3) << 25;
*vcpu_cpsr(vcpu) = cpsr;
}
/**
* kvm_skip_instr - skip a trapped instruction and proceed to the next
* @vcpu: The vcpu pointer
*/
void __hyp_text kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr)
{
bool is_thumb;
is_thumb = !!(*vcpu_cpsr(vcpu) & COMPAT_PSR_T_BIT);
if (is_thumb && !is_wide_instr)
*vcpu_pc(vcpu) += 2;
else
*vcpu_pc(vcpu) += 4;
kvm_adjust_itstate(vcpu);
}