156c7f5e7SAlex Bennée /* 256c7f5e7SAlex Bennée * Debug and Guest Debug support 356c7f5e7SAlex Bennée * 456c7f5e7SAlex Bennée * Copyright (C) 2015 - Linaro Ltd 556c7f5e7SAlex Bennée * Author: Alex Bennée <alex.bennee@linaro.org> 656c7f5e7SAlex Bennée * 756c7f5e7SAlex Bennée * This program is free software; you can redistribute it and/or modify 856c7f5e7SAlex Bennée * it under the terms of the GNU General Public License version 2 as 956c7f5e7SAlex Bennée * published by the Free Software Foundation. 1056c7f5e7SAlex Bennée * 1156c7f5e7SAlex Bennée * This program is distributed in the hope that it will be useful, 1256c7f5e7SAlex Bennée * but WITHOUT ANY WARRANTY; without even the implied warranty of 1356c7f5e7SAlex Bennée * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 1456c7f5e7SAlex Bennée * GNU General Public License for more details. 1556c7f5e7SAlex Bennée * 1656c7f5e7SAlex Bennée * You should have received a copy of the GNU General Public License 1756c7f5e7SAlex Bennée * along with this program. If not, see <http://www.gnu.org/licenses/>. 1856c7f5e7SAlex Bennée */ 1956c7f5e7SAlex Bennée 2056c7f5e7SAlex Bennée #include <linux/kvm_host.h> 21eef8c85aSAlex Bennée #include <linux/hw_breakpoint.h> 2256c7f5e7SAlex Bennée 23337b99bfSAlex Bennée #include <asm/debug-monitors.h> 24337b99bfSAlex Bennée #include <asm/kvm_asm.h> 2556c7f5e7SAlex Bennée #include <asm/kvm_arm.h> 26337b99bfSAlex Bennée #include <asm/kvm_emulate.h> 27337b99bfSAlex Bennée 28eef8c85aSAlex Bennée #include "trace.h" 29eef8c85aSAlex Bennée 30337b99bfSAlex Bennée /* These are the bits of MDSCR_EL1 we may manipulate */ 31337b99bfSAlex Bennée #define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS | \ 32337b99bfSAlex Bennée DBG_MDSCR_KDE | \ 33337b99bfSAlex Bennée DBG_MDSCR_MDE) 3456c7f5e7SAlex Bennée 3556c7f5e7SAlex Bennée static DEFINE_PER_CPU(u32, mdcr_el2); 3656c7f5e7SAlex Bennée 3756c7f5e7SAlex Bennée /** 38337b99bfSAlex Bennée * save/restore_guest_debug_regs 39337b99bfSAlex Bennée * 40337b99bfSAlex Bennée * For some debug operations we need to tweak some guest registers. As 41337b99bfSAlex Bennée * a result we need to save the state of those registers before we 42337b99bfSAlex Bennée * make those modifications. 43337b99bfSAlex Bennée * 44337b99bfSAlex Bennée * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled 45337b99bfSAlex Bennée * after we have restored the preserved value to the main context. 46337b99bfSAlex Bennée */ 47337b99bfSAlex Bennée static void save_guest_debug_regs(struct kvm_vcpu *vcpu) 48337b99bfSAlex Bennée { 498d404c4cSChristoffer Dall u64 val = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 508d404c4cSChristoffer Dall 518d404c4cSChristoffer Dall vcpu->arch.guest_debug_preserved.mdscr_el1 = val; 52eef8c85aSAlex Bennée 53eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("Saved MDSCR_EL1", 54eef8c85aSAlex Bennée vcpu->arch.guest_debug_preserved.mdscr_el1); 55337b99bfSAlex Bennée } 56337b99bfSAlex Bennée 57337b99bfSAlex Bennée static void restore_guest_debug_regs(struct kvm_vcpu *vcpu) 58337b99bfSAlex Bennée { 598d404c4cSChristoffer Dall u64 val = vcpu->arch.guest_debug_preserved.mdscr_el1; 608d404c4cSChristoffer Dall 618d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, val, MDSCR_EL1); 62eef8c85aSAlex Bennée 63eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("Restored MDSCR_EL1", 648d404c4cSChristoffer Dall vcpu_read_sys_reg(vcpu, MDSCR_EL1)); 65337b99bfSAlex Bennée } 66337b99bfSAlex Bennée 67337b99bfSAlex Bennée /** 6856c7f5e7SAlex Bennée * kvm_arm_init_debug - grab what we need for debug 6956c7f5e7SAlex Bennée * 7056c7f5e7SAlex Bennée * Currently the sole task of this function is to retrieve the initial 7156c7f5e7SAlex Bennée * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has 7256c7f5e7SAlex Bennée * presumably been set-up by some knowledgeable bootcode. 7356c7f5e7SAlex Bennée * 7456c7f5e7SAlex Bennée * It is called once per-cpu during CPU hyp initialisation. 7556c7f5e7SAlex Bennée */ 7656c7f5e7SAlex Bennée 7756c7f5e7SAlex Bennée void kvm_arm_init_debug(void) 7856c7f5e7SAlex Bennée { 797aa8d146SMarc Zyngier __this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2)); 8056c7f5e7SAlex Bennée } 8156c7f5e7SAlex Bennée 8256c7f5e7SAlex Bennée /** 8384e690bfSAlex Bennée * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state 8484e690bfSAlex Bennée */ 8584e690bfSAlex Bennée 8684e690bfSAlex Bennée void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) 8784e690bfSAlex Bennée { 8884e690bfSAlex Bennée vcpu->arch.debug_ptr = &vcpu->arch.vcpu_debug_state; 8984e690bfSAlex Bennée } 9084e690bfSAlex Bennée 9184e690bfSAlex Bennée /** 9256c7f5e7SAlex Bennée * kvm_arm_setup_debug - set up debug related stuff 9356c7f5e7SAlex Bennée * 9456c7f5e7SAlex Bennée * @vcpu: the vcpu pointer 9556c7f5e7SAlex Bennée * 9656c7f5e7SAlex Bennée * This is called before each entry into the hypervisor to setup any 9756c7f5e7SAlex Bennée * debug related registers. Currently this just ensures we will trap 9856c7f5e7SAlex Bennée * access to: 9956c7f5e7SAlex Bennée * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR) 10056c7f5e7SAlex Bennée * - Debug ROM Address (MDCR_EL2_TDRA) 10156c7f5e7SAlex Bennée * - OS related registers (MDCR_EL2_TDOSA) 102f85279b4SWill Deacon * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) 10356c7f5e7SAlex Bennée * 10456c7f5e7SAlex Bennée * Additionally, KVM only traps guest accesses to the debug registers if 10556c7f5e7SAlex Bennée * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY 106fa89d31cSDave Martin * flag on vcpu->arch.flags). Since the guest must not interfere 10756c7f5e7SAlex Bennée * with the hardware state when debugging the guest, we must ensure that 10856c7f5e7SAlex Bennée * trapping is enabled whenever we are debugging the guest using the 10956c7f5e7SAlex Bennée * debug registers. 11056c7f5e7SAlex Bennée */ 11156c7f5e7SAlex Bennée 11256c7f5e7SAlex Bennée void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) 11356c7f5e7SAlex Bennée { 114fa89d31cSDave Martin bool trap_debug = !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY); 1158d404c4cSChristoffer Dall unsigned long mdscr; 11656c7f5e7SAlex Bennée 117eef8c85aSAlex Bennée trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug); 118eef8c85aSAlex Bennée 119f85279b4SWill Deacon /* 120f85279b4SWill Deacon * This also clears MDCR_EL2_E2PB_MASK to disable guest access 121f85279b4SWill Deacon * to the profiling buffer. 122f85279b4SWill Deacon */ 12356c7f5e7SAlex Bennée vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK; 12456c7f5e7SAlex Bennée vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | 125f85279b4SWill Deacon MDCR_EL2_TPMS | 12656c7f5e7SAlex Bennée MDCR_EL2_TPMCR | 12756c7f5e7SAlex Bennée MDCR_EL2_TDRA | 12856c7f5e7SAlex Bennée MDCR_EL2_TDOSA); 12956c7f5e7SAlex Bennée 130337b99bfSAlex Bennée /* Is Guest debugging in effect? */ 131337b99bfSAlex Bennée if (vcpu->guest_debug) { 132337b99bfSAlex Bennée /* Route all software debug exceptions to EL2 */ 1334bd611caSAlex Bennée vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; 134337b99bfSAlex Bennée 135337b99bfSAlex Bennée /* Save guest debug state */ 136337b99bfSAlex Bennée save_guest_debug_regs(vcpu); 137337b99bfSAlex Bennée 138337b99bfSAlex Bennée /* 139337b99bfSAlex Bennée * Single Step (ARM ARM D2.12.3 The software step state 140337b99bfSAlex Bennée * machine) 141337b99bfSAlex Bennée * 142337b99bfSAlex Bennée * If we are doing Single Step we need to manipulate 143337b99bfSAlex Bennée * the guest's MDSCR_EL1.SS and PSTATE.SS. Once the 144337b99bfSAlex Bennée * step has occurred the hypervisor will trap the 145337b99bfSAlex Bennée * debug exception and we return to userspace. 146337b99bfSAlex Bennée * 147337b99bfSAlex Bennée * If the guest attempts to single step its userspace 148337b99bfSAlex Bennée * we would have to deal with a trapped exception 149337b99bfSAlex Bennée * while in the guest kernel. Because this would be 150337b99bfSAlex Bennée * hard to unwind we suppress the guest's ability to 151337b99bfSAlex Bennée * do so by masking MDSCR_EL.SS. 152337b99bfSAlex Bennée * 153337b99bfSAlex Bennée * This confuses guest debuggers which use 154337b99bfSAlex Bennée * single-step behind the scenes but everything 155337b99bfSAlex Bennée * returns to normal once the host is no longer 156337b99bfSAlex Bennée * debugging the system. 157337b99bfSAlex Bennée */ 158337b99bfSAlex Bennée if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { 159337b99bfSAlex Bennée *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; 1608d404c4cSChristoffer Dall mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 1618d404c4cSChristoffer Dall mdscr |= DBG_MDSCR_SS; 1628d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); 163337b99bfSAlex Bennée } else { 1648d404c4cSChristoffer Dall mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 1658d404c4cSChristoffer Dall mdscr &= ~DBG_MDSCR_SS; 1668d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); 167337b99bfSAlex Bennée } 168834bf887SAlex Bennée 169eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu)); 170eef8c85aSAlex Bennée 171834bf887SAlex Bennée /* 172834bf887SAlex Bennée * HW Breakpoints and watchpoints 173834bf887SAlex Bennée * 174834bf887SAlex Bennée * We simply switch the debug_ptr to point to our new 175834bf887SAlex Bennée * external_debug_state which has been populated by the 176834bf887SAlex Bennée * debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY 177834bf887SAlex Bennée * mechanism ensures the registers are updated on the 178834bf887SAlex Bennée * world switch. 179834bf887SAlex Bennée */ 180834bf887SAlex Bennée if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { 181834bf887SAlex Bennée /* Enable breakpoints/watchpoints */ 1828d404c4cSChristoffer Dall mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 1838d404c4cSChristoffer Dall mdscr |= DBG_MDSCR_MDE; 1848d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); 185834bf887SAlex Bennée 186834bf887SAlex Bennée vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state; 187fa89d31cSDave Martin vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY; 188834bf887SAlex Bennée trap_debug = true; 189eef8c85aSAlex Bennée 190eef8c85aSAlex Bennée trace_kvm_arm_set_regset("BKPTS", get_num_brps(), 191eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bcr[0], 192eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bvr[0]); 193eef8c85aSAlex Bennée 194eef8c85aSAlex Bennée trace_kvm_arm_set_regset("WAPTS", get_num_wrps(), 195eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wcr[0], 196eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wvr[0]); 197337b99bfSAlex Bennée } 19856c7f5e7SAlex Bennée } 19956c7f5e7SAlex Bennée 200834bf887SAlex Bennée BUG_ON(!vcpu->guest_debug && 201834bf887SAlex Bennée vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state); 202834bf887SAlex Bennée 203834bf887SAlex Bennée /* Trap debug register access */ 204834bf887SAlex Bennée if (trap_debug) 205834bf887SAlex Bennée vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; 206eef8c85aSAlex Bennée 20754ceb1bcSChristoffer Dall /* If KDE or MDE are set, perform a full save/restore cycle. */ 2088d404c4cSChristoffer Dall if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE)) 209fa89d31cSDave Martin vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY; 21054ceb1bcSChristoffer Dall 211eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2); 2128d404c4cSChristoffer Dall trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1)); 213834bf887SAlex Bennée } 214834bf887SAlex Bennée 21556c7f5e7SAlex Bennée void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) 21656c7f5e7SAlex Bennée { 217eef8c85aSAlex Bennée trace_kvm_arm_clear_debug(vcpu->guest_debug); 218eef8c85aSAlex Bennée 219834bf887SAlex Bennée if (vcpu->guest_debug) { 220337b99bfSAlex Bennée restore_guest_debug_regs(vcpu); 221834bf887SAlex Bennée 222834bf887SAlex Bennée /* 223834bf887SAlex Bennée * If we were using HW debug we need to restore the 224834bf887SAlex Bennée * debug_ptr to the guest debug state. 225834bf887SAlex Bennée */ 226eef8c85aSAlex Bennée if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { 227834bf887SAlex Bennée kvm_arm_reset_debug_ptr(vcpu); 228834bf887SAlex Bennée 229eef8c85aSAlex Bennée trace_kvm_arm_set_regset("BKPTS", get_num_brps(), 230eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bcr[0], 231eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bvr[0]); 232eef8c85aSAlex Bennée 233eef8c85aSAlex Bennée trace_kvm_arm_set_regset("WAPTS", get_num_wrps(), 234eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wcr[0], 235eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wvr[0]); 236eef8c85aSAlex Bennée } 237834bf887SAlex Bennée } 23856c7f5e7SAlex Bennée } 239