mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
265 lines
7.5 KiB
265 lines
7.5 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
|
* Debug and Guest Debug support |
|
* |
|
* Copyright (C) 2015 - Linaro Ltd |
|
* Author: Alex Bennée <[email protected]> |
|
*/ |
|
|
|
#include <linux/kvm_host.h> |
|
#include <linux/hw_breakpoint.h> |
|
|
|
#include <asm/debug-monitors.h> |
|
#include <asm/kvm_asm.h> |
|
#include <asm/kvm_arm.h> |
|
#include <asm/kvm_emulate.h> |
|
|
|
#include "trace.h" |
|
|
|
/* These are the bits of MDSCR_EL1 we may manipulate */ |
|
#define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS | \ |
|
DBG_MDSCR_KDE | \ |
|
DBG_MDSCR_MDE) |
|
|
|
static DEFINE_PER_CPU(u32, mdcr_el2); |
|
|
|
/** |
|
* save/restore_guest_debug_regs |
|
* |
|
* For some debug operations we need to tweak some guest registers. As |
|
* a result we need to save the state of those registers before we |
|
* make those modifications. |
|
* |
|
* Guest access to MDSCR_EL1 is trapped by the hypervisor and handled |
|
* after we have restored the preserved value to the main context. |
|
*/ |
|
static void save_guest_debug_regs(struct kvm_vcpu *vcpu) |
|
{ |
|
u64 val = vcpu_read_sys_reg(vcpu, MDSCR_EL1); |
|
|
|
vcpu->arch.guest_debug_preserved.mdscr_el1 = val; |
|
|
|
trace_kvm_arm_set_dreg32("Saved MDSCR_EL1", |
|
vcpu->arch.guest_debug_preserved.mdscr_el1); |
|
} |
|
|
|
static void restore_guest_debug_regs(struct kvm_vcpu *vcpu) |
|
{ |
|
u64 val = vcpu->arch.guest_debug_preserved.mdscr_el1; |
|
|
|
vcpu_write_sys_reg(vcpu, val, MDSCR_EL1); |
|
|
|
trace_kvm_arm_set_dreg32("Restored MDSCR_EL1", |
|
vcpu_read_sys_reg(vcpu, MDSCR_EL1)); |
|
} |
|
|
|
/** |
|
* kvm_arm_init_debug - grab what we need for debug |
|
* |
|
* Currently the sole task of this function is to retrieve the initial |
|
* value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has |
|
* presumably been set-up by some knowledgeable bootcode. |
|
* |
|
* It is called once per-cpu during CPU hyp initialisation. |
|
*/ |
|
|
|
void kvm_arm_init_debug(void) |
|
{ |
|
__this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2)); |
|
} |
|
|
|
/** |
|
* kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value |
|
* |
|
* @vcpu: the vcpu pointer |
|
* |
|
* This ensures we will trap access to: |
|
* - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR) |
|
* - Debug ROM Address (MDCR_EL2_TDRA) |
|
* - OS related registers (MDCR_EL2_TDOSA) |
|
* - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) |
|
* - Self-hosted Trace Filter controls (MDCR_EL2_TTRF) |
|
*/ |
|
static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu) |
|
{ |
|
/* |
|
* This also clears MDCR_EL2_E2PB_MASK to disable guest access |
|
* to the profiling buffer. |
|
*/ |
|
vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK; |
|
vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | |
|
MDCR_EL2_TPMS | |
|
MDCR_EL2_TTRF | |
|
MDCR_EL2_TPMCR | |
|
MDCR_EL2_TDRA | |
|
MDCR_EL2_TDOSA); |
|
|
|
/* Is the VM being debugged by userspace? */ |
|
if (vcpu->guest_debug) |
|
/* Route all software debug exceptions to EL2 */ |
|
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; |
|
|
|
/* |
|
* Trap debug register access when one of the following is true: |
|
* - Userspace is using the hardware to debug the guest |
|
* (KVM_GUESTDBG_USE_HW is set). |
|
* - The guest is not using debug (KVM_ARM64_DEBUG_DIRTY is clear). |
|
*/ |
|
if ((vcpu->guest_debug & KVM_GUESTDBG_USE_HW) || |
|
!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) |
|
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; |
|
|
|
trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2); |
|
} |
|
|
|
/** |
|
* kvm_arm_vcpu_init_debug - setup vcpu debug traps |
|
* |
|
* @vcpu: the vcpu pointer |
|
* |
|
* Set vcpu initial mdcr_el2 value. |
|
*/ |
|
void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu) |
|
{ |
|
preempt_disable(); |
|
kvm_arm_setup_mdcr_el2(vcpu); |
|
preempt_enable(); |
|
} |
|
|
|
/** |
|
* kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state |
|
*/ |
|
|
|
void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) |
|
{ |
|
vcpu->arch.debug_ptr = &vcpu->arch.vcpu_debug_state; |
|
} |
|
|
|
/** |
|
* kvm_arm_setup_debug - set up debug related stuff |
|
* |
|
* @vcpu: the vcpu pointer |
|
* |
|
* This is called before each entry into the hypervisor to setup any |
|
* debug related registers. |
|
* |
|
* Additionally, KVM only traps guest accesses to the debug registers if |
|
* the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY |
|
* flag on vcpu->arch.flags). Since the guest must not interfere |
|
* with the hardware state when debugging the guest, we must ensure that |
|
* trapping is enabled whenever we are debugging the guest using the |
|
* debug registers. |
|
*/ |
|
|
|
void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) |
|
{ |
|
unsigned long mdscr, orig_mdcr_el2 = vcpu->arch.mdcr_el2; |
|
|
|
trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug); |
|
|
|
kvm_arm_setup_mdcr_el2(vcpu); |
|
|
|
/* Is Guest debugging in effect? */ |
|
if (vcpu->guest_debug) { |
|
/* Save guest debug state */ |
|
save_guest_debug_regs(vcpu); |
|
|
|
/* |
|
* Single Step (ARM ARM D2.12.3 The software step state |
|
* machine) |
|
* |
|
* If we are doing Single Step we need to manipulate |
|
* the guest's MDSCR_EL1.SS and PSTATE.SS. Once the |
|
* step has occurred the hypervisor will trap the |
|
* debug exception and we return to userspace. |
|
* |
|
* If the guest attempts to single step its userspace |
|
* we would have to deal with a trapped exception |
|
* while in the guest kernel. Because this would be |
|
* hard to unwind we suppress the guest's ability to |
|
* do so by masking MDSCR_EL.SS. |
|
* |
|
* This confuses guest debuggers which use |
|
* single-step behind the scenes but everything |
|
* returns to normal once the host is no longer |
|
* debugging the system. |
|
*/ |
|
if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { |
|
*vcpu_cpsr(vcpu) |= DBG_SPSR_SS; |
|
mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); |
|
mdscr |= DBG_MDSCR_SS; |
|
vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); |
|
} else { |
|
mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); |
|
mdscr &= ~DBG_MDSCR_SS; |
|
vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); |
|
} |
|
|
|
trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu)); |
|
|
|
/* |
|
* HW Breakpoints and watchpoints |
|
* |
|
* We simply switch the debug_ptr to point to our new |
|
* external_debug_state which has been populated by the |
|
* debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY |
|
* mechanism ensures the registers are updated on the |
|
* world switch. |
|
*/ |
|
if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { |
|
/* Enable breakpoints/watchpoints */ |
|
mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); |
|
mdscr |= DBG_MDSCR_MDE; |
|
vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); |
|
|
|
vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state; |
|
vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY; |
|
|
|
trace_kvm_arm_set_regset("BKPTS", get_num_brps(), |
|
&vcpu->arch.debug_ptr->dbg_bcr[0], |
|
&vcpu->arch.debug_ptr->dbg_bvr[0]); |
|
|
|
trace_kvm_arm_set_regset("WAPTS", get_num_wrps(), |
|
&vcpu->arch.debug_ptr->dbg_wcr[0], |
|
&vcpu->arch.debug_ptr->dbg_wvr[0]); |
|
} |
|
} |
|
|
|
BUG_ON(!vcpu->guest_debug && |
|
vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state); |
|
|
|
/* If KDE or MDE are set, perform a full save/restore cycle. */ |
|
if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE)) |
|
vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY; |
|
|
|
/* Write mdcr_el2 changes since vcpu_load on VHE systems */ |
|
if (has_vhe() && orig_mdcr_el2 != vcpu->arch.mdcr_el2) |
|
write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); |
|
|
|
trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1)); |
|
} |
|
|
|
void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) |
|
{ |
|
trace_kvm_arm_clear_debug(vcpu->guest_debug); |
|
|
|
if (vcpu->guest_debug) { |
|
restore_guest_debug_regs(vcpu); |
|
|
|
/* |
|
* If we were using HW debug we need to restore the |
|
* debug_ptr to the guest debug state. |
|
*/ |
|
if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { |
|
kvm_arm_reset_debug_ptr(vcpu); |
|
|
|
trace_kvm_arm_set_regset("BKPTS", get_num_brps(), |
|
&vcpu->arch.debug_ptr->dbg_bcr[0], |
|
&vcpu->arch.debug_ptr->dbg_bvr[0]); |
|
|
|
trace_kvm_arm_set_regset("WAPTS", get_num_wrps(), |
|
&vcpu->arch.debug_ptr->dbg_wcr[0], |
|
&vcpu->arch.debug_ptr->dbg_wvr[0]); |
|
} |
|
} |
|
}
|
|
|