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qemu/target/arm/debug_helper.c
Peter Maydell f94a6df5dd target/arm: Correctly implement Feat_DoubleLock 
The architecture defines the OS DoubleLock as a register which
(similarly to the OS Lock) suppresses debug events for use in CPU
powerdown sequences.  This functionality is required in Arm v7 and
v8.0; from v8.2 it becomes optional and in v9 it must not be
implemented.

Currently in QEMU we implement the OSDLR_EL1 register as a NOP.  This
is wrong both for the "feature implemented" and the "feature not
implemented" cases: if the feature is implemented then the DLK bit
should read as written and cause suppression of debug exceptions, and
if it is not implemented then the bit must be RAZ/WI.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2022-07-07 11:38:36 +01:00

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/*
* ARM debug helpers.
*
* This code is licensed under the GNU GPL v2 or later.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "cpu.h"
#include "internals.h"
#include "cpregs.h"
#include "exec/exec-all.h"
#include "exec/helper-proto.h"
/* Return the Exception Level targeted by debug exceptions. */
static int arm_debug_target_el(CPUARMState *env)
{
bool secure = arm_is_secure(env);
bool route_to_el2 = false;
if (arm_is_el2_enabled(env)) {
route_to_el2 = env->cp15.hcr_el2 & HCR_TGE ||
env->cp15.mdcr_el2 & MDCR_TDE;
}
if (route_to_el2) {
return 2;
} else if (arm_feature(env, ARM_FEATURE_EL3) &&
!arm_el_is_aa64(env, 3) && secure) {
return 3;
} else {
return 1;
}
}
/*
* Raise an exception to the debug target el.
* Modify syndrome to indicate when origin and target EL are the same.
*/
G_NORETURN static void
raise_exception_debug(CPUARMState *env, uint32_t excp, uint32_t syndrome)
{
int debug_el = arm_debug_target_el(env);
int cur_el = arm_current_el(env);
/*
* If singlestep is targeting a lower EL than the current one, then
* DisasContext.ss_active must be false and we can never get here.
* Similarly for watchpoint and breakpoint matches.
*/
assert(debug_el >= cur_el);
syndrome |= (debug_el == cur_el) << ARM_EL_EC_SHIFT;
raise_exception(env, excp, syndrome, debug_el);
}
/* See AArch64.GenerateDebugExceptionsFrom() in ARM ARM pseudocode */
static bool aa64_generate_debug_exceptions(CPUARMState *env)
{
int cur_el = arm_current_el(env);
int debug_el;
if (cur_el == 3) {
return false;
}
/* MDCR_EL3.SDD disables debug events from Secure state */
if (arm_is_secure_below_el3(env)
&& extract32(env->cp15.mdcr_el3, 16, 1)) {
return false;
}
/*
* Same EL to same EL debug exceptions need MDSCR_KDE enabled
* while not masking the (D)ebug bit in DAIF.
*/
debug_el = arm_debug_target_el(env);
if (cur_el == debug_el) {
return extract32(env->cp15.mdscr_el1, 13, 1)
&& !(env->daif & PSTATE_D);
}
/* Otherwise the debug target needs to be a higher EL */
return debug_el > cur_el;
}
static bool aa32_generate_debug_exceptions(CPUARMState *env)
{
int el = arm_current_el(env);
if (el == 0 && arm_el_is_aa64(env, 1)) {
return aa64_generate_debug_exceptions(env);
}
if (arm_is_secure(env)) {
int spd;
if (el == 0 && (env->cp15.sder & 1)) {
/*
* SDER.SUIDEN means debug exceptions from Secure EL0
* are always enabled. Otherwise they are controlled by
* SDCR.SPD like those from other Secure ELs.
*/
return true;
}
spd = extract32(env->cp15.mdcr_el3, 14, 2);
switch (spd) {
case 1:
/* SPD == 0b01 is reserved, but behaves as 0b00. */
case 0:
/*
* For 0b00 we return true if external secure invasive debug
* is enabled. On real hardware this is controlled by external
* signals to the core. QEMU always permits debug, and behaves
* as if DBGEN, SPIDEN, NIDEN and SPNIDEN are all tied high.
*/
return true;
case 2:
return false;
case 3:
return true;
}
}
return el != 2;
}
/*
* Return true if debugging exceptions are currently enabled.
* This corresponds to what in ARM ARM pseudocode would be
* if UsingAArch32() then
* return AArch32.GenerateDebugExceptions()
* else
* return AArch64.GenerateDebugExceptions()
* We choose to push the if() down into this function for clarity,
* since the pseudocode has it at all callsites except for the one in
* CheckSoftwareStep(), where it is elided because both branches would
* always return the same value.
*/
bool arm_generate_debug_exceptions(CPUARMState *env)
{
if ((env->cp15.oslsr_el1 & 1) || (env->cp15.osdlr_el1 & 1)) {
return false;
}
if (is_a64(env)) {
return aa64_generate_debug_exceptions(env);
} else {
return aa32_generate_debug_exceptions(env);
}
}
/*
* Is single-stepping active? (Note that the "is EL_D AArch64?" check
* implicitly means this always returns false in pre-v8 CPUs.)
*/
bool arm_singlestep_active(CPUARMState *env)
{
return extract32(env->cp15.mdscr_el1, 0, 1)
&& arm_el_is_aa64(env, arm_debug_target_el(env))
&& arm_generate_debug_exceptions(env);
}
/* Return true if the linked breakpoint entry lbn passes its checks */
static bool linked_bp_matches(ARMCPU *cpu, int lbn)
{
CPUARMState *env = &cpu->env;
uint64_t bcr = env->cp15.dbgbcr[lbn];
int brps = arm_num_brps(cpu);
int ctx_cmps = arm_num_ctx_cmps(cpu);
int bt;
uint32_t contextidr;
uint64_t hcr_el2;
/*
* Links to unimplemented or non-context aware breakpoints are
* CONSTRAINED UNPREDICTABLE: either behave as if disabled, or
* as if linked to an UNKNOWN context-aware breakpoint (in which
* case DBGWCR<n>_EL1.LBN must indicate that breakpoint).
* We choose the former.
*/
if (lbn >= brps || lbn < (brps - ctx_cmps)) {
return false;
}
bcr = env->cp15.dbgbcr[lbn];
if (extract64(bcr, 0, 1) == 0) {
/* Linked breakpoint disabled : generate no events */
return false;
}
bt = extract64(bcr, 20, 4);
hcr_el2 = arm_hcr_el2_eff(env);
switch (bt) {
case 3: /* linked context ID match */
switch (arm_current_el(env)) {
default:
/* Context matches never fire in AArch64 EL3 */
return false;
case 2:
if (!(hcr_el2 & HCR_E2H)) {
/* Context matches never fire in EL2 without E2H enabled. */
return false;
}
contextidr = env->cp15.contextidr_el[2];
break;
case 1:
contextidr = env->cp15.contextidr_el[1];
break;
case 0:
if ((hcr_el2 & (HCR_E2H | HCR_TGE)) == (HCR_E2H | HCR_TGE)) {
contextidr = env->cp15.contextidr_el[2];
} else {
contextidr = env->cp15.contextidr_el[1];
}
break;
}
break;
case 7: /* linked contextidr_el1 match */
contextidr = env->cp15.contextidr_el[1];
break;
case 13: /* linked contextidr_el2 match */
contextidr = env->cp15.contextidr_el[2];
break;
case 9: /* linked VMID match (reserved if no EL2) */
case 11: /* linked context ID and VMID match (reserved if no EL2) */
case 15: /* linked full context ID match */
default:
/*
* Links to Unlinked context breakpoints must generate no
* events; we choose to do the same for reserved values too.
*/
return false;
}
/*
* We match the whole register even if this is AArch32 using the
* short descriptor format (in which case it holds both PROCID and ASID),
* since we don't implement the optional v7 context ID masking.
*/
return contextidr == (uint32_t)env->cp15.dbgbvr[lbn];
}
static bool bp_wp_matches(ARMCPU *cpu, int n, bool is_wp)
{
CPUARMState *env = &cpu->env;
uint64_t cr;
int pac, hmc, ssc, wt, lbn;
/*
* Note that for watchpoints the check is against the CPU security
* state, not the S/NS attribute on the offending data access.
*/
bool is_secure = arm_is_secure(env);
int access_el = arm_current_el(env);
if (is_wp) {
CPUWatchpoint *wp = env->cpu_watchpoint[n];
if (!wp || !(wp->flags & BP_WATCHPOINT_HIT)) {
return false;
}
cr = env->cp15.dbgwcr[n];
if (wp->hitattrs.user) {
/*
* The LDRT/STRT/LDT/STT "unprivileged access" instructions should
* match watchpoints as if they were accesses done at EL0, even if
* the CPU is at EL1 or higher.
*/
access_el = 0;
}
} else {
uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
if (!env->cpu_breakpoint[n] || env->cpu_breakpoint[n]->pc != pc) {
return false;
}
cr = env->cp15.dbgbcr[n];
}
/*
* The WATCHPOINT_HIT flag guarantees us that the watchpoint is
* enabled and that the address and access type match; for breakpoints
* we know the address matched; check the remaining fields, including
* linked breakpoints. We rely on WCR and BCR having the same layout
* for the LBN, SSC, HMC, PAC/PMC and is-linked fields.
* Note that some combinations of {PAC, HMC, SSC} are reserved and
* must act either like some valid combination or as if the watchpoint
* were disabled. We choose the former, and use this together with
* the fact that EL3 must always be Secure and EL2 must always be
* Non-Secure to simplify the code slightly compared to the full
* table in the ARM ARM.
*/
pac = FIELD_EX64(cr, DBGWCR, PAC);
hmc = FIELD_EX64(cr, DBGWCR, HMC);
ssc = FIELD_EX64(cr, DBGWCR, SSC);
switch (ssc) {
case 0:
break;
case 1:
case 3:
if (is_secure) {
return false;
}
break;
case 2:
if (!is_secure) {
return false;
}
break;
}
switch (access_el) {
case 3:
case 2:
if (!hmc) {
return false;
}
break;
case 1:
if (extract32(pac, 0, 1) == 0) {
return false;
}
break;
case 0:
if (extract32(pac, 1, 1) == 0) {
return false;
}
break;
default:
g_assert_not_reached();
}
wt = FIELD_EX64(cr, DBGWCR, WT);
lbn = FIELD_EX64(cr, DBGWCR, LBN);
if (wt && !linked_bp_matches(cpu, lbn)) {
return false;
}
return true;
}
static bool check_watchpoints(ARMCPU *cpu)
{
CPUARMState *env = &cpu->env;
int n;
/*
* If watchpoints are disabled globally or we can't take debug
* exceptions here then watchpoint firings are ignored.
*/
if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
|| !arm_generate_debug_exceptions(env)) {
return false;
}
for (n = 0; n < ARRAY_SIZE(env->cpu_watchpoint); n++) {
if (bp_wp_matches(cpu, n, true)) {
return true;
}
}
return false;
}
bool arm_debug_check_breakpoint(CPUState *cs)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
target_ulong pc;
int n;
/*
* If breakpoints are disabled globally or we can't take debug
* exceptions here then breakpoint firings are ignored.
*/
if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
|| !arm_generate_debug_exceptions(env)) {
return false;
}
/*
* Single-step exceptions have priority over breakpoint exceptions.
* If single-step state is active-pending, suppress the bp.
*/
if (arm_singlestep_active(env) && !(env->pstate & PSTATE_SS)) {
return false;
}
/*
* PC alignment faults have priority over breakpoint exceptions.
*/
pc = is_a64(env) ? env->pc : env->regs[15];
if ((is_a64(env) || !env->thumb) && (pc & 3) != 0) {
return false;
}
/*
* Instruction aborts have priority over breakpoint exceptions.
* TODO: We would need to look up the page for PC and verify that
* it is present and executable.
*/
for (n = 0; n < ARRAY_SIZE(env->cpu_breakpoint); n++) {
if (bp_wp_matches(cpu, n, false)) {
return true;
}
}
return false;
}
bool arm_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp)
{
/*
* Called by core code when a CPU watchpoint fires; need to check if this
* is also an architectural watchpoint match.
*/
ARMCPU *cpu = ARM_CPU(cs);
return check_watchpoints(cpu);
}
/*
* Return the FSR value for a debug exception (watchpoint, hardware
* breakpoint or BKPT insn) targeting the specified exception level.
*/
static uint32_t arm_debug_exception_fsr(CPUARMState *env)
{
ARMMMUFaultInfo fi = { .type = ARMFault_Debug };
int target_el = arm_debug_target_el(env);
bool using_lpae = false;
if (target_el == 2 || arm_el_is_aa64(env, target_el)) {
using_lpae = true;
} else {
if (arm_feature(env, ARM_FEATURE_LPAE) &&
(env->cp15.tcr_el[target_el].raw_tcr & TTBCR_EAE)) {
using_lpae = true;
}
}
if (using_lpae) {
return arm_fi_to_lfsc(&fi);
} else {
return arm_fi_to_sfsc(&fi);
}
}
void arm_debug_excp_handler(CPUState *cs)
{
/*
* Called by core code when a watchpoint or breakpoint fires;
* need to check which one and raise the appropriate exception.
*/
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
CPUWatchpoint *wp_hit = cs->watchpoint_hit;
if (wp_hit) {
if (wp_hit->flags & BP_CPU) {
bool wnr = (wp_hit->flags & BP_WATCHPOINT_HIT_WRITE) != 0;
cs->watchpoint_hit = NULL;
env->exception.fsr = arm_debug_exception_fsr(env);
env->exception.vaddress = wp_hit->hitaddr;
raise_exception_debug(env, EXCP_DATA_ABORT,
syn_watchpoint(0, 0, wnr));
}
} else {
uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
/*
* (1) GDB breakpoints should be handled first.
* (2) Do not raise a CPU exception if no CPU breakpoint has fired,
* since singlestep is also done by generating a debug internal
* exception.
*/
if (cpu_breakpoint_test(cs, pc, BP_GDB)
|| !cpu_breakpoint_test(cs, pc, BP_CPU)) {
return;
}
env->exception.fsr = arm_debug_exception_fsr(env);
/*
* FAR is UNKNOWN: clear vaddress to avoid potentially exposing
* values to the guest that it shouldn't be able to see at its
* exception/security level.
*/
env->exception.vaddress = 0;
raise_exception_debug(env, EXCP_PREFETCH_ABORT, syn_breakpoint(0));
}
}
/*
* Raise an EXCP_BKPT with the specified syndrome register value,
* targeting the correct exception level for debug exceptions.
*/
void HELPER(exception_bkpt_insn)(CPUARMState *env, uint32_t syndrome)
{
int debug_el = arm_debug_target_el(env);
int cur_el = arm_current_el(env);
/* FSR will only be used if the debug target EL is AArch32. */
env->exception.fsr = arm_debug_exception_fsr(env);
/*
* FAR is UNKNOWN: clear vaddress to avoid potentially exposing
* values to the guest that it shouldn't be able to see at its
* exception/security level.
*/
env->exception.vaddress = 0;
/*
* Other kinds of architectural debug exception are ignored if
* they target an exception level below the current one (in QEMU
* this is checked by arm_generate_debug_exceptions()). Breakpoint
* instructions are special because they always generate an exception
* to somewhere: if they can't go to the configured debug exception
* level they are taken to the current exception level.
*/
if (debug_el < cur_el) {
debug_el = cur_el;
}
raise_exception(env, EXCP_BKPT, syndrome, debug_el);
}
void HELPER(exception_swstep)(CPUARMState *env, uint32_t syndrome)
{
raise_exception_debug(env, EXCP_UDEF, syndrome);
}
/*
* Check for traps to "powerdown debug" registers, which are controlled
* by MDCR.TDOSA
*/
static CPAccessResult access_tdosa(CPUARMState *env, const ARMCPRegInfo *ri,
bool isread)
{
int el = arm_current_el(env);
uint64_t mdcr_el2 = arm_mdcr_el2_eff(env);
bool mdcr_el2_tdosa = (mdcr_el2 & MDCR_TDOSA) || (mdcr_el2 & MDCR_TDE) ||
(arm_hcr_el2_eff(env) & HCR_TGE);
if (el < 2 && mdcr_el2_tdosa) {
return CP_ACCESS_TRAP_EL2;
}
if (el < 3 && (env->cp15.mdcr_el3 & MDCR_TDOSA)) {
return CP_ACCESS_TRAP_EL3;
}
return CP_ACCESS_OK;
}
/*
* Check for traps to "debug ROM" registers, which are controlled
* by MDCR_EL2.TDRA for EL2 but by the more general MDCR_EL3.TDA for EL3.
*/
static CPAccessResult access_tdra(CPUARMState *env, const ARMCPRegInfo *ri,
bool isread)
{
int el = arm_current_el(env);
uint64_t mdcr_el2 = arm_mdcr_el2_eff(env);
bool mdcr_el2_tdra = (mdcr_el2 & MDCR_TDRA) || (mdcr_el2 & MDCR_TDE) ||
(arm_hcr_el2_eff(env) & HCR_TGE);
if (el < 2 && mdcr_el2_tdra) {
return CP_ACCESS_TRAP_EL2;
}
if (el < 3 && (env->cp15.mdcr_el3 & MDCR_TDA)) {
return CP_ACCESS_TRAP_EL3;
}
return CP_ACCESS_OK;
}
/*
* Check for traps to general debug registers, which are controlled
* by MDCR_EL2.TDA for EL2 and MDCR_EL3.TDA for EL3.
*/
static CPAccessResult access_tda(CPUARMState *env, const ARMCPRegInfo *ri,
bool isread)
{
int el = arm_current_el(env);
uint64_t mdcr_el2 = arm_mdcr_el2_eff(env);
bool mdcr_el2_tda = (mdcr_el2 & MDCR_TDA) || (mdcr_el2 & MDCR_TDE) ||
(arm_hcr_el2_eff(env) & HCR_TGE);
if (el < 2 && mdcr_el2_tda) {
return CP_ACCESS_TRAP_EL2;
}
if (el < 3 && (env->cp15.mdcr_el3 & MDCR_TDA)) {
return CP_ACCESS_TRAP_EL3;
}
return CP_ACCESS_OK;
}
static void oslar_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
{
/*
* Writes to OSLAR_EL1 may update the OS lock status, which can be
* read via a bit in OSLSR_EL1.
*/
int oslock;
if (ri->state == ARM_CP_STATE_AA32) {
oslock = (value == 0xC5ACCE55);
} else {
oslock = value & 1;
}
env->cp15.oslsr_el1 = deposit32(env->cp15.oslsr_el1, 1, 1, oslock);
}
static void osdlr_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
{
ARMCPU *cpu = env_archcpu(env);
/*
* Only defined bit is bit 0 (DLK); if Feat_DoubleLock is not
* implemented this is RAZ/WI.
*/
if(arm_feature(env, ARM_FEATURE_AARCH64)
? cpu_isar_feature(aa64_doublelock, cpu)
: cpu_isar_feature(aa32_doublelock, cpu)) {
env->cp15.osdlr_el1 = value & 1;
}
}
static const ARMCPRegInfo debug_cp_reginfo[] = {
/*
* DBGDRAR, DBGDSAR: always RAZ since we don't implement memory mapped
* debug components. The AArch64 version of DBGDRAR is named MDRAR_EL1;
* unlike DBGDRAR it is never accessible from EL0.
* DBGDSAR is deprecated and must RAZ from v8 anyway, so it has no AArch64
* accessor.
*/
{ .name = "DBGDRAR", .cp = 14, .crn = 1, .crm = 0, .opc1 = 0, .opc2 = 0,
.access = PL0_R, .accessfn = access_tdra,
.type = ARM_CP_CONST, .resetvalue = 0 },
{ .name = "MDRAR_EL1", .state = ARM_CP_STATE_AA64,
.opc0 = 2, .opc1 = 0, .crn = 1, .crm = 0, .opc2 = 0,
.access = PL1_R, .accessfn = access_tdra,
.type = ARM_CP_CONST, .resetvalue = 0 },
{ .name = "DBGDSAR", .cp = 14, .crn = 2, .crm = 0, .opc1 = 0, .opc2 = 0,
.access = PL0_R, .accessfn = access_tdra,
.type = ARM_CP_CONST, .resetvalue = 0 },
/* Monitor debug system control register; the 32-bit alias is DBGDSCRext. */
{ .name = "MDSCR_EL1", .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = 2, .opc2 = 2,
.access = PL1_RW, .accessfn = access_tda,
.fieldoffset = offsetof(CPUARMState, cp15.mdscr_el1),
.resetvalue = 0 },
/*
* MDCCSR_EL0[30:29] map to EDSCR[30:29]. Simply RAZ as the external
* Debug Communication Channel is not implemented.
*/
{ .name = "MDCCSR_EL0", .state = ARM_CP_STATE_AA64,
.opc0 = 2, .opc1 = 3, .crn = 0, .crm = 1, .opc2 = 0,
.access = PL0_R, .accessfn = access_tda,
.type = ARM_CP_CONST, .resetvalue = 0 },
/*
* DBGDSCRint[15,12,5:2] map to MDSCR_EL1[15,12,5:2]. Map all bits as
* it is unlikely a guest will care.
* We don't implement the configurable EL0 access.
*/
{ .name = "DBGDSCRint", .state = ARM_CP_STATE_AA32,
.cp = 14, .opc1 = 0, .crn = 0, .crm = 1, .opc2 = 0,
.type = ARM_CP_ALIAS,
.access = PL1_R, .accessfn = access_tda,
.fieldoffset = offsetof(CPUARMState, cp15.mdscr_el1), },
{ .name = "OSLAR_EL1", .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 1, .crm = 0, .opc2 = 4,
.access = PL1_W, .type = ARM_CP_NO_RAW,
.accessfn = access_tdosa,
.writefn = oslar_write },
{ .name = "OSLSR_EL1", .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 1, .crm = 1, .opc2 = 4,
.access = PL1_R, .resetvalue = 10,
.accessfn = access_tdosa,
.fieldoffset = offsetof(CPUARMState, cp15.oslsr_el1) },
/* Dummy OSDLR_EL1: 32-bit Linux will read this */
{ .name = "OSDLR_EL1", .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 1, .crm = 3, .opc2 = 4,
.access = PL1_RW, .accessfn = access_tdosa,
.writefn = osdlr_write,
.fieldoffset = offsetof(CPUARMState, cp15.osdlr_el1) },
/*
* Dummy DBGVCR: Linux wants to clear this on startup, but we don't
* implement vector catch debug events yet.
*/
{ .name = "DBGVCR",
.cp = 14, .opc1 = 0, .crn = 0, .crm = 7, .opc2 = 0,
.access = PL1_RW, .accessfn = access_tda,
.type = ARM_CP_NOP },
/*
* Dummy DBGVCR32_EL2 (which is only for a 64-bit hypervisor
* to save and restore a 32-bit guest's DBGVCR)
*/
{ .name = "DBGVCR32_EL2", .state = ARM_CP_STATE_AA64,
.opc0 = 2, .opc1 = 4, .crn = 0, .crm = 7, .opc2 = 0,
.access = PL2_RW, .accessfn = access_tda,
.type = ARM_CP_NOP | ARM_CP_EL3_NO_EL2_KEEP },
/*
* Dummy MDCCINT_EL1, since we don't implement the Debug Communications
* Channel but Linux may try to access this register. The 32-bit
* alias is DBGDCCINT.
*/
{ .name = "MDCCINT_EL1", .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = 2, .opc2 = 0,
.access = PL1_RW, .accessfn = access_tda,
.type = ARM_CP_NOP },
};
static const ARMCPRegInfo debug_lpae_cp_reginfo[] = {
/* 64 bit access versions of the (dummy) debug registers */
{ .name = "DBGDRAR", .cp = 14, .crm = 1, .opc1 = 0,
.access = PL0_R, .type = ARM_CP_CONST | ARM_CP_64BIT, .resetvalue = 0 },
{ .name = "DBGDSAR", .cp = 14, .crm = 2, .opc1 = 0,
.access = PL0_R, .type = ARM_CP_CONST | ARM_CP_64BIT, .resetvalue = 0 },
};
void hw_watchpoint_update(ARMCPU *cpu, int n)
{
CPUARMState *env = &cpu->env;
vaddr len = 0;
vaddr wvr = env->cp15.dbgwvr[n];
uint64_t wcr = env->cp15.dbgwcr[n];
int mask;
int flags = BP_CPU | BP_STOP_BEFORE_ACCESS;
if (env->cpu_watchpoint[n]) {
cpu_watchpoint_remove_by_ref(CPU(cpu), env->cpu_watchpoint[n]);
env->cpu_watchpoint[n] = NULL;
}
if (!FIELD_EX64(wcr, DBGWCR, E)) {
/* E bit clear : watchpoint disabled */
return;
}
switch (FIELD_EX64(wcr, DBGWCR, LSC)) {
case 0:
/* LSC 00 is reserved and must behave as if the wp is disabled */
return;
case 1:
flags |= BP_MEM_READ;
break;
case 2:
flags |= BP_MEM_WRITE;
break;
case 3:
flags |= BP_MEM_ACCESS;
break;
}
/*
* Attempts to use both MASK and BAS fields simultaneously are
* CONSTRAINED UNPREDICTABLE; we opt to ignore BAS in this case,
* thus generating a watchpoint for every byte in the masked region.
*/
mask = FIELD_EX64(wcr, DBGWCR, MASK);
if (mask == 1 || mask == 2) {
/*
* Reserved values of MASK; we must act as if the mask value was
* some non-reserved value, or as if the watchpoint were disabled.
* We choose the latter.
*/
return;
} else if (mask) {
/* Watchpoint covers an aligned area up to 2GB in size */
len = 1ULL << mask;
/*
* If masked bits in WVR are not zero it's CONSTRAINED UNPREDICTABLE
* whether the watchpoint fires when the unmasked bits match; we opt
* to generate the exceptions.
*/
wvr &= ~(len - 1);
} else {
/* Watchpoint covers bytes defined by the byte address select bits */
int bas = FIELD_EX64(wcr, DBGWCR, BAS);
int basstart;
if (extract64(wvr, 2, 1)) {
/*
* Deprecated case of an only 4-aligned address. BAS[7:4] are
* ignored, and BAS[3:0] define which bytes to watch.
*/
bas &= 0xf;
}
if (bas == 0) {
/* This must act as if the watchpoint is disabled */
return;
}
/*
* The BAS bits are supposed to be programmed to indicate a contiguous
* range of bytes. Otherwise it is CONSTRAINED UNPREDICTABLE whether
* we fire for each byte in the word/doubleword addressed by the WVR.
* We choose to ignore any non-zero bits after the first range of 1s.
*/
basstart = ctz32(bas);
len = cto32(bas >> basstart);
wvr += basstart;
}
cpu_watchpoint_insert(CPU(cpu), wvr, len, flags,
&env->cpu_watchpoint[n]);
}
void hw_watchpoint_update_all(ARMCPU *cpu)
{
int i;
CPUARMState *env = &cpu->env;
/*
* Completely clear out existing QEMU watchpoints and our array, to
* avoid possible stale entries following migration load.
*/
cpu_watchpoint_remove_all(CPU(cpu), BP_CPU);
memset(env->cpu_watchpoint, 0, sizeof(env->cpu_watchpoint));
for (i = 0; i < ARRAY_SIZE(cpu->env.cpu_watchpoint); i++) {
hw_watchpoint_update(cpu, i);
}
}
static void dbgwvr_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
{
ARMCPU *cpu = env_archcpu(env);
int i = ri->crm;
/*
* Bits [1:0] are RES0.
*
* It is IMPLEMENTATION DEFINED whether [63:49] ([63:53] with FEAT_LVA)
* are hardwired to the value of bit [48] ([52] with FEAT_LVA), or if
* they contain the value written. It is CONSTRAINED UNPREDICTABLE
* whether the RESS bits are ignored when comparing an address.
*
* Therefore we are allowed to compare the entire register, which lets
* us avoid considering whether or not FEAT_LVA is actually enabled.
*/
value &= ~3ULL;
raw_write(env, ri, value);
hw_watchpoint_update(cpu, i);
}
static void dbgwcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
{
ARMCPU *cpu = env_archcpu(env);
int i = ri->crm;
raw_write(env, ri, value);
hw_watchpoint_update(cpu, i);
}
void hw_breakpoint_update(ARMCPU *cpu, int n)
{
CPUARMState *env = &cpu->env;
uint64_t bvr = env->cp15.dbgbvr[n];
uint64_t bcr = env->cp15.dbgbcr[n];
vaddr addr;
int bt;
int flags = BP_CPU;
if (env->cpu_breakpoint[n]) {
cpu_breakpoint_remove_by_ref(CPU(cpu), env->cpu_breakpoint[n]);
env->cpu_breakpoint[n] = NULL;
}
if (!extract64(bcr, 0, 1)) {
/* E bit clear : watchpoint disabled */
return;
}
bt = extract64(bcr, 20, 4);
switch (bt) {
case 4: /* unlinked address mismatch (reserved if AArch64) */
case 5: /* linked address mismatch (reserved if AArch64) */
qemu_log_mask(LOG_UNIMP,
"arm: address mismatch breakpoint types not implemented\n");
return;
case 0: /* unlinked address match */
case 1: /* linked address match */
{
/*
* Bits [1:0] are RES0.
*
* It is IMPLEMENTATION DEFINED whether bits [63:49]
* ([63:53] for FEAT_LVA) are hardwired to a copy of the sign bit
* of the VA field ([48] or [52] for FEAT_LVA), or whether the
* value is read as written. It is CONSTRAINED UNPREDICTABLE
* whether the RESS bits are ignored when comparing an address.
* Therefore we are allowed to compare the entire register, which
* lets us avoid considering whether FEAT_LVA is actually enabled.
*
* The BAS field is used to allow setting breakpoints on 16-bit
* wide instructions; it is CONSTRAINED UNPREDICTABLE whether
* a bp will fire if the addresses covered by the bp and the addresses
* covered by the insn overlap but the insn doesn't start at the
* start of the bp address range. We choose to require the insn and
* the bp to have the same address. The constraints on writing to
* BAS enforced in dbgbcr_write mean we have only four cases:
* 0b0000 => no breakpoint
* 0b0011 => breakpoint on addr
* 0b1100 => breakpoint on addr + 2
* 0b1111 => breakpoint on addr
* See also figure D2-3 in the v8 ARM ARM (DDI0487A.c).
*/
int bas = extract64(bcr, 5, 4);
addr = bvr & ~3ULL;
if (bas == 0) {
return;
}
if (bas == 0xc) {
addr += 2;
}
break;
}
case 2: /* unlinked context ID match */
case 8: /* unlinked VMID match (reserved if no EL2) */
case 10: /* unlinked context ID and VMID match (reserved if no EL2) */
qemu_log_mask(LOG_UNIMP,
"arm: unlinked context breakpoint types not implemented\n");
return;
case 9: /* linked VMID match (reserved if no EL2) */
case 11: /* linked context ID and VMID match (reserved if no EL2) */
case 3: /* linked context ID match */
default:
/*
* We must generate no events for Linked context matches (unless
* they are linked to by some other bp/wp, which is handled in
* updates for the linking bp/wp). We choose to also generate no events
* for reserved values.
*/
return;
}
cpu_breakpoint_insert(CPU(cpu), addr, flags, &env->cpu_breakpoint[n]);
}
void hw_breakpoint_update_all(ARMCPU *cpu)
{
int i;
CPUARMState *env = &cpu->env;
/*
* Completely clear out existing QEMU breakpoints and our array, to
* avoid possible stale entries following migration load.
*/
cpu_breakpoint_remove_all(CPU(cpu), BP_CPU);
memset(env->cpu_breakpoint, 0, sizeof(env->cpu_breakpoint));
for (i = 0; i < ARRAY_SIZE(cpu->env.cpu_breakpoint); i++) {
hw_breakpoint_update(cpu, i);
}
}
static void dbgbvr_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
{
ARMCPU *cpu = env_archcpu(env);
int i = ri->crm;
raw_write(env, ri, value);
hw_breakpoint_update(cpu, i);
}
static void dbgbcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
{
ARMCPU *cpu = env_archcpu(env);
int i = ri->crm;
/*
* BAS[3] is a read-only copy of BAS[2], and BAS[1] a read-only
* copy of BAS[0].
*/
value = deposit64(value, 6, 1, extract64(value, 5, 1));
value = deposit64(value, 8, 1, extract64(value, 7, 1));
raw_write(env, ri, value);
hw_breakpoint_update(cpu, i);
}
void define_debug_regs(ARMCPU *cpu)
{
/*
* Define v7 and v8 architectural debug registers.
* These are just dummy implementations for now.
*/
int i;
int wrps, brps, ctx_cmps;
/*
* The Arm ARM says DBGDIDR is optional and deprecated if EL1 cannot
* use AArch32. Given that bit 15 is RES1, if the value is 0 then
* the register must not exist for this cpu.
*/
if (cpu->isar.dbgdidr != 0) {
ARMCPRegInfo dbgdidr = {
.name = "DBGDIDR", .cp = 14, .crn = 0, .crm = 0,
.opc1 = 0, .opc2 = 0,
.access = PL0_R, .accessfn = access_tda,
.type = ARM_CP_CONST, .resetvalue = cpu->isar.dbgdidr,
};
define_one_arm_cp_reg(cpu, &dbgdidr);
}
/*
* DBGDEVID is present in the v7 debug architecture if
* DBGDIDR.DEVID_imp is 1 (bit 15); from v7.1 and on it is
* mandatory (and bit 15 is RES1). DBGDEVID1 and DBGDEVID2 exist
* from v7.1 of the debug architecture. Because no fields have yet
* been defined in DBGDEVID2 (and quite possibly none will ever
* be) we don't define an ARMISARegisters field for it.
* These registers exist only if EL1 can use AArch32, but that
* happens naturally because they are only PL1 accessible anyway.
*/
if (extract32(cpu->isar.dbgdidr, 15, 1)) {
ARMCPRegInfo dbgdevid = {
.name = "DBGDEVID",
.cp = 14, .opc1 = 0, .crn = 7, .opc2 = 2, .crn = 7,
.access = PL1_R, .accessfn = access_tda,
.type = ARM_CP_CONST, .resetvalue = cpu->isar.dbgdevid,
};
define_one_arm_cp_reg(cpu, &dbgdevid);
}
if (cpu_isar_feature(aa32_debugv7p1, cpu)) {
ARMCPRegInfo dbgdevid12[] = {
{
.name = "DBGDEVID1",
.cp = 14, .opc1 = 0, .crn = 7, .opc2 = 1, .crn = 7,
.access = PL1_R, .accessfn = access_tda,
.type = ARM_CP_CONST, .resetvalue = cpu->isar.dbgdevid1,
}, {
.name = "DBGDEVID2",
.cp = 14, .opc1 = 0, .crn = 7, .opc2 = 0, .crn = 7,
.access = PL1_R, .accessfn = access_tda,
.type = ARM_CP_CONST, .resetvalue = 0,
},
};
define_arm_cp_regs(cpu, dbgdevid12);
}
brps = arm_num_brps(cpu);
wrps = arm_num_wrps(cpu);
ctx_cmps = arm_num_ctx_cmps(cpu);
assert(ctx_cmps <= brps);
define_arm_cp_regs(cpu, debug_cp_reginfo);
if (arm_feature(&cpu->env, ARM_FEATURE_LPAE)) {
define_arm_cp_regs(cpu, debug_lpae_cp_reginfo);
}
for (i = 0; i < brps; i++) {
char *dbgbvr_el1_name = g_strdup_printf("DBGBVR%d_EL1", i);
char *dbgbcr_el1_name = g_strdup_printf("DBGBCR%d_EL1", i);
ARMCPRegInfo dbgregs[] = {
{ .name = dbgbvr_el1_name, .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = i, .opc2 = 4,
.access = PL1_RW, .accessfn = access_tda,
.fieldoffset = offsetof(CPUARMState, cp15.dbgbvr[i]),
.writefn = dbgbvr_write, .raw_writefn = raw_write
},
{ .name = dbgbcr_el1_name, .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = i, .opc2 = 5,
.access = PL1_RW, .accessfn = access_tda,
.fieldoffset = offsetof(CPUARMState, cp15.dbgbcr[i]),
.writefn = dbgbcr_write, .raw_writefn = raw_write
},
};
define_arm_cp_regs(cpu, dbgregs);
g_free(dbgbvr_el1_name);
g_free(dbgbcr_el1_name);
}
for (i = 0; i < wrps; i++) {
char *dbgwvr_el1_name = g_strdup_printf("DBGWVR%d_EL1", i);
char *dbgwcr_el1_name = g_strdup_printf("DBGWCR%d_EL1", i);
ARMCPRegInfo dbgregs[] = {
{ .name = dbgwvr_el1_name, .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = i, .opc2 = 6,
.access = PL1_RW, .accessfn = access_tda,
.fieldoffset = offsetof(CPUARMState, cp15.dbgwvr[i]),
.writefn = dbgwvr_write, .raw_writefn = raw_write
},
{ .name = dbgwcr_el1_name, .state = ARM_CP_STATE_BOTH,
.cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = i, .opc2 = 7,
.access = PL1_RW, .accessfn = access_tda,
.fieldoffset = offsetof(CPUARMState, cp15.dbgwcr[i]),
.writefn = dbgwcr_write, .raw_writefn = raw_write
},
};
define_arm_cp_regs(cpu, dbgregs);
g_free(dbgwvr_el1_name);
g_free(dbgwcr_el1_name);
}
}
#if !defined(CONFIG_USER_ONLY)
vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
/*
* In BE32 system mode, target memory is stored byteswapped (on a
* little-endian host system), and by the time we reach here (via an
* opcode helper) the addresses of subword accesses have been adjusted
* to account for that, which means that watchpoints will not match.
* Undo the adjustment here.
*/
if (arm_sctlr_b(env)) {
if (len == 1) {
addr ^= 3;
} else if (len == 2) {
addr ^= 2;
}
}
return addr;
}
#endif
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