| /* |
| * 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 "cpu.h" |
| #include "internals.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 (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); |
| } |
| |
| #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 |
