target/arm/debug_helper.c - qemu - Git at Google

 /*
  * 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 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 = extract64(cr, 1, 2);
     hmc = extract64(cr, 13, 1);
     ssc = extract64(cr, 14, 2);

     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 = extract64(cr, 20, 1);
     lbn = extract64(cr, 16, 4);

     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;
     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;
     }

     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);
 }

 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;
             bool same_el = arm_debug_target_el(env) == arm_current_el(env);

             cs->watchpoint_hit = NULL;

             env->exception.fsr = arm_debug_exception_fsr(env);
             env->exception.vaddress = wp_hit->hitaddr;
             raise_exception(env, EXCP_DATA_ABORT,
                     syn_watchpoint(same_el, 0, wnr),
                     arm_debug_target_el(env));
         }
     } else {
         uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
         bool same_el = (arm_debug_target_el(env) == arm_current_el(env));

         /*
          * (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(env, EXCP_PREFETCH_ABORT,
                         syn_breakpoint(same_el),
                         arm_debug_target_el(env));
     }
 }

 #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
	/*
	* 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 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 = extract64(cr, 1, 2);
	hmc = extract64(cr, 13, 1);
	ssc = extract64(cr, 14, 2);

	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 = extract64(cr, 20, 1);
	lbn = extract64(cr, 16, 4);

	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;
	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;
	}

	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);
	}

	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;
	bool same_el = arm_debug_target_el(env) == arm_current_el(env);

	cs->watchpoint_hit = NULL;

	env->exception.fsr = arm_debug_exception_fsr(env);
	env->exception.vaddress = wp_hit->hitaddr;
	raise_exception(env, EXCP_DATA_ABORT,
	syn_watchpoint(same_el, 0, wnr),
	arm_debug_target_el(env));
	}
	} else {
	uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
	bool same_el = (arm_debug_target_el(env) == arm_current_el(env));

	/*
	* (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(env, EXCP_PREFETCH_ABORT,
	syn_breakpoint(same_el),
	arm_debug_target_el(env));
	}
	}

	#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