diff options
| -rw-r--r-- | target-arm/cpu.h | 61 | ||||
| -rw-r--r-- | target-arm/op_helper.c | 20 |
2 files changed, 81 insertions, 0 deletions
diff --git a/target-arm/cpu.h b/target-arm/cpu.h index 8380c136e2..74f7b1569f 100644 --- a/target-arm/cpu.h +++ b/target-arm/cpu.h @@ -220,6 +220,7 @@ typedef struct CPUARMState { uint64_t dbgbcr[16]; /* breakpoint control registers */ uint64_t dbgwvr[16]; /* watchpoint value registers */ uint64_t dbgwcr[16]; /* watchpoint control registers */ + uint64_t mdscr_el1; /* If the counter is enabled, this stores the last time the counter * was reset. Otherwise it stores the counter value */ @@ -1119,6 +1120,66 @@ static inline int cpu_mmu_index (CPUARMState *env) return arm_current_pl(env); } +/* Return the Exception Level targeted by debug exceptions; + * currently always EL1 since we don't implement EL2 or EL3. + */ +static inline int arm_debug_target_el(CPUARMState *env) +{ + return 1; +} + +static inline bool aa64_generate_debug_exceptions(CPUARMState *env) +{ + if (arm_current_pl(env) == arm_debug_target_el(env)) { + if ((extract32(env->cp15.mdscr_el1, 13, 1) == 0) + || (env->daif & PSTATE_D)) { + return false; + } + } + return true; +} + +static inline bool aa32_generate_debug_exceptions(CPUARMState *env) +{ + if (arm_current_pl(env) == 0 && arm_el_is_aa64(env, 1)) { + return aa64_generate_debug_exceptions(env); + } + return arm_current_pl(env) != 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. + * + * Parts of the pseudocode relating to EL2 and EL3 are omitted because we + * don't yet implement those exception levels or their associated trap bits. + */ +static inline bool arm_generate_debug_exceptions(CPUARMState *env) +{ + if (env->aarch64) { + 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.) + */ +static inline 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); +} + #include "exec/cpu-all.h" /* Bit usage in the TB flags field: bit 31 indicates whether we are diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c index 180a4a096b..62cc07d448 100644 --- a/target-arm/op_helper.c +++ b/target-arm/op_helper.c @@ -380,12 +380,26 @@ void HELPER(exception_return)(CPUARMState *env) env->exclusive_addr = -1; + /* We must squash the PSTATE.SS bit to zero unless both of the + * following hold: + * 1. debug exceptions are currently disabled + * 2. singlestep will be active in the EL we return to + * We check 1 here and 2 after we've done the pstate/cpsr write() to + * transition to the EL we're going to. + */ + if (arm_generate_debug_exceptions(env)) { + spsr &= ~PSTATE_SS; + } + if (spsr & PSTATE_nRW) { /* TODO: We currently assume EL1/2/3 are running in AArch64. */ env->aarch64 = 0; new_el = 0; env->uncached_cpsr = 0x10; cpsr_write(env, spsr, ~0); + if (!arm_singlestep_active(env)) { + env->uncached_cpsr &= ~PSTATE_SS; + } for (i = 0; i < 15; i++) { env->regs[i] = env->xregs[i]; } @@ -410,6 +424,9 @@ void HELPER(exception_return)(CPUARMState *env) } env->aarch64 = 1; pstate_write(env, spsr); + if (!arm_singlestep_active(env)) { + env->pstate &= ~PSTATE_SS; + } aarch64_restore_sp(env, new_el); env->pc = env->elr_el[cur_el]; } @@ -429,6 +446,9 @@ illegal_return: spsr &= PSTATE_NZCV | PSTATE_DAIF; spsr |= pstate_read(env) & ~(PSTATE_NZCV | PSTATE_DAIF); pstate_write(env, spsr); + if (!arm_singlestep_active(env)) { + env->pstate &= ~PSTATE_SS; + } } /* ??? Flag setting arithmetic is awkward because we need to do comparisons. |