diff options
| -rw-r--r-- | target-arm/op_helper.c | 80 |
1 files changed, 59 insertions, 21 deletions
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c index 7b6b3fd97c..b9f51e0822 100644 --- a/target-arm/op_helper.c +++ b/target-arm/op_helper.c @@ -641,12 +641,51 @@ void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome) } } +static int el_from_spsr(uint32_t spsr) +{ + /* Return the exception level that this SPSR is requesting a return to, + * or -1 if it is invalid (an illegal return) + */ + if (spsr & PSTATE_nRW) { + switch (spsr & CPSR_M) { + case ARM_CPU_MODE_USR: + return 0; + case ARM_CPU_MODE_HYP: + return 2; + case ARM_CPU_MODE_FIQ: + case ARM_CPU_MODE_IRQ: + case ARM_CPU_MODE_SVC: + case ARM_CPU_MODE_ABT: + case ARM_CPU_MODE_UND: + case ARM_CPU_MODE_SYS: + return 1; + case ARM_CPU_MODE_MON: + /* Returning to Mon from AArch64 is never possible, + * so this is an illegal return. + */ + default: + return -1; + } + } else { + if (extract32(spsr, 1, 1)) { + /* Return with reserved M[1] bit set */ + return -1; + } + if (extract32(spsr, 0, 4) == 1) { + /* return to EL0 with M[0] bit set */ + return -1; + } + return extract32(spsr, 2, 2); + } +} + void HELPER(exception_return)(CPUARMState *env) { int cur_el = arm_current_el(env); unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el); uint32_t spsr = env->banked_spsr[spsr_idx]; int new_el; + bool return_to_aa64 = (spsr & PSTATE_nRW) == 0; aarch64_save_sp(env, cur_el); @@ -663,35 +702,34 @@ void HELPER(exception_return)(CPUARMState *env) spsr &= ~PSTATE_SS; } - if (spsr & PSTATE_nRW) { - /* TODO: We currently assume EL1/2/3 are running in AArch64. */ + new_el = el_from_spsr(spsr); + if (new_el == -1) { + goto illegal_return; + } + if (new_el > cur_el + || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) { + /* Disallow return to an EL which is unimplemented or higher + * than the current one. + */ + goto illegal_return; + } + + if (new_el != 0 && arm_el_is_aa64(env, new_el) != return_to_aa64) { + /* Return to an EL which is configured for a different register width */ + goto illegal_return; + } + + if (!return_to_aa64) { env->aarch64 = 0; - new_el = 0; - env->uncached_cpsr = 0x10; + env->uncached_cpsr = spsr & CPSR_M; cpsr_write(env, spsr, ~0); if (!arm_singlestep_active(env)) { env->uncached_cpsr &= ~PSTATE_SS; } aarch64_sync_64_to_32(env); - env->regs[15] = env->elr_el[1] & ~0x1; + env->regs[15] = env->elr_el[cur_el] & ~0x1; } else { - new_el = extract32(spsr, 2, 2); - if (new_el > cur_el - || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) { - /* Disallow return to an EL which is unimplemented or higher - * than the current one. - */ - goto illegal_return; - } - if (extract32(spsr, 1, 1)) { - /* Return with reserved M[1] bit set */ - goto illegal_return; - } - if (new_el == 0 && (spsr & PSTATE_SP)) { - /* Return to EL0 with M[0] bit set */ - goto illegal_return; - } env->aarch64 = 1; pstate_write(env, spsr); if (!arm_singlestep_active(env)) { |