diff options
Diffstat (limited to 'target/arm/tcg/op_helper.c')
| -rw-r--r-- | target/arm/tcg/op_helper.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/target/arm/tcg/op_helper.c b/target/arm/tcg/op_helper.c index c199b69fbf..c083e5cfb8 100644 --- a/target/arm/tcg/op_helper.c +++ b/target/arm/tcg/op_helper.c @@ -409,6 +409,60 @@ void HELPER(wfi)(CPUARMState *env, uint32_t insn_len) #endif } +void HELPER(wfit)(CPUARMState *env, uint64_t timeout) +{ +#ifdef CONFIG_USER_ONLY + /* + * WFI in the user-mode emulator is technically permitted but not + * something any real-world code would do. AArch64 Linux kernels + * trap it via SCTRL_EL1.nTWI and make it an (expensive) NOP; + * AArch32 kernels don't trap it so it will delay a bit. + * For QEMU, make it NOP here, because trying to raise EXCP_HLT + * would trigger an abort. + */ + return; +#else + ARMCPU *cpu = env_archcpu(env); + CPUState *cs = env_cpu(env); + int target_el = check_wfx_trap(env, false); + /* The WFIT should time out when CNTVCT_EL0 >= the specified value. */ + uint64_t cntval = gt_get_countervalue(env); + uint64_t offset = gt_virt_cnt_offset(env); + uint64_t cntvct = cntval - offset; + uint64_t nexttick; + + if (cpu_has_work(cs) || cntvct >= timeout) { + /* + * Don't bother to go into our "low power state" if + * we would just wake up immediately. + */ + return; + } + + if (target_el) { + env->pc -= 4; + raise_exception(env, EXCP_UDEF, syn_wfx(1, 0xe, 0, false), + target_el); + } + + if (uadd64_overflow(timeout, offset, &nexttick)) { + nexttick = UINT64_MAX; + } + if (nexttick > INT64_MAX / gt_cntfrq_period_ns(cpu)) { + /* + * If the timeout is too long for the signed 64-bit range + * of a QEMUTimer, let it expire early. + */ + timer_mod_ns(cpu->wfxt_timer, INT64_MAX); + } else { + timer_mod(cpu->wfxt_timer, nexttick); + } + cs->exception_index = EXCP_HLT; + cs->halted = 1; + cpu_loop_exit(cs); +#endif +} + void HELPER(wfe)(CPUARMState *env) { /* This is a hint instruction that is semantically different |