// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2025 Google LLC * Author: Vincent Donnefort <vdonnefort@google.com> */ #include <nvhe/clock.h> #include <asm/arch_timer.h> #include <asm/div64.h> static struct clock_data { struct { u32 mult; u32 shift; u64 epoch_ns; u64 epoch_cyc; u64 cyc_overflow64; } data[2]; u64 cur; } trace_clock_data; static u64 __clock_mult_uint128(u64 cyc, u32 mult, u32 shift) { __uint128_t ns = (__uint128_t)cyc * mult; ns >>= shift; return (u64)ns; } /* Does not guarantee no reader on the modified bank. */ void trace_clock_update(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc) { struct clock_data *clock = &trace_clock_data; u64 bank = clock->cur ^ 1; if (!mult || shift >= 64) return; clock->data[bank].mult = mult; clock->data[bank].shift = shift; clock->data[bank].epoch_ns = epoch_ns; clock->data[bank].epoch_cyc = epoch_cyc; clock->data[bank].cyc_overflow64 = ULONG_MAX / mult; smp_store_release(&clock->cur, bank); } /* Use untrusted host data */ u64 trace_clock(void) { struct clock_data *clock = &trace_clock_data; u64 bank = smp_load_acquire(&clock->cur); u64 cyc, ns; cyc = __arch_counter_get_cntvct() - clock->data[bank].epoch_cyc; if (likely(cyc < clock->data[bank].cyc_overflow64)) { ns = cyc * clock->data[bank].mult; ns >>= clock->data[bank].shift; } else { ns = __clock_mult_uint128(cyc, clock->data[bank].mult, clock->data[bank].shift); } return (u64)ns + clock->data[bank].epoch_ns; }