third_party/lib/jitterentropy/arch/x86/internal.h

// Copyright 2017 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#pragma once

#include <arch/x86.h>
#include <arch/x86/feature.h>
#include <stddef.h>
#include <stdint.h>

#include <platform.h>

static inline bool jent_have_clock(void) {
    return x86_feature_test(X86_FEATURE_INVAR_TSC);
}

static inline void jent_get_nstime(uint64_t* out) {
    // When running during boot, in particular before the VMM is up, our timers haven't been
    // calibrated yet. But, we only ever get here if jent_have_clock returned true, so our system at
    // least has an invariant tsc. We could do some arithmetic to convert TSC -> nanoseconds, but
    // raw TSC is perfectly reasonable to use too (jitterentropy doesn't care about the unit of
    // time, just that the clock source is monotonic, invariant, and high resolution).
    *out = rdtsc();
}

static inline void* jent_zalloc(size_t len) {
    return NULL;
}

static inline void jent_zfree(void* ptr, size_t len) {
}

static inline int jent_fips_enabled(void) {
    return 0;
}

static inline uint64_t rol64(uint64_t x, uint32_t n) {
    return (x<<n) | (x>>(64-n));
}