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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2018-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/random.h>
#include <linux/perf_event.h>
#include <asm/cpufeature.h>
#include <asm/processor.h>
#include <asm/fpu/api.h>
#include <asm/simd.h>
static unsigned long stamp = 0;
module_param(stamp, ulong, 0);
#define declare_it(name) bool generate_1k_ ##name(u8 out[1024])
#define local_it(name) cycles_t median_ ##name = 0
#define do_it(name) do { \
u32 eax = 0, ebx = 0, ecx = 0, edx = 0; \
for (i = 0; i < TRIALS; ++i) \
asm volatile("cpuid" : "+a" (eax), "=b" (ebx), "=d" (edx), "+c" (ecx)); \
for (i = 0; i < TRIALS; ++i) \
ret |= generate_1k_ ##name(out); \
for (i = 0; i <= TRIALS; ++i) { \
trial_times[i] = native_read_pmc(pmc_index); \
ret |= generate_1k_ ##name(out); \
} \
for (i = 0; i < TRIALS; ++i) \
trial_times[i] = trial_times[i + 1] - trial_times[i]; \
sort(trial_times, TRIALS + 1, sizeof(cycles_t), compare_cycles, NULL); \
median_ ## name = trial_times[TRIALS / 2]; \
} while (0)
#define report_it(name) do { \
pr_err("%lu: %12s: %6llu cycles per call\n", stamp, #name, median_ ## name); \
} while (0)
#define forall(f) \
f(rdrand); \
f(rdseed); \
f(kernel);
forall(declare_it)
static int compare_cycles(const void *a, const void *b)
{
return *((cycles_t *)a) - *((cycles_t *)b);
}
static int __init mod_init(void)
{
enum { TRIALS = 30000 };
int ret = 0, i;
cycles_t *trial_times;
forall(local_it)
unsigned long flags;
struct perf_event *cycles_event;
int pmc_index;
static struct perf_event_attr perf_cycles_attr = {
.type = PERF_TYPE_HARDWARE,
.config = PERF_COUNT_HW_CPU_CYCLES,
.size = sizeof(struct perf_event_attr),
.pinned = 1,
.disabled = 0,
.exclude_user = 1
};
DEFINE_SPINLOCK(lock);
u8 out[1024];
trial_times = kcalloc(TRIALS + 1, sizeof(cycles_t), GFP_KERNEL);
if (!trial_times)
return -ENOMEM;
msleep(1000);
spin_lock_irqsave(&lock, flags);
cycles_event = perf_event_create_kernel_counter(&perf_cycles_attr, raw_smp_processor_id(), NULL, NULL, NULL);
if (IS_ERR(cycles_event)) {
pr_err("unable to create perf counter: %ld\n", PTR_ERR(cycles_event));
goto skip;
}
pmc_index = cycles_event->hw.event_base_rdpmc;
forall(do_it)
perf_event_release_kernel(cycles_event);
skip:
spin_unlock_irqrestore(&lock, flags);
forall(report_it)
kfree(trial_times);
/* We should never actually agree to insert the module. Choosing
* -0x1000 here is an amazing hack. It causes the kernel to not
* actually load the module, while the standard userspace tools
* don't return an error, because it's too big. */
return -0x1000;
}
module_init(mod_init);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("kBench9000 Cycle Counter");
MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
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