/*
 * perf events self profiling example test case for hw breakpoints.
 *
 * This tests perf PERF_TYPE_BREAKPOINT parameters
 * 1) tests all variants of the break on read/write flags
 * 2) tests exclude_user == 0 and 1
 * 3) test array matches (if DAWR is supported))
 * 4) test different numbers of breakpoints matches
 *
 * Configure this breakpoint, then read and write the data a number of
 * times. Then check the output count from perf is as expected.
 *
 * Based on:
 *   http://ozlabs.org/~anton/junkcode/perf_events_example1.c
 *
 * Copyright (C) 2018 Michael Neuling, IBM Corporation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <unistd.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <elf.h>
#include <pthread.h>
#include <sys/syscall.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include "utils.h"

#define MAX_LOOPS 10000

#define DAWR_LENGTH_MAX ((0x3f + 1) * 8)

static inline int sys_perf_event_open(struct perf_event_attr *attr, pid_t pid,
                                      int cpu, int group_fd,
                                      unsigned long flags)
{
        attr->size = sizeof(*attr);
        return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
}

static inline bool breakpoint_test(int len)
{
        struct perf_event_attr attr;
        int fd;

        /* setup counters */
        memset(&attr, 0, sizeof(attr));
        attr.disabled = 1;
        attr.type = PERF_TYPE_BREAKPOINT;
        attr.bp_type = HW_BREAKPOINT_R;
        /* bp_addr can point anywhere but needs to be aligned */
        attr.bp_addr = (__u64)(&attr) & 0xfffffffffffff800;
        attr.bp_len = len;
        fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
        if (fd < 0)
                return false;
        close(fd);
        return true;
}

static inline bool perf_breakpoint_supported(void)
{
        return breakpoint_test(4);
}

static inline bool dawr_supported(void)
{
        return breakpoint_test(DAWR_LENGTH_MAX);
}

static int runtestsingle(int readwriteflag, int exclude_user, int arraytest)
{
        int i,j;
        struct perf_event_attr attr;
        size_t res;
        unsigned long long breaks, needed;
        int readint;
        int readintarraybig[2*DAWR_LENGTH_MAX/sizeof(int)];
        int *readintalign;
        volatile int *ptr;
        int break_fd;
        int loop_num = MAX_LOOPS - (rand() % 100); /* provide some variability */
        volatile int *k;

        /* align to 0x400 boundary as required by DAWR */
        readintalign = (int *)(((unsigned long)readintarraybig + 0x7ff) &
                               0xfffffffffffff800);

        ptr = &readint;
        if (arraytest)
                ptr = &readintalign[0];

        /* setup counters */
        memset(&attr, 0, sizeof(attr));
        attr.disabled = 1;
        attr.type = PERF_TYPE_BREAKPOINT;
        attr.bp_type = readwriteflag;
        attr.bp_addr = (__u64)ptr;
        attr.bp_len = sizeof(int);
        if (arraytest)
                attr.bp_len = DAWR_LENGTH_MAX;
        attr.exclude_user = exclude_user;
        break_fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
        if (break_fd < 0) {
                perror("sys_perf_event_open");
                exit(1);
        }

        /* start counters */
        ioctl(break_fd, PERF_EVENT_IOC_ENABLE);

        /* Test a bunch of reads and writes */
        k = &readint;
        for (i = 0; i < loop_num; i++) {
                if (arraytest)
                        k = &(readintalign[i % (DAWR_LENGTH_MAX/sizeof(int))]);

                j = *k;
                *k = j;
        }

        /* stop counters */
        ioctl(break_fd, PERF_EVENT_IOC_DISABLE);

        /* read and check counters */
        res = read(break_fd, &breaks, sizeof(unsigned long long));
        assert(res == sizeof(unsigned long long));
        /* we read and write each loop, so subtract the ones we are counting */
        needed = 0;
        if (readwriteflag & HW_BREAKPOINT_R)
                needed += loop_num;
        if (readwriteflag & HW_BREAKPOINT_W)
                needed += loop_num;
        needed = needed * (1 - exclude_user);
        printf("TESTED: addr:0x%lx brks:% 8lld loops:% 8i rw:%i !user:%i array:%i\n",
               (unsigned long int)ptr, breaks, loop_num, readwriteflag, exclude_user, arraytest);
        if (breaks != needed) {
                printf("FAILED: 0x%lx brks:%lld needed:%lli %i %i %i\n\n",
                       (unsigned long int)ptr, breaks, needed, loop_num, readwriteflag, exclude_user);
                return 1;
        }
        close(break_fd);

        return 0;
}

static int runtest(void)
{
        int rwflag;
        int exclude_user;
        int ret;

        /*
         * perf defines rwflag as two bits read and write and at least
         * one must be set.  So range 1-3.
         */
        for (rwflag = 1 ; rwflag < 4; rwflag++) {
                for (exclude_user = 0 ; exclude_user < 2; exclude_user++) {
                        ret = runtestsingle(rwflag, exclude_user, 0);
                        if (ret)
                                return ret;

                        /* if we have the dawr, we can do an array test */
                        if (!dawr_supported())
                                continue;
                        ret = runtestsingle(rwflag, exclude_user, 1);
                        if (ret)
                                return ret;
                }
        }
        return 0;
}


static int perf_hwbreak(void)
{
        srand ( time(NULL) );

        SKIP_IF(!perf_breakpoint_supported());

        return runtest();
}

int main(int argc, char *argv[], char **envp)
{
        return test_harness(perf_hwbreak, "perf_hwbreak");
}