// SPDX-License-Identifier: GPL-2.0
/*
 * Inspired by breakpoint overflow test done by
 * Vince Weaver <vincent.weaver@maine.edu> for perf_event_tests
 * (git://github.com/deater/perf_event_tests)
 */

/*
 * Powerpc needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
 * 'int-ll64.h' and avoid compile warnings when printing __u64 with %llu.
 */
#define __SANE_USERSPACE_TYPES__

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <time.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/mman.h>
#include <linux/compiler.h>
#include <linux/hw_breakpoint.h>

#include "tests.h"
#include "debug.h"
#include "event.h"
#include "perf-sys.h"
#include "cloexec.h"

static int fd1;
static int fd2;
static int fd3;
static int overflows;
static int overflows_2;

volatile long the_var;


/*
 * Use ASM to ensure watchpoint and breakpoint can be triggered
 * at one instruction.
 */
#if defined (__x86_64__)
extern void __test_function(volatile long *ptr);
asm (
        ".pushsection .text;"
        ".globl __test_function\n"
        ".type __test_function, @function;"
        "__test_function:\n"
        "incq (%rdi)\n"
        "ret\n"
        ".popsection\n");
#else
static void __test_function(volatile long *ptr)
{
        *ptr = 0x1234;
}
#endif

static noinline int test_function(void)
{
        __test_function(&the_var);
        the_var++;
        return time(NULL);
}

static void sig_handler_2(int signum __maybe_unused,
                          siginfo_t *oh __maybe_unused,
                          void *uc __maybe_unused)
{
        overflows_2++;
        if (overflows_2 > 10) {
                ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
                ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
                ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
        }
}

static void sig_handler(int signum __maybe_unused,
                        siginfo_t *oh __maybe_unused,
                        void *uc __maybe_unused)
{
        overflows++;

        if (overflows > 10) {
                /*
                 * This should be executed only once during
                 * this test, if we are here for the 10th
                 * time, consider this the recursive issue.
                 *
                 * We can get out of here by disable events,
                 * so no new SIGIO is delivered.
                 */
                ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
                ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
                ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
        }
}

static int __event(bool is_x, void *addr, int sig)
{
        struct perf_event_attr pe;
        int fd;

        memset(&pe, 0, sizeof(struct perf_event_attr));
        pe.type = PERF_TYPE_BREAKPOINT;
        pe.size = sizeof(struct perf_event_attr);

        pe.config = 0;
        pe.bp_type = is_x ? HW_BREAKPOINT_X : HW_BREAKPOINT_W;
        pe.bp_addr = (unsigned long) addr;
        pe.bp_len = sizeof(long);

        pe.sample_period = 1;
        pe.sample_type = PERF_SAMPLE_IP;
        pe.wakeup_events = 1;

        pe.disabled = 1;
        pe.exclude_kernel = 1;
        pe.exclude_hv = 1;

        fd = sys_perf_event_open(&pe, 0, -1, -1,
                                 perf_event_open_cloexec_flag());
        if (fd < 0) {
                pr_debug("failed opening event %llx\n", pe.config);
                return TEST_FAIL;
        }

        fcntl(fd, F_SETFL, O_RDWR|O_NONBLOCK|O_ASYNC);
        fcntl(fd, F_SETSIG, sig);
        fcntl(fd, F_SETOWN, getpid());

        ioctl(fd, PERF_EVENT_IOC_RESET, 0);

        return fd;
}

static int bp_event(void *addr, int sig)
{
        return __event(true, addr, sig);
}

static int wp_event(void *addr, int sig)
{
        return __event(false, addr, sig);
}

static long long bp_count(int fd)
{
        long long count;
        int ret;

        ret = read(fd, &count, sizeof(long long));
        if (ret != sizeof(long long)) {
                pr_debug("failed to read: %d\n", ret);
                return TEST_FAIL;
        }

        return count;
}

int test__bp_signal(struct test *test __maybe_unused, int subtest __maybe_unused)
{
        struct sigaction sa;
        long long count1, count2, count3;

        /* setup SIGIO signal handler */
        memset(&sa, 0, sizeof(struct sigaction));
        sa.sa_sigaction = (void *) sig_handler;
        sa.sa_flags = SA_SIGINFO;

        if (sigaction(SIGIO, &sa, NULL) < 0) {
                pr_debug("failed setting up signal handler\n");
                return TEST_FAIL;
        }

        sa.sa_sigaction = (void *) sig_handler_2;
        if (sigaction(SIGUSR1, &sa, NULL) < 0) {
                pr_debug("failed setting up signal handler 2\n");
                return TEST_FAIL;
        }

        /*
         * We create following events:
         *
         * fd1 - breakpoint event on __test_function with SIGIO
         *       signal configured. We should get signal
         *       notification each time the breakpoint is hit
         *
         * fd2 - breakpoint event on sig_handler with SIGUSR1
         *       configured. We should get SIGUSR1 each time when
         *       breakpoint is hit
         *
         * fd3 - watchpoint event on __test_function with SIGIO
         *       configured.
         *
         * Following processing should happen:
         *   Exec:               Action:                       Result:
         *   incq (%rdi)       - fd1 event breakpoint hit   -> count1 == 1
         *                     - SIGIO is delivered
         *   sig_handler       - fd2 event breakpoint hit   -> count2 == 1
         *                     - SIGUSR1 is delivered
         *   sig_handler_2                                  -> overflows_2 == 1  (nested signal)
         *   sys_rt_sigreturn  - return from sig_handler_2
         *   overflows++                                    -> overflows = 1
         *   sys_rt_sigreturn  - return from sig_handler
         *   incq (%rdi)       - fd3 event watchpoint hit   -> count3 == 1       (wp and bp in one insn)
         *                     - SIGIO is delivered
         *   sig_handler       - fd2 event breakpoint hit   -> count2 == 2
         *                     - SIGUSR1 is delivered
         *   sig_handler_2                                  -> overflows_2 == 2  (nested signal)
         *   sys_rt_sigreturn  - return from sig_handler_2
         *   overflows++                                    -> overflows = 2
         *   sys_rt_sigreturn  - return from sig_handler
         *   the_var++         - fd3 event watchpoint hit   -> count3 == 2       (standalone watchpoint)
         *                     - SIGIO is delivered
         *   sig_handler       - fd2 event breakpoint hit   -> count2 == 3
         *                     - SIGUSR1 is delivered
         *   sig_handler_2                                  -> overflows_2 == 3  (nested signal)
         *   sys_rt_sigreturn  - return from sig_handler_2
         *   overflows++                                    -> overflows == 3
         *   sys_rt_sigreturn  - return from sig_handler
         *
         * The test case check following error conditions:
         * - we get stuck in signal handler because of debug
         *   exception being triggered recursively due to
         *   the wrong RF EFLAG management
         *
         * - we never trigger the sig_handler breakpoint due
         *   to the wrong RF EFLAG management
         *
         */

        fd1 = bp_event(__test_function, SIGIO);
        fd2 = bp_event(sig_handler, SIGUSR1);
        fd3 = wp_event((void *)&the_var, SIGIO);

        ioctl(fd1, PERF_EVENT_IOC_ENABLE, 0);
        ioctl(fd2, PERF_EVENT_IOC_ENABLE, 0);
        ioctl(fd3, PERF_EVENT_IOC_ENABLE, 0);

        /*
         * Kick off the test by triggering 'fd1'
         * breakpoint.
         */
        test_function();

        ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
        ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
        ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);

        count1 = bp_count(fd1);
        count2 = bp_count(fd2);
        count3 = bp_count(fd3);

        close(fd1);
        close(fd2);
        close(fd3);

        pr_debug("count1 %lld, count2 %lld, count3 %lld, overflow %d, overflows_2 %d\n",
                 count1, count2, count3, overflows, overflows_2);

        if (count1 != 1) {
                if (count1 == 11)
                        pr_debug("failed: RF EFLAG recursion issue detected\n");
                else
                        pr_debug("failed: wrong count for bp1: %lld, expected 1\n", count1);
        }

        if (overflows != 3)
                pr_debug("failed: wrong overflow (%d) hit, expected 3\n", overflows);

        if (overflows_2 != 3)
                pr_debug("failed: wrong overflow_2 (%d) hit, expected 3\n", overflows_2);

        if (count2 != 3)
                pr_debug("failed: wrong count for bp2 (%lld), expected 3\n", count2);

        if (count3 != 2)
                pr_debug("failed: wrong count for bp3 (%lld), expected 2\n", count3);

        return count1 == 1 && overflows == 3 && count2 == 3 && overflows_2 == 3 && count3 == 2 ?
                TEST_OK : TEST_FAIL;
}

bool test__bp_signal_is_supported(void)
{
        /*
         * PowerPC and S390 do not support creation of instruction
         * breakpoints using the perf_event interface.
         *
         * ARM requires explicit rounding down of the instruction
         * pointer in Thumb mode, and then requires the single-step
         * to be handled explicitly in the overflow handler to avoid
         * stepping into the SIGIO handler and getting stuck on the
         * breakpointed instruction.
         *
         * Since arm64 has the same issue with arm for the single-step
         * handling, this case also gets stuck on the breakpointed
         * instruction.
         *
         * Just disable the test for these architectures until these
         * issues are resolved.
         */
#if defined(__powerpc__) || defined(__s390x__) || defined(__arm__) || \
    defined(__aarch64__)
        return false;
#else
        return true;
#endif
}