// SPDX-License-Identifier: GPL-2.0-only

#include <linux/sched.h>
#include <linux/wait.h>

#include "kselftest.h"

#define SYS_TPIDR2 "S3_3_C13_C0_5"

#define EXPECTED_TESTS 5

static void set_tpidr2(uint64_t val)
{
        asm volatile (
                "msr    " SYS_TPIDR2 ", %0\n"
                :
                : "r"(val)
                : "cc");
}

static uint64_t get_tpidr2(void)
{
        uint64_t val;

        asm volatile (
                "mrs    %0, " SYS_TPIDR2 "\n"
                : "=r"(val)
                :
                : "cc");

        return val;
}

/* Processes should start with TPIDR2 == 0 */
static int default_value(void)
{
        return get_tpidr2() == 0;
}

/* If we set TPIDR2 we should read that value */
static int write_read(void)
{
        set_tpidr2(getpid());

        return getpid() == get_tpidr2();
}

/* If we set a value we should read the same value after scheduling out */
static int write_sleep_read(void)
{
        set_tpidr2(getpid());

        msleep(100);

        return getpid() == get_tpidr2();
}

/*
 * If we fork the value in the parent should be unchanged and the
 * child should start with the same value and be able to set its own
 * value.
 */
static int write_fork_read(void)
{
        pid_t newpid, waiting, oldpid;
        int status;

        set_tpidr2(getpid());

        oldpid = getpid();
        newpid = fork();
        if (newpid == 0) {
                /* In child */
                if (get_tpidr2() != oldpid) {
                        ksft_print_msg("TPIDR2 changed in child: %llx\n",
                                       get_tpidr2());
                        exit(0);
                }

                set_tpidr2(getpid());
                if (get_tpidr2() == getpid()) {
                        exit(1);
                } else {
                        ksft_print_msg("Failed to set TPIDR2 in child\n");
                        exit(0);
                }
        }
        if (newpid < 0) {
                ksft_print_msg("fork() failed: %d\n", newpid);
                return 0;
        }

        for (;;) {
                waiting = waitpid(newpid, &status, 0);

                if (waiting < 0) {
                        if (errno == EINTR)
                                continue;
                        ksft_print_msg("waitpid() failed: %d\n", errno);
                        return 0;
                }
                if (waiting != newpid) {
                        ksft_print_msg("waitpid() returned wrong PID: %d != %d\n",
                                       waiting, newpid);
                        return 0;
                }

                if (!WIFEXITED(status)) {
                        ksft_print_msg("child did not exit\n");
                        return 0;
                }

                if (getpid() != get_tpidr2()) {
                        ksft_print_msg("TPIDR2 corrupted in parent\n");
                        return 0;
                }

                return WEXITSTATUS(status);
        }
}

/*
 * sys_clone() has a lot of per architecture variation so just define
 * it here rather than adding it to nolibc, plus the raw API is a
 * little more convenient for this test.
 */
static int sys_clone(unsigned long clone_flags, unsigned long newsp,
                     int *parent_tidptr, unsigned long tls,
                     int *child_tidptr)
{
        return syscall(__NR_clone, clone_flags, newsp, parent_tidptr, tls, child_tidptr);
}

#define __STACK_SIZE (8 * 1024 * 1024)

/*
 * If we clone with CLONE_VM then the value in the parent should
 * be unchanged and the child should start with zero and be able to
 * set its own value.
 */
static int write_clone_read(void)
{
        int parent_tid, child_tid;
        pid_t parent, waiting;
        int ret, status;
        void *stack;

        parent = getpid();
        set_tpidr2(parent);

        stack = malloc(__STACK_SIZE);
        if (!stack) {
                ksft_print_msg("malloc() failed\n");
                return 0;
        }

        ret = sys_clone(CLONE_VM, (unsigned long)stack + __STACK_SIZE,
                        &parent_tid, 0, &child_tid);
        if (ret == -1) {
                ksft_print_msg("clone() failed: %d\n", errno);
                return 0;
        }

        if (ret == 0) {
                /* In child */
                if (get_tpidr2() != 0) {
                        ksft_print_msg("TPIDR2 non-zero in child: %llx\n",
                                       get_tpidr2());
                        exit(0);
                }

                if (gettid() == 0)
                        ksft_print_msg("Child TID==0\n");
                set_tpidr2(gettid());
                if (get_tpidr2() == gettid()) {
                        exit(1);
                } else {
                        ksft_print_msg("Failed to set TPIDR2 in child\n");
                        exit(0);
                }
        }

        for (;;) {
                waiting = waitpid(ret, &status, __WCLONE);

                if (waiting < 0) {
                        if (errno == EINTR)
                                continue;
                        ksft_print_msg("waitpid() failed: %d\n", errno);
                        return 0;
                }
                if (waiting != ret) {
                        ksft_print_msg("waitpid() returned wrong PID %d\n",
                                       waiting);
                        return 0;
                }

                if (!WIFEXITED(status)) {
                        ksft_print_msg("child did not exit\n");
                        return 0;
                }

                if (parent != get_tpidr2()) {
                        ksft_print_msg("TPIDR2 corrupted in parent\n");
                        return 0;
                }

                return WEXITSTATUS(status);
        }
}

int main(int argc, char **argv)
{
        int ret;

        ksft_print_header();
        ksft_set_plan(5);

        ksft_print_msg("PID: %d\n", getpid());

        /*
         * This test is run with nolibc which doesn't support hwcap and
         * it's probably disproportionate to implement so instead check
         * for the default vector length configuration in /proc.
         */
        ret = open("/proc/sys/abi/sme_default_vector_length", O_RDONLY, 0);
        if (ret >= 0) {
                ksft_test_result(default_value(), "default_value\n");
                ksft_test_result(write_read(), "write_read\n");
                ksft_test_result(write_sleep_read(), "write_sleep_read\n");
                ksft_test_result(write_fork_read(), "write_fork_read\n");
                ksft_test_result(write_clone_read(), "write_clone_read\n");

        } else {
                ksft_print_msg("SME support not present\n");

                ksft_test_result_skip("default_value\n");
                ksft_test_result_skip("write_read\n");
                ksft_test_result_skip("write_sleep_read\n");
                ksft_test_result_skip("write_fork_read\n");
                ksft_test_result_skip("write_clone_read\n");
        }

        ksft_finished();
}