// SPDX-License-Identifier: GPL-2.0-only
/*
 * POWER Data Stream Control Register (DSCR) fork exec test
 *
 * This testcase modifies the DSCR using mtspr, forks & execs and
 * verifies that the child is using the changed DSCR using mfspr.
 *
 * When using the privilege state SPR, the instructions such as
 * mfspr or mtspr are privileged and the kernel emulates them
 * for us. Instructions using problem state SPR can be executed
 * directly without any emulation if the HW supports them. Else
 * they also get emulated by the kernel.
 *
 * Copyright 2012, Anton Blanchard, IBM Corporation.
 * Copyright 2015, Anshuman Khandual, IBM Corporation.
 */
#include "dscr.h"

static char *prog;

static void do_exec(unsigned long parent_dscr)
{
        unsigned long cur_dscr, cur_dscr_usr;

        cur_dscr = get_dscr();
        cur_dscr_usr = get_dscr_usr();

        if (cur_dscr != parent_dscr) {
                fprintf(stderr, "Parent DSCR %ld was not inherited "
                                "over exec (kernel value)\n", parent_dscr);
                exit(1);
        }

        if (cur_dscr_usr != parent_dscr) {
                fprintf(stderr, "Parent DSCR %ld was not inherited "
                                "over exec (user value)\n", parent_dscr);
                exit(1);
        }
        exit(0);
}

int dscr_inherit_exec(void)
{
        unsigned long i, dscr = 0;
        pid_t pid;

        SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));

        for (i = 0; i < COUNT; i++) {
                dscr++;
                if (dscr > DSCR_MAX)
                        dscr = 0;

                if (dscr == get_default_dscr())
                        continue;

                if (i % 2 == 0)
                        set_dscr_usr(dscr);
                else
                        set_dscr(dscr);

                pid = fork();
                if (pid == -1) {
                        perror("fork() failed");
                        exit(1);
                } else if (pid) {
                        int status;

                        if (waitpid(pid, &status, 0) == -1) {
                                perror("waitpid() failed");
                                exit(1);
                        }

                        if (!WIFEXITED(status)) {
                                fprintf(stderr, "Child didn't exit cleanly\n");
                                exit(1);
                        }

                        if (WEXITSTATUS(status) != 0) {
                                fprintf(stderr, "Child didn't exit cleanly\n");
                                return 1;
                        }
                } else {
                        char dscr_str[16];

                        sprintf(dscr_str, "%ld", dscr);
                        execlp(prog, prog, "exec", dscr_str, NULL);
                        exit(1);
                }
        }
        return 0;
}

int main(int argc, char *argv[])
{
        if (argc == 3 && !strcmp(argv[1], "exec")) {
                unsigned long parent_dscr;

                parent_dscr = atoi(argv[2]);
                do_exec(parent_dscr);
        } else if (argc != 1) {
                fprintf(stderr, "Usage: %s\n", argv[0]);
                exit(1);
        }

        prog = argv[0];
        return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
}