1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * POWER Data Stream Control Register (DSCR) fork exec test
  4 *
  5 * This testcase modifies the DSCR using mtspr, forks & execs and
  6 * verifies that the child is using the changed DSCR using mfspr.
  7 *
  8 * When using the privilege state SPR, the instructions such as
  9 * mfspr or mtspr are privileged and the kernel emulates them
 10 * for us. Instructions using problem state SPR can be executed
 11 * directly without any emulation if the HW supports them. Else
 12 * they also get emulated by the kernel.
 13 *
 14 * Copyright 2012, Anton Blanchard, IBM Corporation.
 15 * Copyright 2015, Anshuman Khandual, IBM Corporation.
 16 */
 17#include "dscr.h"
 18
 19static char *prog;
 20
 21static void do_exec(unsigned long parent_dscr)
 22{
 23	unsigned long cur_dscr, cur_dscr_usr;
 24
 25	cur_dscr = get_dscr();
 26	cur_dscr_usr = get_dscr_usr();
 27
 28	if (cur_dscr != parent_dscr) {
 29		fprintf(stderr, "Parent DSCR %ld was not inherited "
 30				"over exec (kernel value)\n", parent_dscr);
 31		exit(1);
 32	}
 33
 34	if (cur_dscr_usr != parent_dscr) {
 35		fprintf(stderr, "Parent DSCR %ld was not inherited "
 36				"over exec (user value)\n", parent_dscr);
 37		exit(1);
 38	}
 39	exit(0);
 40}
 41
 42int dscr_inherit_exec(void)
 43{
 44	unsigned long i, dscr = 0;
 45	pid_t pid;
 46
 47	SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
 48
 49	for (i = 0; i < COUNT; i++) {
 50		dscr++;
 51		if (dscr > DSCR_MAX)
 52			dscr = 0;
 53
 54		if (dscr == get_default_dscr())
 55			continue;
 56
 57		if (i % 2 == 0)
 58			set_dscr_usr(dscr);
 59		else
 60			set_dscr(dscr);
 61
 62		pid = fork();
 63		if (pid == -1) {
 64			perror("fork() failed");
 65			exit(1);
 66		} else if (pid) {
 67			int status;
 68
 69			if (waitpid(pid, &status, 0) == -1) {
 70				perror("waitpid() failed");
 71				exit(1);
 72			}
 73
 74			if (!WIFEXITED(status)) {
 75				fprintf(stderr, "Child didn't exit cleanly\n");
 76				exit(1);
 77			}
 78
 79			if (WEXITSTATUS(status) != 0) {
 80				fprintf(stderr, "Child didn't exit cleanly\n");
 81				return 1;
 82			}
 83		} else {
 84			char dscr_str[16];
 85
 86			sprintf(dscr_str, "%ld", dscr);
 87			execlp(prog, prog, "exec", dscr_str, NULL);
 88			exit(1);
 89		}
 90	}
 91	return 0;
 92}
 93
 94int main(int argc, char *argv[])
 95{
 96	if (argc == 3 && !strcmp(argv[1], "exec")) {
 97		unsigned long parent_dscr;
 98
 99		parent_dscr = atoi(argv[2]);
100		do_exec(parent_dscr);
101	} else if (argc != 1) {
102		fprintf(stderr, "Usage: %s\n", argv[0]);
103		exit(1);
104	}
105
106	prog = argv[0];
107	return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
108}