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 19 static char *prog; 20 21 static 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 42 int 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 94 int 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 } 109