cregit-Linux how code gets into the kernel

Release 4.10 tools/testing/selftests/powerpc/dscr/dscr_inherit_test.c

/*
 * POWER Data Stream Control Register (DSCR) fork test
 *
 * This testcase modifies the DSCR using mtspr, forks and then
 * verifies that the child process has the correct changed DSCR
 * value using mfspr.
 *
 * When using the privilege state SPR, the instructions such as
 * mfspr or mtspr are priviledged and the kernel emulates them
 * for us. Instructions using problem state SPR can be exuecuted
 * 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.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */
#include "dscr.h"


int dscr_inherit(void) { unsigned long i, dscr = 0; pid_t pid; srand(getpid()); set_dscr(dscr); for (i = 0; i < COUNT; i++) { unsigned long cur_dscr, cur_dscr_usr; dscr++; if (dscr > DSCR_MAX) dscr = 0; 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 { cur_dscr = get_dscr(); if (cur_dscr != dscr) { fprintf(stderr, "Kernel DSCR should be %ld " "but is %ld\n", dscr, cur_dscr); exit(1); } cur_dscr_usr = get_dscr_usr(); if (cur_dscr_usr != dscr) { fprintf(stderr, "User DSCR should be %ld " "but is %ld\n", dscr, cur_dscr_usr); exit(1); } exit(0); } } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
anshuman khandualanshuman khandual257100.00%1100.00%
Total257100.00%1100.00%


int main(int argc, char *argv[]) { return test_harness(dscr_inherit, "dscr_inherit_test"); }

Contributors

PersonTokensPropCommitsCommitProp
anshuman khandualanshuman khandual21100.00%1100.00%
Total21100.00%1100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
anshuman khandualanshuman khandual282100.00%1100.00%
Total282100.00%1100.00%
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