From 6f844261e16b3a66ccec29667b2713ce0bb8adc7 Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Thu, 21 May 2015 12:13:10 +0530 Subject: [PATCH] selftests/powerpc: Add test for DSCR inheritence across fork & exec This patch adds a test case to verify that the changed DSCR value inside any process would be inherited to it's child across the fork and exec system call. Acked-by: Shuah Khan Signed-off-by: Anshuman Khandual Signed-off-by: Anton Blanchard Signed-off-by: Michael Ellerman --- tools/testing/selftests/powerpc/dscr/Makefile | 2 +- .../powerpc/dscr/dscr_inherit_exec_test.c | 117 ++++++++++++++++++ 2 files changed, 118 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c diff --git a/tools/testing/selftests/powerpc/dscr/Makefile b/tools/testing/selftests/powerpc/dscr/Makefile index 764fadc36cbb..0f53a4d586fa 100644 --- a/tools/testing/selftests/powerpc/dscr/Makefile +++ b/tools/testing/selftests/powerpc/dscr/Makefile @@ -1,5 +1,5 @@ TEST_PROGS := dscr_default_test dscr_explicit_test dscr_user_test \ - dscr_inherit_test + dscr_inherit_test dscr_inherit_exec_test dscr_default_test: LDLIBS += -lpthread diff --git a/tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c b/tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c new file mode 100644 index 000000000000..8265504de571 --- /dev/null +++ b/tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c @@ -0,0 +1,117 @@ +/* + * 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 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" + +static char prog[LEN_MAX]; + +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; + + 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); + + /* + * XXX: Force a context switch out so that DSCR + * current value is copied into the thread struct + * which is required for the child to inherit the + * changed value. + */ + sleep(1); + + 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); + } + + strncpy(prog, argv[0], strlen(argv[0])); + return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test"); +} -- 2.20.1