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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 <shuahkh@osg.samsung.com> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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2 changed files with 118 additions and 1 deletions
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@ -1,5 +1,5 @@
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TEST_PROGS := dscr_default_test dscr_explicit_test dscr_user_test \
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dscr_inherit_test
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dscr_inherit_test dscr_inherit_exec_test
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dscr_default_test: LDLIBS += -lpthread
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117
tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c
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117
tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c
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/*
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* POWER Data Stream Control Register (DSCR) fork exec test
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*
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* This testcase modifies the DSCR using mtspr, forks & execs and
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* verifies that the child is using the changed DSCR using mfspr.
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*
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* When using the privilege state SPR, the instructions such as
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* mfspr or mtspr are priviledged and the kernel emulates them
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* for us. Instructions using problem state SPR can be exuecuted
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* directly without any emulation if the HW supports them. Else
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* they also get emulated by the kernel.
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*
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* Copyright 2012, Anton Blanchard, IBM Corporation.
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* Copyright 2015, Anshuman Khandual, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*/
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#include "dscr.h"
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static char prog[LEN_MAX];
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static void do_exec(unsigned long parent_dscr)
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{
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unsigned long cur_dscr, cur_dscr_usr;
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cur_dscr = get_dscr();
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cur_dscr_usr = get_dscr_usr();
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if (cur_dscr != parent_dscr) {
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fprintf(stderr, "Parent DSCR %ld was not inherited "
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"over exec (kernel value)\n", parent_dscr);
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exit(1);
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}
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if (cur_dscr_usr != parent_dscr) {
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fprintf(stderr, "Parent DSCR %ld was not inherited "
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"over exec (user value)\n", parent_dscr);
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exit(1);
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}
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exit(0);
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}
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int dscr_inherit_exec(void)
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{
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unsigned long i, dscr = 0;
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pid_t pid;
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for (i = 0; i < COUNT; i++) {
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dscr++;
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if (dscr > DSCR_MAX)
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dscr = 0;
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if (dscr == get_default_dscr())
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continue;
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if (i % 2 == 0)
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set_dscr_usr(dscr);
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else
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set_dscr(dscr);
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/*
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* XXX: Force a context switch out so that DSCR
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* current value is copied into the thread struct
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* which is required for the child to inherit the
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* changed value.
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*/
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sleep(1);
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pid = fork();
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if (pid == -1) {
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perror("fork() failed");
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exit(1);
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} else if (pid) {
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int status;
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if (waitpid(pid, &status, 0) == -1) {
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perror("waitpid() failed");
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exit(1);
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}
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if (!WIFEXITED(status)) {
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fprintf(stderr, "Child didn't exit cleanly\n");
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exit(1);
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}
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if (WEXITSTATUS(status) != 0) {
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fprintf(stderr, "Child didn't exit cleanly\n");
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return 1;
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}
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} else {
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char dscr_str[16];
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sprintf(dscr_str, "%ld", dscr);
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execlp(prog, prog, "exec", dscr_str, NULL);
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exit(1);
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}
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}
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return 0;
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}
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int main(int argc, char *argv[])
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{
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if (argc == 3 && !strcmp(argv[1], "exec")) {
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unsigned long parent_dscr;
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parent_dscr = atoi(argv[2]);
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do_exec(parent_dscr);
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} else if (argc != 1) {
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fprintf(stderr, "Usage: %s\n", argv[0]);
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exit(1);
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}
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strncpy(prog, argv[0], strlen(argv[0]));
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return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
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}
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