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