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/*
* Adapted from Anton Blanchard's context switch microbenchmark.
*
* Copyright 2009, Anton Blanchard, IBM Corporation.
* Copyright 2016, Mikey Neuling, Chris Smart, IBM Corporation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* This program tests the copy paste abort functionality of a P9
* (or later) by setting up two processes on the same CPU, one
* which executes the copy instruction and the other which
* executes paste.
*
* The paste instruction should never succeed, as the cp_abort
* instruction is called by the kernel during a context switch.
*
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include "utils.h"
#include <sched.h>
#define READ_FD 0
#define WRITE_FD 1
#define NUM_LOOPS 1000
/* This defines the "paste" instruction from Power ISA 3.0 Book II, section 4.4. */
#define PASTE(RA, RB, L, RC) \
.long (0x7c00070c | (RA) << (31-15) | (RB) << (31-20) | (L) << (31-10) | (RC) << (31-31))
int paste(void *i)
{
int cr;
asm volatile(str(PASTE(0, %1, 1, 1))";"
"mfcr %0;"
: "=r" (cr)
: "b" (i)
: "memory"
);
return cr;
}
/* This defines the "copy" instruction from Power ISA 3.0 Book II, section 4.4. */
#define COPY(RA, RB, L) \
.long (0x7c00060c | (RA) << (31-15) | (RB) << (31-20) | (L) << (31-10))
void copy(void *i)
{
asm volatile(str(COPY(0, %0, 1))";"
:
: "b" (i)
: "memory"
);
}
int test_cp_abort(void)
{
/* 128 bytes for a full cache line */
char buf[128] __cacheline_aligned;
cpu_set_t cpuset;
int fd1[2], fd2[2], pid;
char c;
/* only run this test on a P9 or later */
SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_3_00));
/*
* Run both processes on the same CPU, so that copy is more likely
* to leak into a paste.
*/
CPU_ZERO(&cpuset);
CPU_SET(pick_online_cpu(), &cpuset);
FAIL_IF(sched_setaffinity(0, sizeof(cpuset), &cpuset));
FAIL_IF(pipe(fd1) || pipe(fd2));
pid = fork();
FAIL_IF(pid < 0);
if (!pid) {
for (int i = 0; i < NUM_LOOPS; i++) {
FAIL_IF((write(fd1[WRITE_FD], &c, 1)) != 1);
FAIL_IF((read(fd2[READ_FD], &c, 1)) != 1);
/* A paste succeeds if CR0 EQ bit is set */
FAIL_IF(paste(buf) & 0x20000000);
}
} else {
for (int i = 0; i < NUM_LOOPS; i++) {
FAIL_IF((read(fd1[READ_FD], &c, 1)) != 1);
copy(buf);
FAIL_IF((write(fd2[WRITE_FD], &c, 1) != 1));
}
}
return 0;
}
int main(int argc, char *argv[])
{
return test_harness(test_cp_abort, "cp_abort");
}
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