1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright 2016, Michael Ellerman, IBM Corp.
4  */
5 
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <sys/mman.h>
10 #include <unistd.h>
11 
12 #include <asm/cputable.h>
13 
14 #include "utils.h"
15 
16 #define SIZE (64 * 1024)
17 
18 int test_prot_sao(void)
19 {
20 	char *p;
21 
22 	/*
23 	 * SAO was introduced in 2.06 and removed in 3.1. It's disabled in
24 	 * guests/LPARs by default, so also skip if we are running in a guest.
25 	 */
26 	SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06) ||
27 		have_hwcap2(PPC_FEATURE2_ARCH_3_1) ||
28 		access("/proc/device-tree/rtas/ibm,hypertas-functions", F_OK) == 0);
29 
30 	/*
31 	 * Ensure we can ask for PROT_SAO.
32 	 * We can't really verify that it does the right thing, but at least we
33 	 * confirm the kernel will accept it.
34 	 */
35 	p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE | PROT_SAO,
36 		 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
37 	FAIL_IF(p == MAP_FAILED);
38 
39 	/* Write to the mapping, to at least cause a fault */
40 	memset(p, 0xaa, SIZE);
41 
42 	return 0;
43 }
44 
45 int main(void)
46 {
47 	return test_harness(test_prot_sao, "prot-sao");
48 }
49