summaryrefslogtreecommitdiff
path: root/tools/testing/selftests/powerpc/tm/tm-poison.c
blob: 977558497c16893ece4d13ff35ba864154ee0d0e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2019, Gustavo Romero, Michael Neuling, IBM Corp.
 *
 * This test will spawn two processes. Both will be attached to the same
 * CPU (CPU 0). The child will be in a loop writing to FP register f31 and
 * VMX/VEC/Altivec register vr31 a known value, called poison, calling
 * sched_yield syscall after to allow the parent to switch on the CPU.
 * Parent will set f31 and vr31 to 1 and in a loop will check if f31 and
 * vr31 remain 1 as expected until a given timeout (2m). If the issue is
 * present child's poison will leak into parent's f31 or vr31 registers,
 * otherwise, poison will never leak into parent's f31 and vr31 registers.
 */

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>
#include <sched.h>
#include <sys/types.h>
#include <signal.h>
#include <inttypes.h>

#include "tm.h"

int tm_poison_test(void)
{
	int pid;
	cpu_set_t cpuset;
	uint64_t poison = 0xdeadbeefc0dec0fe;
	uint64_t unknown = 0;
	bool fail_fp = false;
	bool fail_vr = false;

	SKIP_IF(!have_htm());

	/* Attach both Child and Parent to CPU 0 */
	CPU_ZERO(&cpuset);
	CPU_SET(0, &cpuset);
	sched_setaffinity(0, sizeof(cpuset), &cpuset);

	pid = fork();
	if (!pid) {
		/**
		 * child
		 */
		while (1) {
			sched_yield();
			asm (
				"mtvsrd 31, %[poison];" // f31 = poison
				"mtvsrd 63, %[poison];" // vr31 = poison

				: : [poison] "r" (poison) : );
		}
	}

	/**
	 * parent
	 */
	asm (
		/*
		 * Set r3, r4, and f31 to known value 1 before entering
		 * in transaction. They won't be written after that.
		 */
		"       li      3, 0x1          ;"
		"       li      4, 0x1          ;"
		"       mtvsrd  31, 4           ;"

		/*
		 * The Time Base (TB) is a 64-bit counter register that is
		 * independent of the CPU clock and which is incremented
		 * at a frequency of 512000000 Hz, so every 1.953125ns.
		 * So it's necessary 120s/0.000000001953125s = 61440000000
		 * increments to get a 2 minutes timeout. Below we set that
		 * value in r5 and then use r6 to track initial TB value,
		 * updating TB values in r7 at every iteration and comparing it
		 * to r6. When r7 (current) - r6 (initial) > 61440000000 we bail
		 * out since for sure we spent already 2 minutes in the loop.
		 * SPR 268 is the TB register.
		 */
		"       lis     5, 14           ;"
		"       ori     5, 5, 19996     ;"
		"       sldi    5, 5, 16        ;" // r5 = 61440000000

		"       mfspr   6, 268          ;" // r6 (TB initial)
		"1:     mfspr   7, 268          ;" // r7 (TB current)
		"       subf    7, 6, 7         ;" // r7 - r6 > 61440000000 ?
		"       cmpd    7, 5            ;"
		"       bgt     3f              ;" // yes, exit

		/*
		 * Main loop to check f31
		 */
		"       tbegin.                 ;" // no, try again
		"       beq     1b              ;" // restart if no timeout
		"       mfvsrd  3, 31           ;" // read f31
		"       cmpd    3, 4            ;" // f31 == 1 ?
		"       bne     2f              ;" // broken :-(
		"       tabort. 3               ;" // try another transaction
		"2:     tend.                   ;" // commit transaction
		"3:     mr    %[unknown], 3     ;" // record r3

		: [unknown] "=r" (unknown)
		:
		: "cr0", "r3", "r4", "r5", "r6", "r7", "vs31"

		);

	/*
	 * On leak 'unknown' will contain 'poison' value from child,
	 * otherwise (no leak) 'unknown' will contain the same value
	 * as r3 before entering in transactional mode, i.e. 0x1.
	 */
	fail_fp = unknown != 0x1;
	if (fail_fp)
		printf("Unknown value %#"PRIx64" leaked into f31!\n", unknown);
	else
		printf("Good, no poison or leaked value into FP registers\n");

	asm (
		/*
		 * Set r3, r4, and vr31 to known value 1 before entering
		 * in transaction. They won't be written after that.
		 */
		"       li      3, 0x1          ;"
		"       li      4, 0x1          ;"
		"       mtvsrd  63, 4           ;"

		"       lis     5, 14           ;"
		"       ori     5, 5, 19996     ;"
		"       sldi    5, 5, 16        ;" // r5 = 61440000000

		"       mfspr   6, 268          ;" // r6 (TB initial)
		"1:     mfspr   7, 268          ;" // r7 (TB current)
		"       subf    7, 6, 7         ;" // r7 - r6 > 61440000000 ?
		"       cmpd    7, 5            ;"
		"       bgt     3f              ;" // yes, exit

		/*
		 * Main loop to check vr31
		 */
		"       tbegin.                 ;" // no, try again
		"       beq     1b              ;" // restart if no timeout
		"       mfvsrd  3, 63           ;" // read vr31
		"       cmpd    3, 4            ;" // vr31 == 1 ?
		"       bne     2f              ;" // broken :-(
		"       tabort. 3               ;" // try another transaction
		"2:     tend.                   ;" // commit transaction
		"3:     mr    %[unknown], 3     ;" // record r3

		: [unknown] "=r" (unknown)
		:
		: "cr0", "r3", "r4", "r5", "r6", "r7", "vs63"

		);

	/*
	 * On leak 'unknown' will contain 'poison' value from child,
	 * otherwise (no leak) 'unknown' will contain the same value
	 * as r3 before entering in transactional mode, i.e. 0x1.
	 */
	fail_vr = unknown != 0x1;
	if (fail_vr)
		printf("Unknown value %#"PRIx64" leaked into vr31!\n", unknown);
	else
		printf("Good, no poison or leaked value into VEC registers\n");

	kill(pid, SIGKILL);

	return (fail_fp | fail_vr);
}

int main(int argc, char *argv[])
{
	/* Test completes in about 4m */
	test_harness_set_timeout(250);
	return test_harness(tm_poison_test, "tm_poison_test");
}