1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2015, Michael Neuling, IBM Corp.
4 *
5 * Test the kernel's signal delievery code to ensure that we don't
6 * trelaim twice in the kernel signal delivery code. This can happen
7 * if we trigger a signal when in a transaction and the stack pointer
8 * is bogus.
9 *
10 * This test case registers a SEGV handler, sets the stack pointer
11 * (r1) to NULL, starts a transaction and then generates a SEGV. The
12 * SEGV should be handled but we exit here as the stack pointer is
13 * invalid and hance we can't sigreturn. We only need to check that
14 * this flow doesn't crash the kernel.
15 */
16
17 #include <unistd.h>
18 #include <sys/types.h>
19 #include <sys/wait.h>
20 #include <stdlib.h>
21 #include <stdio.h>
22 #include <signal.h>
23
24 #include "utils.h"
25 #include "tm.h"
26
signal_segv(int signum)27 void signal_segv(int signum)
28 {
29 /* This should never actually run since stack is foobar */
30 exit(1);
31 }
32
tm_signal_stack()33 int tm_signal_stack()
34 {
35 int pid;
36
37 SKIP_IF(!have_htm());
38 SKIP_IF(htm_is_synthetic());
39
40 pid = fork();
41 if (pid < 0)
42 exit(1);
43
44 if (pid) { /* Parent */
45 /*
46 * It's likely the whole machine will crash here so if
47 * the child ever exits, we are good.
48 */
49 wait(NULL);
50 return 0;
51 }
52
53 /*
54 * The flow here is:
55 * 1) register a signal handler (so signal delievery occurs)
56 * 2) make stack pointer (r1) = NULL
57 * 3) start transaction
58 * 4) cause segv
59 */
60 if (signal(SIGSEGV, signal_segv) == SIG_ERR)
61 exit(1);
62 asm volatile("li 1, 0 ;" /* stack ptr == NULL */
63 "1:"
64 "tbegin.;"
65 "beq 1b ;" /* retry forever */
66 "tsuspend.;"
67 "ld 2, 0(1) ;" /* trigger segv" */
68 : : : "memory");
69
70 /* This should never get here due to above segv */
71 return 1;
72 }
73
main(void)74 int main(void)
75 {
76 return test_harness(tm_signal_stack, "tm_signal_stack");
77 }
78