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
39 pid = fork();
40 if (pid < 0)
41 exit(1);
42
43 if (pid) { /* Parent */
44 /*
45 * It's likely the whole machine will crash here so if
46 * the child ever exits, we are good.
47 */
48 wait(NULL);
49 return 0;
50 }
51
52 /*
53 * The flow here is:
54 * 1) register a signal handler (so signal delievery occurs)
55 * 2) make stack pointer (r1) = NULL
56 * 3) start transaction
57 * 4) cause segv
58 */
59 if (signal(SIGSEGV, signal_segv) == SIG_ERR)
60 exit(1);
61 asm volatile("li 1, 0 ;" /* stack ptr == NULL */
62 "1:"
63 "tbegin.;"
64 "beq 1b ;" /* retry forever */
65 "tsuspend.;"
66 "ld 2, 0(1) ;" /* trigger segv" */
67 : : : "memory");
68
69 /* This should never get here due to above segv */
70 return 1;
71 }
72
main(void)73 int main(void)
74 {
75 return test_harness(tm_signal_stack, "tm_signal_stack");
76 }
77