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
27void signal_segv(int signum)
28{
29	/* This should never actually run since stack is foobar */
30	exit(1);
31}
32
33int 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
74int main(void)
75{
76	return test_harness(tm_signal_stack, "tm_signal_stack");
77}
78