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