1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Test that signal delivery is able to expand the stack segment without
4 * triggering a SEGV.
5 *
6 * Based on test code by Tom Lane.
7 */
8
9#include <err.h>
10#include <stdio.h>
11#include <stdlib.h>
12#include <signal.h>
13#include <sys/types.h>
14#include <unistd.h>
15
16#include "../pmu/lib.h"
17#include "utils.h"
18
19#define _KB (1024)
20#define _MB (1024 * 1024)
21
22static char *stack_base_ptr;
23static char *stack_top_ptr;
24
25static volatile sig_atomic_t sig_occurred = 0;
26
27static void sigusr1_handler(int signal_arg)
28{
29	sig_occurred = 1;
30}
31
32static int consume_stack(unsigned int stack_size, union pipe write_pipe)
33{
34	char stack_cur;
35
36	if ((stack_base_ptr - &stack_cur) < stack_size)
37		return consume_stack(stack_size, write_pipe);
38	else {
39		stack_top_ptr = &stack_cur;
40
41		FAIL_IF(notify_parent(write_pipe));
42
43		while (!sig_occurred)
44			barrier();
45	}
46
47	return 0;
48}
49
50static int child(unsigned int stack_size, union pipe write_pipe)
51{
52	struct sigaction act;
53	char stack_base;
54
55	act.sa_handler = sigusr1_handler;
56	sigemptyset(&act.sa_mask);
57	act.sa_flags = 0;
58	if (sigaction(SIGUSR1, &act, NULL) < 0)
59		err(1, "sigaction");
60
61	stack_base_ptr = (char *) (((size_t) &stack_base + 65535) & ~65535UL);
62
63	FAIL_IF(consume_stack(stack_size, write_pipe));
64
65	printf("size 0x%06x: OK, stack base %p top %p (%zx used)\n",
66		stack_size, stack_base_ptr, stack_top_ptr,
67		stack_base_ptr - stack_top_ptr);
68
69	return 0;
70}
71
72static int test_one_size(unsigned int stack_size)
73{
74	union pipe read_pipe, write_pipe;
75	pid_t pid;
76
77	FAIL_IF(pipe(read_pipe.fds) == -1);
78	FAIL_IF(pipe(write_pipe.fds) == -1);
79
80	pid = fork();
81	if (pid == 0) {
82		close(read_pipe.read_fd);
83		close(write_pipe.write_fd);
84		exit(child(stack_size, read_pipe));
85	}
86
87	close(read_pipe.write_fd);
88	close(write_pipe.read_fd);
89	FAIL_IF(sync_with_child(read_pipe, write_pipe));
90
91	kill(pid, SIGUSR1);
92
93	FAIL_IF(wait_for_child(pid));
94
95	close(read_pipe.read_fd);
96	close(write_pipe.write_fd);
97
98	return 0;
99}
100
101int test(void)
102{
103	unsigned int i, size;
104
105	// Test with used stack from 1MB - 64K to 1MB + 64K
106	// Increment by 64 to get more coverage of odd sizes
107	for (i = 0; i < (128 * _KB); i += 64) {
108		size = i + (1 * _MB) - (64 * _KB);
109		FAIL_IF(test_one_size(size));
110	}
111
112	return 0;
113}
114
115int main(void)
116{
117	return test_harness(test, "stack_expansion_signal");
118}
119