Unix/Linux/paranoia.cpp

/*
 *  paranoia.cpp - Check undocumented features of the Linux kernel that
 *                 SheepShaver relies upon
 *
 *  SheepShaver (C) 1997-2005 Christian Bauer and Marc Hellwig
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <errno.h>

#include "sysdeps.h"
#include "main.h"
#include "user_strings.h"

typedef struct {
        uint32 u[4];
} __attribute((aligned(16))) vector128;
#include <linux/elf.h>

#define DEBUG 1
#include "debug.h"


// Constants
const uint32 SIG_STACK_SIZE = 0x10000;          // Size of signal stack

// Prototypes
extern "C" void *get_sp(void);
extern "C" void *get_r2(void);
extern "C" void set_r2(void *);
extern "C" void *get_r13(void);
extern void paranoia_check(void);
static void sigusr2_handler(int sig, sigcontext_struct *sc);

// Global variables
static void *sig_stack = NULL;

static int err = 0;
static void *sig_sp = NULL;
static void *sig_r4 = NULL;
static int sig_sc_signal = 0;
static void *sig_sc_regs = NULL;
static uint32 sig_r2 = 0;


int raise(int sig)
{
        // Reimplement to get rid of access to r2 (TLS pointer)
        return kill(getpid(), sig);
}

void paranoia_check(void)
{
        char str[256];

        D(bug("Paranoia checks...\n"));

        // Create and install stack for signal handler
        sig_stack = malloc(SIG_STACK_SIZE);
        if (sig_stack == NULL) {
                ErrorAlert(GetString(STR_NOT_ENOUGH_MEMORY_ERR));
                exit(1);
        }

        struct sigaltstack old_stack;
        struct sigaltstack new_stack;
        new_stack.ss_sp = sig_stack;
        new_stack.ss_flags = 0;
        new_stack.ss_size = SIG_STACK_SIZE;
        if (sigaltstack(&new_stack, &old_stack) < 0) {
                sprintf(str, GetString(STR_SIGALTSTACK_ERR), strerror(errno));
                ErrorAlert(str);
                exit(1);
        }

        // Install SIGUSR2 signal handler
        static struct sigaction old_action;
        static struct sigaction sigusr2_action;
        sigemptyset(&sigusr2_action.sa_mask);
        sigusr2_action.sa_handler = (__sighandler_t)sigusr2_handler;
        sigusr2_action.sa_flags = SA_ONSTACK | SA_RESTART;
        sigusr2_action.sa_restorer = NULL;
        if (sigaction(SIGUSR2, &sigusr2_action, &old_action) < 0) {
                sprintf(str, GetString(STR_SIGUSR2_INSTALL_ERR), strerror(errno));
                ErrorAlert(str);
                exit(1);
        }

        // Raise SIGUSR2
        TOC = get_r2();
        R13 = get_r13();
        set_r2((void *)0xaffebad5);
        raise(SIGUSR2);
        if (TOC != get_r2())
                err = 6;
        if (R13 != get_r13())
                err = 7;

        // Check error code
        switch (err) {
                case 1:
                        printf("FATAL: sigaltstack() doesn't seem to work (sp in signal handler was %08lx, expected %08lx..%08lx)\n", (uint32)sig_sp, (uint32)sig_stack, (uint32)sig_stack + SIG_STACK_SIZE);
                        break;
                case 2:
                        printf("FATAL: r4 in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_r4);
                        break;
                case 3:
                        printf("FATAL: r4 in signal handler doesn't seem to point to a sigcontext_struct (signal number was %d, expected %d)", sig_sc_signal, SIGUSR2);
                        break;
                case 4:
                        printf("FATAL: sc->regs in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_sc_regs);
                        break;
                case 5:
                        printf("FATAL: sc->regs->gpr[2] in signal handler (%08lx) doesn't have expected value (%08x)\n", (uint32)sig_r2, 0xaffebad5);
                        break;
                case 6:
                        printf("FATAL: signal handler failed to restore initial r2 value (%08x, was %08x)\n", (uint32)get_r2(), (uint32)TOC);
                        break;
                case 7:
                        printf("FATAL: signal handler failed to restore initial r13 value (%08x, was %08x)\n", get_r13(), (uint32)R13);
        }
        if (err) {
                printf("Maybe you need a different kernel?\n");
                exit(1);
        }

        // Clean up
        D(bug("...passed\n"));
        sigaction(SIGUSR2, &old_action, NULL);
        sigaltstack(&old_stack, NULL);
        free(sig_stack);
}


static void sigusr2_handler(int sig, sigcontext_struct *sc)
{
        // Check whether sigaltstack works
        sig_sp = get_sp();
        if (sig_sp < sig_stack || sig_sp >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
                err = 1;
                goto ret;
        }

        // Check whether r4 points to info on the stack
        sig_r4 = sc;
        if (sig_r4 < sig_stack || sig_r4 >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
                err = 2;
                goto ret;
        }

        // Check whether r4 looks like a sigcontext
        sig_sc_signal = sc->signal;
        if (sig_sc_signal != SIGUSR2) {
                err = 3;
                goto ret;
        }

        // Check whether sc->regs points to info on the stack
        sig_sc_regs = sc->regs;
        if (sig_sc_regs < sig_stack || sig_sc_regs >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
                err = 4;
                goto ret;
        }

        // Check whether r2 still holds the value we set it to
        sig_r2 = sc->regs->gpr[2];
        if (sig_r2 != 0xaffebad5) {
                err = 5;
                goto ret;
        }

        // Restore pointer to Thread Local Storage
  ret:
#ifdef SYSTEM_CLOBBERS_R2
        sc->regs->gpr[2] = (unsigned long)TOC;
#endif
}
Revision:	1.5
Committed:	2005-07-04T06:09:59Z (19 years, 4 months ago) by gbeauche
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.4:	+0 -0 lines
State:	*FILE REMOVED*
Log Message:	New paranoia checks that better match was SheepShaver is doing with threads and sigaltstack(). At least, this time we force use of threads and also alter r1 to see whether the current threading model relies on it or not.
#	Content
1	/*
2	* paranoia.cpp - Check undocumented features of the Linux kernel that
3	* SheepShaver relies upon
4	*
5	* SheepShaver (C) 1997-2005 Christian Bauer and Marc Hellwig
6	*
7	* This program is free software; you can redistribute it and/or modify
8	* it under the terms of the GNU General Public License as published by
9	* the Free Software Foundation; either version 2 of the License, or
10	* (at your option) any later version.
11	*
12	* This program is distributed in the hope that it will be useful,
13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15	* GNU General Public License for more details.
16	*
17	* You should have received a copy of the GNU General Public License
18	* along with this program; if not, write to the Free Software
19	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20	*/
21
22	#include <unistd.h>
23	#include <stdio.h>
24	#include <signal.h>
25	#include <errno.h>
26
27	#include "sysdeps.h"
28	#include "main.h"
29	#include "user_strings.h"
30
31	typedef struct {
32	uint32 u[4];
33	} __attribute((aligned(16))) vector128;
34	#include <linux/elf.h>
35
36	#define DEBUG 1
37	#include "debug.h"
38
39
40	// Constants
41	const uint32 SIG_STACK_SIZE = 0x10000; // Size of signal stack
42
43	// Prototypes
44	extern "C" void *get_sp(void);
45	extern "C" void *get_r2(void);
46	extern "C" void set_r2(void *);
47	extern "C" void *get_r13(void);
48	extern void paranoia_check(void);
49	static void sigusr2_handler(int sig, sigcontext_struct *sc);
50
51	// Global variables
52	static void *sig_stack = NULL;
53
54	static int err = 0;
55	static void *sig_sp = NULL;
56	static void *sig_r4 = NULL;
57	static int sig_sc_signal = 0;
58	static void *sig_sc_regs = NULL;
59	static uint32 sig_r2 = 0;
60
61
62	int raise(int sig)
63	{
64	// Reimplement to get rid of access to r2 (TLS pointer)
65	return kill(getpid(), sig);
66	}
67
68	void paranoia_check(void)
69	{
70	char str[256];
71
72	D(bug("Paranoia checks...\n"));
73
74	// Create and install stack for signal handler
75	sig_stack = malloc(SIG_STACK_SIZE);
76	if (sig_stack == NULL) {
77	ErrorAlert(GetString(STR_NOT_ENOUGH_MEMORY_ERR));
78	exit(1);
79	}
80
81	struct sigaltstack old_stack;
82	struct sigaltstack new_stack;
83	new_stack.ss_sp = sig_stack;
84	new_stack.ss_flags = 0;
85	new_stack.ss_size = SIG_STACK_SIZE;
86	if (sigaltstack(&new_stack, &old_stack) < 0) {
87	sprintf(str, GetString(STR_SIGALTSTACK_ERR), strerror(errno));
88	ErrorAlert(str);
89	exit(1);
90	}
91
92	// Install SIGUSR2 signal handler
93	static struct sigaction old_action;
94	static struct sigaction sigusr2_action;
95	sigemptyset(&sigusr2_action.sa_mask);
96	sigusr2_action.sa_handler = (__sighandler_t)sigusr2_handler;
97	sigusr2_action.sa_flags = SA_ONSTACK \| SA_RESTART;
98	sigusr2_action.sa_restorer = NULL;
99	if (sigaction(SIGUSR2, &sigusr2_action, &old_action) < 0) {
100	sprintf(str, GetString(STR_SIGUSR2_INSTALL_ERR), strerror(errno));
101	ErrorAlert(str);
102	exit(1);
103	}
104
105	// Raise SIGUSR2
106	TOC = get_r2();
107	R13 = get_r13();
108	set_r2((void *)0xaffebad5);
109	raise(SIGUSR2);
110	if (TOC != get_r2())
111	err = 6;
112	if (R13 != get_r13())
113	err = 7;
114
115	// Check error code
116	switch (err) {
117	case 1:
118	printf("FATAL: sigaltstack() doesn't seem to work (sp in signal handler was %08lx, expected %08lx..%08lx)\n", (uint32)sig_sp, (uint32)sig_stack, (uint32)sig_stack + SIG_STACK_SIZE);
119	break;
120	case 2:
121	printf("FATAL: r4 in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_r4);
122	break;
123	case 3:
124	printf("FATAL: r4 in signal handler doesn't seem to point to a sigcontext_struct (signal number was %d, expected %d)", sig_sc_signal, SIGUSR2);
125	break;
126	case 4:
127	printf("FATAL: sc->regs in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_sc_regs);
128	break;
129	case 5:
130	printf("FATAL: sc->regs->gpr[2] in signal handler (%08lx) doesn't have expected value (%08x)\n", (uint32)sig_r2, 0xaffebad5);
131	break;
132	case 6:
133	printf("FATAL: signal handler failed to restore initial r2 value (%08x, was %08x)\n", (uint32)get_r2(), (uint32)TOC);
134	break;
135	case 7:
136	printf("FATAL: signal handler failed to restore initial r13 value (%08x, was %08x)\n", get_r13(), (uint32)R13);
137	}
138	if (err) {
139	printf("Maybe you need a different kernel?\n");
140	exit(1);
141	}
142
143	// Clean up
144	D(bug("...passed\n"));
145	sigaction(SIGUSR2, &old_action, NULL);
146	sigaltstack(&old_stack, NULL);
147	free(sig_stack);
148	}
149
150
151	static void sigusr2_handler(int sig, sigcontext_struct *sc)
152	{
153	// Check whether sigaltstack works
154	sig_sp = get_sp();
155	if (sig_sp < sig_stack \|\| sig_sp >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
156	err = 1;
157	goto ret;
158	}
159
160	// Check whether r4 points to info on the stack
161	sig_r4 = sc;
162	if (sig_r4 < sig_stack \|\| sig_r4 >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
163	err = 2;
164	goto ret;
165	}
166
167	// Check whether r4 looks like a sigcontext
168	sig_sc_signal = sc->signal;
169	if (sig_sc_signal != SIGUSR2) {
170	err = 3;
171	goto ret;
172	}
173
174	// Check whether sc->regs points to info on the stack
175	sig_sc_regs = sc->regs;
176	if (sig_sc_regs < sig_stack \|\| sig_sc_regs >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
177	err = 4;
178	goto ret;
179	}
180
181	// Check whether r2 still holds the value we set it to
182	sig_r2 = sc->regs->gpr[2];
183	if (sig_r2 != 0xaffebad5) {
184	err = 5;
185	goto ret;
186	}
187
188	// Restore pointer to Thread Local Storage
189	ret:
190	#ifdef SYSTEM_CLOBBERS_R2
191	sc->regs->gpr[2] = (unsigned long)TOC;
192	#endif
193	}