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, 2 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.
#	User	Rev	Content
1	cebix	1.1	/*
2			* paranoia.cpp - Check undocumented features of the Linux kernel that
3			* SheepShaver relies upon
4			*
5	gbeauche	1.3	* SheepShaver (C) 1997-2005 Christian Bauer and Marc Hellwig
6	cebix	1.1	*
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	gbeauche	1.4	extern "C" void *get_r2(void);
46			extern "C" void set_r2(void *);
47			extern "C" void *get_r13(void);
48	cebix	1.1	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	gbeauche	1.4	int raise(int sig)
63			{
64			// Reimplement to get rid of access to r2 (TLS pointer)
65			return kill(getpid(), sig);
66			}
67
68	cebix	1.1	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	gbeauche	1.4	TOC = get_r2();
107			R13 = get_r13();
108			set_r2((void *)0xaffebad5);
109	cebix	1.1	raise(SIGUSR2);
110	gbeauche	1.4	if (TOC != get_r2())
111			err = 6;
112			if (R13 != get_r13())
113			err = 7;
114	cebix	1.1
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	gbeauche	1.4	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	cebix	1.1	}
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	gbeauche	1.4	goto ret;
158	cebix	1.1	}
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	gbeauche	1.4	goto ret;
165	cebix	1.1	}
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	gbeauche	1.4	goto ret;
172	cebix	1.1	}
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	gbeauche	1.4	goto ret;
179	cebix	1.1	}
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	gbeauche	1.4	goto ret;
186	cebix	1.1	}
187	gbeauche	1.4
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	cebix	1.1	}