src/Unix/sigsegv.cpp

/*
 *  sigsegv.cpp - SIGSEGV signals support
 *
 *  Derived from Bruno Haible's work on his SIGSEGV library for clisp
 *  <http://clisp.sourceforge.net/>
 *
 *  Basilisk II (C) 1997-2002 Christian Bauer
 *
 *  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
 */

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <signal.h>
#include "sigsegv.h"

// Return value type of a signal handler (standard type if not defined)
#ifndef RETSIGTYPE
#define RETSIGTYPE void
#endif

// Type of the system signal handler
typedef RETSIGTYPE (*signal_handler)(int);

// Is the fault to be ignored?
static bool sigsegv_ignore_fault = false;

// User's SIGSEGV handler
static sigsegv_handler_t sigsegv_user_handler = 0;

// Function called to dump state if we can't handle the fault
static sigsegv_handler_t sigsegv_dump_state = 0;

// Actual SIGSEGV handler installer
static bool sigsegv_do_install_handler(int sig);


/*
 *  OS-dependant SIGSEGV signals support section
 */

#if HAVE_SIGINFO_T
// Generic extended signal handler
#if defined(__NetBSD__) || defined(__FreeBSD__)
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGBUS)
#else
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGSEGV)
#endif
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, siginfo_t *sip, void *scp
#define SIGSEGV_FAULT_ADDRESS                   sip->si_addr
#if defined(__linux__)
#if (defined(i386) || defined(__i386__))
#include <sys/ucontext.h>
#define SIGSEGV_FAULT_INSTRUCTION               (((ucontext_t *)scp)->uc_mcontext.gregs[14]) /* should use REG_EIP instead */
#define SIGSEGV_REGISTER_FILE                   (unsigned long *)(((ucontext_t *)scp)->uc_mcontext.gregs)
#define SIGSEGV_SKIP_INSTRUCTION                ix86_skip_instruction
#endif
#if (defined(ia64) || defined(__ia64__))
#define SIGSEGV_FAULT_INSTRUCTION               (((struct sigcontext *)scp)->sc_ip & ~0x3ULL) /* slot number is in bits 0 and 1 */
#endif
#if (defined(powerpc) || defined(__powerpc__))
#include <sys/ucontext.h>
#define SIGSEGV_FAULT_INSTRUCTION               (((ucontext_t *)scp)->uc_mcontext.regs->nip)
#endif
#endif
#endif

#if HAVE_SIGCONTEXT_SUBTERFUGE
// Linux kernels prior to 2.4 ?
#if defined(__linux__)
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGSEGV)
#if (defined(i386) || defined(__i386__))
#include <asm/sigcontext.h>
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, struct sigcontext scs
#define SIGSEGV_FAULT_ADDRESS                   scs.cr2
#define SIGSEGV_FAULT_INSTRUCTION               scs.eip
#define SIGSEGV_REGISTER_FILE                   (unsigned long *)(&scs)
#define SIGSEGV_SKIP_INSTRUCTION                ix86_skip_instruction
#endif
#if (defined(sparc) || defined(__sparc__))
#include <asm/sigcontext.h>
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp, char *addr
#define SIGSEGV_FAULT_ADDRESS                   addr
#endif
#if (defined(powerpc) || defined(__powerpc__))
#include <asm/sigcontext.h>
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   scp->regs->dar
#define SIGSEGV_FAULT_INSTRUCTION               scp->regs->nip
#endif
#if (defined(alpha) || defined(__alpha__))
#include <asm/sigcontext.h>
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   get_fault_address(scp)
#define SIGSEGV_FAULT_INSTRUCTION               scp->sc_pc

// From Boehm's GC 6.0alpha8
static sigsegv_address_t get_fault_address(struct sigcontext *scp)
{
        unsigned int instruction = *((unsigned int *)(scp->sc_pc));
        unsigned long fault_address = scp->sc_regs[(instruction >> 16) & 0x1f];
        fault_address += (signed long)(signed short)(instruction & 0xffff);
        return (sigsegv_address_t)fault_address;
}
#endif
#endif

// Irix 5 or 6 on MIPS
#if (defined(sgi) || defined(__sgi)) && (defined(SYSTYPE_SVR4) || defined(__SYSTYPE_SVR4))
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   scp->sc_badvaddr
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGSEGV)
#endif

// OSF/1 on Alpha
#if defined(__osf__)
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   scp->sc_traparg_a0
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGSEGV)
#endif

// AIX
#if defined(_AIX)
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   scp->sc_jmpbuf.jmp_context.o_vaddr
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGSEGV)
#endif

// NetBSD or FreeBSD
#if defined(__NetBSD__) || defined(__FreeBSD__)
#if (defined(m68k) || defined(__m68k__))
#include <m68k/frame.h>
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   ({                                                                                                                              \
        struct sigstate {                                                                                                                                                                       \
                int ss_flags;                                                                                                                                                                   \
                struct frame ss_frame;                                                                                                                                                  \
        };                                                                                                                                                                                                      \
        struct sigstate *state = (struct sigstate *)scp->sc_ap;                                                                                         \
        char *fault_addr;                                                                                                                                                                       \
        switch (state->ss_frame.f_format) {                                                                                                                                     \
        case 7:         /* 68040 access error */                                                                                                                                \
                /* "code" is sometimes unreliable (i.e. contains NULL or a bogus address), reason unknown */    \
                fault_addr = state->ss_frame.f_fmt7.f_fa;                                                                                                               \
                break;                                                                                                                                                                                  \
        default:                                                                                                                                                                                        \
                fault_addr = (char *)code;                                                                                                                                              \
                break;                                                                                                                                                                                  \
        }                                                                                                                                                                                                       \
        fault_addr;                                                                                                                                                                                     \
})
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGSEGV)
#else
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, void *scp, char *addr
#define SIGSEGV_FAULT_ADDRESS                   addr
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGBUS)
#endif
#endif

// MacOS X
#if defined(__APPLE__) && defined(__MACH__)
#if (defined(ppc) || defined(__ppc__))
#define SIGSEGV_FAULT_HANDLER_ARGLIST   int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_ADDRESS                   get_fault_address(scp)
#define SIGSEGV_FAULT_INSTRUCTION               scp->sc_ir
#define SIGSEGV_ALL_SIGNALS                             FAULT_HANDLER(SIGBUS)

// From Boehm's GC 6.0alpha8
#define EXTRACT_OP1(iw)     (((iw) & 0xFC000000) >> 26)
#define EXTRACT_OP2(iw)     (((iw) & 0x000007FE) >> 1)
#define EXTRACT_REGA(iw)    (((iw) & 0x001F0000) >> 16)
#define EXTRACT_REGB(iw)    (((iw) & 0x03E00000) >> 21)
#define EXTRACT_REGC(iw)    (((iw) & 0x0000F800) >> 11)
#define EXTRACT_DISP(iw)    ((short *) &(iw))[1]

static sigsegv_address_t get_fault_address(struct sigcontext *scp)
{
        unsigned int   instr = *((unsigned int *) scp->sc_ir);
        unsigned int * regs = &((unsigned int *) scp->sc_regs)[2];
        int            disp = 0, tmp;
        unsigned int   baseA = 0, baseB = 0;
        unsigned int   addr, alignmask = 0xFFFFFFFF;

        switch(EXTRACT_OP1(instr)) {
        case 38:   /* stb */
        case 39:   /* stbu */
        case 54:   /* stfd */
        case 55:   /* stfdu */
        case 52:   /* stfs */
        case 53:   /* stfsu */
        case 44:   /* sth */
        case 45:   /* sthu */
        case 47:   /* stmw */
        case 36:   /* stw */
        case 37:   /* stwu */
                tmp = EXTRACT_REGA(instr);
                if(tmp > 0)
                        baseA = regs[tmp];
                disp = EXTRACT_DISP(instr);
                break;
        case 31:
                switch(EXTRACT_OP2(instr)) {
                case 86:    /* dcbf */
                case 54:    /* dcbst */
                case 1014:  /* dcbz */
                case 247:   /* stbux */
                case 215:   /* stbx */
                case 759:   /* stfdux */
                case 727:   /* stfdx */
                case 983:   /* stfiwx */
                case 695:   /* stfsux */
                case 663:   /* stfsx */
                case 918:   /* sthbrx */
                case 439:   /* sthux */
                case 407:   /* sthx */
                case 661:   /* stswx */
                case 662:   /* stwbrx */
                case 150:   /* stwcx. */
                case 183:   /* stwux */
                case 151:   /* stwx */
                case 135:   /* stvebx */
                case 167:   /* stvehx */
                case 199:   /* stvewx */
                case 231:   /* stvx */
                case 487:   /* stvxl */
                        tmp = EXTRACT_REGA(instr);
                        if(tmp > 0)
                                baseA = regs[tmp];
                        baseB = regs[EXTRACT_REGC(instr)];
                        /* determine Altivec alignment mask */
                        switch(EXTRACT_OP2(instr)) {
                        case 167:   /* stvehx */
                                alignmask = 0xFFFFFFFE;
                                break;
                        case 199:   /* stvewx */
                                alignmask = 0xFFFFFFFC;
                                break;
                        case 231:   /* stvx */
                                alignmask = 0xFFFFFFF0;
                                break;
                        case 487:  /* stvxl */
                                alignmask = 0xFFFFFFF0;
                                break;
                        }
                        break;
                case 725:   /* stswi */
                        tmp = EXTRACT_REGA(instr);
                        if(tmp > 0)
                                baseA = regs[tmp];
                        break;
                default:   /* ignore instruction */
                        return 0;
                        break;
                }
                break;
        default:   /* ignore instruction */
                return 0;
                break;
        }
        
        addr = (baseA + baseB) + disp;
        addr &= alignmask;
        return (sigsegv_address_t)addr;
}
#endif
#endif
#endif

#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
// Decode and skip X86 instruction
#if (defined(i386) || defined(__i386__))
#if defined(__linux__)
enum {
        X86_REG_EIP = 14,
        X86_REG_EAX = 11,
        X86_REG_ECX = 10,
        X86_REG_EDX = 9,
        X86_REG_EBX = 8,
        X86_REG_ESP = 7,
        X86_REG_EBP = 6,
        X86_REG_ESI = 5,
        X86_REG_EDI = 4
};
#endif
// FIXME: this is partly redundant with the instruction decoding phase
// to discover transfer type and register number
static inline int ix86_step_over_modrm(unsigned char * p)
{
        int mod = (p[0] >> 6) & 3;
        int rm = p[0] & 7;
        int offset = 0;

        // ModR/M Byte
        switch (mod) {
        case 0: // [reg]
                if (rm == 5) return 4; // disp32
                break;
        case 1: // disp8[reg]
                offset = 1;
                break;
        case 2: // disp32[reg]
                offset = 4;
                break;
        case 3: // register
                return 0;
        }
        
        // SIB Byte
        if (rm == 4) {
                if (mod == 0 && (p[1] & 7) == 5)
                        offset = 5; // disp32[index]
                else
                        offset++;
        }

        return offset;
}

static bool ix86_skip_instruction(sigsegv_address_t fault_instruction, unsigned long * regs)
{
        unsigned char * eip = (unsigned char *)fault_instruction;

        if (eip == 0)
                return false;
        
        // Transfer type
        enum {
                TYPE_UNKNOWN,
                TYPE_LOAD,
                TYPE_STORE
        } transfer_type = TYPE_UNKNOWN;
        
        // Transfer size
        enum {
                SIZE_BYTE,
                SIZE_WORD,
                SIZE_LONG
        } transfer_size = SIZE_LONG;
        
        int reg = -1;
        int len = 0;
        
        // Operand size prefix
        if (*eip == 0x66) {
                eip++;
                len++;
                transfer_size = SIZE_WORD;
        }

        // Decode instruction
        switch (eip[0]) {
        case 0x8a: // MOV r8, r/m8
                transfer_size = SIZE_BYTE;
        case 0x8b: // MOV r32, r/m32 (or 16-bit operation)
                switch (eip[1] & 0xc0) {
                case 0x80:
                        reg = (eip[1] >> 3) & 7;
                        transfer_type = TYPE_LOAD;
                        break;
                case 0x40:
                        reg = (eip[1] >> 3) & 7;
                        transfer_type = TYPE_LOAD;
                        break;
                case 0x00:
                        reg = (eip[1] >> 3) & 7;
                        transfer_type = TYPE_LOAD;
                        break;
                }
                len += 2 + ix86_step_over_modrm(eip + 1);
                break;
        case 0x88: // MOV r/m8, r8
                transfer_size = SIZE_BYTE;
        case 0x89: // MOV r/m32, r32 (or 16-bit operation)
                switch (eip[1] & 0xc0) {
                case 0x80:
                        reg = (eip[1] >> 3) & 7;
                        transfer_type = TYPE_STORE;
                        break;
                case 0x40:
                        reg = (eip[1] >> 3) & 7;
                        transfer_type = TYPE_STORE;
                        break;
                case 0x00:
                        reg = (eip[1] >> 3) & 7;
                        transfer_type = TYPE_STORE;
                        break;
                }
                len += 2 + ix86_step_over_modrm(eip + 1);
                break;
        }

        if (transfer_type == TYPE_UNKNOWN) {
                // Unknown machine code, let it crash. Then patch the decoder
                return false;
        }

        if (transfer_type == TYPE_LOAD && reg != -1) {
                static const int x86_reg_map[8] = {
                        X86_REG_EAX, X86_REG_ECX, X86_REG_EDX, X86_REG_EBX,
                        X86_REG_ESP, X86_REG_EBP, X86_REG_ESI, X86_REG_EDI
                };
                
                if (reg < 0 || reg >= 8)
                        return false;

                int rloc = x86_reg_map[reg];
                switch (transfer_size) {
                case SIZE_BYTE:
                        regs[rloc] = (regs[rloc] & ~0xff);
                        break;
                case SIZE_WORD:
                        regs[rloc] = (regs[rloc] & ~0xffff);
                        break;
                case SIZE_LONG:
                        regs[rloc] = 0;
                        break;
                }
        }

#if DEBUG
        printf("%08x: %s %s access", regs[X86_REG_EIP],
                   transfer_size == SIZE_BYTE ? "byte" : transfer_size == SIZE_WORD ? "word" : "long",
                   transfer_type == TYPE_LOAD ? "read" : "write");
        
        if (reg != -1) {
                static const char * x86_reg_str_map[8] = {
                        "eax", "ecx", "edx", "ebx",
                        "esp", "ebp", "esi", "edi"
                };
                printf(" %s register %%%s", transfer_type == TYPE_LOAD ? "to" : "from", x86_reg_str_map[reg]);
        }
        printf(", %d bytes instruction\n", len);
#endif
        
        regs[X86_REG_EIP] += len;
        return true;
}
#endif
#endif

// Fallbacks
#ifndef SIGSEGV_FAULT_INSTRUCTION
#define SIGSEGV_FAULT_INSTRUCTION               SIGSEGV_INVALID_PC
#endif

// SIGSEGV recovery supported ?
#if defined(SIGSEGV_ALL_SIGNALS) && defined(SIGSEGV_FAULT_HANDLER_ARGLIST) && defined(SIGSEGV_FAULT_ADDRESS)
#define HAVE_SIGSEGV_RECOVERY
#endif


/*
 *  SIGSEGV global handler
 */

#ifdef HAVE_SIGSEGV_RECOVERY
static void sigsegv_handler(SIGSEGV_FAULT_HANDLER_ARGLIST)
{
        sigsegv_address_t fault_address = (sigsegv_address_t)SIGSEGV_FAULT_ADDRESS;
        sigsegv_address_t fault_instruction = (sigsegv_address_t)SIGSEGV_FAULT_INSTRUCTION;
        bool fault_recovered = false;
        
        // Call user's handler and reinstall the global handler, if required
        if (sigsegv_user_handler(fault_address, fault_instruction)) {
#if (defined(HAVE_SIGACTION) ? defined(SIGACTION_NEED_REINSTALL) : defined(SIGNAL_NEED_REINSTALL))
                sigsegv_do_install_handler(sig);
#endif
                fault_recovered = true;
        }
#if HAVE_SIGSEGV_SKIP_INSTRUCTION
        else if (sigsegv_ignore_fault) {
                // Call the instruction skipper with the register file available
                if (SIGSEGV_SKIP_INSTRUCTION(fault_instruction, SIGSEGV_REGISTER_FILE))
                        fault_recovered = true;
        }
#endif

        if (!fault_recovered) {
                // FAIL: reinstall default handler for "safe" crash
#define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
                SIGSEGV_ALL_SIGNALS
#undef FAULT_HANDLER
                
                // We can't do anything with the fault_address, dump state?
                if (sigsegv_dump_state != 0)
                        sigsegv_dump_state(fault_address, fault_instruction);
        }
}
#endif


/*
 *  SIGSEGV handler initialization
 */

#if defined(HAVE_SIGINFO_T)
static bool sigsegv_do_install_handler(int sig)
{
        // Setup SIGSEGV handler to process writes to frame buffer
#ifdef HAVE_SIGACTION
        struct sigaction vosf_sa;
        sigemptyset(&vosf_sa.sa_mask);
        vosf_sa.sa_sigaction = sigsegv_handler;
        vosf_sa.sa_flags = SA_SIGINFO;
        return (sigaction(sig, &vosf_sa, 0) == 0);
#else
        return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
#endif
}
#endif

#if defined(HAVE_SIGCONTEXT_SUBTERFUGE)
static bool sigsegv_do_install_handler(int sig)
{
        // Setup SIGSEGV handler to process writes to frame buffer
#ifdef HAVE_SIGACTION
        struct sigaction vosf_sa;
        sigemptyset(&vosf_sa.sa_mask);
        vosf_sa.sa_handler = (signal_handler)sigsegv_handler;
#if !EMULATED_68K && defined(__NetBSD__)
        sigaddset(&vosf_sa.sa_mask, SIGALRM);
        vosf_sa.sa_flags = SA_ONSTACK;
#else
        vosf_sa.sa_flags = 0;
#endif
        return (sigaction(sig, &vosf_sa, 0) == 0);
#else
        return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
#endif
}
#endif

bool sigsegv_install_handler(sigsegv_handler_t handler)
{
#ifdef HAVE_SIGSEGV_RECOVERY
        sigsegv_user_handler = handler;
        bool success = true;
#define FAULT_HANDLER(sig) success = success && sigsegv_do_install_handler(sig);
        SIGSEGV_ALL_SIGNALS
#undef FAULT_HANDLER
        return success;
#else
        // FAIL: no siginfo_t nor sigcontext subterfuge is available
        return false;
#endif
}


/*
 *  SIGSEGV handler deinitialization
 */

void sigsegv_deinstall_handler(void)
{
#ifdef HAVE_SIGSEGV_RECOVERY
        sigsegv_user_handler = 0;
#define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
        SIGSEGV_ALL_SIGNALS
#undef FAULT_HANDLER
#endif
}


/*
 *  SIGSEGV ignore state modifier
 */

void sigsegv_set_ignore_state(bool ignore_fault)
{
        sigsegv_ignore_fault = ignore_fault;
}


/*
 *  Set callback function when we cannot handle the fault
 */

void sigsegv_set_dump_state(sigsegv_handler_t handler)
{
        sigsegv_dump_state = handler;
}


/*
 *  Test program used for configure/test
 */

#ifdef CONFIGURE_TEST_SIGSEGV_RECOVERY
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#include "vm_alloc.h"

static int page_size;
static volatile char * page = 0;
static volatile int handler_called = 0;

static bool sigsegv_test_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
{
        handler_called++;
        if ((fault_address - 123) != page)
                exit(1);
        if (vm_protect((char *)((unsigned long)fault_address & -page_size), page_size, VM_PAGE_READ | VM_PAGE_WRITE) != 0)
                exit(1);
        return true;
}

#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
static bool sigsegv_insn_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
{
        return false;
}
#endif

int main(void)
{
        if (vm_init() < 0)
                return 1;

        page_size = getpagesize();
        if ((page = (char *)vm_acquire(page_size)) == VM_MAP_FAILED)
                return 1;
        
        if (vm_protect((char *)page, page_size, VM_PAGE_READ) < 0)
                return 1;
        
        if (!sigsegv_install_handler(sigsegv_test_handler))
                return 1;
        
        page[123] = 45;
        page[123] = 45;
        
        if (handler_called != 1)
                return 1;

#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
        if (!sigsegv_install_handler(sigsegv_insn_handler))
                return 1;
        
        if (vm_protect((char *)page, page_size, VM_PAGE_WRITE) < 0)
                return 1;
        
        for (int i = 0; i < page_size; i++)
                page[i] = (i + 1) % page_size;
        
        if (vm_protect((char *)page, page_size, VM_PAGE_NOACCESS) < 0)
                return 1;
        
        sigsegv_set_ignore_state(true);

#define TEST_SKIP_INSTRUCTION(TYPE) do {                                \
                const unsigned int TAG = 0x12345678;                    \
                TYPE data = *((TYPE *)(page + sizeof(TYPE)));   \
                volatile unsigned int effect = data + TAG;              \
                if (effect != TAG)                                                              \
                        return 1;                                                                       \
        } while (0)
        
        TEST_SKIP_INSTRUCTION(unsigned char);
        TEST_SKIP_INSTRUCTION(unsigned short);
        TEST_SKIP_INSTRUCTION(unsigned int);
#endif

        vm_exit();
        return 0;
}
#endif
Revision:	1.10
Committed:	2002-05-12T11:10:50Z (22 years, 2 months ago) by gbeauche
Branch:	MAIN
Changes since 1.9:	+257 -2 lines
Log Message:	Implement the "ignoresegv" feature from SheepShaver. This is Unix-specific so far. Target platform is currently Linux/x86.
#	User	Rev	Content
1	gbeauche	1.1	/*
2			* sigsegv.cpp - SIGSEGV signals support
3			*
4			* Derived from Bruno Haible's work on his SIGSEGV library for clisp
5			* <http://clisp.sourceforge.net/>
6			*
7	cebix	1.7	* Basilisk II (C) 1997-2002 Christian Bauer
8	gbeauche	1.1	*
9			* This program is free software; you can redistribute it and/or modify
10			* it under the terms of the GNU General Public License as published by
11			* the Free Software Foundation; either version 2 of the License, or
12			* (at your option) any later version.
13			*
14			* This program is distributed in the hope that it will be useful,
15			* but WITHOUT ANY WARRANTY; without even the implied warranty of
16			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17			* GNU General Public License for more details.
18			*
19			* You should have received a copy of the GNU General Public License
20			* along with this program; if not, write to the Free Software
21			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22			*/
23
24			#ifdef HAVE_UNISTD_H
25			#include <unistd.h>
26			#endif
27
28			#ifdef HAVE_CONFIG_H
29			#include "config.h"
30			#endif
31
32			#include <signal.h>
33			#include "sigsegv.h"
34
35			// Return value type of a signal handler (standard type if not defined)
36			#ifndef RETSIGTYPE
37			#define RETSIGTYPE void
38			#endif
39
40			// Type of the system signal handler
41			typedef RETSIGTYPE (*signal_handler)(int);
42
43	gbeauche	1.10	// Is the fault to be ignored?
44			static bool sigsegv_ignore_fault = false;
45
46	gbeauche	1.1	// User's SIGSEGV handler
47			static sigsegv_handler_t sigsegv_user_handler = 0;
48
49	gbeauche	1.10	// Function called to dump state if we can't handle the fault
50			static sigsegv_handler_t sigsegv_dump_state = 0;
51
52	gbeauche	1.1	// Actual SIGSEGV handler installer
53			static bool sigsegv_do_install_handler(int sig);
54
55
56			/*
57			* OS-dependant SIGSEGV signals support section
58			*/
59
60			#if HAVE_SIGINFO_T
61			// Generic extended signal handler
62	cebix	1.8	#if defined(__NetBSD__) \|\| defined(__FreeBSD__)
63			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
64			#else
65	gbeauche	1.1	#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
66	cebix	1.8	#endif
67	gbeauche	1.5	#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, siginfo_t sip, void scp
68	gbeauche	1.1	#define SIGSEGV_FAULT_ADDRESS sip->si_addr
69	gbeauche	1.5	#if defined(__linux__)
70	gbeauche	1.6	#if (defined(i386) \|\| defined(__i386__))
71			#include <sys/ucontext.h>
72			#define SIGSEGV_FAULT_INSTRUCTION (((ucontext_t )scp)->uc_mcontext.gregs[14]) / should use REG_EIP instead */
73	gbeauche	1.10	#define SIGSEGV_REGISTER_FILE (unsigned long )(((ucontext_t )scp)->uc_mcontext.gregs)
74			#define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
75	gbeauche	1.6	#endif
76	gbeauche	1.5	#if (defined(ia64) \|\| defined(__ia64__))
77			#define SIGSEGV_FAULT_INSTRUCTION (((struct sigcontext )scp)->sc_ip & ~0x3ULL) / slot number is in bits 0 and 1 */
78			#endif
79	gbeauche	1.9	#if (defined(powerpc) \|\| defined(__powerpc__))
80			#include <sys/ucontext.h>
81			#define SIGSEGV_FAULT_INSTRUCTION (((ucontext_t *)scp)->uc_mcontext.regs->nip)
82			#endif
83	gbeauche	1.5	#endif
84	gbeauche	1.1	#endif
85
86			#if HAVE_SIGCONTEXT_SUBTERFUGE
87			// Linux kernels prior to 2.4 ?
88			#if defined(__linux__)
89			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
90			#if (defined(i386) \|\| defined(__i386__))
91			#include <asm/sigcontext.h>
92			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext scs
93			#define SIGSEGV_FAULT_ADDRESS scs.cr2
94			#define SIGSEGV_FAULT_INSTRUCTION scs.eip
95	gbeauche	1.10	#define SIGSEGV_REGISTER_FILE (unsigned long *)(&scs)
96			#define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
97	gbeauche	1.1	#endif
98			#if (defined(sparc) \|\| defined(__sparc__))
99			#include <asm/sigcontext.h>
100	gbeauche	1.5	#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext scp, char addr
101	gbeauche	1.1	#define SIGSEGV_FAULT_ADDRESS addr
102			#endif
103			#if (defined(powerpc) \|\| defined(__powerpc__))
104			#include <asm/sigcontext.h>
105	gbeauche	1.4	#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext *scp
106	gbeauche	1.1	#define SIGSEGV_FAULT_ADDRESS scp->regs->dar
107			#define SIGSEGV_FAULT_INSTRUCTION scp->regs->nip
108			#endif
109	gbeauche	1.4	#if (defined(alpha) \|\| defined(__alpha__))
110			#include <asm/sigcontext.h>
111			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
112			#define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
113			#define SIGSEGV_FAULT_INSTRUCTION scp->sc_pc
114
115			// From Boehm's GC 6.0alpha8
116			static sigsegv_address_t get_fault_address(struct sigcontext *scp)
117			{
118			unsigned int instruction = ((unsigned int )(scp->sc_pc));
119			unsigned long fault_address = scp->sc_regs[(instruction >> 16) & 0x1f];
120			fault_address += (signed long)(signed short)(instruction & 0xffff);
121			return (sigsegv_address_t)fault_address;
122			}
123			#endif
124	gbeauche	1.1	#endif
125
126			// Irix 5 or 6 on MIPS
127			#if (defined(sgi) \|\| defined(__sgi)) && (defined(SYSTYPE_SVR4) \|\| defined(__SYSTYPE_SVR4))
128			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
129			#define SIGSEGV_FAULT_ADDRESS scp->sc_badvaddr
130			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
131			#endif
132
133			// OSF/1 on Alpha
134			#if defined(__osf__)
135			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
136			#define SIGSEGV_FAULT_ADDRESS scp->sc_traparg_a0
137			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
138			#endif
139
140			// AIX
141			#if defined(_AIX)
142			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
143			#define SIGSEGV_FAULT_ADDRESS scp->sc_jmpbuf.jmp_context.o_vaddr
144			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
145			#endif
146
147			// NetBSD or FreeBSD
148			#if defined(__NetBSD__) \|\| defined(__FreeBSD__)
149			#if (defined(m68k) \|\| defined(__m68k__))
150			#include <m68k/frame.h>
151			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
152			#define SIGSEGV_FAULT_ADDRESS ({ \
153			struct sigstate { \
154			int ss_flags; \
155			struct frame ss_frame; \
156			}; \
157			struct sigstate state = (struct sigstate )scp->sc_ap; \
158			char *fault_addr; \
159			switch (state->ss_frame.f_format) { \
160			case 7: /* 68040 access error */ \
161			/* "code" is sometimes unreliable (i.e. contains NULL or a bogus address), reason unknown */ \
162			fault_addr = state->ss_frame.f_fmt7.f_fa; \
163			break; \
164			default: \
165			fault_addr = (char *)code; \
166			break; \
167			} \
168			fault_addr; \
169			})
170			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
171			#else
172			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, void scp, char addr
173			#define SIGSEGV_FAULT_ADDRESS addr
174			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
175			#endif
176			#endif
177	gbeauche	1.4
178			// MacOS X
179			#if defined(__APPLE__) && defined(__MACH__)
180			#if (defined(ppc) \|\| defined(__ppc__))
181			#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
182			#define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
183			#define SIGSEGV_FAULT_INSTRUCTION scp->sc_ir
184			#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
185
186			// From Boehm's GC 6.0alpha8
187			#define EXTRACT_OP1(iw) (((iw) & 0xFC000000) >> 26)
188			#define EXTRACT_OP2(iw) (((iw) & 0x000007FE) >> 1)
189			#define EXTRACT_REGA(iw) (((iw) & 0x001F0000) >> 16)
190			#define EXTRACT_REGB(iw) (((iw) & 0x03E00000) >> 21)
191			#define EXTRACT_REGC(iw) (((iw) & 0x0000F800) >> 11)
192			#define EXTRACT_DISP(iw) ((short *) &(iw))[1]
193
194			static sigsegv_address_t get_fault_address(struct sigcontext *scp)
195			{
196			unsigned int instr = ((unsigned int ) scp->sc_ir);
197			unsigned int * regs = &((unsigned int *) scp->sc_regs)[2];
198			int disp = 0, tmp;
199			unsigned int baseA = 0, baseB = 0;
200			unsigned int addr, alignmask = 0xFFFFFFFF;
201
202			switch(EXTRACT_OP1(instr)) {
203			case 38: /* stb */
204			case 39: /* stbu */
205			case 54: /* stfd */
206			case 55: /* stfdu */
207			case 52: /* stfs */
208			case 53: /* stfsu */
209			case 44: /* sth */
210			case 45: /* sthu */
211			case 47: /* stmw */
212			case 36: /* stw */
213			case 37: /* stwu */
214			tmp = EXTRACT_REGA(instr);
215			if(tmp > 0)
216			baseA = regs[tmp];
217			disp = EXTRACT_DISP(instr);
218			break;
219			case 31:
220			switch(EXTRACT_OP2(instr)) {
221			case 86: /* dcbf */
222			case 54: /* dcbst */
223			case 1014: /* dcbz */
224			case 247: /* stbux */
225			case 215: /* stbx */
226			case 759: /* stfdux */
227			case 727: /* stfdx */
228			case 983: /* stfiwx */
229			case 695: /* stfsux */
230			case 663: /* stfsx */
231			case 918: /* sthbrx */
232			case 439: /* sthux */
233			case 407: /* sthx */
234			case 661: /* stswx */
235			case 662: /* stwbrx */
236			case 150: /* stwcx. */
237			case 183: /* stwux */
238			case 151: /* stwx */
239			case 135: /* stvebx */
240			case 167: /* stvehx */
241			case 199: /* stvewx */
242			case 231: /* stvx */
243			case 487: /* stvxl */
244			tmp = EXTRACT_REGA(instr);
245			if(tmp > 0)
246			baseA = regs[tmp];
247			baseB = regs[EXTRACT_REGC(instr)];
248			/* determine Altivec alignment mask */
249			switch(EXTRACT_OP2(instr)) {
250			case 167: /* stvehx */
251			alignmask = 0xFFFFFFFE;
252			break;
253			case 199: /* stvewx */
254			alignmask = 0xFFFFFFFC;
255			break;
256			case 231: /* stvx */
257			alignmask = 0xFFFFFFF0;
258			break;
259			case 487: /* stvxl */
260			alignmask = 0xFFFFFFF0;
261			break;
262			}
263			break;
264			case 725: /* stswi */
265			tmp = EXTRACT_REGA(instr);
266			if(tmp > 0)
267			baseA = regs[tmp];
268			break;
269			default: /* ignore instruction */
270			return 0;
271			break;
272			}
273			break;
274			default: /* ignore instruction */
275			return 0;
276			break;
277			}
278
279			addr = (baseA + baseB) + disp;
280			addr &= alignmask;
281			return (sigsegv_address_t)addr;
282			}
283			#endif
284			#endif
285	gbeauche	1.1	#endif
286
287	gbeauche	1.10	#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
288			// Decode and skip X86 instruction
289			#if (defined(i386) \|\| defined(__i386__))
290			#if defined(__linux__)
291			enum {
292			X86_REG_EIP = 14,
293			X86_REG_EAX = 11,
294			X86_REG_ECX = 10,
295			X86_REG_EDX = 9,
296			X86_REG_EBX = 8,
297			X86_REG_ESP = 7,
298			X86_REG_EBP = 6,
299			X86_REG_ESI = 5,
300			X86_REG_EDI = 4
301			};
302			#endif
303			// FIXME: this is partly redundant with the instruction decoding phase
304			// to discover transfer type and register number
305			static inline int ix86_step_over_modrm(unsigned char * p)
306			{
307			int mod = (p[0] >> 6) & 3;
308			int rm = p[0] & 7;
309			int offset = 0;
310
311			// ModR/M Byte
312			switch (mod) {
313			case 0: // [reg]
314			if (rm == 5) return 4; // disp32
315			break;
316			case 1: // disp8[reg]
317			offset = 1;
318			break;
319			case 2: // disp32[reg]
320			offset = 4;
321			break;
322			case 3: // register
323			return 0;
324			}
325
326			// SIB Byte
327			if (rm == 4) {
328			if (mod == 0 && (p[1] & 7) == 5)
329			offset = 5; // disp32[index]
330			else
331			offset++;
332			}
333
334			return offset;
335			}
336
337			static bool ix86_skip_instruction(sigsegv_address_t fault_instruction, unsigned long * regs)
338			{
339			unsigned char * eip = (unsigned char *)fault_instruction;
340
341			if (eip == 0)
342			return false;
343
344			// Transfer type
345			enum {
346			TYPE_UNKNOWN,
347			TYPE_LOAD,
348			TYPE_STORE
349			} transfer_type = TYPE_UNKNOWN;
350
351			// Transfer size
352			enum {
353			SIZE_BYTE,
354			SIZE_WORD,
355			SIZE_LONG
356			} transfer_size = SIZE_LONG;
357
358			int reg = -1;
359			int len = 0;
360
361			// Operand size prefix
362			if (*eip == 0x66) {
363			eip++;
364			len++;
365			transfer_size = SIZE_WORD;
366			}
367
368			// Decode instruction
369			switch (eip[0]) {
370			case 0x8a: // MOV r8, r/m8
371			transfer_size = SIZE_BYTE;
372			case 0x8b: // MOV r32, r/m32 (or 16-bit operation)
373			switch (eip[1] & 0xc0) {
374			case 0x80:
375			reg = (eip[1] >> 3) & 7;
376			transfer_type = TYPE_LOAD;
377			break;
378			case 0x40:
379			reg = (eip[1] >> 3) & 7;
380			transfer_type = TYPE_LOAD;
381			break;
382			case 0x00:
383			reg = (eip[1] >> 3) & 7;
384			transfer_type = TYPE_LOAD;
385			break;
386			}
387			len += 2 + ix86_step_over_modrm(eip + 1);
388			break;
389			case 0x88: // MOV r/m8, r8
390			transfer_size = SIZE_BYTE;
391			case 0x89: // MOV r/m32, r32 (or 16-bit operation)
392			switch (eip[1] & 0xc0) {
393			case 0x80:
394			reg = (eip[1] >> 3) & 7;
395			transfer_type = TYPE_STORE;
396			break;
397			case 0x40:
398			reg = (eip[1] >> 3) & 7;
399			transfer_type = TYPE_STORE;
400			break;
401			case 0x00:
402			reg = (eip[1] >> 3) & 7;
403			transfer_type = TYPE_STORE;
404			break;
405			}
406			len += 2 + ix86_step_over_modrm(eip + 1);
407			break;
408			}
409
410			if (transfer_type == TYPE_UNKNOWN) {
411			// Unknown machine code, let it crash. Then patch the decoder
412			return false;
413			}
414
415			if (transfer_type == TYPE_LOAD && reg != -1) {
416			static const int x86_reg_map[8] = {
417			X86_REG_EAX, X86_REG_ECX, X86_REG_EDX, X86_REG_EBX,
418			X86_REG_ESP, X86_REG_EBP, X86_REG_ESI, X86_REG_EDI
419			};
420
421			if (reg < 0 \|\| reg >= 8)
422			return false;
423
424			int rloc = x86_reg_map[reg];
425			switch (transfer_size) {
426			case SIZE_BYTE:
427			regs[rloc] = (regs[rloc] & ~0xff);
428			break;
429			case SIZE_WORD:
430			regs[rloc] = (regs[rloc] & ~0xffff);
431			break;
432			case SIZE_LONG:
433			regs[rloc] = 0;
434			break;
435			}
436			}
437
438			#if DEBUG
439			printf("%08x: %s %s access", regs[X86_REG_EIP],
440			transfer_size == SIZE_BYTE ? "byte" : transfer_size == SIZE_WORD ? "word" : "long",
441			transfer_type == TYPE_LOAD ? "read" : "write");
442
443			if (reg != -1) {
444			static const char * x86_reg_str_map[8] = {
445			"eax", "ecx", "edx", "ebx",
446			"esp", "ebp", "esi", "edi"
447			};
448			printf(" %s register %%%s", transfer_type == TYPE_LOAD ? "to" : "from", x86_reg_str_map[reg]);
449			}
450			printf(", %d bytes instruction\n", len);
451			#endif
452
453			regs[X86_REG_EIP] += len;
454			return true;
455			}
456			#endif
457			#endif
458
459	gbeauche	1.1	// Fallbacks
460			#ifndef SIGSEGV_FAULT_INSTRUCTION
461			#define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_INVALID_PC
462			#endif
463
464	gbeauche	1.2	// SIGSEGV recovery supported ?
465			#if defined(SIGSEGV_ALL_SIGNALS) && defined(SIGSEGV_FAULT_HANDLER_ARGLIST) && defined(SIGSEGV_FAULT_ADDRESS)
466			#define HAVE_SIGSEGV_RECOVERY
467			#endif
468
469	gbeauche	1.1
470			/*
471			* SIGSEGV global handler
472			*/
473
474	gbeauche	1.2	#ifdef HAVE_SIGSEGV_RECOVERY
475	gbeauche	1.1	static void sigsegv_handler(SIGSEGV_FAULT_HANDLER_ARGLIST)
476			{
477	gbeauche	1.10	sigsegv_address_t fault_address = (sigsegv_address_t)SIGSEGV_FAULT_ADDRESS;
478			sigsegv_address_t fault_instruction = (sigsegv_address_t)SIGSEGV_FAULT_INSTRUCTION;
479			bool fault_recovered = false;
480
481	gbeauche	1.1	// Call user's handler and reinstall the global handler, if required
482	gbeauche	1.10	if (sigsegv_user_handler(fault_address, fault_instruction)) {
483	gbeauche	1.1	#if (defined(HAVE_SIGACTION) ? defined(SIGACTION_NEED_REINSTALL) : defined(SIGNAL_NEED_REINSTALL))
484			sigsegv_do_install_handler(sig);
485			#endif
486	gbeauche	1.10	fault_recovered = true;
487	gbeauche	1.1	}
488	gbeauche	1.10	#if HAVE_SIGSEGV_SKIP_INSTRUCTION
489			else if (sigsegv_ignore_fault) {
490			// Call the instruction skipper with the register file available
491			if (SIGSEGV_SKIP_INSTRUCTION(fault_instruction, SIGSEGV_REGISTER_FILE))
492			fault_recovered = true;
493			}
494			#endif
495
496			if (!fault_recovered) {
497	gbeauche	1.1	// FAIL: reinstall default handler for "safe" crash
498			#define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
499			SIGSEGV_ALL_SIGNALS
500			#undef FAULT_HANDLER
501	gbeauche	1.10
502			// We can't do anything with the fault_address, dump state?
503			if (sigsegv_dump_state != 0)
504			sigsegv_dump_state(fault_address, fault_instruction);
505	gbeauche	1.1	}
506			}
507	gbeauche	1.2	#endif
508	gbeauche	1.1
509
510			/*
511			* SIGSEGV handler initialization
512			*/
513
514			#if defined(HAVE_SIGINFO_T)
515			static bool sigsegv_do_install_handler(int sig)
516			{
517			// Setup SIGSEGV handler to process writes to frame buffer
518			#ifdef HAVE_SIGACTION
519			struct sigaction vosf_sa;
520			sigemptyset(&vosf_sa.sa_mask);
521			vosf_sa.sa_sigaction = sigsegv_handler;
522			vosf_sa.sa_flags = SA_SIGINFO;
523			return (sigaction(sig, &vosf_sa, 0) == 0);
524			#else
525			return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
526			#endif
527			}
528	gbeauche	1.2	#endif
529
530			#if defined(HAVE_SIGCONTEXT_SUBTERFUGE)
531	gbeauche	1.1	static bool sigsegv_do_install_handler(int sig)
532			{
533			// Setup SIGSEGV handler to process writes to frame buffer
534			#ifdef HAVE_SIGACTION
535			struct sigaction vosf_sa;
536			sigemptyset(&vosf_sa.sa_mask);
537			vosf_sa.sa_handler = (signal_handler)sigsegv_handler;
538			#if !EMULATED_68K && defined(__NetBSD__)
539			sigaddset(&vosf_sa.sa_mask, SIGALRM);
540			vosf_sa.sa_flags = SA_ONSTACK;
541			#else
542			vosf_sa.sa_flags = 0;
543			#endif
544			return (sigaction(sig, &vosf_sa, 0) == 0);
545			#else
546			return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
547			#endif
548			}
549			#endif
550
551			bool sigsegv_install_handler(sigsegv_handler_t handler)
552			{
553	gbeauche	1.2	#ifdef HAVE_SIGSEGV_RECOVERY
554	gbeauche	1.1	sigsegv_user_handler = handler;
555			bool success = true;
556			#define FAULT_HANDLER(sig) success = success && sigsegv_do_install_handler(sig);
557			SIGSEGV_ALL_SIGNALS
558			#undef FAULT_HANDLER
559			return success;
560			#else
561			// FAIL: no siginfo_t nor sigcontext subterfuge is available
562			return false;
563			#endif
564			}
565
566
567			/*
568			* SIGSEGV handler deinitialization
569			*/
570
571			void sigsegv_deinstall_handler(void)
572			{
573	gbeauche	1.2	#ifdef HAVE_SIGSEGV_RECOVERY
574	gbeauche	1.1	sigsegv_user_handler = 0;
575			#define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
576			SIGSEGV_ALL_SIGNALS
577			#undef FAULT_HANDLER
578	gbeauche	1.2	#endif
579	gbeauche	1.1	}
580
581	gbeauche	1.10
582			/*
583			* SIGSEGV ignore state modifier
584			*/
585
586			void sigsegv_set_ignore_state(bool ignore_fault)
587			{
588			sigsegv_ignore_fault = ignore_fault;
589			}
590
591
592			/*
593			* Set callback function when we cannot handle the fault
594			*/
595
596			void sigsegv_set_dump_state(sigsegv_handler_t handler)
597			{
598			sigsegv_dump_state = handler;
599			}
600
601
602	gbeauche	1.1	/*
603			* Test program used for configure/test
604			*/
605
606	gbeauche	1.4	#ifdef CONFIGURE_TEST_SIGSEGV_RECOVERY
607	gbeauche	1.1	#include <stdio.h>
608			#include <stdlib.h>
609			#include <fcntl.h>
610			#include <sys/mman.h>
611	gbeauche	1.4	#include "vm_alloc.h"
612	gbeauche	1.1
613			static int page_size;
614	gbeauche	1.3	static volatile char * page = 0;
615			static volatile int handler_called = 0;
616	gbeauche	1.1
617			static bool sigsegv_test_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
618			{
619			handler_called++;
620			if ((fault_address - 123) != page)
621			exit(1);
622	gbeauche	1.4	if (vm_protect((char *)((unsigned long)fault_address & -page_size), page_size, VM_PAGE_READ \| VM_PAGE_WRITE) != 0)
623	gbeauche	1.1	exit(1);
624			return true;
625			}
626
627	gbeauche	1.10	#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
628			static bool sigsegv_insn_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
629			{
630			return false;
631			}
632			#endif
633
634	gbeauche	1.1	int main(void)
635			{
636	gbeauche	1.4	if (vm_init() < 0)
637	gbeauche	1.1	return 1;
638
639			page_size = getpagesize();
640	gbeauche	1.4	if ((page = (char *)vm_acquire(page_size)) == VM_MAP_FAILED)
641			return 1;
642
643			if (vm_protect((char *)page, page_size, VM_PAGE_READ) < 0)
644	gbeauche	1.1	return 1;
645
646			if (!sigsegv_install_handler(sigsegv_test_handler))
647			return 1;
648
649			page[123] = 45;
650			page[123] = 45;
651
652			if (handler_called != 1)
653			return 1;
654	gbeauche	1.10
655			#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
656			if (!sigsegv_install_handler(sigsegv_insn_handler))
657			return 1;
658
659			if (vm_protect((char *)page, page_size, VM_PAGE_WRITE) < 0)
660			return 1;
661
662			for (int i = 0; i < page_size; i++)
663			page[i] = (i + 1) % page_size;
664
665			if (vm_protect((char *)page, page_size, VM_PAGE_NOACCESS) < 0)
666			return 1;
667
668			sigsegv_set_ignore_state(true);
669
670			#define TEST_SKIP_INSTRUCTION(TYPE) do { \
671			const unsigned int TAG = 0x12345678; \
672			TYPE data = ((TYPE )(page + sizeof(TYPE))); \
673			volatile unsigned int effect = data + TAG; \
674			if (effect != TAG) \
675			return 1; \
676			} while (0)
677
678			TEST_SKIP_INSTRUCTION(unsigned char);
679			TEST_SKIP_INSTRUCTION(unsigned short);
680			TEST_SKIP_INSTRUCTION(unsigned int);
681			#endif
682	gbeauche	1.1
683	gbeauche	1.4	vm_exit();
684	gbeauche	1.1	return 0;
685			}
686			#endif