/*
* sigsegv.cpp - SIGSEGV signals support
*
* Derived from Bruno Haible's work on his SIGSEGV library for clisp
*
*
* MacOS X support derived from the post by Timothy J. Wood to the
* omnigroup macosx-dev list:
* Mach Exception Handlers 101 (Was Re: ptrace, gdb)
* tjw@omnigroup.com Sun, 4 Jun 2000
* www.omnigroup.com/mailman/archive/macosx-dev/2000-June/002030.html
*
* 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
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include
#include
#include "sigsegv.h"
#ifndef NO_STD_NAMESPACE
using std::list;
#endif
// 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);
// User's SIGSEGV handler
static sigsegv_fault_handler_t sigsegv_fault_handler = 0;
// Function called to dump state if we can't handle the fault
static sigsegv_state_dumper_t sigsegv_state_dumper = 0;
// Actual SIGSEGV handler installer
static bool sigsegv_do_install_handler(int sig);
/*
* Instruction decoding aids
*/
// Transfer size
enum transfer_size_t {
SIZE_UNKNOWN,
SIZE_BYTE,
SIZE_WORD,
SIZE_LONG
};
// Transfer type
typedef sigsegv_transfer_type_t transfer_type_t;
#if (defined(powerpc) || defined(__powerpc__) || defined(__ppc__))
// Addressing mode
enum addressing_mode_t {
MODE_UNKNOWN,
MODE_NORM,
MODE_U,
MODE_X,
MODE_UX
};
// Decoded instruction
struct instruction_t {
transfer_type_t transfer_type;
transfer_size_t transfer_size;
addressing_mode_t addr_mode;
unsigned int addr;
char ra, rd;
};
static void powerpc_decode_instruction(instruction_t *instruction, unsigned int nip, unsigned int * gpr)
{
// Get opcode and divide into fields
unsigned int opcode = *((unsigned int *)nip);
unsigned int primop = opcode >> 26;
unsigned int exop = (opcode >> 1) & 0x3ff;
unsigned int ra = (opcode >> 16) & 0x1f;
unsigned int rb = (opcode >> 11) & 0x1f;
unsigned int rd = (opcode >> 21) & 0x1f;
signed int imm = (signed short)(opcode & 0xffff);
// Analyze opcode
transfer_type_t transfer_type = SIGSEGV_TRANSFER_UNKNOWN;
transfer_size_t transfer_size = SIZE_UNKNOWN;
addressing_mode_t addr_mode = MODE_UNKNOWN;
switch (primop) {
case 31:
switch (exop) {
case 23: // lwzx
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_X; break;
case 55: // lwzux
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_UX; break;
case 87: // lbzx
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_X; break;
case 119: // lbzux
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_UX; break;
case 151: // stwx
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_X; break;
case 183: // stwux
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_UX; break;
case 215: // stbx
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_X; break;
case 247: // stbux
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_UX; break;
case 279: // lhzx
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
case 311: // lhzux
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
case 343: // lhax
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
case 375: // lhaux
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
case 407: // sthx
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
case 439: // sthux
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
}
break;
case 32: // lwz
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_NORM; break;
case 33: // lwzu
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_U; break;
case 34: // lbz
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_NORM; break;
case 35: // lbzu
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_U; break;
case 36: // stw
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_NORM; break;
case 37: // stwu
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_U; break;
case 38: // stb
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_NORM; break;
case 39: // stbu
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_U; break;
case 40: // lhz
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
case 41: // lhzu
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
case 42: // lha
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
case 43: // lhau
transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
case 44: // sth
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
case 45: // sthu
transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
}
// Calculate effective address
unsigned int addr = 0;
switch (addr_mode) {
case MODE_X:
case MODE_UX:
if (ra == 0)
addr = gpr[rb];
else
addr = gpr[ra] + gpr[rb];
break;
case MODE_NORM:
case MODE_U:
if (ra == 0)
addr = (signed int)(signed short)imm;
else
addr = gpr[ra] + (signed int)(signed short)imm;
break;
default:
break;
}
// Commit decoded instruction
instruction->addr = addr;
instruction->addr_mode = addr_mode;
instruction->transfer_type = transfer_type;
instruction->transfer_size = transfer_size;
instruction->ra = ra;
instruction->rd = rd;
}
#endif
/*
* OS-dependant SIGSEGV signals support section
*/
#if HAVE_SIGINFO_T
// Generic extended signal handler
#define SIGSEGV_FAULT_HANDLER sigsegv_fault_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_HANDLER_ARGLIST_1 siginfo_t *sip, void *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sip, scp
#define SIGSEGV_FAULT_ADDRESS sip->si_addr
#if defined(__NetBSD__) || defined(__FreeBSD__)
#if (defined(i386) || defined(__i386__))
#define SIGSEGV_FAULT_INSTRUCTION (((struct sigcontext *)scp)->sc_eip)
#define SIGSEGV_REGISTER_FILE ((unsigned int *)&(((struct sigcontext *)scp)->sc_edi)) /* EDI is the first GPR (even below EIP) in sigcontext */
#define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
#endif
#endif
#if defined(__linux__)
#if (defined(i386) || defined(__i386__))
#include
#define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.gregs)
#define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_CONTEXT_REGS[14] /* should use REG_EIP instead */
#define SIGSEGV_REGISTER_FILE (unsigned int *)SIGSEGV_CONTEXT_REGS
#define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
#endif
#if (defined(x86_64) || defined(__x86_64__))
#include
#define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.gregs)
#define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_CONTEXT_REGS[16] /* should use REG_RIP instead */
#define SIGSEGV_REGISTER_FILE (unsigned long *)SIGSEGV_CONTEXT_REGS
#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
#define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.regs)
#define SIGSEGV_FAULT_INSTRUCTION (SIGSEGV_CONTEXT_REGS->nip)
#define SIGSEGV_REGISTER_FILE (unsigned int *)&SIGSEGV_CONTEXT_REGS->nip, (unsigned int *)(SIGSEGV_CONTEXT_REGS->gpr)
#define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
#endif
#endif
#endif
#if HAVE_SIGCONTEXT_SUBTERFUGE
#define SIGSEGV_FAULT_HANDLER sigsegv_fault_handler
// Linux kernels prior to 2.4 ?
#if defined(__linux__)
#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
#if (defined(i386) || defined(__i386__))
#include
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext scs
#define SIGSEGV_FAULT_HANDLER_ARGLIST_1 struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS &scs
#define SIGSEGV_FAULT_ADDRESS scp->cr2
#define SIGSEGV_FAULT_INSTRUCTION scp->eip
#define SIGSEGV_REGISTER_FILE (unsigned int *)scp
#define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
#endif
#if (defined(sparc) || defined(__sparc__))
#include
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp, char *addr
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, scp, addr
#define SIGSEGV_FAULT_ADDRESS addr
#endif
#if (defined(powerpc) || defined(__powerpc__))
#include
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sig, scp
#define SIGSEGV_FAULT_ADDRESS scp->regs->dar
#define SIGSEGV_FAULT_INSTRUCTION scp->regs->nip
#define SIGSEGV_REGISTER_FILE (unsigned int *)&scp->regs->nip, (unsigned int *)(scp->regs->gpr)
#define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
#endif
#if (defined(alpha) || defined(__alpha__))
#include
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, 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))
#include
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, scp
#define SIGSEGV_FAULT_ADDRESS scp->sc_badvaddr
#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
#endif
// HP-UX
#if (defined(hpux) || defined(__hpux__))
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, scp
#define SIGSEGV_FAULT_ADDRESS scp->sc_sl.sl_ss.ss_narrow.ss_cr21
#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV) FAULT_HANDLER(SIGBUS)
#endif
// OSF/1 on Alpha
#if defined(__osf__)
#include
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, 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_HANDLER_ARGS sig, code, 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
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, scp
#define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
// Use decoding scheme from BasiliskII/m68k native
static sigsegv_address_t get_fault_address(struct sigcontext *scp)
{
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;
}
return (sigsegv_address_t)fault_addr;
}
#else
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, void *scp, char *addr
#define SIGSEGV_FAULT_HANDLER_ARGS sig, code, scp, addr
#define SIGSEGV_FAULT_ADDRESS addr
#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
#endif
#endif
// MacOS X, not sure which version this works in. Under 10.1
// vm_protect does not appear to work from a signal handler. Under
// 10.2 signal handlers get siginfo type arguments but the si_addr
// field is the address of the faulting instruction and not the
// address that caused the SIGBUS. Maybe this works in 10.0? In any
// case with Mach exception handlers there is a way to do what this
// was meant to do.
#ifndef HAVE_MACH_EXCEPTIONS
#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_HANDLER_ARGS sig, code, scp
#define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
#define SIGSEGV_FAULT_INSTRUCTION scp->sc_ir
#define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
#define SIGSEGV_REGISTER_FILE (unsigned int *)&scp->sc_ir, &((unsigned int *) scp->sc_regs)[2]
#define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
// Use decoding scheme from SheepShaver
static sigsegv_address_t get_fault_address(struct sigcontext *scp)
{
unsigned int nip = (unsigned int) scp->sc_ir;
unsigned int * gpr = &((unsigned int *) scp->sc_regs)[2];
instruction_t instr;
powerpc_decode_instruction(&instr, nip, gpr);
return (sigsegv_address_t)instr.addr;
}
#endif
#endif
#endif
#endif
#if HAVE_MACH_EXCEPTIONS
// This can easily be extended to other Mach systems, but really who
// uses HURD (oops GNU/HURD), Darwin/x86, NextStep, Rhapsody, or CMU
// Mach 2.5/3.0?
#if defined(__APPLE__) && defined(__MACH__)
#include
#include
#include
#include
/*
* If you are familiar with MIG then you will understand the frustration
* that was necessary to get these embedded into C++ code by hand.
*/
extern "C" {
#include
#include
extern boolean_t exc_server(mach_msg_header_t *, mach_msg_header_t *);
extern kern_return_t catch_exception_raise(mach_port_t, mach_port_t,
mach_port_t, exception_type_t, exception_data_t, mach_msg_type_number_t);
extern kern_return_t exception_raise(mach_port_t, mach_port_t, mach_port_t,
exception_type_t, exception_data_t, mach_msg_type_number_t);
extern kern_return_t exception_raise_state(mach_port_t, exception_type_t,
exception_data_t, mach_msg_type_number_t, thread_state_flavor_t *,
thread_state_t, mach_msg_type_number_t, thread_state_t, mach_msg_type_number_t *);
extern kern_return_t exception_raise_state_identity(mach_port_t, mach_port_t, mach_port_t,
exception_type_t, exception_data_t, mach_msg_type_number_t, thread_state_flavor_t *,
thread_state_t, mach_msg_type_number_t, thread_state_t, mach_msg_type_number_t *);
}
// Could make this dynamic by looking for a result of MIG_ARRAY_TOO_LARGE
#define HANDLER_COUNT 64
// structure to tuck away existing exception handlers
typedef struct _ExceptionPorts {
mach_msg_type_number_t maskCount;
exception_mask_t masks[HANDLER_COUNT];
exception_handler_t handlers[HANDLER_COUNT];
exception_behavior_t behaviors[HANDLER_COUNT];
thread_state_flavor_t flavors[HANDLER_COUNT];
} ExceptionPorts;
// exception handler thread
static pthread_t exc_thread;
// place where old exception handler info is stored
static ExceptionPorts ports;
// our exception port
static mach_port_t _exceptionPort = MACH_PORT_NULL;
#define MACH_CHECK_ERROR(name,ret) \
if (ret != KERN_SUCCESS) { \
mach_error(#name, ret); \
exit (1); \
}
#define SIGSEGV_FAULT_ADDRESS code[1]
#define SIGSEGV_FAULT_INSTRUCTION get_fault_instruction(thread, state)
#define SIGSEGV_FAULT_HANDLER (code[0] == KERN_PROTECTION_FAILURE) && sigsegv_fault_handler
#define SIGSEGV_FAULT_HANDLER_ARGLIST mach_port_t thread, exception_data_t code, ppc_thread_state_t *state
#define SIGSEGV_FAULT_HANDLER_ARGS thread, code, &state
#define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
#define SIGSEGV_REGISTER_FILE &state->srr0, &state->r0
// Given a suspended thread, stuff the current instruction and
// registers into state.
//
// It would have been nice to have this be ppc/x86 independant which
// could have been done easily with a thread_state_t instead of
// ppc_thread_state_t, but because of the way this is called it is
// easier to do it this way.
#if (defined(ppc) || defined(__ppc__))
static inline sigsegv_address_t get_fault_instruction(mach_port_t thread, ppc_thread_state_t *state)
{
kern_return_t krc;
mach_msg_type_number_t count;
count = MACHINE_THREAD_STATE_COUNT;
krc = thread_get_state(thread, MACHINE_THREAD_STATE, (thread_state_t)state, &count);
MACH_CHECK_ERROR (thread_get_state, krc);
return (sigsegv_address_t)state->srr0;
}
#endif
// Since there can only be one exception thread running at any time
// this is not a problem.
#define MSG_SIZE 512
static char msgbuf[MSG_SIZE];
static char replybuf[MSG_SIZE];
/*
* This is the entry point for the exception handler thread. The job
* of this thread is to wait for exception messages on the exception
* port that was setup beforehand and to pass them on to exc_server.
* exc_server is a MIG generated function that is a part of Mach.
* Its job is to decide what to do with the exception message. In our
* case exc_server calls catch_exception_raise on our behalf. After
* exc_server returns, it is our responsibility to send the reply.
*/
static void *
handleExceptions(void *priv)
{
mach_msg_header_t *msg, *reply;
kern_return_t krc;
msg = (mach_msg_header_t *)msgbuf;
reply = (mach_msg_header_t *)replybuf;
for (;;) {
krc = mach_msg(msg, MACH_RCV_MSG, MSG_SIZE, MSG_SIZE,
_exceptionPort, 0, MACH_PORT_NULL);
MACH_CHECK_ERROR(mach_msg, krc);
if (!exc_server(msg, reply)) {
fprintf(stderr, "exc_server hated the message\n");
exit(1);
}
krc = mach_msg(reply, MACH_SEND_MSG, reply->msgh_size, 0,
msg->msgh_local_port, 0, MACH_PORT_NULL);
if (krc != KERN_SUCCESS) {
fprintf(stderr, "Error sending message to original reply port, krc = %d, %s",
krc, mach_error_string(krc));
exit(1);
}
}
}
#endif
#endif
/*
* Instruction skipping
*/
#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
#if defined(__NetBSD__) || defined(__FreeBSD__)
enum {
X86_REG_EIP = 10,
X86_REG_EAX = 7,
X86_REG_ECX = 6,
X86_REG_EDX = 5,
X86_REG_EBX = 4,
X86_REG_ESP = 13,
X86_REG_EBP = 2,
X86_REG_ESI = 1,
X86_REG_EDI = 0
};
#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(unsigned int * regs)
{
unsigned char * eip = (unsigned char *)regs[X86_REG_EIP];
if (eip == 0)
return false;
transfer_type_t transfer_type = SIGSEGV_TRANSFER_UNKNOWN;
transfer_size_t 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 0x0f:
switch (eip[1]) {
case 0xb6: // MOVZX r32, r/m8
case 0xb7: // MOVZX r32, r/m16
switch (eip[2] & 0xc0) {
case 0x80:
reg = (eip[2] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_LOAD;
break;
case 0x40:
reg = (eip[2] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_LOAD;
break;
case 0x00:
reg = (eip[2] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_LOAD;
break;
}
len += 3 + ix86_step_over_modrm(eip + 2);
break;
}
break;
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 = SIGSEGV_TRANSFER_LOAD;
break;
case 0x40:
reg = (eip[1] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_LOAD;
break;
case 0x00:
reg = (eip[1] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_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 = SIGSEGV_TRANSFER_STORE;
break;
case 0x40:
reg = (eip[1] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_STORE;
break;
case 0x00:
reg = (eip[1] >> 3) & 7;
transfer_type = SIGSEGV_TRANSFER_STORE;
break;
}
len += 2 + ix86_step_over_modrm(eip + 1);
break;
}
if (transfer_type == SIGSEGV_TRANSFER_UNKNOWN) {
// Unknown machine code, let it crash. Then patch the decoder
return false;
}
if (transfer_type == SIGSEGV_TRANSFER_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 == SIGSEGV_TRANSFER_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 == SIGSEGV_TRANSFER_LOAD ? "to" : "from", x86_reg_str_map[reg]);
}
printf(", %d bytes instruction\n", len);
#endif
regs[X86_REG_EIP] += len;
return true;
}
#endif
// Decode and skip PPC instruction
#if (defined(powerpc) || defined(__powerpc__) || defined(__ppc__))
static bool powerpc_skip_instruction(unsigned int * nip_p, unsigned int * regs)
{
instruction_t instr;
powerpc_decode_instruction(&instr, *nip_p, regs);
if (instr.transfer_type == SIGSEGV_TRANSFER_UNKNOWN) {
// Unknown machine code, let it crash. Then patch the decoder
return false;
}
#if DEBUG
printf("%08x: %s %s access", *nip_p,
instr.transfer_size == SIZE_BYTE ? "byte" : instr.transfer_size == SIZE_WORD ? "word" : "long",
instr.transfer_type == SIGSEGV_TRANSFER_LOAD ? "read" : "write");
if (instr.addr_mode == MODE_U || instr.addr_mode == MODE_UX)
printf(" r%d (ra = %08x)\n", instr.ra, instr.addr);
if (instr.transfer_type == SIGSEGV_TRANSFER_LOAD)
printf(" r%d (rd = 0)\n", instr.rd);
#endif
if (instr.addr_mode == MODE_U || instr.addr_mode == MODE_UX)
regs[instr.ra] = instr.addr;
if (instr.transfer_type == SIGSEGV_TRANSFER_LOAD)
regs[instr.rd] = 0;
*nip_p += 4;
return true;
}
#endif
#endif
// Fallbacks
#ifndef SIGSEGV_FAULT_INSTRUCTION
#define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_INVALID_PC
#endif
#ifndef SIGSEGV_FAULT_HANDLER_ARGLIST_1
#define SIGSEGV_FAULT_HANDLER_ARGLIST_1 SIGSEGV_FAULT_HANDLER_ARGLIST
#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
*/
#if defined(HAVE_SIGSEGV_RECOVERY) || defined(HAVE_MACH_EXCEPTIONS)
// This function handles the badaccess to memory.
// It is called from the signal handler or the exception handler.
static bool handle_badaccess(SIGSEGV_FAULT_HANDLER_ARGLIST_1)
{
sigsegv_address_t fault_address = (sigsegv_address_t)SIGSEGV_FAULT_ADDRESS;
sigsegv_address_t fault_instruction = (sigsegv_address_t)SIGSEGV_FAULT_INSTRUCTION;
// Call user's handler and reinstall the global handler, if required
switch (sigsegv_fault_handler(fault_address, fault_instruction)) {
case SIGSEGV_RETURN_SUCCESS:
return true;
#if HAVE_SIGSEGV_SKIP_INSTRUCTION
case SIGSEGV_RETURN_SKIP_INSTRUCTION:
// Call the instruction skipper with the register file
// available
if (SIGSEGV_SKIP_INSTRUCTION(SIGSEGV_REGISTER_FILE)) {
#ifdef HAVE_MACH_EXCEPTIONS
// Unlike UNIX signals where the thread state
// is modified off of the stack, in Mach we
// need to actually call thread_set_state to
// have the register values updated.
kern_return_t krc;
krc = thread_set_state(thread,
MACHINE_THREAD_STATE, (thread_state_t)state,
MACHINE_THREAD_STATE_COUNT);
MACH_CHECK_ERROR (thread_get_state, krc);
#endif
return true;
}
break;
#endif
}
// We can't do anything with the fault_address, dump state?
if (sigsegv_state_dumper != 0)
sigsegv_state_dumper(fault_address, fault_instruction);
return false;
}
#endif
/*
* There are two mechanisms for handling a bad memory access,
* Mach exceptions and UNIX signals. The implementation specific
* code appears below. Its reponsibility is to call handle_badaccess
* which is the routine that handles the fault in an implementation
* agnostic manner. The implementation specific code below is then
* reponsible for checking whether handle_badaccess was able
* to handle the memory access error and perform any implementation
* specific tasks necessary afterwards.
*/
#ifdef HAVE_MACH_EXCEPTIONS
/*
* We need to forward all exceptions that we do not handle.
* This is important, there are many exceptions that may be
* handled by other exception handlers. For example debuggers
* use exceptions and the exception hander is in another
* process in such a case. (Timothy J. Wood states in his
* message to the list that he based this code on that from
* gdb for Darwin.)
*/
static inline kern_return_t
forward_exception(mach_port_t thread_port,
mach_port_t task_port,
exception_type_t exception_type,
exception_data_t exception_data,
mach_msg_type_number_t data_count,
ExceptionPorts *oldExceptionPorts)
{
kern_return_t kret;
unsigned int portIndex;
mach_port_t port;
exception_behavior_t behavior;
thread_state_flavor_t flavor;
thread_state_t thread_state;
mach_msg_type_number_t thread_state_count;
for (portIndex = 0; portIndex < oldExceptionPorts->maskCount; portIndex++) {
if (oldExceptionPorts->masks[portIndex] & (1 << exception_type)) {
// This handler wants the exception
break;
}
}
if (portIndex >= oldExceptionPorts->maskCount) {
fprintf(stderr, "No handler for exception_type = %d. Not fowarding\n", exception_type);
return KERN_FAILURE;
}
port = oldExceptionPorts->handlers[portIndex];
behavior = oldExceptionPorts->behaviors[portIndex];
flavor = oldExceptionPorts->flavors[portIndex];
/*
fprintf(stderr, "forwarding exception, port = 0x%x, behaviour = %d, flavor = %d\n", port, behavior, flavor);
*/
if (behavior != EXCEPTION_DEFAULT) {
thread_state_count = THREAD_STATE_MAX;
kret = thread_get_state (thread_port, flavor, thread_state,
&thread_state_count);
MACH_CHECK_ERROR (thread_get_state, kret);
}
switch (behavior) {
case EXCEPTION_DEFAULT:
// fprintf(stderr, "forwarding to exception_raise\n");
kret = exception_raise(port, thread_port, task_port, exception_type,
exception_data, data_count);
MACH_CHECK_ERROR (exception_raise, kret);
break;
case EXCEPTION_STATE:
// fprintf(stderr, "forwarding to exception_raise_state\n");
kret = exception_raise_state(port, exception_type, exception_data,
data_count, &flavor,
thread_state, thread_state_count,
thread_state, &thread_state_count);
MACH_CHECK_ERROR (exception_raise_state, kret);
break;
case EXCEPTION_STATE_IDENTITY:
// fprintf(stderr, "forwarding to exception_raise_state_identity\n");
kret = exception_raise_state_identity(port, thread_port, task_port,
exception_type, exception_data,
data_count, &flavor,
thread_state, thread_state_count,
thread_state, &thread_state_count);
MACH_CHECK_ERROR (exception_raise_state_identity, kret);
break;
default:
fprintf(stderr, "forward_exception got unknown behavior\n");
break;
}
if (behavior != EXCEPTION_DEFAULT) {
kret = thread_set_state (thread_port, flavor, thread_state,
thread_state_count);
MACH_CHECK_ERROR (thread_set_state, kret);
}
return KERN_SUCCESS;
}
/*
* This is the code that actually handles the exception.
* It is called by exc_server. For Darwin 5 Apple changed
* this a bit from how this family of functions worked in
* Mach. If you are familiar with that it is a little
* different. The main variation that concerns us here is
* that code is an array of exception specific codes and
* codeCount is a count of the number of codes in the code
* array. In typical Mach all exceptions have a code
* and sub-code. It happens to be the case that for a
* EXC_BAD_ACCESS exception the first entry is the type of
* bad access that occurred and the second entry is the
* faulting address so these entries correspond exactly to
* how the code and sub-code are used on Mach.
*
* This is a MIG interface. No code in Basilisk II should
* call this directley. This has to have external C
* linkage because that is what exc_server expects.
*/
kern_return_t
catch_exception_raise(mach_port_t exception_port,
mach_port_t thread,
mach_port_t task,
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t codeCount)
{
ppc_thread_state_t state;
kern_return_t krc;
if ((exception == EXC_BAD_ACCESS) && (codeCount >= 2)) {
if (handle_badaccess(SIGSEGV_FAULT_HANDLER_ARGS))
return KERN_SUCCESS;
}
// In Mach we do not need to remove the exception handler.
// If we forward the exception, eventually some exception handler
// will take care of this exception.
krc = forward_exception(thread, task, exception, code, codeCount, &ports);
return krc;
}
#endif
#ifdef HAVE_SIGSEGV_RECOVERY
// Handle bad memory accesses with signal handler
static void sigsegv_handler(SIGSEGV_FAULT_HANDLER_ARGLIST)
{
// Call handler and reinstall the global handler, if required
if (handle_badaccess(SIGSEGV_FAULT_HANDLER_ARGS)) {
#if (defined(HAVE_SIGACTION) ? defined(SIGACTION_NEED_REINSTALL) : defined(SIGNAL_NEED_REINSTALL))
sigsegv_do_install_handler(sig);
#endif
return;
}
// Failure: reinstall default handler for "safe" crash
#define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
SIGSEGV_ALL_SIGNALS
#undef FAULT_HANDLER
}
#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 sigsegv_sa;
sigemptyset(&sigsegv_sa.sa_mask);
sigsegv_sa.sa_sigaction = sigsegv_handler;
sigsegv_sa.sa_flags = SA_SIGINFO;
return (sigaction(sig, &sigsegv_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 sigsegv_sa;
sigemptyset(&sigsegv_sa.sa_mask);
sigsegv_sa.sa_handler = (signal_handler)sigsegv_handler;
sigsegv_sa.sa_flags = 0;
#if !EMULATED_68K && defined(__NetBSD__)
sigaddset(&sigsegv_sa.sa_mask, SIGALRM);
sigsegv_sa.sa_flags |= SA_ONSTACK;
#endif
return (sigaction(sig, &sigsegv_sa, 0) == 0);
#else
return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
#endif
}
#endif
#if defined(HAVE_MACH_EXCEPTIONS)
static bool sigsegv_do_install_handler(sigsegv_fault_handler_t handler)
{
/*
* Except for the exception port functions, this should be
* pretty much stock Mach. If later you choose to support
* other Mach's besides Darwin, just check for __MACH__
* here and __APPLE__ where the actual differences are.
*/
#if defined(__APPLE__) && defined(__MACH__)
if (sigsegv_fault_handler != NULL) {
sigsegv_fault_handler = handler;
return true;
}
kern_return_t krc;
// create the the exception port
krc = mach_port_allocate(mach_task_self(),
MACH_PORT_RIGHT_RECEIVE, &_exceptionPort);
if (krc != KERN_SUCCESS) {
mach_error("mach_port_allocate", krc);
return false;
}
// add a port send right
krc = mach_port_insert_right(mach_task_self(),
_exceptionPort, _exceptionPort,
MACH_MSG_TYPE_MAKE_SEND);
if (krc != KERN_SUCCESS) {
mach_error("mach_port_insert_right", krc);
return false;
}
// get the old exception ports
ports.maskCount = sizeof (ports.masks) / sizeof (ports.masks[0]);
krc = thread_get_exception_ports(mach_thread_self(), EXC_MASK_BAD_ACCESS, ports.masks,
&ports.maskCount, ports.handlers, ports.behaviors, ports.flavors);
if (krc != KERN_SUCCESS) {
mach_error("thread_get_exception_ports", krc);
return false;
}
// set the new exception port
//
// We could have used EXCEPTION_STATE_IDENTITY instead of
// EXCEPTION_DEFAULT to get the thread state in the initial
// message, but it turns out that in the common case this is not
// neccessary. If we need it we can later ask for it from the
// suspended thread.
//
// Even with THREAD_STATE_NONE, Darwin provides the program
// counter in the thread state. The comments in the header file
// seem to imply that you can count on the GPR's on an exception
// as well but just to be safe I use MACHINE_THREAD_STATE because
// you have to ask for all of the GPR's anyway just to get the
// program counter. In any case because of update effective
// address from immediate and update address from effective
// addresses of ra and rb modes (as good an name as any for these
// addressing modes) used in PPC instructions, you will need the
// GPR state anyway.
krc = thread_set_exception_ports(mach_thread_self(), EXC_MASK_BAD_ACCESS, _exceptionPort,
EXCEPTION_DEFAULT, MACHINE_THREAD_STATE);
if (krc != KERN_SUCCESS) {
mach_error("thread_set_exception_ports", krc);
return false;
}
// create the exception handler thread
if (pthread_create(&exc_thread, NULL, &handleExceptions, NULL) != 0) {
(void)fprintf(stderr, "creation of exception thread failed\n");
return false;
}
// do not care about the exception thread any longer, let is run standalone
(void)pthread_detach(exc_thread);
sigsegv_fault_handler = handler;
return true;
#else
return false;
#endif
}
#endif
bool sigsegv_install_handler(sigsegv_fault_handler_t handler)
{
#if defined(HAVE_SIGSEGV_RECOVERY)
bool success = true;
#define FAULT_HANDLER(sig) success = success && sigsegv_do_install_handler(sig);
SIGSEGV_ALL_SIGNALS
#undef FAULT_HANDLER
if (success)
sigsegv_fault_handler = handler;
return success;
#elif defined(HAVE_MACH_EXCEPTIONS)
return sigsegv_do_install_handler(handler);
#else
// FAIL: no siginfo_t nor sigcontext subterfuge is available
return false;
#endif
}
/*
* SIGSEGV handler deinitialization
*/
void sigsegv_deinstall_handler(void)
{
// We do nothing for Mach exceptions, the thread would need to be
// suspended if not already so, and we might mess with other
// exception handlers that came after we registered ours. There is
// no need to remove the exception handler, in fact this function is
// not called anywhere in Basilisk II.
#ifdef HAVE_SIGSEGV_RECOVERY
sigsegv_fault_handler = 0;
#define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
SIGSEGV_ALL_SIGNALS
#undef FAULT_HANDLER
#endif
}
/*
* Set callback function when we cannot handle the fault
*/
void sigsegv_set_dump_state(sigsegv_state_dumper_t handler)
{
sigsegv_state_dumper = handler;
}
/*
* Test program used for configure/test
*/
#ifdef CONFIGURE_TEST_SIGSEGV_RECOVERY
#include
#include
#include
#include
#include "vm_alloc.h"
static int page_size;
static volatile char * page = 0;
static volatile int handler_called = 0;
static sigsegv_return_t sigsegv_test_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
{
handler_called++;
if ((fault_address - 123) != page)
exit(10);
if (vm_protect((char *)((unsigned long)fault_address & -page_size), page_size, VM_PAGE_READ | VM_PAGE_WRITE) != 0)
exit(11);
return SIGSEGV_RETURN_SUCCESS;
}
#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
#ifdef __GNUC__
// Code range where we expect the fault to come from
static void *b_region, *e_region;
#endif
static sigsegv_return_t sigsegv_insn_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
{
if (((unsigned long)fault_address - (unsigned long)page) < page_size) {
#ifdef __GNUC__
// Make sure reported fault instruction address falls into
// expected code range
if (instruction_address != SIGSEGV_INVALID_PC
&& ((instruction_address < (sigsegv_address_t)b_region) ||
(instruction_address >= (sigsegv_address_t)e_region)))
return SIGSEGV_RETURN_FAILURE;
#endif
return SIGSEGV_RETURN_SKIP_INSTRUCTION;
}
return SIGSEGV_RETURN_FAILURE;
}
#endif
int main(void)
{
if (vm_init() < 0)
return 1;
page_size = getpagesize();
if ((page = (char *)vm_acquire(page_size)) == VM_MAP_FAILED)
return 2;
if (vm_protect((char *)page, page_size, VM_PAGE_READ) < 0)
return 3;
if (!sigsegv_install_handler(sigsegv_test_handler))
return 4;
page[123] = 45;
page[123] = 45;
if (handler_called != 1)
return 5;
#ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
if (!sigsegv_install_handler(sigsegv_insn_handler))
return 6;
if (vm_protect((char *)page, page_size, VM_PAGE_READ | VM_PAGE_WRITE) < 0)
return 7;
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 8;
#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 9; \
} while (0)
#ifdef __GNUC__
b_region = &&L_b_region;
e_region = &&L_e_region;
#endif
L_b_region:
TEST_SKIP_INSTRUCTION(unsigned char);
TEST_SKIP_INSTRUCTION(unsigned short);
TEST_SKIP_INSTRUCTION(unsigned int);
L_e_region:
#endif
vm_exit();
return 0;
}
#endif