From cf3d36a3a75fe4bb3a134bc2e988590002c6e470 Mon Sep 17 00:00:00 2001 From: gbeauche <> Date: Sun, 12 Oct 2003 21:15:52 +0000 Subject: [PATCH] Mach memory fault recovery from Michael Z. Sliczniak --- BasiliskII/README | 1 + BasiliskII/src/Unix/sigsegv.cpp | 475 ++++++++++++++++++++++++++++++-- 2 files changed, 453 insertions(+), 23 deletions(-) diff --git a/BasiliskII/README b/BasiliskII/README index e72b5c6f..917832eb 100644 --- a/BasiliskII/README +++ b/BasiliskII/README @@ -838,6 +838,7 @@ Contributions by (in alphabetical order): - Nigel Pearson : Mac OS X port - Lauri Pesonen : Windows NT port - Bernd Schmidt : UAE 68k emulation + - Michael Z. Sliczniak : Mach memory fault recovery - and others... Special thanks to: diff --git a/BasiliskII/src/Unix/sigsegv.cpp b/BasiliskII/src/Unix/sigsegv.cpp index bc73f141..d4bd5afa 100644 --- a/BasiliskII/src/Unix/sigsegv.cpp +++ b/BasiliskII/src/Unix/sigsegv.cpp @@ -4,6 +4,12 @@ * 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 @@ -206,12 +212,14 @@ static void powerpc_decode_instruction(instruction_t *instruction, unsigned int #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_ARGS sig, sip, scp #define SIGSEGV_FAULT_ADDRESS sip->si_addr #if defined(__NetBSD__) || defined(__FreeBSD__) #if (defined(i386) || defined(__i386__)) @@ -248,12 +256,14 @@ static void powerpc_decode_instruction(instruction_t *instruction, unsigned int #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_ARGS sig, scs #define SIGSEGV_FAULT_ADDRESS scs.cr2 #define SIGSEGV_FAULT_INSTRUCTION scs.eip #define SIGSEGV_REGISTER_FILE (unsigned int *)(&scs) @@ -262,11 +272,13 @@ static void powerpc_decode_instruction(instruction_t *instruction, unsigned int #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) @@ -275,6 +287,7 @@ static void powerpc_decode_instruction(instruction_t *instruction, unsigned int #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 @@ -293,6 +306,7 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) #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 @@ -300,6 +314,7 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) // 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 @@ -308,6 +323,7 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) #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 @@ -315,6 +331,7 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) // 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 @@ -324,6 +341,7 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) #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) @@ -349,15 +367,24 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) } #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 +// 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) @@ -377,6 +404,142 @@ static sigsegv_address_t get_fault_address(struct sigcontext *scp) #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 /* @@ -627,40 +790,213 @@ static bool powerpc_skip_instruction(unsigned int * nip_p, unsigned int * regs) * SIGSEGV global handler */ -#ifdef HAVE_SIGSEGV_RECOVERY -static void sigsegv_handler(SIGSEGV_FAULT_HANDLER_ARGLIST) +#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) { 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 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 - fault_recovered = true; - break; -#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)) - fault_recovered = true; - break; -#endif + return; } - if (!fault_recovered) { - // Failure: reinstall default handler for "safe" crash + // Failure: reinstall default handler for "safe" crash #define FAULT_HANDLER(sig) signal(sig, SIG_DFL); - SIGSEGV_ALL_SIGNALS + SIGSEGV_ALL_SIGNALS #undef FAULT_HANDLER - - // We can't do anything with the fault_address, dump state? - if (sigsegv_state_dumper != 0) - sigsegv_state_dumper(fault_address, fault_instruction); - } } #endif @@ -705,15 +1041,103 @@ static bool sigsegv_do_install_handler(int sig) } #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) { -#ifdef HAVE_SIGSEGV_RECOVERY - sigsegv_fault_handler = 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; @@ -727,6 +1151,11 @@ bool sigsegv_install_handler(sigsegv_fault_handler_t handler) 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);