/*
* sigsegv.cpp - SIGSEGV signals support
*
* Derived from Bruno Haible's work on his SIGSEGV library for clisp
*
*
* 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 "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_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);
/*
* 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
#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
#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
#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
#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
#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
#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))
#include
#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
// HP-UX
#if (defined(hpux) || defined(__hpux__))
#define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *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_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
#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_fault_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_state_dumper != 0)
sigsegv_state_dumper(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_fault_handler_t handler)
{
#ifdef HAVE_SIGSEGV_RECOVERY
sigsegv_fault_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_fault_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_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 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