Archipelago » qemu

/*

 *  i386 emulator main execution loop

 * 

 *  Copyright (c) 2003 Fabrice Bellard

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include "config.h"

#include "exec.h"

#include "disas.h"

int tb_invalidated_flag;

//#define DEBUG_EXEC

//#define DEBUG_SIGNAL

#if defined(TARGET_ARM) || defined(TARGET_SPARC)

/* XXX: unify with i386 target */

void cpu_loop_exit(void)

{

    longjmp(env->jmp_env, 1);

}

#endif

/* main execution loop */

int cpu_exec(CPUState *env1)

{

    int saved_T0, saved_T1, saved_T2;

    CPUState *saved_env;

#ifdef reg_EAX

    int saved_EAX;

#endif

#ifdef reg_ECX

    int saved_ECX;

#endif

#ifdef reg_EDX

    int saved_EDX;

#endif

#ifdef reg_EBX

    int saved_EBX;

#endif

#ifdef reg_ESP

    int saved_ESP;

#endif

#ifdef reg_EBP

    int saved_EBP;

#endif

#ifdef reg_ESI

    int saved_ESI;

#endif

#ifdef reg_EDI

    int saved_EDI;

#endif

#ifdef __sparc__

    int saved_i7, tmp_T0;

#endif

    int code_gen_size, ret, interrupt_request;

    void (*gen_func)(void);

    TranslationBlock *tb, **ptb;

    uint8_t *tc_ptr, *cs_base, *pc;

    unsigned int flags;

    /* first we save global registers */

    saved_T0 = T0;

    saved_T1 = T1;

    saved_T2 = T2;

    saved_env = env;

    env = env1;

#ifdef __sparc__

    /* we also save i7 because longjmp may not restore it */

    asm volatile ("mov %%i7, %0" : "=r" (saved_i7));

#endif

#if defined(TARGET_I386)

#ifdef reg_EAX

    saved_EAX = EAX;

    EAX = env->regs[R_EAX];

#endif

#ifdef reg_ECX

    saved_ECX = ECX;

    ECX = env->regs[R_ECX];

#endif

#ifdef reg_EDX

    saved_EDX = EDX;

    EDX = env->regs[R_EDX];

#endif

#ifdef reg_EBX

    saved_EBX = EBX;

    EBX = env->regs[R_EBX];

#endif

#ifdef reg_ESP

    saved_ESP = ESP;

    ESP = env->regs[R_ESP];

#endif

#ifdef reg_EBP

    saved_EBP = EBP;

    EBP = env->regs[R_EBP];

#endif

#ifdef reg_ESI

    saved_ESI = ESI;

    ESI = env->regs[R_ESI];

#endif

#ifdef reg_EDI

    saved_EDI = EDI;

    EDI = env->regs[R_EDI];

#endif

    /* put eflags in CPU temporary format */

    CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);

    DF = 1 - (2 * ((env->eflags >> 10) & 1));

    CC_OP = CC_OP_EFLAGS;

    env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);

#elif defined(TARGET_ARM)

    {

        unsigned int psr;

        psr = env->cpsr;

        env->CF = (psr >> 29) & 1;

        env->NZF = (psr & 0xc0000000) ^ 0x40000000;

        env->VF = (psr << 3) & 0x80000000;

        env->cpsr = psr & ~0xf0000000;

    }

#elif defined(TARGET_SPARC)

#elif defined(TARGET_PPC)

#else

#error unsupported target CPU

#endif

    env->exception_index = -1;

    /* prepare setjmp context for exception handling */

    for(;;) {

        if (setjmp(env->jmp_env) == 0) {

            env->current_tb = NULL;

            /* if an exception is pending, we execute it here */

            if (env->exception_index >= 0) {

                if (env->exception_index >= EXCP_INTERRUPT) {

                    /* exit request from the cpu execution loop */

                    ret = env->exception_index;

                    break;

                } else if (env->user_mode_only) {

                    /* if user mode only, we simulate a fake exception

                       which will be hanlded outside the cpu execution

                       loop */

#if defined(TARGET_I386)

                    do_interrupt_user(env->exception_index, 

                                      env->exception_is_int, 

                                      env->error_code, 

                                      env->exception_next_eip);

#endif

                    ret = env->exception_index;

                    break;

                } else {

#if defined(TARGET_I386)

                    /* simulate a real cpu exception. On i386, it can

                       trigger new exceptions, but we do not handle

                       double or triple faults yet. */

                    do_interrupt(env->exception_index, 

                                 env->exception_is_int, 

                                 env->error_code, 

                                 env->exception_next_eip, 0);

#elif defined(TARGET_PPC)

                    do_interrupt(env);

#endif

                }

                env->exception_index = -1;

            }

            T0 = 0; /* force lookup of first TB */

            for(;;) {

#ifdef __sparc__

                /* g1 can be modified by some libc? functions */ 

                tmp_T0 = T0;

#endif            

                interrupt_request = env->interrupt_request;

                if (__builtin_expect(interrupt_request, 0)) {

#if defined(TARGET_I386)

                    /* if hardware interrupt pending, we execute it */

                    if ((interrupt_request & CPU_INTERRUPT_HARD) &&

                        (env->eflags & IF_MASK) && 

                        !(env->hflags & HF_INHIBIT_IRQ_MASK)) {

                        int intno;

                        intno = cpu_x86_get_pic_interrupt(env);

                        if (loglevel) {

                            fprintf(logfile, "Servicing hardware INT=0x%02x\n", intno);

                        }

                        do_interrupt(intno, 0, 0, 0, 1);

                        env->interrupt_request &= ~CPU_INTERRUPT_HARD;

                        /* ensure that no TB jump will be modified as

                           the program flow was changed */

#ifdef __sparc__

                        tmp_T0 = 0;

#else

                        T0 = 0;

#endif

                    }

#elif defined(TARGET_PPC)

                    if ((interrupt_request & CPU_INTERRUPT_HARD)) {

                        do_queue_exception(EXCP_EXTERNAL);

                        if (check_exception_state(env))

                            do_interrupt(env);

                        env->interrupt_request &= ~CPU_INTERRUPT_HARD;

                    }

#endif

                    if (interrupt_request & CPU_INTERRUPT_EXIT) {

                        env->interrupt_request &= ~CPU_INTERRUPT_EXIT;

                        env->exception_index = EXCP_INTERRUPT;

                        cpu_loop_exit();

                    }

                }

#ifdef DEBUG_EXEC

                if (loglevel) {

#if defined(TARGET_I386)

                    /* restore flags in standard format */

                    env->regs[R_EAX] = EAX;

                    env->regs[R_EBX] = EBX;

                    env->regs[R_ECX] = ECX;

                    env->regs[R_EDX] = EDX;

                    env->regs[R_ESI] = ESI;

                    env->regs[R_EDI] = EDI;

                    env->regs[R_EBP] = EBP;

                    env->regs[R_ESP] = ESP;

                    env->eflags = env->eflags | cc_table[CC_OP].compute_all() | (DF & DF_MASK);

                    cpu_x86_dump_state(env, logfile, X86_DUMP_CCOP);

                    env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);

#elif defined(TARGET_ARM)

                    env->cpsr = compute_cpsr();

                    cpu_arm_dump_state(env, logfile, 0);

                    env->cpsr &= ~0xf0000000;

#elif defined(TARGET_SPARC)

                    cpu_sparc_dump_state (env, logfile, 0);

#elif defined(TARGET_PPC)

                    cpu_ppc_dump_state(env, logfile, 0);

#else

#error unsupported target CPU 

#endif

                }

#endif

                /* we record a subset of the CPU state. It will

                   always be the same before a given translated block

                   is executed. */

#if defined(TARGET_I386)

                flags = env->hflags;

                flags |= (env->eflags & (IOPL_MASK | TF_MASK | VM_MASK));

                cs_base = env->segs[R_CS].base;

                pc = cs_base + env->eip;

#elif defined(TARGET_ARM)

                flags = 0;

                cs_base = 0;

                pc = (uint8_t *)env->regs[15];

#elif defined(TARGET_SPARC)

                flags = 0;

                cs_base = (uint8_t *)env->npc;

                pc = (uint8_t *) env->pc;

#elif defined(TARGET_PPC)

                flags = 0;

                cs_base = 0;

                pc = (uint8_t *)env->nip;

#else

#error unsupported CPU

#endif

                tb = tb_find(&ptb, (unsigned long)pc, (unsigned long)cs_base, 

                             flags);

                if (!tb) {

                    TranslationBlock **ptb1;

                    unsigned int h;

                    target_ulong phys_pc, phys_page1, phys_page2, virt_page2;

                    spin_lock(&tb_lock);

                    tb_invalidated_flag = 0;

                    /* find translated block using physical mappings */

                    phys_pc = get_phys_addr_code(env, (unsigned long)pc);

                    phys_page1 = phys_pc & TARGET_PAGE_MASK;

                    phys_page2 = -1;

                    h = tb_phys_hash_func(phys_pc);

                    ptb1 = &tb_phys_hash[h];

                    for(;;) {

                        tb = *ptb1;

                        if (!tb)

                            goto not_found;

                        if (tb->pc == (unsigned long)pc && 

                            tb->page_addr[0] == phys_page1 &&

                            tb->cs_base == (unsigned long)cs_base && 

                            tb->flags == flags) {

                            /* check next page if needed */

                            if (tb->page_addr[1] != -1) {

                                virt_page2 = ((unsigned long)pc & TARGET_PAGE_MASK) + 

                                    TARGET_PAGE_SIZE;

                                phys_page2 = get_phys_addr_code(env, virt_page2);

                                if (tb->page_addr[1] == phys_page2)

                                    goto found;

                            } else {

                                goto found;

                            }

                        }

                        ptb1 = &tb->phys_hash_next;

                    }

                not_found:

                    /* if no translated code available, then translate it now */

                    tb = tb_alloc((unsigned long)pc);

                    if (!tb) {

                        /* flush must be done */

                        tb_flush(env);

                        /* cannot fail at this point */

                        tb = tb_alloc((unsigned long)pc);

                        /* don't forget to invalidate previous TB info */

                        ptb = &tb_hash[tb_hash_func((unsigned long)pc)];

                        T0 = 0;

                    }

                    tc_ptr = code_gen_ptr;

                    tb->tc_ptr = tc_ptr;

                    tb->cs_base = (unsigned long)cs_base;

                    tb->flags = flags;

                    cpu_gen_code(env, tb, CODE_GEN_MAX_SIZE, &code_gen_size);

                    code_gen_ptr = (void *)(((unsigned long)code_gen_ptr + code_gen_size + CODE_GEN_ALIGN - 1) & ~(CODE_GEN_ALIGN - 1));

                    /* check next page if needed */

                    virt_page2 = ((unsigned long)pc + tb->size - 1) & TARGET_PAGE_MASK;

                    phys_page2 = -1;

                    if (((unsigned long)pc & TARGET_PAGE_MASK) != virt_page2) {

                        phys_page2 = get_phys_addr_code(env, virt_page2);

                    }

                    tb_link_phys(tb, phys_pc, phys_page2);

                found:

                    if (tb_invalidated_flag) {

                        /* as some TB could have been invalidated because

                           of memory exceptions while generating the code, we

                           must recompute the hash index here */

                        ptb = &tb_hash[tb_hash_func((unsigned long)pc)];

                        while (*ptb != NULL)

                            ptb = &(*ptb)->hash_next;

                        T0 = 0;

                    }

                    /* we add the TB in the virtual pc hash table */

                    *ptb = tb;

                    tb->hash_next = NULL;

                    tb_link(tb);

                    spin_unlock(&tb_lock);

                }

#ifdef DEBUG_EXEC

                if (loglevel) {

                    fprintf(logfile, "Trace 0x%08lx [0x%08lx] %s\n",

                            (long)tb->tc_ptr, (long)tb->pc,

                            lookup_symbol((void *)tb->pc));

                }

#endif

#ifdef __sparc__

                T0 = tmp_T0;

#endif            

                /* see if we can patch the calling TB. */

                if (T0 != 0) {

                    spin_lock(&tb_lock);

                    tb_add_jump((TranslationBlock *)(T0 & ~3), T0 & 3, tb);

                    spin_unlock(&tb_lock);

                }

                tc_ptr = tb->tc_ptr;

                env->current_tb = tb;

                /* execute the generated code */

                gen_func = (void *)tc_ptr;

#if defined(__sparc__)

                __asm__ __volatile__("call        %0\n\t"

                                     "mov        %%o7,%%i0"

                                     : /* no outputs */

                                     : "r" (gen_func) 

                                     : "i0", "i1", "i2", "i3", "i4", "i5");

#elif defined(__arm__)

                asm volatile ("mov pc, %0\n\t"

                              ".global exec_loop\n\t"

                              "exec_loop:\n\t"

                              : /* no outputs */

                              : "r" (gen_func)

                              : "r1", "r2", "r3", "r8", "r9", "r10", "r12", "r14");

#else

                gen_func();

#endif

                env->current_tb = NULL;

                /* reset soft MMU for next block (it can currently

                   only be set by a memory fault) */

#if defined(TARGET_I386) && !defined(CONFIG_SOFTMMU)

                if (env->hflags & HF_SOFTMMU_MASK) {

                    env->hflags &= ~HF_SOFTMMU_MASK;

                    /* do not allow linking to another block */

                    T0 = 0;

                }

#endif

            }

        } else {

        }

    } /* for(;;) */

#if defined(TARGET_I386)

    /* restore flags in standard format */

    env->eflags = env->eflags | cc_table[CC_OP].compute_all() | (DF & DF_MASK);

    /* restore global registers */

#ifdef reg_EAX

    EAX = saved_EAX;

#endif

#ifdef reg_ECX

    ECX = saved_ECX;

#endif

#ifdef reg_EDX

    EDX = saved_EDX;

#endif

#ifdef reg_EBX

    EBX = saved_EBX;

#endif

#ifdef reg_ESP

    ESP = saved_ESP;

#endif

#ifdef reg_EBP

    EBP = saved_EBP;

#endif

#ifdef reg_ESI

    ESI = saved_ESI;

#endif

#ifdef reg_EDI

    EDI = saved_EDI;

#endif

#elif defined(TARGET_ARM)

    env->cpsr = compute_cpsr();

#elif defined(TARGET_SPARC)

#elif defined(TARGET_PPC)

#else

#error unsupported target CPU

#endif

#ifdef __sparc__

    asm volatile ("mov %0, %%i7" : : "r" (saved_i7));

#endif

    T0 = saved_T0;

    T1 = saved_T1;

    T2 = saved_T2;

    env = saved_env;

    return ret;

}

#if defined(TARGET_I386) && defined(CONFIG_USER_ONLY)

void cpu_x86_load_seg(CPUX86State *s, int seg_reg, int selector)

{

    CPUX86State *saved_env;

    saved_env = env;

    env = s;

    if (!(env->cr[0] & CR0_PE_MASK) || (env->eflags & VM_MASK)) {

        selector &= 0xffff;

        cpu_x86_load_seg_cache(env, seg_reg, selector, 

                               (uint8_t *)(selector << 4), 0xffff, 0);

    } else {

        load_seg(seg_reg, selector);

    }

    env = saved_env;

}

void cpu_x86_fsave(CPUX86State *s, uint8_t *ptr, int data32)

{

    CPUX86State *saved_env;

    saved_env = env;

    env = s;

    helper_fsave(ptr, data32);

    env = saved_env;

}

void cpu_x86_frstor(CPUX86State *s, uint8_t *ptr, int data32)

{

    CPUX86State *saved_env;

    saved_env = env;

    env = s;

    helper_frstor(ptr, data32);

    env = saved_env;

}

#endif /* TARGET_I386 */

#undef EAX

#undef ECX

#undef EDX

#undef EBX

#undef ESP

#undef EBP

#undef ESI

#undef EDI

#undef EIP

#include <signal.h>

#include <sys/ucontext.h>

#if defined(TARGET_I386)

/* 'pc' is the host PC at which the exception was raised. 'address' is

   the effective address of the memory exception. 'is_write' is 1 if a

   write caused the exception and otherwise 0'. 'old_set' is the

   signal set which should be restored */

static inline int handle_cpu_signal(unsigned long pc, unsigned long address,

                                    int is_write, sigset_t *old_set)

{

    TranslationBlock *tb;

    int ret;

    if (cpu_single_env)

        env = cpu_single_env; /* XXX: find a correct solution for multithread */

#if defined(DEBUG_SIGNAL)

    printf("qemu: SIGSEGV pc=0x%08lx address=%08lx w=%d oldset=0x%08lx\n", 

           pc, address, is_write, *(unsigned long *)old_set);

#endif

    /* XXX: locking issue */

    if (is_write && page_unprotect(address)) {

        return 1;

    }

    /* see if it is an MMU fault */

    ret = cpu_x86_handle_mmu_fault(env, address, is_write, 

                                   ((env->hflags & HF_CPL_MASK) == 3), 0);

    if (ret < 0)

        return 0; /* not an MMU fault */

    if (ret == 0)

        return 1; /* the MMU fault was handled without causing real CPU fault */

    /* now we have a real cpu fault */

    tb = tb_find_pc(pc);

    if (tb) {

        /* the PC is inside the translated code. It means that we have

           a virtual CPU fault */

        cpu_restore_state(tb, env, pc);

    }

    if (ret == 1) {

#if 0

        printf("PF exception: EIP=0x%08x CR2=0x%08x error=0x%x\n", 

               env->eip, env->cr[2], env->error_code);

#endif

        /* we restore the process signal mask as the sigreturn should

           do it (XXX: use sigsetjmp) */

        sigprocmask(SIG_SETMASK, old_set, NULL);

        raise_exception_err(EXCP0E_PAGE, env->error_code);

    } else {

        /* activate soft MMU for this block */

        env->hflags |= HF_SOFTMMU_MASK;

        sigprocmask(SIG_SETMASK, old_set, NULL);

        cpu_loop_exit();

    }

    /* never comes here */

    return 1;

}

#elif defined(TARGET_ARM)

static inline int handle_cpu_signal(unsigned long pc, unsigned long address,

                                    int is_write, sigset_t *old_set)

{

    /* XXX: do more */

    return 0;

}

#elif defined(TARGET_SPARC)

static inline int handle_cpu_signal(unsigned long pc, unsigned long address,

                                    int is_write, sigset_t *old_set)

{

    /* XXX: locking issue */

    if (is_write && page_unprotect(address)) {

        return 1;

    }

    return 0;

}

#elif defined (TARGET_PPC)

static inline int handle_cpu_signal(unsigned long pc, unsigned long address,

                                    int is_write, sigset_t *old_set)

{

    TranslationBlock *tb;

    int ret;

#if 1

    if (cpu_single_env)

        env = cpu_single_env; /* XXX: find a correct solution for multithread */

#endif

#if defined(DEBUG_SIGNAL)

    printf("qemu: SIGSEGV pc=0x%08lx address=%08lx w=%d oldset=0x%08lx\n", 

           pc, address, is_write, *(unsigned long *)old_set);

#endif

    /* XXX: locking issue */

    if (is_write && page_unprotect(address)) {

        return 1;

    }

    /* see if it is an MMU fault */

    ret = cpu_ppc_handle_mmu_fault(env, address, is_write, msr_pr, 0);

    if (ret < 0)

        return 0; /* not an MMU fault */

    if (ret == 0)

        return 1; /* the MMU fault was handled without causing real CPU fault */

    /* now we have a real cpu fault */

    tb = tb_find_pc(pc);

    if (tb) {

        /* the PC is inside the translated code. It means that we have

           a virtual CPU fault */

        cpu_restore_state(tb, env, pc);

    }

    if (ret == 1) {

#if 0

        printf("PF exception: NIP=0x%08x error=0x%x %p\n", 

               env->nip, env->error_code, tb);

#endif

    /* we restore the process signal mask as the sigreturn should

       do it (XXX: use sigsetjmp) */

    sigprocmask(SIG_SETMASK, old_set, NULL);

        do_queue_exception_err(env->exception_index, env->error_code);

    } else {

        /* activate soft MMU for this block */

        sigprocmask(SIG_SETMASK, old_set, NULL);

        cpu_loop_exit();

    }

    /* never comes here */

    return 1;

}

#else

#error unsupported target CPU

#endif

#if defined(__i386__)

int cpu_signal_handler(int host_signum, struct siginfo *info, 

                       void *puc)

{

    struct ucontext *uc = puc;

    unsigned long pc;

#ifndef REG_EIP

/* for glibc 2.1 */

#define REG_EIP    EIP

#define REG_ERR    ERR

#define REG_TRAPNO TRAPNO

#endif

    pc = uc->uc_mcontext.gregs[REG_EIP];

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, 

                             uc->uc_mcontext.gregs[REG_TRAPNO] == 0xe ? 

                             (uc->uc_mcontext.gregs[REG_ERR] >> 1) & 1 : 0,

                             &uc->uc_sigmask);

}

#elif defined(__powerpc)

int cpu_signal_handler(int host_signum, struct siginfo *info, 

                       void *puc)

{

    struct ucontext *uc = puc;

    struct pt_regs *regs = uc->uc_mcontext.regs;

    unsigned long pc;

    int is_write;

    pc = regs->nip;

    is_write = 0;

#if 0

    /* ppc 4xx case */

    if (regs->dsisr & 0x00800000)

        is_write = 1;

#else

    if (regs->trap != 0x400 && (regs->dsisr & 0x02000000))

        is_write = 1;

#endif

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, 

                             is_write, &uc->uc_sigmask);

}

#elif defined(__alpha__)

int cpu_signal_handler(int host_signum, struct siginfo *info, 

                           void *puc)

{

    struct ucontext *uc = puc;

    uint32_t *pc = uc->uc_mcontext.sc_pc;

    uint32_t insn = *pc;

    int is_write = 0;

    /* XXX: need kernel patch to get write flag faster */

    switch (insn >> 26) {

    case 0x0d: // stw

    case 0x0e: // stb

    case 0x0f: // stq_u

    case 0x24: // stf

    case 0x25: // stg

    case 0x26: // sts

    case 0x27: // stt

    case 0x2c: // stl

    case 0x2d: // stq

    case 0x2e: // stl_c

    case 0x2f: // stq_c

        is_write = 1;

    }

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, 

                             is_write, &uc->uc_sigmask);

}

#elif defined(__sparc__)

int cpu_signal_handler(int host_signum, struct siginfo *info, 

                       void *puc)

{

    uint32_t *regs = (uint32_t *)(info + 1);

    void *sigmask = (regs + 20);

    unsigned long pc;

    int is_write;

    uint32_t insn;

    /* XXX: is there a standard glibc define ? */

    pc = regs[1];

    /* XXX: need kernel patch to get write flag faster */

    is_write = 0;

    insn = *(uint32_t *)pc;

    if ((insn >> 30) == 3) {

      switch((insn >> 19) & 0x3f) {

      case 0x05: // stb

      case 0x06: // sth

      case 0x04: // st

      case 0x07: // std

      case 0x24: // stf

      case 0x27: // stdf

      case 0x25: // stfsr

        is_write = 1;

        break;

      }

    }

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, 

                             is_write, sigmask);

}

#elif defined(__arm__)

int cpu_signal_handler(int host_signum, struct siginfo *info, 

                       void *puc)

{

    struct ucontext *uc = puc;

    unsigned long pc;

    int is_write;

    pc = uc->uc_mcontext.gregs[R15];

    /* XXX: compute is_write */

    is_write = 0;

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, 

                             is_write,

                             &uc->uc_sigmask);

}

#elif defined(__mc68000)

int cpu_signal_handler(int host_signum, struct siginfo *info, 

                       void *puc)

{

    struct ucontext *uc = puc;

    unsigned long pc;

    int is_write;

    pc = uc->uc_mcontext.gregs[16];

    /* XXX: compute is_write */

    is_write = 0;

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, 

                             is_write,

                             &uc->uc_sigmask);

}

#else

#error host CPU specific signal handler needed

#endif