/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */

#include <string.h>

#include <mach/boolean.h>
#include <vm/vm_map.h>
#include <kern/thread.h>
#include <kern/task.h>

#include <machine/asm.h>
#include <machine/db_machdep.h>
#include <machine/setjmp.h>
#include <mach/machine.h>

#include <ddb/db_access.h>
#include <ddb/db_sym.h>
#include <ddb/db_variables.h>
#include <ddb/db_command.h>
#include <ddb/db_task_thread.h>
#include <ddb/db_output.h>

extern jmp_buf_t *db_recover;
extern struct i386_saved_state *saved_state[];

struct i386_kernel_state ddb_null_kregs;

/*
 * Stack trace.
 */

extern vm_offset_t vm_min_inks_addr;    /* set by db_clone_symtabXXX */
#define INKSERVER(va)   (((vm_offset_t)(va)) >= vm_min_inks_addr)

extern vm_offset_t interrupt_stack[];
#define ININTSTACK(va)                                          \
        (((vm_offset_t)(va)) >= interrupt_stack[cpu_number()] &&\
         (((vm_offset_t)(va)) < interrupt_stack[cpu_number()] + \
                                INTSTACK_SIZE))

#define INKERNELSTACK(va, th)                                   \
        (th == THREAD_NULL ||                           \
         (((vm_offset_t)(va)) >= th->thread->kernel_stack &&    \
          (((vm_offset_t)(va)) < th->thread->kernel_stack +     \
                                 KERNEL_STACK_SIZE)) ||         \
         ININTSTACK(va))

struct i386_frame {
        struct i386_frame       *f_frame;
        int                     f_retaddr;
        int                     f_arg0;
};

#define TRAP            1
#define INTERRUPT       2
#define SYSCALL         3

db_addr_t       db_user_trap_symbol_value = 0;
db_addr_t       db_kernel_trap_symbol_value = 0;
db_addr_t       db_interrupt_symbol_value = 0;
db_addr_t       db_return_to_iret_symbol_value = 0;
db_addr_t       db_syscall_symbol_value = 0;
boolean_t       db_trace_symbols_found = FALSE;

struct i386_kregs {
        char    *name;
        int     offset;
} i386_kregs[] = {
        { "ebx", (int)(&((struct i386_kernel_state *)0)->k_ebx) },
        { "esp", (int)(&((struct i386_kernel_state *)0)->k_esp) },
        { "ebp", (int)(&((struct i386_kernel_state *)0)->k_ebp) },
        { "edi", (int)(&((struct i386_kernel_state *)0)->k_edi) },
        { "esi", (int)(&((struct i386_kernel_state *)0)->k_esi) },
        { "eip", (int)(&((struct i386_kernel_state *)0)->k_eip) },
        { 0 },
};

/* Forward */

extern int *    db_lookup_i386_kreg(
                        char                    *name,
                        int                     *kregp);
extern int      db_i386_reg_value(
                        struct db_variable      * vp,
                        db_expr_t               * val,
                        int                     flag,
                        db_var_aux_param_t      ap);
extern void     db_find_trace_symbols(void);
extern int      db_numargs(
                        struct i386_frame       *fp,
                        task_t                  task);
extern void     db_nextframe(
                        struct i386_frame       **lfp,
                        struct i386_frame       **fp,
                        db_addr_t               *ip,
                        int                     frame_type,
                        thread_t                thr_act);
extern int      _setjmp(
                        jmp_buf_t               * jb);

/*
 * Machine register set.
 */
struct db_variable db_regs[] = {
        { "cs", (int *)&ddb_regs.cs,  db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "ds", (int *)&ddb_regs.ds,  db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "es", (int *)&ddb_regs.es,  db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "fs", (int *)&ddb_regs.fs,  db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "gs", (int *)&ddb_regs.gs,  db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "ss", (int *)&ddb_regs.ss,  db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "eax",(int *)&ddb_regs.eax, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "ecx",(int *)&ddb_regs.ecx, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "edx",(int *)&ddb_regs.edx, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "ebx",(int *)&ddb_regs.ebx, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "esp",(int *)&ddb_regs.uesp,db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "ebp",(int *)&ddb_regs.ebp, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "esi",(int *)&ddb_regs.esi, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "edi",(int *)&ddb_regs.edi, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "eip",(int *)&ddb_regs.eip, db_i386_reg_value, 0, 0, 0, 0, TRUE },
        { "efl",(int *)&ddb_regs.efl, db_i386_reg_value, 0, 0, 0, 0, TRUE },
};
struct db_variable *db_eregs = db_regs + sizeof(db_regs)/sizeof(db_regs[0]);

int *
db_lookup_i386_kreg(
        char    *name,
        int     *kregp)
{
        register struct i386_kregs *kp;

        for (kp = i386_kregs; kp->name; kp++) {
            if (strcmp(name, kp->name) == 0)
                return((int *)((int)kregp + kp->offset));
        }
        return(0);
}
        
int
db_i386_reg_value(
        struct  db_variable     *vp,
        db_expr_t               *valuep,
        int                     flag,
        db_var_aux_param_t      ap)
{
        extern char             etext;
        int                     *dp = 0;
        db_expr_t               null_reg = 0;
        register thread_t       thr_act = ap->thr_act;
        extern unsigned         int_stack_high;
        int                     cpu;

        if (db_option(ap->modif, 'u')) {
            if (thr_act == THREAD_NULL) {
                if ((thr_act = current_thread()) == THREAD_NULL)
                    db_error("no user registers\n");
            }
            if (thr_act == current_thread()) {
                if (IS_USER_TRAP(&ddb_regs, &etext))
                    dp = vp->valuep;
                else if (ddb_regs.ebp < int_stack_high)
                    db_error("cannot get/set user registers in nested interrupt\n");
            }
        } else {
            if (thr_act == THREAD_NULL || thr_act == current_thread()) {
                dp = vp->valuep;
            } else {
              if (thr_act->thread &&
                  !(thr_act->thread->state & TH_STACK_HANDOFF) && 
                        thr_act->thread->kernel_stack) {
                int cpu;

                for (cpu = 0; cpu < real_ncpus; cpu++) {
                    if (cpu_datap(cpu)->cpu_running == TRUE &&
                        cpu_datap(cpu)->cpu_active_thread == thr_act->thread && saved_state[cpu]) {
                        dp = (int *) (((int)saved_state[cpu]) +
                                      (((int) vp->valuep) -
                                       (int) &ddb_regs));
                        break;
                    }
                }
                if (dp == 0 && thr_act && thr_act->thread)
                    dp = db_lookup_i386_kreg(vp->name,
                         (int *)(STACK_IKS(thr_act->thread->kernel_stack)));
                if (dp == 0)
                    dp = &null_reg;
              } else if (thr_act->thread &&
                         (thr_act->thread->state&TH_STACK_HANDOFF)){
                /* only EIP is valid */
                if (vp->valuep == (int *) &ddb_regs.eip) {
                    dp = (int *)(&thr_act->thread->continuation);
                } else {
                    dp = &null_reg;
                }
              }
            }
        }
        if (dp == 0) {
            int cpu;

            if (!db_option(ap->modif, 'u')) {
                for (cpu = 0; cpu < real_ncpus; cpu++) {
                    if (cpu_datap(cpu)->cpu_running == TRUE &&
                        cpu_datap(cpu)->cpu_active_thread == thr_act->thread && saved_state[cpu]) {
                            dp = (int *) (((int)saved_state[cpu]) +
                                          (((int) vp->valuep) -
                                           (int) &ddb_regs));
                            break;
                    }
                }
            }
            if (dp == 0) {
                if (!thr_act || thr_act->machine.pcb == 0)
                    db_error("no pcb\n");
                dp = (int *)((int)(&thr_act->machine.pcb->iss) + 
                             ((int)vp->valuep - (int)&ddb_regs));
            }
        }
        if (flag == DB_VAR_SET)
            *dp = *valuep;
        else
            *valuep = *dp;
        return(0);
}

void
db_find_trace_symbols(void)
{
        db_expr_t       value;
        boolean_t       found_some;

        found_some = FALSE;
        if (db_value_of_name(CC_SYM_PREFIX "user_trap", &value)) {
            db_user_trap_symbol_value = (db_addr_t) value;
            found_some = TRUE;
        }
        if (db_value_of_name(CC_SYM_PREFIX "kernel_trap", &value)) {
            db_kernel_trap_symbol_value = (db_addr_t) value;
            found_some = TRUE;
        }
        if (db_value_of_name(CC_SYM_PREFIX "interrupt", &value)) {
            db_interrupt_symbol_value = (db_addr_t) value;
            found_some = TRUE;
        }
        if (db_value_of_name(CC_SYM_PREFIX "return_to_iret", &value)) {
            db_return_to_iret_symbol_value = (db_addr_t) value;
            found_some = TRUE;
        }
        if (db_value_of_name(CC_SYM_PREFIX "syscall", &value)) {
            db_syscall_symbol_value = (db_addr_t) value;
            found_some = TRUE;
        }
        if (found_some) 
            db_trace_symbols_found = TRUE;
}

/*
 * Figure out how many arguments were passed into the frame at "fp".
 */
int db_numargs_default = 5;

int
db_numargs(
        struct i386_frame       *fp,
        task_t                  task)
{
        int     *argp;
        int     inst;
        int     args;
        extern char     etext;

        argp = (int *)db_get_task_value((int)&fp->f_retaddr, 4, FALSE, task);
        if (argp < (int *)VM_MIN_KERNEL_ADDRESS || (char *)argp > &etext)
            args = db_numargs_default;
        else if (!DB_CHECK_ACCESS((int)argp, 4, task))
            args = db_numargs_default;
        else {
            inst = db_get_task_value((int)argp, 4, FALSE, task);
            if ((inst & 0xff) == 0x59)  /* popl %ecx */
                args = 1;
            else if ((inst & 0xffff) == 0xc483) /* addl %n, %esp */
                args = ((inst >> 16) & 0xff) / 4;
            else
                args = db_numargs_default;
        }
        return (args);
}

struct interrupt_frame {
        struct i386_frame *if_frame;    /* point to next frame */
        int               if_retaddr;   /* return address to _interrupt */
        int               if_unit;      /* unit number */
        int               if_spl;       /* saved spl */
        int               if_iretaddr;  /* _return_to_{iret,iret_i} */
        int               if_edx;       /* old sp(iret) or saved edx(iret_i) */
        int               if_ecx;       /* saved ecx(iret_i) */
        int               if_eax;       /* saved eax(iret_i) */
        int               if_eip;       /* saved eip(iret_i) */
        int               if_cs;        /* saved cs(iret_i) */
        int               if_efl;       /* saved efl(iret_i) */
};

/* 
 * Figure out the next frame up in the call stack.  
 * For trap(), we print the address of the faulting instruction and 
 *   proceed with the calling frame.  We return the ip that faulted.
 *   If the trap was caused by jumping through a bogus pointer, then
 *   the next line in the backtrace will list some random function as 
 *   being called.  It should get the argument list correct, though.  
 *   It might be possible to dig out from the next frame up the name
 *   of the function that faulted, but that could get hairy.
 */
void
db_nextframe(
        struct i386_frame       **lfp,          /* in/out */
        struct i386_frame       **fp,           /* in/out */
        db_addr_t               *ip,            /* out */
        int                     frame_type,     /* in */
        thread_t                thr_act)        /* in */
{
        extern char *   trap_type[];
        extern int      TRAP_TYPES;

        struct i386_saved_state *saved_regs;
        struct interrupt_frame *ifp;
        struct i386_interrupt_state *isp;
        task_t task = (thr_act != THREAD_NULL)? thr_act->task: TASK_NULL;

        switch(frame_type) {
        case TRAP:
            /*
             * We know that trap() has 1 argument and we know that
             * it is an (strcut i386_saved_state *).
             */
            saved_regs = (struct i386_saved_state *)
                        db_get_task_value((int)&((*fp)->f_arg0),4,FALSE,task);
            if (saved_regs->trapno >= 0 && saved_regs->trapno < TRAP_TYPES) {
                db_printf(">>>>> %s trap at ",
                        trap_type[saved_regs->trapno]);
            } else {
                db_printf(">>>>> trap (number %d) at ",
                        saved_regs->trapno & 0xffff);
            }
            db_task_printsym(saved_regs->eip, DB_STGY_PROC, task);
            db_printf(" <<<<<\n");
            *fp = (struct i386_frame *)saved_regs->ebp;
            *ip = (db_addr_t)saved_regs->eip;
            break;
        case INTERRUPT:
            if (*lfp == 0) {
                db_printf(">>>>> interrupt <<<<<\n");
                goto miss_frame;
            }
            db_printf(">>>>> interrupt at "); 
            ifp = (struct interrupt_frame *)(*lfp);
            *fp = ifp->if_frame;
            if (ifp->if_iretaddr == db_return_to_iret_symbol_value)
                *ip = ((struct i386_interrupt_state *) ifp->if_edx)->eip;
            else
                *ip = (db_addr_t) ifp->if_eip;
            db_task_printsym(*ip, DB_STGY_PROC, task);
            db_printf(" <<<<<\n");
            break;
        case SYSCALL:
            if (thr_act != THREAD_NULL && thr_act->machine.pcb) {
                *ip = (db_addr_t) thr_act->machine.pcb->iss.eip;
                *fp = (struct i386_frame *) thr_act->machine.pcb->iss.ebp;
                break;
            }
            /* falling down for unknown case */
        default:
        miss_frame:
            *ip = (db_addr_t)
                db_get_task_value((int)&(*fp)->f_retaddr, 4, FALSE, task);
            *lfp = *fp;
            *fp = (struct i386_frame *)
                db_get_task_value((int)&(*fp)->f_frame, 4, FALSE, task);
            break;
        }
}

void
db_stack_trace_cmd(
        db_expr_t       addr,
        boolean_t       have_addr,
        db_expr_t       count,
        char            *modif)
{
        struct i386_frame *frame, *lastframe;
        int             *argp;
        db_addr_t       callpc, lastcallpc;
        int             frame_type;
        boolean_t       kernel_only = TRUE;
        boolean_t       trace_thread = FALSE;
        boolean_t       trace_all_threads = FALSE;
        int             thcount = 0;
        char            *filename;
        int             linenum;
        task_t          task;
        thread_t        th, top_act;
        int             user_frame;
        int             frame_count;
        jmp_buf_t       *prev;
        jmp_buf_t       db_jmp_buf;
        queue_entry_t   act_list;

        if (!db_trace_symbols_found)
            db_find_trace_symbols();

        {
            register char *cp = modif;
            register char c;

            while ((c = *cp++) != 0) {
                if (c == 't')
                    trace_thread = TRUE;
                if (c == 'T') {
                    trace_all_threads = TRUE;
                    trace_thread = TRUE;
                }
                if (c == 'u')
                    kernel_only = FALSE;
            }
        }

        if (trace_all_threads) {
            if (!have_addr && !trace_thread) {
                have_addr = TRUE;
                trace_thread = TRUE;
                act_list = &(current_task()->thr_acts);
                addr = (db_expr_t) queue_first(act_list);
            } else if (trace_thread) {
                if (have_addr) {
                    if (!db_check_act_address_valid((thread_t)addr)) {
                        if (db_lookup_task((task_t)addr) == -1)
                            return;
                        act_list = &(((task_t)addr)->thr_acts);
                        addr = (db_expr_t) queue_first(act_list);
                    } else {
                        act_list = &(((thread_t)addr)->task->thr_acts);
                        thcount = db_lookup_task_act(((thread_t)addr)->task,
                                                        (thread_t)addr);
                    }
                } else {
                    th = db_default_act;
                    if (th == THREAD_NULL)
                        th = current_thread();
                    if (th == THREAD_NULL) {
                        db_printf("no active thr_act\n");
                        return;
                    }
                    have_addr = TRUE;
                    act_list = &th->task->thr_acts;
                    addr = (db_expr_t) queue_first(act_list);
                }
            }
        }

        if (count == -1)
            count = 65535;

    next_thread:
        top_act = THREAD_NULL;

        user_frame = 0;
        frame_count = count;

        if (!have_addr && !trace_thread) {
            frame = (struct i386_frame *)ddb_regs.ebp;
            callpc = (db_addr_t)ddb_regs.eip;
            th = current_thread();
            task = (th != THREAD_NULL)? th->task: TASK_NULL;
        } else if (trace_thread) {
            if (have_addr) {
                th = (thread_t) addr;
                if (!db_check_act_address_valid(th))
                    return;
            } else {
                th = db_default_act;
                if (th == THREAD_NULL)
                   th = current_thread();
                if (th == THREAD_NULL) {
                   db_printf("no active thread\n");
                   return;
                }
            }
            if (trace_all_threads)
                db_printf("---------- Thread 0x%x (#%d of %d) ----------\n",
                      addr, thcount, th->task->thr_act_count);

        next_activation:
            user_frame = 0;

            task = th->task;
            if (th == current_thread()) {
                frame = (struct i386_frame *)ddb_regs.ebp;
                callpc = (db_addr_t)ddb_regs.eip;
            } else {
                if (th->machine.pcb == 0) {
                    db_printf("thread has no pcb\n");
                    return;
                }
                if (!th->thread) {
                    register struct i386_saved_state *iss =
                                                &th->machine.pcb->iss;

                    db_printf("thread has no shuttle\n");
#if 0
                    frame = (struct i386_frame *) (iss->ebp);
                    callpc = (db_addr_t) (iss->eip);
#else
                    goto thread_done;
#endif
                }
                else if ((th->thread->state & TH_STACK_HANDOFF) ||
                          th->thread->kernel_stack == 0) {
                    register struct i386_saved_state *iss =
                                                &th->machine.pcb->iss;

                    db_printf("Continuation ");
                    db_task_printsym((db_expr_t)th->thread->continuation,
                                                        DB_STGY_PROC, task);
                    db_printf("\n");
                    frame = (struct i386_frame *) (iss->ebp);
                    callpc = (db_addr_t) (iss->eip);
                } else {
                    int cpu;

                    for (cpu = 0; cpu < real_ncpus; cpu++) {
                        if (cpu_datap(cpu)->cpu_running == TRUE &&
                            cpu_datap(cpu)->cpu_active_thread == th->thread &&
                            saved_state[cpu]) {
                            break;
                        }
                    }
                    if (top_act != THREAD_NULL) {
                            /*
                             * Trying to get the backtrace of an activation
                             * which is not the top_most one in the RPC chain:
                             * use the activation's pcb.
                             */
                            register struct i386_saved_state *iss =
                                &th->machine.pcb->iss;
                            frame = (struct i386_frame *) (iss->ebp);
                            callpc = (db_addr_t) (iss->eip);
                    } else {
                        if (cpu == NCPUS) {
                            register struct i386_kernel_state *iks;
                            int r;

                            iks = STACK_IKS(th->thread->kernel_stack);
                            prev = db_recover;
                            if ((r = _setjmp(db_recover = &db_jmp_buf)) == 0) {
                                frame = (struct i386_frame *) (iks->k_ebp);
                                callpc = (db_addr_t) (iks->k_eip);
                            } else {
                                /*
                                 * The kernel stack has probably been
                                 * paged out (swapped out activation).
                                 */
                                db_recover = prev;
                                if (r == 2)     /* 'q' from db_more() */
                                    db_error(0);
                                db_printf("<kernel stack (0x%x) error "
                                          "(probably swapped out)>\n",
                                          iks);
                                goto thread_done;
                            }
                            db_recover = prev;
                        } else {
                            db_printf(">>>>> active on cpu %d <<<<<\n",
                                      cpu);
                            frame = (struct i386_frame *)
                                saved_state[cpu]->ebp;
                            callpc = (db_addr_t) saved_state[cpu]->eip;
                        }
                    }
                }
            }
        } else {
            frame = (struct i386_frame *)addr;
            th = (db_default_act)? db_default_act: current_thread();
            task = (th != THREAD_NULL)? th->task: TASK_NULL;
            callpc = (db_addr_t)db_get_task_value((int)&frame->f_retaddr,
                                                  4, 
                                                  FALSE, 
                                                  (user_frame) ? task : 0);
        }

        if (!INKERNELSTACK((unsigned)frame, th)) {
            db_printf(">>>>> user space <<<<<\n");
            if (kernel_only)
                goto thread_done;
            user_frame++;
        } else if (INKSERVER(callpc) && INKSERVER(frame)) {
            db_printf(">>>>> INKserver space <<<<<\n");
        }

        lastframe = 0;
        lastcallpc = (db_addr_t) 0;
        while (frame_count-- && frame != 0) {
            int narg;
            char *      name;
            db_expr_t   offset;
            db_addr_t call_func = 0;
            int r;

            db_symbol_values(NULL,
                             db_search_task_symbol_and_line(
                                        callpc,
                                        DB_STGY_XTRN, 
                                        &offset,
                                        &filename,
                                        &linenum,
                                        (user_frame) ? task : 0,
                                        &narg),
                             &name, (db_expr_t *)&call_func);
            if (user_frame == 0) {
                if (call_func == db_user_trap_symbol_value ||
                    call_func == db_kernel_trap_symbol_value) {
                    frame_type = TRAP;
                    narg = 1;
                } else if (call_func == db_interrupt_symbol_value) {
                    frame_type = INTERRUPT;
                    goto next_frame;
                } else if (call_func == db_syscall_symbol_value) {
                    frame_type = SYSCALL;
                    goto next_frame;
                } else {
                    frame_type = 0;
                    prev = db_recover;
                    if ((r = _setjmp(db_recover = &db_jmp_buf)) == 0) {
                        if (narg < 0)
                            narg = db_numargs(frame,
                                              (user_frame) ? task : 0);
                        db_recover = prev;
                    } else {
                        db_recover = prev;
                        goto thread_done;
                    }
                }
            } else {
                frame_type = 0;
                prev = db_recover;
                if ((r = _setjmp(db_recover = &db_jmp_buf)) == 0) {
                    if (narg < 0)
                        narg = db_numargs(frame,
                                          (user_frame) ? task : 0);
                    db_recover = prev;
                } else {
                    db_recover = prev;
                    goto thread_done;
                }
            }

            if (name == 0 || offset > db_maxoff) {
                db_printf("0x%x 0x%x(", frame, callpc);
                offset = 0;
            } else
                db_printf("0x%x %s(", frame, name);

            argp = &frame->f_arg0;
            while (narg > 0) {
                int value;

                prev = db_recover;
                if ((r = _setjmp(db_recover = &db_jmp_buf)) == 0) {
                    value = db_get_task_value((int)argp,
                                              4,
                                              FALSE,
                                              (user_frame) ? task : 0);
                } else {
                    db_recover = prev;
                    if (r == 2)         /* 'q' from db_more() */
                        db_error(0);
                    db_printf("... <stack error>)");
                    if (offset)
                        db_printf("+%x", offset);
                    if (filename) {
                        db_printf(" [%s", filename);
                        if (linenum > 0)
                            db_printf(":%d", linenum);
                        db_printf("]");
                    }
                    db_printf("\n");
                    goto thread_done;
                }
                db_recover = prev;
                db_printf("%x", value);
                argp++;
                if (--narg != 0)
                    db_printf(",");
            }
            if (narg < 0)
                db_printf("...");
            db_printf(")");
            if (offset) {
                db_printf("+%x", offset);
            }
            if (filename) {
                db_printf(" [%s", filename);
                if (linenum > 0)
                    db_printf(":%d", linenum);
                db_printf("]");
            }
            db_printf("\n");

        next_frame:
            lastcallpc = callpc;
            db_nextframe(&lastframe, &frame, &callpc, frame_type,
                         (user_frame) ? th : THREAD_NULL);

            if (frame == 0) {
                if (th->lower != THREAD_NULL) {
                    if (top_act == THREAD_NULL)
                        top_act = th;
                    th = th->lower;
                    db_printf(">>>>> next activation 0x%x ($task%d.%d) <<<<<\n",
                              th,
                              db_lookup_task(th->task),
                              db_lookup_task_act(th->task, th));
                    goto next_activation;
                }
                /* end of chain */
                break;
            }
            if (!INKERNELSTACK(lastframe, th) ||
                !INKERNELSTACK((unsigned)frame, th))
                user_frame++;
            if (user_frame == 1) {
                db_printf(">>>>> user space <<<<<\n");
                if (kernel_only)
                    break;
            } else if ((!INKSERVER(lastframe) || !INKSERVER(lastcallpc)) &&
                        (INKSERVER(callpc) && INKSERVER(frame))) {
                db_printf(">>>>> inkserver space <<<<<\n");
            }
            if (frame <= lastframe) {
                if ((INKERNELSTACK(lastframe, th) &&
                     !INKERNELSTACK(frame, th)) ||
                    (INKSERVER(lastframe) ^ INKSERVER(frame)))
                    continue;
                db_printf("Bad frame pointer: 0x%x\n", frame);
                break;
            }
        }

    thread_done:
        if (trace_all_threads) {
            if (top_act != THREAD_NULL)
                th = top_act;
            th = (thread_t) queue_next(&th->thr_acts);
            if (! queue_end(act_list, (queue_entry_t) th)) {
                db_printf("\n");
                addr = (db_expr_t) th;
                thcount++;
                goto next_thread;

            }
        }
}