text: /*	$OpenBSD: db_trace.c,v 1.4 2010/11/27 20:46:39 miod Exp $	*/
  /*	$NetBSD: db_trace.c,v 1.8 2003/01/17 22:28:48 thorpej Exp $	*/
  
  /* 
   * Copyright (c) 2000, 2001 Ben Harris
   * Copyright (c) 1996 Scott K. Stevens
   *
   * 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 the
   * rights to redistribute these changes.
   */
  
  #include <sys/param.h>
  
  #include <sys/proc.h>
  #include <sys/user.h>
  #include <arm/armreg.h>
  #include <arm/cpufunc.h>
  #include <machine/db_machdep.h>
  
  #include <ddb/db_access.h>
  #include <ddb/db_interface.h>
  #include <ddb/db_sym.h>
  #include <ddb/db_output.h>
  
  db_regs_t ddb_regs;
  
  #define INKERNEL(va)	(((vaddr_t)(va)) >= VM_MIN_KERNEL_ADDRESS)
  
  /*
   * APCS stack frames are awkward beasts, so I don't think even trying to use
   * a structure to represent them is a good idea.
   *
   * Here's the diagram from the APCS.  Increasing address is _up_ the page.
   * 
   *          save code pointer       [fp]        <- fp points to here
   *          return link value       [fp, #-4]
   *          return sp value         [fp, #-8]
   *          return fp value         [fp, #-12]
   *          [saved v7 value]
   *          [saved v6 value]
   *          [saved v5 value]
   *          [saved v4 value]
   *          [saved v3 value]
   *          [saved v2 value]
   *          [saved v1 value]
   *          [saved a4 value]
   *          [saved a3 value]
   *          [saved a2 value]
   *          [saved a1 value]
   *
   * The save code pointer points twelve bytes beyond the start of the 
   * code sequence (usually a single STM) that created the stack frame.  
   * We have to disassemble it if we want to know which of the optional 
   * fields are actually present.
   */
  
  #define FR_SCP	(0)
  #define FR_RLV	(-1)
  #define FR_RSP	(-2)
  #define FR_RFP	(-3)
  
  void
  db_stack_trace_print(addr, have_addr, count, modif, pr)
  	db_expr_t       addr;
  	int             have_addr;
  	db_expr_t       count;
  	char            *modif;
  	int		(*pr) (const char *, ...);
  {
  	u_int32_t	*frame, *lastframe;
  	char c, *cp = modif;
  	boolean_t	kernel_only = TRUE;
  	boolean_t	trace_thread = FALSE;
  	int	scp_offset;
  
  	while ((c = *cp++) != 0) {
  		if (c == 'u')
  			kernel_only = FALSE;
  		if (c == 't')
  			trace_thread = TRUE;
  	}
  
  	if (!have_addr)
  		frame = (u_int32_t *)(DDB_REGS->tf_r11);
  	else {
  		if (trace_thread) {
  			struct proc *p;
  			struct user *u;
  			(*pr) ("trace: pid %d ", (int)addr);
  			p = pfind(addr);
  			if (p == NULL) {
  				(*pr)("not found\n");
  				return;
  			}	
  			u = p->p_addr;
  #ifdef acorn26
  			frame = (u_int32_t *)(u->u_pcb.pcb_sf->sf_r11);
  #else
  			frame = (u_int32_t *)(u->u_pcb.pcb_un.un_32.pcb32_r11);
  #endif
  			(*pr)("at %p\n", frame);
  		} else
  			frame = (u_int32_t *)(addr);
  	}
  	lastframe = NULL;
  	scp_offset = -(get_pc_str_offset() >> 2);
  
  	while (count-- && frame != NULL) {
  		db_addr_t	scp;
  		u_int32_t	savecode;
  		int		r, n;
  		u_int32_t	*rp;
  		const char	*sep;
  
  		/*
  		 * In theory, the SCP isn't guaranteed to be in the function
  		 * that generated the stack frame.  We hope for the best.
  		 */
  #ifdef __PROG26
  		scp = frame[FR_SCP] & R15_PC;
  #else
  		scp = frame[FR_SCP];
  #endif
  
  		db_printsym(scp, DB_STGY_PROC, pr);
  		(*pr)("\n\t");
  #ifdef __PROG26
  		(*pr)("scp=0x%08x rlv=0x%08x (", scp, frame[FR_RLV] & R15_PC);
  		db_printsym(frame[FR_RLV] & R15_PC, DB_STGY_PROC, pr);
  		(*pr)(")\n");
  #else
  		(*pr)("scp=0x%08x rlv=0x%08x (", scp, frame[FR_RLV]);
  		db_printsym(frame[FR_RLV], DB_STGY_PROC, pr);
  		(*pr)(")\n");
  #endif
  		(*pr)("\trsp=0x%08x rfp=0x%08x", frame[FR_RSP], frame[FR_RFP]);
  
  		savecode = ((u_int32_t *)scp)[scp_offset];
  		if ((savecode & 0x0e100000) == 0x08000000) {
  			/* Looks like an STM */
  			rp = frame - 4;
  			n = 0;
  			for (r = 10; r >= 0; r--) {
  				if (savecode & (1 << r)) {
  					sep = n++ % 4 == 0 ? "\n\t" : " ";
  					(*pr)("%sr%d=0x%08x", sep, r, *rp--);
  				}
  			}
  		}
  
  		(*pr)("\n");
  
  		/*
  		 * Switch to next frame up
  		 */
  		if (frame[FR_RFP] == 0)
  			break; /* Top of stack */
  
  		lastframe = frame;
  		frame = (u_int32_t *)(frame[FR_RFP]);
  
  		if (INKERNEL((int)frame)) {
  			/* staying in kernel */
  			if (frame <= lastframe) {
  				(*pr)("Bad frame pointer: %p\n", frame);
  				break;
  			}
  		} else if (INKERNEL((int)lastframe)) {
  			/* switch from user to kernel */
  			if (kernel_only)
  				break;	/* kernel stack only */
  		} else {
  			/* in user */
  			if (frame <= lastframe) {
  				(*pr)("Bad user frame pointer: %p\n",
  					  frame);
  				break;
  			}
  		}
  	}
  }
  