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      1 /*
      2  * This file is part of ltrace.
      3  * Copyright (C) 2012,2013 Petr Machata, Red Hat Inc.
      4  * Copyright (C) 1998,2002,2004,2008,2009 Juan Cespedes
      5  * Copyright (C) 2006 Ian Wienand
      6  *
      7  * This program is free software; you can redistribute it and/or
      8  * modify it under the terms of the GNU General Public License as
      9  * published by the Free Software Foundation; either version 2 of the
     10  * License, or (at your option) any later version.
     11  *
     12  * This program is distributed in the hope that it will be useful, but
     13  * WITHOUT ANY WARRANTY; without even the implied warranty of
     14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     15  * General Public License for more details.
     16  *
     17  * You should have received a copy of the GNU General Public License
     18  * along with this program; if not, write to the Free Software
     19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
     20  * 02110-1301 USA
     21  */
     22 #include "config.h"
     23 
     24 #include <sys/types.h>
     25 #include <sys/ptrace.h>
     26 #include <sys/reg.h>
     27 #include <errno.h>
     28 #include <stdio.h>
     29 #include <string.h>
     30 
     31 #include "backend.h"
     32 #include "proc.h"
     33 
     34 #if (!defined(PTRACE_PEEKUSER) && defined(PTRACE_PEEKUSR))
     35 # define PTRACE_PEEKUSER PTRACE_PEEKUSR
     36 #endif
     37 
     38 #if (!defined(PTRACE_POKEUSER) && defined(PTRACE_POKEUSR))
     39 # define PTRACE_POKEUSER PTRACE_POKEUSR
     40 #endif
     41 
     42 #ifdef __x86_64__
     43 # define XIP (8 * RIP)
     44 # define XSP (8 * RSP)
     45 #else
     46 # define XIP (4 * EIP)
     47 # define XSP (4 * UESP)
     48 #endif
     49 
     50 static arch_addr_t
     51 conv_32(arch_addr_t val)
     52 {
     53 	/* XXX Drop the multiple double casts when arch_addr_t
     54 	 * becomes integral.  */
     55 	return (arch_addr_t)(uintptr_t)(uint32_t)(uintptr_t)val;
     56 }
     57 
     58 void *
     59 get_instruction_pointer(struct process *proc)
     60 {
     61 	long int ret = ptrace(PTRACE_PEEKUSER, proc->pid, XIP, 0);
     62 	if (proc->e_machine == EM_386)
     63 		ret &= 0xffffffff;
     64 	return (void *)ret;
     65 }
     66 
     67 void
     68 set_instruction_pointer(struct process *proc, arch_addr_t addr)
     69 {
     70 	if (proc->e_machine == EM_386)
     71 		addr = conv_32(addr);
     72 	ptrace(PTRACE_POKEUSER, proc->pid, XIP, addr);
     73 }
     74 
     75 void *
     76 get_stack_pointer(struct process *proc)
     77 {
     78 	long sp = ptrace(PTRACE_PEEKUSER, proc->pid, XSP, 0);
     79 	if (sp == -1 && errno) {
     80 		fprintf(stderr, "Couldn't read SP register: %s\n",
     81 			strerror(errno));
     82 		return NULL;
     83 	}
     84 
     85 	/* XXX Drop the multiple double casts when arch_addr_t
     86 	 * becomes integral.  */
     87 	arch_addr_t ret = (arch_addr_t)(uintptr_t)sp;
     88 	if (proc->e_machine == EM_386)
     89 		ret = conv_32(ret);
     90 	return ret;
     91 }
     92 
     93 void *
     94 get_return_addr(struct process *proc, void *sp)
     95 {
     96 	long a = ptrace(PTRACE_PEEKTEXT, proc->pid, sp, 0);
     97 	if (a == -1 && errno) {
     98 		fprintf(stderr, "Couldn't read return value: %s\n",
     99 			strerror(errno));
    100 		return NULL;
    101 	}
    102 
    103 	/* XXX Drop the multiple double casts when arch_addr_t
    104 	 * becomes integral.  */
    105 	arch_addr_t ret = (arch_addr_t)(uintptr_t)a;
    106 	if (proc->e_machine == EM_386)
    107 		ret = conv_32(ret);
    108 	return ret;
    109 }
    110