regs.c revision f25af517a06521f69fbc53eaf3c245a7a2298c75 
1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2013 Petr Machata, Red Hat Inc.
4 * Copyright (C) 1998,2002,2004,2008,2009 Juan Cespedes
5 * Copyright (C) 2009 Juan Cespedes
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
23#include "config.h"
24
25#include <sys/types.h>
26#include <sys/ptrace.h>
27#include <asm/ptrace.h>
28#include <errno.h>
29
30#include "proc.h"
31#include "common.h"
32#include "regs.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
42int
43arm_get_register(struct process *proc, enum arm_register reg, uint32_t *lp)
44{
45	errno = 0;
46	long l = ptrace(PTRACE_PEEKUSER, proc->pid, (void *)(reg * 4L), 0);
47	if (l == -1 && errno != 0)
48		return -1;
49	*lp = (uint32_t)l;
50	return 0;
51}
52
53int
54arm_set_register(struct process *proc, enum arm_register reg, uint32_t lp)
55{
56	return ptrace(PTRACE_PEEKUSER, proc->pid,
57		      (void *)(reg * 4L), (void *)lp);
58}
59
60int
61arm_get_register_offpc(struct process *proc, enum arm_register reg,
62		       uint32_t *lp)
63{
64	if (arm_get_register(proc, reg, lp) < 0)
65		return -1;
66	if (reg == ARM_REG_PC)
67		*lp += 8;
68	return 0;
69}
70
71int
72arm_get_shifted_register(struct process *proc, uint32_t inst, int carry,
73			 arch_addr_t pc_val, uint32_t *lp)
74{
75	enum arm_register rm = BITS(inst, 0, 3);
76	unsigned long shifttype = BITS(inst, 5, 6);
77
78	uint32_t shift;
79	if (BIT(inst, 4)) {
80		if (arm_get_register_offpc(proc, BITS(inst, 8, 11), &shift) < 0)
81			return -1;
82		shift &= 0xff;
83	} else {
84		shift = BITS(inst, 7, 11);
85	}
86
87	uint32_t res;
88	if (rm == ARM_REG_PC)
89		/* xxx double cast */
90		res = (uintptr_t)pc_val + (BIT(inst, 4) ? 12 : 8);
91	else if (arm_get_register(proc, rm, &res) < 0)
92		return -1;
93
94	switch (shifttype) {
95	case 0:			/* LSL */
96		res = shift >= 32 ? 0 : res << shift;
97		break;
98
99	case 1:			/* LSR */
100		res = shift >= 32 ? 0 : res >> shift;
101		break;
102
103	case 2:			/* ASR */
104		if (shift >= 32)
105			shift = 31;
106		res = ((res & 0x80000000L)
107		       ? ~((~res) >> shift) : res >> shift);
108		break;
109
110	case 3:			/* ROR/RRX */
111		shift &= 31;
112		if (shift == 0)
113			res = (res >> 1) | (carry ? 0x80000000L : 0);
114		else
115			res = (res >> shift) | (res << (32 - shift));
116		break;
117	}
118
119	*lp = res & 0xffffffff;
120	return 0;
121}
122
123static arch_addr_t
124get_register_nocheck(struct process *proc, enum arm_register r)
125{
126	uint32_t reg;
127	if (arm_get_register(proc, r, &reg) < 0)
128		/* XXX double cast. */
129		return (arch_addr_t)-1;
130	/* XXX double cast.  */
131	return (arch_addr_t)(uintptr_t)reg;
132}
133
134arch_addr_t
135get_instruction_pointer(struct process *proc)
136{
137	return get_register_nocheck(proc, ARM_REG_PC);
138}
139
140void
141set_instruction_pointer(struct process *proc, arch_addr_t addr)
142{
143	/* XXX double cast.  */
144	arm_set_register(proc, ARM_REG_PC, (uint32_t)addr);
145}
146
147void *
148get_stack_pointer(struct process *proc)
149{
150	return get_register_nocheck(proc, ARM_REG_SP);
151}
152
153arch_addr_t
154get_return_addr(struct process *proc, arch_addr_t stack_pointer)
155{
156	return get_register_nocheck(proc, ARM_REG_LR);
157}
158