xref: /openbmc/linux/arch/m68k/kernel/ptrace.c (revision b6dcefde)
1 /*
2  *  linux/arch/m68k/kernel/ptrace.c
3  *
4  *  Copyright (C) 1994 by Hamish Macdonald
5  *  Taken from linux/kernel/ptrace.c and modified for M680x0.
6  *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
7  *
8  * This file is subject to the terms and conditions of the GNU General
9  * Public License.  See the file COPYING in the main directory of
10  * this archive for more details.
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/mm.h>
16 #include <linux/smp.h>
17 #include <linux/errno.h>
18 #include <linux/ptrace.h>
19 #include <linux/user.h>
20 #include <linux/signal.h>
21 
22 #include <asm/uaccess.h>
23 #include <asm/page.h>
24 #include <asm/pgtable.h>
25 #include <asm/system.h>
26 #include <asm/processor.h>
27 
28 /*
29  * does not yet catch signals sent when the child dies.
30  * in exit.c or in signal.c.
31  */
32 
33 /* determines which bits in the SR the user has access to. */
34 /* 1 = access 0 = no access */
35 #define SR_MASK 0x001f
36 
37 /* sets the trace bits. */
38 #define TRACE_BITS 0xC000
39 #define T1_BIT 0x8000
40 #define T0_BIT 0x4000
41 
42 /* Find the stack offset for a register, relative to thread.esp0. */
43 #define PT_REG(reg)	((long)&((struct pt_regs *)0)->reg)
44 #define SW_REG(reg)	((long)&((struct switch_stack *)0)->reg \
45 			 - sizeof(struct switch_stack))
46 /* Mapping from PT_xxx to the stack offset at which the register is
47    saved.  Notice that usp has no stack-slot and needs to be treated
48    specially (see get_reg/put_reg below). */
49 static const int regoff[] = {
50 	[0]	= PT_REG(d1),
51 	[1]	= PT_REG(d2),
52 	[2]	= PT_REG(d3),
53 	[3]	= PT_REG(d4),
54 	[4]	= PT_REG(d5),
55 	[5]	= SW_REG(d6),
56 	[6]	= SW_REG(d7),
57 	[7]	= PT_REG(a0),
58 	[8]	= PT_REG(a1),
59 	[9]	= PT_REG(a2),
60 	[10]	= SW_REG(a3),
61 	[11]	= SW_REG(a4),
62 	[12]	= SW_REG(a5),
63 	[13]	= SW_REG(a6),
64 	[14]	= PT_REG(d0),
65 	[15]	= -1,
66 	[16]	= PT_REG(orig_d0),
67 	[17]	= PT_REG(sr),
68 	[18]	= PT_REG(pc),
69 };
70 
71 /*
72  * Get contents of register REGNO in task TASK.
73  */
74 static inline long get_reg(struct task_struct *task, int regno)
75 {
76 	unsigned long *addr;
77 
78 	if (regno == PT_USP)
79 		addr = &task->thread.usp;
80 	else if (regno < ARRAY_SIZE(regoff))
81 		addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
82 	else
83 		return 0;
84 	/* Need to take stkadj into account. */
85 	if (regno == PT_SR || regno == PT_PC) {
86 		long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
87 		addr = (unsigned long *) ((unsigned long)addr + stkadj);
88 		/* The sr is actually a 16 bit register.  */
89 		if (regno == PT_SR)
90 			return *(unsigned short *)addr;
91 	}
92 	return *addr;
93 }
94 
95 /*
96  * Write contents of register REGNO in task TASK.
97  */
98 static inline int put_reg(struct task_struct *task, int regno,
99 			  unsigned long data)
100 {
101 	unsigned long *addr;
102 
103 	if (regno == PT_USP)
104 		addr = &task->thread.usp;
105 	else if (regno < ARRAY_SIZE(regoff))
106 		addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
107 	else
108 		return -1;
109 	/* Need to take stkadj into account. */
110 	if (regno == PT_SR || regno == PT_PC) {
111 		long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
112 		addr = (unsigned long *) ((unsigned long)addr + stkadj);
113 		/* The sr is actually a 16 bit register.  */
114 		if (regno == PT_SR) {
115 			*(unsigned short *)addr = data;
116 			return 0;
117 		}
118 	}
119 	*addr = data;
120 	return 0;
121 }
122 
123 /*
124  * Make sure the single step bit is not set.
125  */
126 static inline void singlestep_disable(struct task_struct *child)
127 {
128 	unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
129 	put_reg(child, PT_SR, tmp);
130 	clear_tsk_thread_flag(child, TIF_DELAYED_TRACE);
131 }
132 
133 /*
134  * Called by kernel/ptrace.c when detaching..
135  */
136 void ptrace_disable(struct task_struct *child)
137 {
138 	singlestep_disable(child);
139 }
140 
141 void user_enable_single_step(struct task_struct *child)
142 {
143 	unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
144 	put_reg(child, PT_SR, tmp | T1_BIT);
145 	set_tsk_thread_flag(child, TIF_DELAYED_TRACE);
146 }
147 
148 void user_enable_block_step(struct task_struct *child)
149 {
150 	unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
151 	put_reg(child, PT_SR, tmp | T0_BIT);
152 }
153 
154 void user_disable_single_step(struct task_struct *child)
155 {
156 	singlestep_disable(child);
157 }
158 
159 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
160 {
161 	unsigned long tmp;
162 	int i, ret = 0;
163 
164 	switch (request) {
165 	/* read the word at location addr in the USER area. */
166 	case PTRACE_PEEKUSR:
167 		if (addr & 3)
168 			goto out_eio;
169 		addr >>= 2;	/* temporary hack. */
170 
171 		if (addr >= 0 && addr < 19) {
172 			tmp = get_reg(child, addr);
173 		} else if (addr >= 21 && addr < 49) {
174 			tmp = child->thread.fp[addr - 21];
175 			/* Convert internal fpu reg representation
176 			 * into long double format
177 			 */
178 			if (FPU_IS_EMU && (addr < 45) && !(addr % 3))
179 				tmp = ((tmp & 0xffff0000) << 15) |
180 				      ((tmp & 0x0000ffff) << 16);
181 		} else
182 			goto out_eio;
183 		ret = put_user(tmp, (unsigned long *)data);
184 		break;
185 
186 	case PTRACE_POKEUSR:	/* write the word at location addr in the USER area */
187 		if (addr & 3)
188 			goto out_eio;
189 		addr >>= 2;	/* temporary hack. */
190 
191 		if (addr == PT_SR) {
192 			data &= SR_MASK;
193 			data |= get_reg(child, PT_SR) & ~SR_MASK;
194 		}
195 		if (addr >= 0 && addr < 19) {
196 			if (put_reg(child, addr, data))
197 				goto out_eio;
198 		} else if (addr >= 21 && addr < 48) {
199 			/* Convert long double format
200 			 * into internal fpu reg representation
201 			 */
202 			if (FPU_IS_EMU && (addr < 45) && !(addr % 3)) {
203 				data = (unsigned long)data << 15;
204 				data = (data & 0xffff0000) |
205 				       ((data & 0x0000ffff) >> 1);
206 			}
207 			child->thread.fp[addr - 21] = data;
208 		} else
209 			goto out_eio;
210 		break;
211 
212 	case PTRACE_GETREGS:	/* Get all gp regs from the child. */
213 		for (i = 0; i < 19; i++) {
214 			tmp = get_reg(child, i);
215 			ret = put_user(tmp, (unsigned long *)data);
216 			if (ret)
217 				break;
218 			data += sizeof(long);
219 		}
220 		break;
221 
222 	case PTRACE_SETREGS:	/* Set all gp regs in the child. */
223 		for (i = 0; i < 19; i++) {
224 			ret = get_user(tmp, (unsigned long *)data);
225 			if (ret)
226 				break;
227 			if (i == PT_SR) {
228 				tmp &= SR_MASK;
229 				tmp |= get_reg(child, PT_SR) & ~SR_MASK;
230 			}
231 			put_reg(child, i, tmp);
232 			data += sizeof(long);
233 		}
234 		break;
235 
236 	case PTRACE_GETFPREGS:	/* Get the child FPU state. */
237 		if (copy_to_user((void *)data, &child->thread.fp,
238 				 sizeof(struct user_m68kfp_struct)))
239 			ret = -EFAULT;
240 		break;
241 
242 	case PTRACE_SETFPREGS:	/* Set the child FPU state. */
243 		if (copy_from_user(&child->thread.fp, (void *)data,
244 				   sizeof(struct user_m68kfp_struct)))
245 			ret = -EFAULT;
246 		break;
247 
248 	default:
249 		ret = ptrace_request(child, request, addr, data);
250 		break;
251 	}
252 
253 	return ret;
254 out_eio:
255 	return -EIO;
256 }
257 
258 asmlinkage void syscall_trace(void)
259 {
260 	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
261 				 ? 0x80 : 0));
262 	/*
263 	 * this isn't the same as continuing with a signal, but it will do
264 	 * for normal use.  strace only continues with a signal if the
265 	 * stopping signal is not SIGTRAP.  -brl
266 	 */
267 	if (current->exit_code) {
268 		send_sig(current->exit_code, current, 1);
269 		current->exit_code = 0;
270 	}
271 }
272