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5f97f7f9 HS |
1 | /* |
2 | * Copyright (C) 2004-2006 Atmel Corporation | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | */ | |
8 | #undef DEBUG | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/mm.h> | |
5f97f7f9 HS |
12 | #include <linux/ptrace.h> |
13 | #include <linux/errno.h> | |
14 | #include <linux/user.h> | |
15 | #include <linux/security.h> | |
16 | #include <linux/unistd.h> | |
17 | #include <linux/notifier.h> | |
18 | ||
19 | #include <asm/traps.h> | |
20 | #include <asm/uaccess.h> | |
21 | #include <asm/ocd.h> | |
22 | #include <asm/mmu_context.h> | |
1eeb66a1 | 23 | #include <linux/kdebug.h> |
5f97f7f9 HS |
24 | |
25 | static struct pt_regs *get_user_regs(struct task_struct *tsk) | |
26 | { | |
c9f4f06d | 27 | return (struct pt_regs *)((unsigned long)task_stack_page(tsk) + |
5f97f7f9 HS |
28 | THREAD_SIZE - sizeof(struct pt_regs)); |
29 | } | |
30 | ||
9e584fbb | 31 | void user_enable_single_step(struct task_struct *tsk) |
5f97f7f9 | 32 | { |
1d839317 | 33 | pr_debug("user_enable_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n", |
2507bc13 | 34 | tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr); |
5f97f7f9 | 35 | |
2507bc13 HS |
36 | /* |
37 | * We can't schedule in Debug mode, so when TIF_BREAKPOINT is | |
38 | * set, the system call or exception handler will do a | |
39 | * breakpoint to enter monitor mode before returning to | |
40 | * userspace. | |
41 | * | |
42 | * The monitor code will then notice that TIF_SINGLE_STEP is | |
43 | * set and return to userspace with single stepping enabled. | |
44 | * The CPU will then enter monitor mode again after exactly | |
45 | * one instruction has been executed, and the monitor code | |
46 | * will then send a SIGTRAP to the process. | |
47 | */ | |
48 | set_tsk_thread_flag(tsk, TIF_BREAKPOINT); | |
5f97f7f9 HS |
49 | set_tsk_thread_flag(tsk, TIF_SINGLE_STEP); |
50 | } | |
51 | ||
1d839317 CH |
52 | void user_disable_single_step(struct task_struct *child) |
53 | { | |
54 | /* XXX(hch): a no-op here seems wrong.. */ | |
55 | } | |
56 | ||
5f97f7f9 HS |
57 | /* |
58 | * Called by kernel/ptrace.c when detaching | |
59 | * | |
60 | * Make sure any single step bits, etc. are not set | |
61 | */ | |
62 | void ptrace_disable(struct task_struct *child) | |
63 | { | |
64 | clear_tsk_thread_flag(child, TIF_SINGLE_STEP); | |
2507bc13 | 65 | clear_tsk_thread_flag(child, TIF_BREAKPOINT); |
13b54a50 | 66 | ocd_disable(child); |
5f97f7f9 HS |
67 | } |
68 | ||
69 | /* | |
70 | * Read the word at offset "offset" into the task's "struct user". We | |
71 | * actually access the pt_regs struct stored on the kernel stack. | |
72 | */ | |
73 | static int ptrace_read_user(struct task_struct *tsk, unsigned long offset, | |
74 | unsigned long __user *data) | |
75 | { | |
76 | unsigned long *regs; | |
77 | unsigned long value; | |
78 | ||
5f97f7f9 HS |
79 | if (offset & 3 || offset >= sizeof(struct user)) { |
80 | printk("ptrace_read_user: invalid offset 0x%08lx\n", offset); | |
81 | return -EIO; | |
82 | } | |
83 | ||
84 | regs = (unsigned long *)get_user_regs(tsk); | |
85 | ||
86 | value = 0; | |
87 | if (offset < sizeof(struct pt_regs)) | |
88 | value = regs[offset / sizeof(regs[0])]; | |
89 | ||
2507bc13 HS |
90 | pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n", |
91 | tsk->comm, tsk->pid, offset, data, value); | |
92 | ||
5f97f7f9 HS |
93 | return put_user(value, data); |
94 | } | |
95 | ||
96 | /* | |
97 | * Write the word "value" to offset "offset" into the task's "struct | |
98 | * user". We actually access the pt_regs struct stored on the kernel | |
99 | * stack. | |
100 | */ | |
101 | static int ptrace_write_user(struct task_struct *tsk, unsigned long offset, | |
102 | unsigned long value) | |
103 | { | |
104 | unsigned long *regs; | |
105 | ||
2507bc13 HS |
106 | pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n", |
107 | tsk->comm, tsk->pid, offset, value); | |
108 | ||
5f97f7f9 | 109 | if (offset & 3 || offset >= sizeof(struct user)) { |
2507bc13 | 110 | pr_debug(" invalid offset 0x%08lx\n", offset); |
5f97f7f9 HS |
111 | return -EIO; |
112 | } | |
113 | ||
114 | if (offset >= sizeof(struct pt_regs)) | |
115 | return 0; | |
116 | ||
117 | regs = (unsigned long *)get_user_regs(tsk); | |
118 | regs[offset / sizeof(regs[0])] = value; | |
119 | ||
120 | return 0; | |
121 | } | |
122 | ||
123 | static int ptrace_getregs(struct task_struct *tsk, void __user *uregs) | |
124 | { | |
125 | struct pt_regs *regs = get_user_regs(tsk); | |
126 | ||
127 | return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0; | |
128 | } | |
129 | ||
130 | static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs) | |
131 | { | |
132 | struct pt_regs newregs; | |
133 | int ret; | |
134 | ||
135 | ret = -EFAULT; | |
136 | if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) { | |
137 | struct pt_regs *regs = get_user_regs(tsk); | |
138 | ||
139 | ret = -EINVAL; | |
140 | if (valid_user_regs(&newregs)) { | |
141 | *regs = newregs; | |
142 | ret = 0; | |
143 | } | |
144 | } | |
145 | ||
146 | return ret; | |
147 | } | |
148 | ||
149 | long arch_ptrace(struct task_struct *child, long request, long addr, long data) | |
150 | { | |
5f97f7f9 HS |
151 | int ret; |
152 | ||
5f97f7f9 HS |
153 | switch (request) { |
154 | /* Read the word at location addr in the child process */ | |
155 | case PTRACE_PEEKTEXT: | |
156 | case PTRACE_PEEKDATA: | |
76647323 | 157 | ret = generic_ptrace_peekdata(child, addr, data); |
5f97f7f9 HS |
158 | break; |
159 | ||
160 | case PTRACE_PEEKUSR: | |
161 | ret = ptrace_read_user(child, addr, | |
162 | (unsigned long __user *)data); | |
163 | break; | |
164 | ||
165 | /* Write the word in data at location addr */ | |
166 | case PTRACE_POKETEXT: | |
167 | case PTRACE_POKEDATA: | |
f284ce72 | 168 | ret = generic_ptrace_pokedata(child, addr, data); |
5f97f7f9 HS |
169 | break; |
170 | ||
171 | case PTRACE_POKEUSR: | |
172 | ret = ptrace_write_user(child, addr, data); | |
173 | break; | |
174 | ||
5f97f7f9 HS |
175 | case PTRACE_GETREGS: |
176 | ret = ptrace_getregs(child, (void __user *)data); | |
177 | break; | |
178 | ||
179 | case PTRACE_SETREGS: | |
180 | ret = ptrace_setregs(child, (const void __user *)data); | |
181 | break; | |
182 | ||
183 | default: | |
184 | ret = ptrace_request(child, request, addr, data); | |
185 | break; | |
186 | } | |
187 | ||
5f97f7f9 HS |
188 | return ret; |
189 | } | |
190 | ||
191 | asmlinkage void syscall_trace(void) | |
192 | { | |
5f97f7f9 HS |
193 | if (!test_thread_flag(TIF_SYSCALL_TRACE)) |
194 | return; | |
195 | if (!(current->ptrace & PT_PTRACED)) | |
196 | return; | |
197 | ||
5f97f7f9 HS |
198 | /* The 0x80 provides a way for the tracing parent to |
199 | * distinguish between a syscall stop and SIGTRAP delivery */ | |
200 | ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) | |
201 | ? 0x80 : 0)); | |
202 | ||
203 | /* | |
204 | * this isn't the same as continuing with a signal, but it | |
205 | * will do for normal use. strace only continues with a | |
206 | * signal if the stopping signal is not SIGTRAP. -brl | |
207 | */ | |
208 | if (current->exit_code) { | |
209 | pr_debug("syscall_trace: sending signal %d to PID %u\n", | |
210 | current->exit_code, current->pid); | |
211 | send_sig(current->exit_code, current, 1); | |
212 | current->exit_code = 0; | |
213 | } | |
214 | } | |
215 | ||
5f97f7f9 | 216 | /* |
2507bc13 HS |
217 | * debug_trampoline() is an assembly stub which will store all user |
218 | * registers on the stack and execute a breakpoint instruction. | |
219 | * | |
220 | * If we single-step into an exception handler which runs with | |
221 | * interrupts disabled the whole time so it doesn't have to check for | |
222 | * pending work, its return address will be modified so that it ends | |
223 | * up returning to debug_trampoline. | |
224 | * | |
225 | * If the exception handler decides to store the user context and | |
226 | * enable interrupts after all, it will restore the original return | |
227 | * address and status register value. Before it returns, it will | |
228 | * notice that TIF_BREAKPOINT is set and execute a breakpoint | |
229 | * instruction. | |
5f97f7f9 | 230 | */ |
2507bc13 | 231 | extern void debug_trampoline(void); |
5f97f7f9 | 232 | |
2507bc13 HS |
233 | asmlinkage struct pt_regs *do_debug(struct pt_regs *regs) |
234 | { | |
235 | struct thread_info *ti; | |
236 | unsigned long trampoline_addr; | |
237 | u32 status; | |
238 | u32 ctrl; | |
239 | int code; | |
240 | ||
241 | status = ocd_read(DS); | |
242 | ti = current_thread_info(); | |
243 | code = TRAP_BRKPT; | |
244 | ||
245 | pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n", | |
246 | status, regs->pc, regs->sr, ti->flags); | |
247 | ||
248 | if (!user_mode(regs)) { | |
249 | unsigned long die_val = DIE_BREAKPOINT; | |
250 | ||
251 | if (status & (1 << OCD_DS_SSS_BIT)) | |
252 | die_val = DIE_SSTEP; | |
253 | ||
254 | if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP) | |
255 | == NOTIFY_STOP) | |
256 | return regs; | |
257 | ||
258 | if ((status & (1 << OCD_DS_SWB_BIT)) | |
259 | && test_and_clear_ti_thread_flag( | |
260 | ti, TIF_BREAKPOINT)) { | |
261 | /* | |
262 | * Explicit breakpoint from trampoline or | |
263 | * exception/syscall/interrupt handler. | |
264 | * | |
265 | * The real saved regs are on the stack right | |
266 | * after the ones we saved on entry. | |
267 | */ | |
268 | regs++; | |
269 | pr_debug(" -> TIF_BREAKPOINT done, adjusted regs:" | |
270 | "PC=0x%08lx SR=0x%08lx\n", | |
271 | regs->pc, regs->sr); | |
272 | BUG_ON(!user_mode(regs)); | |
273 | ||
274 | if (test_thread_flag(TIF_SINGLE_STEP)) { | |
275 | pr_debug("Going to do single step...\n"); | |
276 | return regs; | |
277 | } | |
278 | ||
279 | /* | |
280 | * No TIF_SINGLE_STEP means we're done | |
281 | * stepping over a syscall. Do the trap now. | |
282 | */ | |
283 | code = TRAP_TRACE; | |
284 | } else if ((status & (1 << OCD_DS_SSS_BIT)) | |
285 | && test_ti_thread_flag(ti, TIF_SINGLE_STEP)) { | |
286 | ||
287 | pr_debug("Stepped into something, " | |
288 | "setting TIF_BREAKPOINT...\n"); | |
289 | set_ti_thread_flag(ti, TIF_BREAKPOINT); | |
290 | ||
291 | /* | |
292 | * We stepped into an exception, interrupt or | |
293 | * syscall handler. Some exception handlers | |
294 | * don't check for pending work, so we need to | |
295 | * set up a trampoline just in case. | |
296 | * | |
297 | * The exception entry code will undo the | |
298 | * trampoline stuff if it does a full context | |
299 | * save (which also means that it'll check for | |
300 | * pending work later.) | |
301 | */ | |
302 | if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) { | |
303 | trampoline_addr | |
304 | = (unsigned long)&debug_trampoline; | |
305 | ||
306 | pr_debug("Setting up trampoline...\n"); | |
307 | ti->rar_saved = sysreg_read(RAR_EX); | |
308 | ti->rsr_saved = sysreg_read(RSR_EX); | |
309 | sysreg_write(RAR_EX, trampoline_addr); | |
310 | sysreg_write(RSR_EX, (MODE_EXCEPTION | |
311 | | SR_EM | SR_GM)); | |
312 | BUG_ON(ti->rsr_saved & MODE_MASK); | |
313 | } | |
314 | ||
315 | /* | |
316 | * If we stepped into a system call, we | |
317 | * shouldn't do a single step after we return | |
318 | * since the return address is right after the | |
319 | * "scall" instruction we were told to step | |
320 | * over. | |
321 | */ | |
322 | if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) { | |
323 | pr_debug("Supervisor; no single step\n"); | |
324 | clear_ti_thread_flag(ti, TIF_SINGLE_STEP); | |
325 | } | |
326 | ||
327 | ctrl = ocd_read(DC); | |
328 | ctrl &= ~(1 << OCD_DC_SS_BIT); | |
329 | ocd_write(DC, ctrl); | |
330 | ||
331 | return regs; | |
332 | } else { | |
333 | printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n", | |
334 | status); | |
335 | printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags); | |
336 | die("Unhandled debug trap in kernel mode", | |
337 | regs, SIGTRAP); | |
338 | } | |
339 | } else if (status & (1 << OCD_DS_SSS_BIT)) { | |
340 | /* Single step in user mode */ | |
341 | code = TRAP_TRACE; | |
5f97f7f9 | 342 | |
2507bc13 HS |
343 | ctrl = ocd_read(DC); |
344 | ctrl &= ~(1 << OCD_DC_SS_BIT); | |
345 | ocd_write(DC, ctrl); | |
5f97f7f9 HS |
346 | } |
347 | ||
2507bc13 HS |
348 | pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n", |
349 | code, regs->pc, regs->sr); | |
5f97f7f9 | 350 | |
2507bc13 HS |
351 | clear_thread_flag(TIF_SINGLE_STEP); |
352 | _exception(SIGTRAP, regs, code, instruction_pointer(regs)); | |
353 | ||
354 | return regs; | |
5f97f7f9 | 355 | } |