1 // SPDX-License-Identifier: GPL-2.0
2 /* ptrace.c */
3 /* By Ross Biro 1/23/92 */
4 /* edited by Linus Torvalds */
5 /* mangled further by Bob Manson (manson@santafe.edu) */
6 /* more mutilation by David Mosberger (davidm@azstarnet.com) */
7
8 #include <linux/kernel.h>
9 #include <linux/sched.h>
10 #include <linux/sched/task_stack.h>
11 #include <linux/mm.h>
12 #include <linux/smp.h>
13 #include <linux/errno.h>
14 #include <linux/ptrace.h>
15 #include <linux/user.h>
16 #include <linux/security.h>
17 #include <linux/signal.h>
18 #include <linux/audit.h>
19
20 #include <linux/uaccess.h>
21 #include <asm/fpu.h>
22
23 #include "proto.h"
24
25 #define DEBUG DBG_MEM
26 #undef DEBUG
27
28 #ifdef DEBUG
29 enum {
30 DBG_MEM = (1<<0),
31 DBG_BPT = (1<<1),
32 DBG_MEM_ALL = (1<<2)
33 };
34 #define DBG(fac,args) {if ((fac) & DEBUG) printk args;}
35 #else
36 #define DBG(fac,args)
37 #endif
38
39 #define BREAKINST 0x00000080 /* call_pal bpt */
40
41 /*
42 * does not yet catch signals sent when the child dies.
43 * in exit.c or in signal.c.
44 */
45
46 /*
47 * Processes always block with the following stack-layout:
48 *
49 * +================================+ <---- task + 2*PAGE_SIZE
50 * | PALcode saved frame (ps, pc, | ^
51 * | gp, a0, a1, a2) | |
52 * +================================+ | struct pt_regs
53 * | | |
54 * | frame generated by SAVE_ALL | |
55 * | | v
56 * +================================+
57 * | | ^
58 * | frame saved by do_switch_stack | | struct switch_stack
59 * | | v
60 * +================================+
61 */
62
63 /*
64 * The following table maps a register index into the stack offset at
65 * which the register is saved. Register indices are 0-31 for integer
66 * regs, 32-63 for fp regs, and 64 for the pc. Notice that sp and
67 * zero have no stack-slot and need to be treated specially (see
68 * get_reg/put_reg below).
69 */
70 enum {
71 REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
72 };
73
74 #define PT_REG(reg) \
75 (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
76
77 #define SW_REG(reg) \
78 (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
79 + offsetof(struct switch_stack, reg))
80
81 static int regoff[] = {
82 PT_REG( r0), PT_REG( r1), PT_REG( r2), PT_REG( r3),
83 PT_REG( r4), PT_REG( r5), PT_REG( r6), PT_REG( r7),
84 PT_REG( r8), SW_REG( r9), SW_REG( r10), SW_REG( r11),
85 SW_REG( r12), SW_REG( r13), SW_REG( r14), SW_REG( r15),
86 PT_REG( r16), PT_REG( r17), PT_REG( r18), PT_REG( r19),
87 PT_REG( r20), PT_REG( r21), PT_REG( r22), PT_REG( r23),
88 PT_REG( r24), PT_REG( r25), PT_REG( r26), PT_REG( r27),
89 PT_REG( r28), PT_REG( gp), -1, -1,
90 SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
91 SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
92 SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
93 SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
94 SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
95 SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
96 SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
97 SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
98 PT_REG( pc)
99 };
100
101 static unsigned long zero;
102
103 /*
104 * Get address of register REGNO in task TASK.
105 */
106 static unsigned long *
get_reg_addr(struct task_struct * task,unsigned long regno)107 get_reg_addr(struct task_struct * task, unsigned long regno)
108 {
109 unsigned long *addr;
110
111 if (regno == 30) {
112 addr = &task_thread_info(task)->pcb.usp;
113 } else if (regno == 65) {
114 addr = &task_thread_info(task)->pcb.unique;
115 } else if (regno == 31 || regno > 65) {
116 zero = 0;
117 addr = &zero;
118 } else {
119 addr = task_stack_page(task) + regoff[regno];
120 }
121 return addr;
122 }
123
124 /*
125 * Get contents of register REGNO in task TASK.
126 */
127 static unsigned long
get_reg(struct task_struct * task,unsigned long regno)128 get_reg(struct task_struct * task, unsigned long regno)
129 {
130 /* Special hack for fpcr -- combine hardware and software bits. */
131 if (regno == 63) {
132 unsigned long fpcr = *get_reg_addr(task, regno);
133 unsigned long swcr
134 = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
135 swcr = swcr_update_status(swcr, fpcr);
136 return fpcr | swcr;
137 }
138 return *get_reg_addr(task, regno);
139 }
140
141 /*
142 * Write contents of register REGNO in task TASK.
143 */
144 static int
put_reg(struct task_struct * task,unsigned long regno,unsigned long data)145 put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
146 {
147 if (regno == 63) {
148 task_thread_info(task)->ieee_state
149 = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
150 | (data & IEEE_SW_MASK));
151 data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
152 }
153 *get_reg_addr(task, regno) = data;
154 return 0;
155 }
156
157 static inline int
read_int(struct task_struct * task,unsigned long addr,int * data)158 read_int(struct task_struct *task, unsigned long addr, int * data)
159 {
160 int copied = access_process_vm(task, addr, data, sizeof(int),
161 FOLL_FORCE);
162 return (copied == sizeof(int)) ? 0 : -EIO;
163 }
164
165 static inline int
write_int(struct task_struct * task,unsigned long addr,int data)166 write_int(struct task_struct *task, unsigned long addr, int data)
167 {
168 int copied = access_process_vm(task, addr, &data, sizeof(int),
169 FOLL_FORCE | FOLL_WRITE);
170 return (copied == sizeof(int)) ? 0 : -EIO;
171 }
172
173 /*
174 * Set breakpoint.
175 */
176 int
ptrace_set_bpt(struct task_struct * child)177 ptrace_set_bpt(struct task_struct * child)
178 {
179 int displ, i, res, reg_b, nsaved = 0;
180 unsigned int insn, op_code;
181 unsigned long pc;
182
183 pc = get_reg(child, REG_PC);
184 res = read_int(child, pc, (int *) &insn);
185 if (res < 0)
186 return res;
187
188 op_code = insn >> 26;
189 if (op_code >= 0x30) {
190 /*
191 * It's a branch: instead of trying to figure out
192 * whether the branch will be taken or not, we'll put
193 * a breakpoint at either location. This is simpler,
194 * more reliable, and probably not a whole lot slower
195 * than the alternative approach of emulating the
196 * branch (emulation can be tricky for fp branches).
197 */
198 displ = ((s32)(insn << 11)) >> 9;
199 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
200 if (displ) /* guard against unoptimized code */
201 task_thread_info(child)->bpt_addr[nsaved++]
202 = pc + 4 + displ;
203 DBG(DBG_BPT, ("execing branch\n"));
204 } else if (op_code == 0x1a) {
205 reg_b = (insn >> 16) & 0x1f;
206 task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
207 DBG(DBG_BPT, ("execing jump\n"));
208 } else {
209 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
210 DBG(DBG_BPT, ("execing normal insn\n"));
211 }
212
213 /* install breakpoints: */
214 for (i = 0; i < nsaved; ++i) {
215 res = read_int(child, task_thread_info(child)->bpt_addr[i],
216 (int *) &insn);
217 if (res < 0)
218 return res;
219 task_thread_info(child)->bpt_insn[i] = insn;
220 DBG(DBG_BPT, (" -> next_pc=%lx\n",
221 task_thread_info(child)->bpt_addr[i]));
222 res = write_int(child, task_thread_info(child)->bpt_addr[i],
223 BREAKINST);
224 if (res < 0)
225 return res;
226 }
227 task_thread_info(child)->bpt_nsaved = nsaved;
228 return 0;
229 }
230
231 /*
232 * Ensure no single-step breakpoint is pending. Returns non-zero
233 * value if child was being single-stepped.
234 */
235 int
ptrace_cancel_bpt(struct task_struct * child)236 ptrace_cancel_bpt(struct task_struct * child)
237 {
238 int i, nsaved = task_thread_info(child)->bpt_nsaved;
239
240 task_thread_info(child)->bpt_nsaved = 0;
241
242 if (nsaved > 2) {
243 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
244 nsaved = 2;
245 }
246
247 for (i = 0; i < nsaved; ++i) {
248 write_int(child, task_thread_info(child)->bpt_addr[i],
249 task_thread_info(child)->bpt_insn[i]);
250 }
251 return (nsaved != 0);
252 }
253
user_enable_single_step(struct task_struct * child)254 void user_enable_single_step(struct task_struct *child)
255 {
256 /* Mark single stepping. */
257 task_thread_info(child)->bpt_nsaved = -1;
258 }
259
user_disable_single_step(struct task_struct * child)260 void user_disable_single_step(struct task_struct *child)
261 {
262 ptrace_cancel_bpt(child);
263 }
264
265 /*
266 * Called by kernel/ptrace.c when detaching..
267 *
268 * Make sure the single step bit is not set.
269 */
ptrace_disable(struct task_struct * child)270 void ptrace_disable(struct task_struct *child)
271 {
272 user_disable_single_step(child);
273 }
274
arch_ptrace(struct task_struct * child,long request,unsigned long addr,unsigned long data)275 long arch_ptrace(struct task_struct *child, long request,
276 unsigned long addr, unsigned long data)
277 {
278 unsigned long tmp;
279 size_t copied;
280 long ret;
281
282 switch (request) {
283 /* When I and D space are separate, these will need to be fixed. */
284 case PTRACE_PEEKTEXT: /* read word at location addr. */
285 case PTRACE_PEEKDATA:
286 copied = ptrace_access_vm(child, addr, &tmp, sizeof(tmp),
287 FOLL_FORCE);
288 ret = -EIO;
289 if (copied != sizeof(tmp))
290 break;
291
292 force_successful_syscall_return();
293 ret = tmp;
294 break;
295
296 /* Read register number ADDR. */
297 case PTRACE_PEEKUSR:
298 force_successful_syscall_return();
299 ret = get_reg(child, addr);
300 DBG(DBG_MEM, ("peek $%lu->%#lx\n", addr, ret));
301 break;
302
303 /* When I and D space are separate, this will have to be fixed. */
304 case PTRACE_POKETEXT: /* write the word at location addr. */
305 case PTRACE_POKEDATA:
306 ret = generic_ptrace_pokedata(child, addr, data);
307 break;
308
309 case PTRACE_POKEUSR: /* write the specified register */
310 DBG(DBG_MEM, ("poke $%lu<-%#lx\n", addr, data));
311 ret = put_reg(child, addr, data);
312 break;
313 default:
314 ret = ptrace_request(child, request, addr, data);
315 break;
316 }
317 return ret;
318 }
319
syscall_trace_enter(void)320 asmlinkage unsigned long syscall_trace_enter(void)
321 {
322 unsigned long ret = 0;
323 struct pt_regs *regs = current_pt_regs();
324 if (test_thread_flag(TIF_SYSCALL_TRACE) &&
325 ptrace_report_syscall_entry(current_pt_regs()))
326 ret = -1UL;
327 audit_syscall_entry(regs->r0, regs->r16, regs->r17, regs->r18, regs->r19);
328 return ret ?: current_pt_regs()->r0;
329 }
330
331 asmlinkage void
syscall_trace_leave(void)332 syscall_trace_leave(void)
333 {
334 audit_syscall_exit(current_pt_regs());
335 if (test_thread_flag(TIF_SYSCALL_TRACE))
336 ptrace_report_syscall_exit(current_pt_regs(), 0);
337 }
338