xref: /openbmc/linux/arch/loongarch/kernel/ptrace.c (revision 5b4fc395)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Author: Hanlu Li <lihanlu@loongson.cn>
4  *         Huacai Chen <chenhuacai@loongson.cn>
5  *
6  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
7  *
8  * Derived from MIPS:
9  * Copyright (C) 1992 Ross Biro
10  * Copyright (C) Linus Torvalds
11  * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
12  * Copyright (C) 1996 David S. Miller
13  * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
14  * Copyright (C) 1999 MIPS Technologies, Inc.
15  * Copyright (C) 2000 Ulf Carlsson
16  */
17 #include <linux/kernel.h>
18 #include <linux/audit.h>
19 #include <linux/compiler.h>
20 #include <linux/context_tracking.h>
21 #include <linux/elf.h>
22 #include <linux/errno.h>
23 #include <linux/mm.h>
24 #include <linux/ptrace.h>
25 #include <linux/regset.h>
26 #include <linux/sched.h>
27 #include <linux/sched/task_stack.h>
28 #include <linux/security.h>
29 #include <linux/smp.h>
30 #include <linux/stddef.h>
31 #include <linux/seccomp.h>
32 #include <linux/uaccess.h>
33 
34 #include <asm/byteorder.h>
35 #include <asm/cpu.h>
36 #include <asm/cpu-info.h>
37 #include <asm/fpu.h>
38 #include <asm/loongarch.h>
39 #include <asm/page.h>
40 #include <asm/pgtable.h>
41 #include <asm/processor.h>
42 #include <asm/reg.h>
43 #include <asm/syscall.h>
44 
45 static void init_fp_ctx(struct task_struct *target)
46 {
47 	/* The target already has context */
48 	if (tsk_used_math(target))
49 		return;
50 
51 	/* Begin with data registers set to all 1s... */
52 	memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
53 	set_stopped_child_used_math(target);
54 }
55 
56 /*
57  * Called by kernel/ptrace.c when detaching..
58  *
59  * Make sure single step bits etc are not set.
60  */
61 void ptrace_disable(struct task_struct *child)
62 {
63 	/* Don't load the watchpoint registers for the ex-child. */
64 	clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
65 	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
66 }
67 
68 /* regset get/set implementations */
69 
70 static int gpr_get(struct task_struct *target,
71 		   const struct user_regset *regset,
72 		   struct membuf to)
73 {
74 	int r;
75 	struct pt_regs *regs = task_pt_regs(target);
76 
77 	r = membuf_write(&to, &regs->regs, sizeof(u64) * GPR_NUM);
78 	r = membuf_write(&to, &regs->orig_a0, sizeof(u64));
79 	r = membuf_write(&to, &regs->csr_era, sizeof(u64));
80 	r = membuf_write(&to, &regs->csr_badvaddr, sizeof(u64));
81 
82 	return r;
83 }
84 
85 static int gpr_set(struct task_struct *target,
86 		   const struct user_regset *regset,
87 		   unsigned int pos, unsigned int count,
88 		   const void *kbuf, const void __user *ubuf)
89 {
90 	int err;
91 	int a0_start = sizeof(u64) * GPR_NUM;
92 	int era_start = a0_start + sizeof(u64);
93 	int badvaddr_start = era_start + sizeof(u64);
94 	struct pt_regs *regs = task_pt_regs(target);
95 
96 	err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
97 				 &regs->regs,
98 				 0, a0_start);
99 	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
100 				 &regs->orig_a0,
101 				 a0_start, a0_start + sizeof(u64));
102 	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
103 				 &regs->csr_era,
104 				 era_start, era_start + sizeof(u64));
105 	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
106 				 &regs->csr_badvaddr,
107 				 badvaddr_start, badvaddr_start + sizeof(u64));
108 
109 	return err;
110 }
111 
112 
113 /*
114  * Get the general floating-point registers.
115  */
116 static int gfpr_get(struct task_struct *target, struct membuf *to)
117 {
118 	return membuf_write(to, &target->thread.fpu.fpr,
119 			    sizeof(elf_fpreg_t) * NUM_FPU_REGS);
120 }
121 
122 static int gfpr_get_simd(struct task_struct *target, struct membuf *to)
123 {
124 	int i, r;
125 	u64 fpr_val;
126 
127 	BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
128 	for (i = 0; i < NUM_FPU_REGS; i++) {
129 		fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
130 		r = membuf_write(to, &fpr_val, sizeof(elf_fpreg_t));
131 	}
132 
133 	return r;
134 }
135 
136 /*
137  * Choose the appropriate helper for general registers, and then copy
138  * the FCC and FCSR registers separately.
139  */
140 static int fpr_get(struct task_struct *target,
141 		   const struct user_regset *regset,
142 		   struct membuf to)
143 {
144 	int r;
145 
146 	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
147 		r = gfpr_get(target, &to);
148 	else
149 		r = gfpr_get_simd(target, &to);
150 
151 	r = membuf_write(&to, &target->thread.fpu.fcc, sizeof(target->thread.fpu.fcc));
152 	r = membuf_write(&to, &target->thread.fpu.fcsr, sizeof(target->thread.fpu.fcsr));
153 
154 	return r;
155 }
156 
157 static int gfpr_set(struct task_struct *target,
158 		    unsigned int *pos, unsigned int *count,
159 		    const void **kbuf, const void __user **ubuf)
160 {
161 	return user_regset_copyin(pos, count, kbuf, ubuf,
162 				  &target->thread.fpu.fpr,
163 				  0, NUM_FPU_REGS * sizeof(elf_fpreg_t));
164 }
165 
166 static int gfpr_set_simd(struct task_struct *target,
167 		       unsigned int *pos, unsigned int *count,
168 		       const void **kbuf, const void __user **ubuf)
169 {
170 	int i, err;
171 	u64 fpr_val;
172 
173 	BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
174 	for (i = 0; i < NUM_FPU_REGS && *count > 0; i++) {
175 		err = user_regset_copyin(pos, count, kbuf, ubuf,
176 					 &fpr_val, i * sizeof(elf_fpreg_t),
177 					 (i + 1) * sizeof(elf_fpreg_t));
178 		if (err)
179 			return err;
180 		set_fpr64(&target->thread.fpu.fpr[i], 0, fpr_val);
181 	}
182 
183 	return 0;
184 }
185 
186 /*
187  * Choose the appropriate helper for general registers, and then copy
188  * the FCC register separately.
189  */
190 static int fpr_set(struct task_struct *target,
191 		   const struct user_regset *regset,
192 		   unsigned int pos, unsigned int count,
193 		   const void *kbuf, const void __user *ubuf)
194 {
195 	const int fcc_start = NUM_FPU_REGS * sizeof(elf_fpreg_t);
196 	const int fcsr_start = fcc_start + sizeof(u64);
197 	int err;
198 
199 	BUG_ON(count % sizeof(elf_fpreg_t));
200 	if (pos + count > sizeof(elf_fpregset_t))
201 		return -EIO;
202 
203 	init_fp_ctx(target);
204 
205 	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
206 		err = gfpr_set(target, &pos, &count, &kbuf, &ubuf);
207 	else
208 		err = gfpr_set_simd(target, &pos, &count, &kbuf, &ubuf);
209 	if (err)
210 		return err;
211 
212 	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
213 				  &target->thread.fpu.fcc, fcc_start,
214 				  fcc_start + sizeof(u64));
215 	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
216 				  &target->thread.fpu.fcsr, fcsr_start,
217 				  fcsr_start + sizeof(u32));
218 
219 	return err;
220 }
221 
222 static int cfg_get(struct task_struct *target,
223 		   const struct user_regset *regset,
224 		   struct membuf to)
225 {
226 	int i, r;
227 	u32 cfg_val;
228 
229 	i = 0;
230 	while (to.left > 0) {
231 		cfg_val = read_cpucfg(i++);
232 		r = membuf_write(&to, &cfg_val, sizeof(u32));
233 	}
234 
235 	return r;
236 }
237 
238 /*
239  * CFG registers are read-only.
240  */
241 static int cfg_set(struct task_struct *target,
242 		   const struct user_regset *regset,
243 		   unsigned int pos, unsigned int count,
244 		   const void *kbuf, const void __user *ubuf)
245 {
246 	return 0;
247 }
248 
249 struct pt_regs_offset {
250 	const char *name;
251 	int offset;
252 };
253 
254 #define REG_OFFSET_NAME(n, r) {.name = #n, .offset = offsetof(struct pt_regs, r)}
255 #define REG_OFFSET_END {.name = NULL, .offset = 0}
256 
257 static const struct pt_regs_offset regoffset_table[] = {
258 	REG_OFFSET_NAME(r0, regs[0]),
259 	REG_OFFSET_NAME(r1, regs[1]),
260 	REG_OFFSET_NAME(r2, regs[2]),
261 	REG_OFFSET_NAME(r3, regs[3]),
262 	REG_OFFSET_NAME(r4, regs[4]),
263 	REG_OFFSET_NAME(r5, regs[5]),
264 	REG_OFFSET_NAME(r6, regs[6]),
265 	REG_OFFSET_NAME(r7, regs[7]),
266 	REG_OFFSET_NAME(r8, regs[8]),
267 	REG_OFFSET_NAME(r9, regs[9]),
268 	REG_OFFSET_NAME(r10, regs[10]),
269 	REG_OFFSET_NAME(r11, regs[11]),
270 	REG_OFFSET_NAME(r12, regs[12]),
271 	REG_OFFSET_NAME(r13, regs[13]),
272 	REG_OFFSET_NAME(r14, regs[14]),
273 	REG_OFFSET_NAME(r15, regs[15]),
274 	REG_OFFSET_NAME(r16, regs[16]),
275 	REG_OFFSET_NAME(r17, regs[17]),
276 	REG_OFFSET_NAME(r18, regs[18]),
277 	REG_OFFSET_NAME(r19, regs[19]),
278 	REG_OFFSET_NAME(r20, regs[20]),
279 	REG_OFFSET_NAME(r21, regs[21]),
280 	REG_OFFSET_NAME(r22, regs[22]),
281 	REG_OFFSET_NAME(r23, regs[23]),
282 	REG_OFFSET_NAME(r24, regs[24]),
283 	REG_OFFSET_NAME(r25, regs[25]),
284 	REG_OFFSET_NAME(r26, regs[26]),
285 	REG_OFFSET_NAME(r27, regs[27]),
286 	REG_OFFSET_NAME(r28, regs[28]),
287 	REG_OFFSET_NAME(r29, regs[29]),
288 	REG_OFFSET_NAME(r30, regs[30]),
289 	REG_OFFSET_NAME(r31, regs[31]),
290 	REG_OFFSET_NAME(orig_a0, orig_a0),
291 	REG_OFFSET_NAME(csr_era, csr_era),
292 	REG_OFFSET_NAME(csr_badvaddr, csr_badvaddr),
293 	REG_OFFSET_NAME(csr_crmd, csr_crmd),
294 	REG_OFFSET_NAME(csr_prmd, csr_prmd),
295 	REG_OFFSET_NAME(csr_euen, csr_euen),
296 	REG_OFFSET_NAME(csr_ecfg, csr_ecfg),
297 	REG_OFFSET_NAME(csr_estat, csr_estat),
298 	REG_OFFSET_END,
299 };
300 
301 /**
302  * regs_query_register_offset() - query register offset from its name
303  * @name:       the name of a register
304  *
305  * regs_query_register_offset() returns the offset of a register in struct
306  * pt_regs from its name. If the name is invalid, this returns -EINVAL;
307  */
308 int regs_query_register_offset(const char *name)
309 {
310 	const struct pt_regs_offset *roff;
311 
312 	for (roff = regoffset_table; roff->name != NULL; roff++)
313 		if (!strcmp(roff->name, name))
314 			return roff->offset;
315 	return -EINVAL;
316 }
317 
318 enum loongarch_regset {
319 	REGSET_GPR,
320 	REGSET_FPR,
321 	REGSET_CPUCFG,
322 };
323 
324 static const struct user_regset loongarch64_regsets[] = {
325 	[REGSET_GPR] = {
326 		.core_note_type	= NT_PRSTATUS,
327 		.n		= ELF_NGREG,
328 		.size		= sizeof(elf_greg_t),
329 		.align		= sizeof(elf_greg_t),
330 		.regset_get	= gpr_get,
331 		.set		= gpr_set,
332 	},
333 	[REGSET_FPR] = {
334 		.core_note_type	= NT_PRFPREG,
335 		.n		= ELF_NFPREG,
336 		.size		= sizeof(elf_fpreg_t),
337 		.align		= sizeof(elf_fpreg_t),
338 		.regset_get	= fpr_get,
339 		.set		= fpr_set,
340 	},
341 	[REGSET_CPUCFG] = {
342 		.core_note_type	= NT_LOONGARCH_CPUCFG,
343 		.n		= 64,
344 		.size		= sizeof(u32),
345 		.align		= sizeof(u32),
346 		.regset_get	= cfg_get,
347 		.set		= cfg_set,
348 	},
349 };
350 
351 static const struct user_regset_view user_loongarch64_view = {
352 	.name		= "loongarch64",
353 	.e_machine	= ELF_ARCH,
354 	.regsets	= loongarch64_regsets,
355 	.n		= ARRAY_SIZE(loongarch64_regsets),
356 };
357 
358 
359 const struct user_regset_view *task_user_regset_view(struct task_struct *task)
360 {
361 	return &user_loongarch64_view;
362 }
363 
364 static inline int read_user(struct task_struct *target, unsigned long addr,
365 			    unsigned long __user *data)
366 {
367 	unsigned long tmp = 0;
368 
369 	switch (addr) {
370 	case 0 ... 31:
371 		tmp = task_pt_regs(target)->regs[addr];
372 		break;
373 	case ARG0:
374 		tmp = task_pt_regs(target)->orig_a0;
375 		break;
376 	case PC:
377 		tmp = task_pt_regs(target)->csr_era;
378 		break;
379 	case BADVADDR:
380 		tmp = task_pt_regs(target)->csr_badvaddr;
381 		break;
382 	default:
383 		return -EIO;
384 	}
385 
386 	return put_user(tmp, data);
387 }
388 
389 static inline int write_user(struct task_struct *target, unsigned long addr,
390 			    unsigned long data)
391 {
392 	switch (addr) {
393 	case 0 ... 31:
394 		task_pt_regs(target)->regs[addr] = data;
395 		break;
396 	case ARG0:
397 		task_pt_regs(target)->orig_a0 = data;
398 		break;
399 	case PC:
400 		task_pt_regs(target)->csr_era = data;
401 		break;
402 	case BADVADDR:
403 		task_pt_regs(target)->csr_badvaddr = data;
404 		break;
405 	default:
406 		return -EIO;
407 	}
408 
409 	return 0;
410 }
411 
412 long arch_ptrace(struct task_struct *child, long request,
413 		 unsigned long addr, unsigned long data)
414 {
415 	int ret;
416 	unsigned long __user *datap = (void __user *) data;
417 
418 	switch (request) {
419 	case PTRACE_PEEKUSR:
420 		ret = read_user(child, addr, datap);
421 		break;
422 
423 	case PTRACE_POKEUSR:
424 		ret = write_user(child, addr, data);
425 		break;
426 
427 	default:
428 		ret = ptrace_request(child, request, addr, data);
429 		break;
430 	}
431 
432 	return ret;
433 }
434