1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PowerPC version
4 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
5 *
6 * Derived from "arch/m68k/kernel/ptrace.c"
7 * Copyright (C) 1994 by Hamish Macdonald
8 * Taken from linux/kernel/ptrace.c and modified for M680x0.
9 * linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
10 *
11 * Modified by Cort Dougan (cort@hq.fsmlabs.com)
12 * and Paul Mackerras (paulus@samba.org).
13 */
14
15#include <linux/regset.h>
16#include <linux/ptrace.h>
17#include <linux/audit.h>
18#include <linux/context_tracking.h>
19#include <linux/syscalls.h>
20
21#include <asm/switch_to.h>
22#include <asm/debug.h>
23
24#define CREATE_TRACE_POINTS
25#include <trace/events/syscalls.h>
26
27#include "ptrace-decl.h"
28
29/*
30 * Called by kernel/ptrace.c when detaching..
31 *
32 * Make sure single step bits etc are not set.
33 */
34void ptrace_disable(struct task_struct *child)
35{
36 /* make sure the single step bit is not set. */
37 user_disable_single_step(child);
38}
39
40long arch_ptrace(struct task_struct *child, long request,
41 unsigned long addr, unsigned long data)
42{
43 int ret = -EPERM;
44 void __user *datavp = (void __user *) data;
45 unsigned long __user *datalp = datavp;
46
47 switch (request) {
48 /* read the word at location addr in the USER area. */
49 case PTRACE_PEEKUSR: {
50 unsigned long index, tmp;
51
52 ret = -EIO;
53 /* convert to index and check */
54 index = addr / sizeof(long);
55 if ((addr & (sizeof(long) - 1)) || !child->thread.regs)
56 break;
57
58 if (index < PT_FPR0)
59 ret = ptrace_get_reg(task: child, regno: (int) index, data: &tmp);
60 else
61 ret = ptrace_get_fpr(child, index, data: &tmp);
62
63 if (ret)
64 break;
65 ret = put_user(tmp, datalp);
66 break;
67 }
68
69 /* write the word at location addr in the USER area */
70 case PTRACE_POKEUSR: {
71 unsigned long index;
72
73 ret = -EIO;
74 /* convert to index and check */
75 index = addr / sizeof(long);
76 if ((addr & (sizeof(long) - 1)) || !child->thread.regs)
77 break;
78
79 if (index < PT_FPR0)
80 ret = ptrace_put_reg(task: child, regno: index, data);
81 else
82 ret = ptrace_put_fpr(child, index, data);
83 break;
84 }
85
86 case PPC_PTRACE_GETHWDBGINFO: {
87 struct ppc_debug_info dbginfo;
88
89 ppc_gethwdinfo(dbginfo: &dbginfo);
90
91 if (copy_to_user(datavp, &dbginfo,
92 sizeof(struct ppc_debug_info)))
93 return -EFAULT;
94 return 0;
95 }
96
97 case PPC_PTRACE_SETHWDEBUG: {
98 struct ppc_hw_breakpoint bp_info;
99
100 if (copy_from_user(&bp_info, datavp,
101 sizeof(struct ppc_hw_breakpoint)))
102 return -EFAULT;
103 return ppc_set_hwdebug(child, bp_info: &bp_info);
104 }
105
106 case PPC_PTRACE_DELHWDEBUG: {
107 ret = ppc_del_hwdebug(child, data);
108 break;
109 }
110
111 case PTRACE_GET_DEBUGREG:
112 ret = ptrace_get_debugreg(child, addr, datalp);
113 break;
114
115 case PTRACE_SET_DEBUGREG:
116 ret = ptrace_set_debugreg(task: child, addr, data);
117 break;
118
119#ifdef CONFIG_PPC64
120 case PTRACE_GETREGS64:
121#endif
122 case PTRACE_GETREGS: /* Get all pt_regs from the child. */
123 return copy_regset_to_user(child, &user_ppc_native_view,
124 REGSET_GPR,
125 0, sizeof(struct user_pt_regs),
126 datavp);
127
128#ifdef CONFIG_PPC64
129 case PTRACE_SETREGS64:
130#endif
131 case PTRACE_SETREGS: /* Set all gp regs in the child. */
132 return copy_regset_from_user(child, &user_ppc_native_view,
133 REGSET_GPR,
134 0, sizeof(struct user_pt_regs),
135 datavp);
136
137 case PTRACE_GETFPREGS: /* Get the child FPU state (FPR0...31 + FPSCR) */
138 return copy_regset_to_user(target: child, view: &user_ppc_native_view,
139 setno: REGSET_FPR,
140 offset: 0, size: sizeof(elf_fpregset_t),
141 data: datavp);
142
143 case PTRACE_SETFPREGS: /* Set the child FPU state (FPR0...31 + FPSCR) */
144 return copy_regset_from_user(target: child, view: &user_ppc_native_view,
145 setno: REGSET_FPR,
146 offset: 0, size: sizeof(elf_fpregset_t),
147 data: datavp);
148
149#ifdef CONFIG_ALTIVEC
150 case PTRACE_GETVRREGS:
151 return copy_regset_to_user(child, &user_ppc_native_view,
152 REGSET_VMX,
153 0, (33 * sizeof(vector128) +
154 sizeof(u32)),
155 datavp);
156
157 case PTRACE_SETVRREGS:
158 return copy_regset_from_user(child, &user_ppc_native_view,
159 REGSET_VMX,
160 0, (33 * sizeof(vector128) +
161 sizeof(u32)),
162 datavp);
163#endif
164#ifdef CONFIG_VSX
165 case PTRACE_GETVSRREGS:
166 return copy_regset_to_user(child, &user_ppc_native_view,
167 REGSET_VSX,
168 0, 32 * sizeof(double),
169 datavp);
170
171 case PTRACE_SETVSRREGS:
172 return copy_regset_from_user(child, &user_ppc_native_view,
173 REGSET_VSX,
174 0, 32 * sizeof(double),
175 datavp);
176#endif
177#ifdef CONFIG_SPE
178 case PTRACE_GETEVRREGS:
179 /* Get the child spe register state. */
180 return copy_regset_to_user(child, &user_ppc_native_view,
181 REGSET_SPE, 0, 35 * sizeof(u32),
182 datavp);
183
184 case PTRACE_SETEVRREGS:
185 /* Set the child spe register state. */
186 return copy_regset_from_user(child, &user_ppc_native_view,
187 REGSET_SPE, 0, 35 * sizeof(u32),
188 datavp);
189#endif
190
191 default:
192 ret = ptrace_request(child, request, addr, data);
193 break;
194 }
195 return ret;
196}
197
198#ifdef CONFIG_SECCOMP
199static int do_seccomp(struct pt_regs *regs)
200{
201 if (!test_thread_flag(TIF_SECCOMP))
202 return 0;
203
204 /*
205 * The ABI we present to seccomp tracers is that r3 contains
206 * the syscall return value and orig_gpr3 contains the first
207 * syscall parameter. This is different to the ptrace ABI where
208 * both r3 and orig_gpr3 contain the first syscall parameter.
209 */
210 regs->gpr[3] = -ENOSYS;
211
212 /*
213 * We use the __ version here because we have already checked
214 * TIF_SECCOMP. If this fails, there is nothing left to do, we
215 * have already loaded -ENOSYS into r3, or seccomp has put
216 * something else in r3 (via SECCOMP_RET_ERRNO/TRACE).
217 */
218 if (__secure_computing())
219 return -1;
220
221 /*
222 * The syscall was allowed by seccomp, restore the register
223 * state to what audit expects.
224 * Note that we use orig_gpr3, which means a seccomp tracer can
225 * modify the first syscall parameter (in orig_gpr3) and also
226 * allow the syscall to proceed.
227 */
228 regs->gpr[3] = regs->orig_gpr3;
229
230 return 0;
231}
232#else
233static inline int do_seccomp(struct pt_regs *regs) { return 0; }
234#endif /* CONFIG_SECCOMP */
235
236/**
237 * do_syscall_trace_enter() - Do syscall tracing on kernel entry.
238 * @regs: the pt_regs of the task to trace (current)
239 *
240 * Performs various types of tracing on syscall entry. This includes seccomp,
241 * ptrace, syscall tracepoints and audit.
242 *
243 * The pt_regs are potentially visible to userspace via ptrace, so their
244 * contents is ABI.
245 *
246 * One or more of the tracers may modify the contents of pt_regs, in particular
247 * to modify arguments or even the syscall number itself.
248 *
249 * It's also possible that a tracer can choose to reject the system call. In
250 * that case this function will return an illegal syscall number, and will put
251 * an appropriate return value in regs->r3.
252 *
253 * Return: the (possibly changed) syscall number.
254 */
255long do_syscall_trace_enter(struct pt_regs *regs)
256{
257 u32 flags;
258
259 flags = read_thread_flags() & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
260
261 if (flags) {
262 int rc = ptrace_report_syscall_entry(regs);
263
264 if (unlikely(flags & _TIF_SYSCALL_EMU)) {
265 /*
266 * A nonzero return code from
267 * ptrace_report_syscall_entry() tells us to prevent
268 * the syscall execution, but we are not going to
269 * execute it anyway.
270 *
271 * Returning -1 will skip the syscall execution. We want
272 * to avoid clobbering any registers, so we don't goto
273 * the skip label below.
274 */
275 return -1;
276 }
277
278 if (rc) {
279 /*
280 * The tracer decided to abort the syscall. Note that
281 * the tracer may also just change regs->gpr[0] to an
282 * invalid syscall number, that is handled below on the
283 * exit path.
284 */
285 goto skip;
286 }
287 }
288
289 /* Run seccomp after ptrace; allow it to set gpr[3]. */
290 if (do_seccomp(regs))
291 return -1;
292
293 /* Avoid trace and audit when syscall is invalid. */
294 if (regs->gpr[0] >= NR_syscalls)
295 goto skip;
296
297 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
298 trace_sys_enter(regs, id: regs->gpr[0]);
299
300 if (!is_32bit_task())
301 audit_syscall_entry(major: regs->gpr[0], a0: regs->gpr[3], a1: regs->gpr[4],
302 a2: regs->gpr[5], a3: regs->gpr[6]);
303 else
304 audit_syscall_entry(major: regs->gpr[0],
305 a0: regs->gpr[3] & 0xffffffff,
306 a1: regs->gpr[4] & 0xffffffff,
307 a2: regs->gpr[5] & 0xffffffff,
308 a3: regs->gpr[6] & 0xffffffff);
309
310 /* Return the possibly modified but valid syscall number */
311 return regs->gpr[0];
312
313skip:
314 /*
315 * If we are aborting explicitly, or if the syscall number is
316 * now invalid, set the return value to -ENOSYS.
317 */
318 regs->gpr[3] = -ENOSYS;
319 return -1;
320}
321
322void do_syscall_trace_leave(struct pt_regs *regs)
323{
324 int step;
325
326 audit_syscall_exit(pt_regs: regs);
327
328 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
329 trace_sys_exit(regs, ret: regs->result);
330
331 step = test_thread_flag(TIF_SINGLESTEP);
332 if (step || test_thread_flag(TIF_SYSCALL_TRACE))
333 ptrace_report_syscall_exit(regs, step);
334}
335
336void __init pt_regs_check(void);
337
338/*
339 * Dummy function, its purpose is to break the build if struct pt_regs and
340 * struct user_pt_regs don't match.
341 */
342void __init pt_regs_check(void)
343{
344 BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
345 offsetof(struct user_pt_regs, gpr));
346 BUILD_BUG_ON(offsetof(struct pt_regs, nip) !=
347 offsetof(struct user_pt_regs, nip));
348 BUILD_BUG_ON(offsetof(struct pt_regs, msr) !=
349 offsetof(struct user_pt_regs, msr));
350 BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
351 offsetof(struct user_pt_regs, orig_gpr3));
352 BUILD_BUG_ON(offsetof(struct pt_regs, ctr) !=
353 offsetof(struct user_pt_regs, ctr));
354 BUILD_BUG_ON(offsetof(struct pt_regs, link) !=
355 offsetof(struct user_pt_regs, link));
356 BUILD_BUG_ON(offsetof(struct pt_regs, xer) !=
357 offsetof(struct user_pt_regs, xer));
358 BUILD_BUG_ON(offsetof(struct pt_regs, ccr) !=
359 offsetof(struct user_pt_regs, ccr));
360#ifdef __powerpc64__
361 BUILD_BUG_ON(offsetof(struct pt_regs, softe) !=
362 offsetof(struct user_pt_regs, softe));
363#else
364 BUILD_BUG_ON(offsetof(struct pt_regs, mq) !=
365 offsetof(struct user_pt_regs, mq));
366#endif
367 BUILD_BUG_ON(offsetof(struct pt_regs, trap) !=
368 offsetof(struct user_pt_regs, trap));
369 BUILD_BUG_ON(offsetof(struct pt_regs, dar) !=
370 offsetof(struct user_pt_regs, dar));
371 BUILD_BUG_ON(offsetof(struct pt_regs, dear) !=
372 offsetof(struct user_pt_regs, dar));
373 BUILD_BUG_ON(offsetof(struct pt_regs, dsisr) !=
374 offsetof(struct user_pt_regs, dsisr));
375 BUILD_BUG_ON(offsetof(struct pt_regs, esr) !=
376 offsetof(struct user_pt_regs, dsisr));
377 BUILD_BUG_ON(offsetof(struct pt_regs, result) !=
378 offsetof(struct user_pt_regs, result));
379
380 BUILD_BUG_ON(sizeof(struct user_pt_regs) > sizeof(struct pt_regs));
381
382 // Now check that the pt_regs offsets match the uapi #defines
383 #define CHECK_REG(_pt, _reg) \
384 BUILD_BUG_ON(_pt != (offsetof(struct user_pt_regs, _reg) / \
385 sizeof(unsigned long)));
386
387 CHECK_REG(PT_R0, gpr[0]);
388 CHECK_REG(PT_R1, gpr[1]);
389 CHECK_REG(PT_R2, gpr[2]);
390 CHECK_REG(PT_R3, gpr[3]);
391 CHECK_REG(PT_R4, gpr[4]);
392 CHECK_REG(PT_R5, gpr[5]);
393 CHECK_REG(PT_R6, gpr[6]);
394 CHECK_REG(PT_R7, gpr[7]);
395 CHECK_REG(PT_R8, gpr[8]);
396 CHECK_REG(PT_R9, gpr[9]);
397 CHECK_REG(PT_R10, gpr[10]);
398 CHECK_REG(PT_R11, gpr[11]);
399 CHECK_REG(PT_R12, gpr[12]);
400 CHECK_REG(PT_R13, gpr[13]);
401 CHECK_REG(PT_R14, gpr[14]);
402 CHECK_REG(PT_R15, gpr[15]);
403 CHECK_REG(PT_R16, gpr[16]);
404 CHECK_REG(PT_R17, gpr[17]);
405 CHECK_REG(PT_R18, gpr[18]);
406 CHECK_REG(PT_R19, gpr[19]);
407 CHECK_REG(PT_R20, gpr[20]);
408 CHECK_REG(PT_R21, gpr[21]);
409 CHECK_REG(PT_R22, gpr[22]);
410 CHECK_REG(PT_R23, gpr[23]);
411 CHECK_REG(PT_R24, gpr[24]);
412 CHECK_REG(PT_R25, gpr[25]);
413 CHECK_REG(PT_R26, gpr[26]);
414 CHECK_REG(PT_R27, gpr[27]);
415 CHECK_REG(PT_R28, gpr[28]);
416 CHECK_REG(PT_R29, gpr[29]);
417 CHECK_REG(PT_R30, gpr[30]);
418 CHECK_REG(PT_R31, gpr[31]);
419 CHECK_REG(PT_NIP, nip);
420 CHECK_REG(PT_MSR, msr);
421 CHECK_REG(PT_ORIG_R3, orig_gpr3);
422 CHECK_REG(PT_CTR, ctr);
423 CHECK_REG(PT_LNK, link);
424 CHECK_REG(PT_XER, xer);
425 CHECK_REG(PT_CCR, ccr);
426#ifdef CONFIG_PPC64
427 CHECK_REG(PT_SOFTE, softe);
428#else
429 CHECK_REG(PT_MQ, mq);
430#endif
431 CHECK_REG(PT_TRAP, trap);
432 CHECK_REG(PT_DAR, dar);
433 CHECK_REG(PT_DSISR, dsisr);
434 CHECK_REG(PT_RESULT, result);
435 #undef CHECK_REG
436
437 BUILD_BUG_ON(PT_REGS_COUNT != sizeof(struct user_pt_regs) / sizeof(unsigned long));
438
439 /*
440 * PT_DSCR isn't a real reg, but it's important that it doesn't overlap the
441 * real registers.
442 */
443 BUILD_BUG_ON(PT_DSCR < sizeof(struct user_pt_regs) / sizeof(unsigned long));
444
445 // ptrace_get/put_fpr() rely on PPC32 and VSX being incompatible
446 BUILD_BUG_ON(IS_ENABLED(CONFIG_PPC32) && IS_ENABLED(CONFIG_VSX));
447}
448

source code of linux/arch/powerpc/kernel/ptrace/ptrace.c