ptrace.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * OpenRISC ptrace.c
  4 *
  5 * Linux architectural port borrowing liberally from similar works of
  6 * others.  All original copyrights apply as per the original source
  7 * declaration.
  8 *
  9 * Modifications for the OpenRISC architecture:
 10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 11 * Copyright (C) 2005 Gyorgy Jeney <nog@bsemi.com>
 12 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 13 */
 14
 15#include <linux/kernel.h>
 16#include <linux/sched.h>
 17#include <linux/sched/task_stack.h>
 18#include <linux/string.h>
 19
 20#include <linux/mm.h>
 21#include <linux/errno.h>
 22#include <linux/ptrace.h>
 23#include <linux/audit.h>
 24#include <linux/regset.h>
 25#include <linux/elf.h>
 26
 27#include <asm/thread_info.h>
 28#include <asm/page.h>
 29
 30asmlinkage long do_syscall_trace_enter(struct pt_regs *regs);
 31
 32asmlinkage void do_syscall_trace_leave(struct pt_regs *regs);
 33
 34/*
 35 * Copy the thread state to a regset that can be interpreted by userspace.
 36 *
 37 * It doesn't matter what our internal pt_regs structure looks like.  The
 38 * important thing is that we export a consistent view of the thread state
 39 * to userspace.  As such, we need to make sure that the regset remains
 40 * ABI compatible as defined by the struct user_regs_struct:
 41 *
 42 * (Each item is a 32-bit word)
 43 * r0 = 0 (exported for clarity)
 44 * 31 GPRS r1-r31
 45 * PC (Program counter)
 46 * SR (Supervision register)
 47 */
 48static int genregs_get(struct task_struct *target,
 49		       const struct user_regset *regset,
 50		       struct membuf to)
 51{
 52	const struct pt_regs *regs = task_pt_regs(target);
 53
 54	/* r0 */
 55	membuf_zero(&to, 4);
 56	membuf_write(&to, regs->gpr + 1, 31 * 4);
 57	membuf_store(&to, regs->pc);
 58	return membuf_store(&to, regs->sr);
 59}
 60
 61/*
 62 * Set the thread state from a regset passed in via ptrace
 63 */
 64static int genregs_set(struct task_struct *target,
 65		       const struct user_regset *regset,
 66		       unsigned int pos, unsigned int count,
 67		       const void *kbuf, const void __user * ubuf)
 68{
 69	struct pt_regs *regs = task_pt_regs(target);
 70	int ret;
 71
 72	/* ignore r0 */
 73	user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 0, 4);
 74	/* r1 - r31 */
 75	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 76					 regs->gpr+1, 4, 4*32);
 77	/* PC */
 78	if (!ret)
 79		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 80				 &regs->pc, 4*32, 4*33);
 81	/*
 82	 * Skip SR and padding... userspace isn't allowed to changes bits in
 83	 * the Supervision register
 84	 */
 85	if (!ret)
 86		user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 4*33, -1);
 87
 88	return ret;
 89}
 90
 91#ifdef CONFIG_FPU
 92/*
 93 * As OpenRISC shares GPRs and floating point registers we don't need to export
 94 * the floating point registers again.  So here we only export the fpcsr special
 95 * purpose register.
 96 */
 97static int fpregs_get(struct task_struct *target,
 98		       const struct user_regset *regset,
 99		       struct membuf to)
100{
101	return membuf_store(&to, target->thread.fpcsr);
102}
103
104static int fpregs_set(struct task_struct *target,
105		       const struct user_regset *regset,
106		       unsigned int pos, unsigned int count,
107		       const void *kbuf, const void __user *ubuf)
108{
109	/* FPCSR */
110	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
111				  &target->thread.fpcsr, 0, 4);
112}
113#endif
114
115/*
116 * Define the register sets available on OpenRISC under Linux
117 */
118enum or1k_regset {
119	REGSET_GENERAL,
120#ifdef CONFIG_FPU
121	REGSET_FPU,
122#endif
123};
124
125static const struct user_regset or1k_regsets[] = {
126	[REGSET_GENERAL] = {
127			    USER_REGSET_NOTE_TYPE(PRSTATUS),
128			    .n = ELF_NGREG,
129			    .size = sizeof(long),
130			    .align = sizeof(long),
131			    .regset_get = genregs_get,
132			    .set = genregs_set,
133			    },
134#ifdef CONFIG_FPU
135	[REGSET_FPU] = {
136			    USER_REGSET_NOTE_TYPE(PRFPREG),
137			    .n = sizeof(struct __or1k_fpu_state) / sizeof(long),
138			    .size = sizeof(long),
139			    .align = sizeof(long),
140			    .regset_get = fpregs_get,
141			    .set = fpregs_set,
142			    },
143#endif
144};
145
146static const struct user_regset_view user_or1k_native_view = {
147	.name = "or1k",
148	.e_machine = EM_OPENRISC,
149	.regsets = or1k_regsets,
150	.n = ARRAY_SIZE(or1k_regsets),
151};
152
153const struct user_regset_view *task_user_regset_view(struct task_struct *task)
154{
155	return &user_or1k_native_view;
156}
157
158/*
159 * does not yet catch signals sent when the child dies.
160 * in exit.c or in signal.c.
161 */
162
163struct pt_regs_offset {
164	const char *name;
165	int offset;
166};
167
168#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
169#define REG_OFFSET_END {.name = NULL, .offset = 0}
170
171static const struct pt_regs_offset regoffset_table[] = {
172	REG_OFFSET_NAME(sr),
173	REG_OFFSET_NAME(sp),
174	REG_OFFSET_NAME(gpr2),
175	REG_OFFSET_NAME(gpr3),
176	REG_OFFSET_NAME(gpr4),
177	REG_OFFSET_NAME(gpr5),
178	REG_OFFSET_NAME(gpr6),
179	REG_OFFSET_NAME(gpr7),
180	REG_OFFSET_NAME(gpr8),
181	REG_OFFSET_NAME(gpr9),
182	REG_OFFSET_NAME(gpr10),
183	REG_OFFSET_NAME(gpr11),
184	REG_OFFSET_NAME(gpr12),
185	REG_OFFSET_NAME(gpr13),
186	REG_OFFSET_NAME(gpr14),
187	REG_OFFSET_NAME(gpr15),
188	REG_OFFSET_NAME(gpr16),
189	REG_OFFSET_NAME(gpr17),
190	REG_OFFSET_NAME(gpr18),
191	REG_OFFSET_NAME(gpr19),
192	REG_OFFSET_NAME(gpr20),
193	REG_OFFSET_NAME(gpr21),
194	REG_OFFSET_NAME(gpr22),
195	REG_OFFSET_NAME(gpr23),
196	REG_OFFSET_NAME(gpr24),
197	REG_OFFSET_NAME(gpr25),
198	REG_OFFSET_NAME(gpr26),
199	REG_OFFSET_NAME(gpr27),
200	REG_OFFSET_NAME(gpr28),
201	REG_OFFSET_NAME(gpr29),
202	REG_OFFSET_NAME(gpr30),
203	REG_OFFSET_NAME(gpr31),
204	REG_OFFSET_NAME(pc),
205	REG_OFFSET_NAME(orig_gpr11),
206	REG_OFFSET_END,
207};
208
209/**
210 * regs_query_register_offset() - query register offset from its name
211 * @name:	the name of a register
212 *
213 * regs_query_register_offset() returns the offset of a register in struct
214 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
215 */
216int regs_query_register_offset(const char *name)
217{
218	const struct pt_regs_offset *roff;
219
220	for (roff = regoffset_table; roff->name != NULL; roff++)
221		if (!strcmp(roff->name, name))
222			return roff->offset;
223	return -EINVAL;
224}
225
226/**
227 * regs_within_kernel_stack() - check the address in the stack
228 * @regs:      pt_regs which contains kernel stack pointer.
229 * @addr:      address which is checked.
230 *
231 * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
232 * If @addr is within the kernel stack, it returns true. If not, returns false.
233 */
234static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
235{
236	return (addr & ~(THREAD_SIZE - 1))  ==
237		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1));
238}
239
240/**
241 * regs_get_kernel_stack_nth() - get Nth entry of the stack
242 * @regs:	pt_regs which contains kernel stack pointer.
243 * @n:		stack entry number.
244 *
245 * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
246 * is specified by @regs. If the @n th entry is NOT in the kernel stack,
247 * this returns 0.
248 */
249unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
250{
251	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
252
253	addr += n;
254	if (regs_within_kernel_stack(regs, (unsigned long)addr))
255		return *addr;
256	else
257		return 0;
258}
259
260/*
261 * Called by kernel/ptrace.c when detaching..
262 *
263 * Make sure the single step bit is not set.
264 */
265void ptrace_disable(struct task_struct *child)
266{
267	pr_debug("ptrace_disable(): TODO\n");
268
269	user_disable_single_step(child);
270	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
271}
272
273long arch_ptrace(struct task_struct *child, long request, unsigned long addr,
274		 unsigned long data)
275{
276	int ret;
277
278	switch (request) {
279	default:
280		ret = ptrace_request(child, request, addr, data);
281		break;
282	}
283
284	return ret;
285}
286
287/*
288 * Notification of system call entry/exit
289 * - triggered by current->work.syscall_trace
290 */
291asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
292{
293	long ret = 0;
294
295	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
296	    ptrace_report_syscall_entry(regs))
297		/*
298		 * Tracing decided this syscall should not happen.
299		 * We'll return a bogus call number to get an ENOSYS
300		 * error, but leave the original number in <something>.
301		 */
302		ret = -1L;
303
304	audit_syscall_entry(regs->gpr[11], regs->gpr[3], regs->gpr[4],
305			    regs->gpr[5], regs->gpr[6]);
306
307	return ret ? : regs->gpr[11];
308}
309
310asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
311{
312	int step;
313
314	audit_syscall_exit(regs);
315
316	step = test_thread_flag(TIF_SINGLESTEP);
317	if (step || test_thread_flag(TIF_SYSCALL_TRACE))
318		ptrace_report_syscall_exit(regs, step);
319}