xref: /openbmc/linux/arch/x86/include/asm/ptrace.h (revision 9dd7c463)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_PTRACE_H
3 #define _ASM_X86_PTRACE_H
4 
5 #include <asm/segment.h>
6 #include <asm/page_types.h>
7 #include <uapi/asm/ptrace.h>
8 
9 #ifndef __ASSEMBLY__
10 #ifdef __i386__
11 
12 struct pt_regs {
13 	/*
14 	 * NB: 32-bit x86 CPUs are inconsistent as what happens in the
15 	 * following cases (where %seg represents a segment register):
16 	 *
17 	 * - pushl %seg: some do a 16-bit write and leave the high
18 	 *   bits alone
19 	 * - movl %seg, [mem]: some do a 16-bit write despite the movl
20 	 * - IDT entry: some (e.g. 486) will leave the high bits of CS
21 	 *   and (if applicable) SS undefined.
22 	 *
23 	 * Fortunately, x86-32 doesn't read the high bits on POP or IRET,
24 	 * so we can just treat all of the segment registers as 16-bit
25 	 * values.
26 	 */
27 	unsigned long bx;
28 	unsigned long cx;
29 	unsigned long dx;
30 	unsigned long si;
31 	unsigned long di;
32 	unsigned long bp;
33 	unsigned long ax;
34 	unsigned short ds;
35 	unsigned short __dsh;
36 	unsigned short es;
37 	unsigned short __esh;
38 	unsigned short fs;
39 	unsigned short __fsh;
40 	/*
41 	 * On interrupt, gs and __gsh store the vector number.  They never
42 	 * store gs any more.
43 	 */
44 	unsigned short gs;
45 	unsigned short __gsh;
46 	/* On interrupt, this is the error code. */
47 	unsigned long orig_ax;
48 	unsigned long ip;
49 	unsigned short cs;
50 	unsigned short __csh;
51 	unsigned long flags;
52 	unsigned long sp;
53 	unsigned short ss;
54 	unsigned short __ssh;
55 };
56 
57 #else /* __i386__ */
58 
59 struct pt_regs {
60 /*
61  * C ABI says these regs are callee-preserved. They aren't saved on kernel entry
62  * unless syscall needs a complete, fully filled "struct pt_regs".
63  */
64 	unsigned long r15;
65 	unsigned long r14;
66 	unsigned long r13;
67 	unsigned long r12;
68 	unsigned long bp;
69 	unsigned long bx;
70 /* These regs are callee-clobbered. Always saved on kernel entry. */
71 	unsigned long r11;
72 	unsigned long r10;
73 	unsigned long r9;
74 	unsigned long r8;
75 	unsigned long ax;
76 	unsigned long cx;
77 	unsigned long dx;
78 	unsigned long si;
79 	unsigned long di;
80 /*
81  * On syscall entry, this is syscall#. On CPU exception, this is error code.
82  * On hw interrupt, it's IRQ number:
83  */
84 	unsigned long orig_ax;
85 /* Return frame for iretq */
86 	unsigned long ip;
87 	unsigned long cs;
88 	unsigned long flags;
89 	unsigned long sp;
90 	unsigned long ss;
91 /* top of stack page */
92 };
93 
94 #endif /* !__i386__ */
95 
96 #ifdef CONFIG_PARAVIRT
97 #include <asm/paravirt_types.h>
98 #endif
99 
100 #include <asm/proto.h>
101 
102 struct cpuinfo_x86;
103 struct task_struct;
104 
105 extern unsigned long profile_pc(struct pt_regs *regs);
106 
107 extern unsigned long
108 convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
109 extern void send_sigtrap(struct pt_regs *regs, int error_code, int si_code);
110 
111 
112 static inline unsigned long regs_return_value(struct pt_regs *regs)
113 {
114 	return regs->ax;
115 }
116 
117 static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
118 {
119 	regs->ax = rc;
120 }
121 
122 /*
123  * user_mode(regs) determines whether a register set came from user
124  * mode.  On x86_32, this is true if V8086 mode was enabled OR if the
125  * register set was from protected mode with RPL-3 CS value.  This
126  * tricky test checks that with one comparison.
127  *
128  * On x86_64, vm86 mode is mercifully nonexistent, and we don't need
129  * the extra check.
130  */
131 static __always_inline int user_mode(struct pt_regs *regs)
132 {
133 #ifdef CONFIG_X86_32
134 	return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;
135 #else
136 	return !!(regs->cs & 3);
137 #endif
138 }
139 
140 static inline int v8086_mode(struct pt_regs *regs)
141 {
142 #ifdef CONFIG_X86_32
143 	return (regs->flags & X86_VM_MASK);
144 #else
145 	return 0;	/* No V86 mode support in long mode */
146 #endif
147 }
148 
149 static inline bool user_64bit_mode(struct pt_regs *regs)
150 {
151 #ifdef CONFIG_X86_64
152 #ifndef CONFIG_PARAVIRT_XXL
153 	/*
154 	 * On non-paravirt systems, this is the only long mode CPL 3
155 	 * selector.  We do not allow long mode selectors in the LDT.
156 	 */
157 	return regs->cs == __USER_CS;
158 #else
159 	/* Headers are too twisted for this to go in paravirt.h. */
160 	return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
161 #endif
162 #else /* !CONFIG_X86_64 */
163 	return false;
164 #endif
165 }
166 
167 /*
168  * Determine whether the register set came from any context that is running in
169  * 64-bit mode.
170  */
171 static inline bool any_64bit_mode(struct pt_regs *regs)
172 {
173 #ifdef CONFIG_X86_64
174 	return !user_mode(regs) || user_64bit_mode(regs);
175 #else
176 	return false;
177 #endif
178 }
179 
180 #ifdef CONFIG_X86_64
181 #define current_user_stack_pointer()	current_pt_regs()->sp
182 #define compat_user_stack_pointer()	current_pt_regs()->sp
183 
184 static __always_inline bool ip_within_syscall_gap(struct pt_regs *regs)
185 {
186 	bool ret = (regs->ip >= (unsigned long)entry_SYSCALL_64 &&
187 		    regs->ip <  (unsigned long)entry_SYSCALL_64_safe_stack);
188 
189 #ifdef CONFIG_IA32_EMULATION
190 	ret = ret || (regs->ip >= (unsigned long)entry_SYSCALL_compat &&
191 		      regs->ip <  (unsigned long)entry_SYSCALL_compat_safe_stack);
192 #endif
193 
194 	return ret;
195 }
196 #endif
197 
198 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
199 {
200 	return regs->sp;
201 }
202 
203 static inline unsigned long instruction_pointer(struct pt_regs *regs)
204 {
205 	return regs->ip;
206 }
207 
208 static inline void instruction_pointer_set(struct pt_regs *regs,
209 		unsigned long val)
210 {
211 	regs->ip = val;
212 }
213 
214 static inline unsigned long frame_pointer(struct pt_regs *regs)
215 {
216 	return regs->bp;
217 }
218 
219 static inline unsigned long user_stack_pointer(struct pt_regs *regs)
220 {
221 	return regs->sp;
222 }
223 
224 static inline void user_stack_pointer_set(struct pt_regs *regs,
225 		unsigned long val)
226 {
227 	regs->sp = val;
228 }
229 
230 static __always_inline bool regs_irqs_disabled(struct pt_regs *regs)
231 {
232 	return !(regs->flags & X86_EFLAGS_IF);
233 }
234 
235 /* Query offset/name of register from its name/offset */
236 extern int regs_query_register_offset(const char *name);
237 extern const char *regs_query_register_name(unsigned int offset);
238 #define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
239 
240 /**
241  * regs_get_register() - get register value from its offset
242  * @regs:	pt_regs from which register value is gotten.
243  * @offset:	offset number of the register.
244  *
245  * regs_get_register returns the value of a register. The @offset is the
246  * offset of the register in struct pt_regs address which specified by @regs.
247  * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
248  */
249 static inline unsigned long regs_get_register(struct pt_regs *regs,
250 					      unsigned int offset)
251 {
252 	if (unlikely(offset > MAX_REG_OFFSET))
253 		return 0;
254 #ifdef CONFIG_X86_32
255 	/* The selector fields are 16-bit. */
256 	if (offset == offsetof(struct pt_regs, cs) ||
257 	    offset == offsetof(struct pt_regs, ss) ||
258 	    offset == offsetof(struct pt_regs, ds) ||
259 	    offset == offsetof(struct pt_regs, es) ||
260 	    offset == offsetof(struct pt_regs, fs) ||
261 	    offset == offsetof(struct pt_regs, gs)) {
262 		return *(u16 *)((unsigned long)regs + offset);
263 
264 	}
265 #endif
266 	return *(unsigned long *)((unsigned long)regs + offset);
267 }
268 
269 /**
270  * regs_within_kernel_stack() - check the address in the stack
271  * @regs:	pt_regs which contains kernel stack pointer.
272  * @addr:	address which is checked.
273  *
274  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
275  * If @addr is within the kernel stack, it returns true. If not, returns false.
276  */
277 static inline int regs_within_kernel_stack(struct pt_regs *regs,
278 					   unsigned long addr)
279 {
280 	return ((addr & ~(THREAD_SIZE - 1)) == (regs->sp & ~(THREAD_SIZE - 1)));
281 }
282 
283 /**
284  * regs_get_kernel_stack_nth_addr() - get the address of the Nth entry on stack
285  * @regs:	pt_regs which contains kernel stack pointer.
286  * @n:		stack entry number.
287  *
288  * regs_get_kernel_stack_nth() returns the address of the @n th entry of the
289  * kernel stack which is specified by @regs. If the @n th entry is NOT in
290  * the kernel stack, this returns NULL.
291  */
292 static inline unsigned long *regs_get_kernel_stack_nth_addr(struct pt_regs *regs, unsigned int n)
293 {
294 	unsigned long *addr = (unsigned long *)regs->sp;
295 
296 	addr += n;
297 	if (regs_within_kernel_stack(regs, (unsigned long)addr))
298 		return addr;
299 	else
300 		return NULL;
301 }
302 
303 /* To avoid include hell, we can't include uaccess.h */
304 extern long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
305 
306 /**
307  * regs_get_kernel_stack_nth() - get Nth entry of the stack
308  * @regs:	pt_regs which contains kernel stack pointer.
309  * @n:		stack entry number.
310  *
311  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
312  * is specified by @regs. If the @n th entry is NOT in the kernel stack
313  * this returns 0.
314  */
315 static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
316 						      unsigned int n)
317 {
318 	unsigned long *addr;
319 	unsigned long val;
320 	long ret;
321 
322 	addr = regs_get_kernel_stack_nth_addr(regs, n);
323 	if (addr) {
324 		ret = copy_from_kernel_nofault(&val, addr, sizeof(val));
325 		if (!ret)
326 			return val;
327 	}
328 	return 0;
329 }
330 
331 /**
332  * regs_get_kernel_argument() - get Nth function argument in kernel
333  * @regs:	pt_regs of that context
334  * @n:		function argument number (start from 0)
335  *
336  * regs_get_argument() returns @n th argument of the function call.
337  * Note that this chooses most probably assignment, in some case
338  * it can be incorrect.
339  * This is expected to be called from kprobes or ftrace with regs
340  * where the top of stack is the return address.
341  */
342 static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
343 						     unsigned int n)
344 {
345 	static const unsigned int argument_offs[] = {
346 #ifdef __i386__
347 		offsetof(struct pt_regs, ax),
348 		offsetof(struct pt_regs, dx),
349 		offsetof(struct pt_regs, cx),
350 #define NR_REG_ARGUMENTS 3
351 #else
352 		offsetof(struct pt_regs, di),
353 		offsetof(struct pt_regs, si),
354 		offsetof(struct pt_regs, dx),
355 		offsetof(struct pt_regs, cx),
356 		offsetof(struct pt_regs, r8),
357 		offsetof(struct pt_regs, r9),
358 #define NR_REG_ARGUMENTS 6
359 #endif
360 	};
361 
362 	if (n >= NR_REG_ARGUMENTS) {
363 		n -= NR_REG_ARGUMENTS - 1;
364 		return regs_get_kernel_stack_nth(regs, n);
365 	} else
366 		return regs_get_register(regs, argument_offs[n]);
367 }
368 
369 #define arch_has_single_step()	(1)
370 #ifdef CONFIG_X86_DEBUGCTLMSR
371 #define arch_has_block_step()	(1)
372 #else
373 #define arch_has_block_step()	(boot_cpu_data.x86 >= 6)
374 #endif
375 
376 #define ARCH_HAS_USER_SINGLE_STEP_REPORT
377 
378 struct user_desc;
379 extern int do_get_thread_area(struct task_struct *p, int idx,
380 			      struct user_desc __user *info);
381 extern int do_set_thread_area(struct task_struct *p, int idx,
382 			      struct user_desc __user *info, int can_allocate);
383 
384 #ifdef CONFIG_X86_64
385 # define do_set_thread_area_64(p, s, t)	do_arch_prctl_64(p, s, t)
386 #else
387 # define do_set_thread_area_64(p, s, t)	(0)
388 #endif
389 
390 #endif /* !__ASSEMBLY__ */
391 #endif /* _ASM_X86_PTRACE_H */
392