[deliverable/linux.git] / tools / testing / selftests / rseq / rseq-x86.h

/*
 * rseq-x86.h
 *
 * (C) Copyright 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifdef __x86_64__

#define smp_mb()	__asm__ __volatile__ ("mfence" : : : "memory")
#define smp_rmb()	barrier()
#define smp_wmb()	barrier()

#define smp_load_acquire(p)						\
__extension__ ({							\
	__typeof(*p) ____p1 = READ_ONCE(*p);				\
	barrier();							\
	____p1;								\
})

#define smp_acquire__after_ctrl_dep()	smp_rmb()

#define smp_store_release(p, v)						\
do {									\
	barrier();							\
	WRITE_ONCE(*p, v);						\
} while (0)

#define has_fast_acquire_release()	1
#define has_single_copy_load_64()	1

/*
 * The __rseq_table section can be used by debuggers to better handle
 * single-stepping through the restartable critical sections.
 */
#define RSEQ_FINISH_ASM(_target_final, _to_write_final, _start_value, \
		_failure, _spec_store, _spec_input, \
		_final_store, _final_input, _extra_clobber, \
		_setup, _teardown, _scratch) \
do { \
	_scratch \
	__asm__ __volatile__ goto ( \
		".pushsection __rseq_table, \"aw\"\n\t" \
		".balign 32\n\t" \
		"3:\n\t" \
		".quad 1f, 2f, 4f, 0x0\n\t" \
		".popsection\n\t" \
		"1:\n\t" \
		_setup \
		RSEQ_INJECT_ASM(1) \
		"movq $3b, %[rseq_cs]\n\t" \
		RSEQ_INJECT_ASM(2) \
		"cmpl %[start_event_counter], %[current_event_counter]\n\t" \
		"jnz 4f\n\t" \
		RSEQ_INJECT_ASM(3) \
		_spec_store \
		_final_store \
		"2:\n\t" \
		RSEQ_INJECT_ASM(5) \
		"movq $0, %[rseq_cs]\n\t" \
		_teardown \
		".pushsection __rseq_failure, \"a\"\n\t" \
		"4:\n\t" \
		"movq $0, %[rseq_cs]\n\t" \
		_teardown \
		"jmp %l[failure]\n\t" \
		".popsection\n\t" \
		: /* gcc asm goto does not allow outputs */ \
		: [start_event_counter]"r"((_start_value).event_counter), \
		  [current_event_counter]"m"((_start_value).rseqp->u.e.event_counter), \
		  [rseq_cs]"m"((_start_value).rseqp->rseq_cs) \
		  _spec_input \
		  _final_input \
		  RSEQ_INJECT_INPUT \
		: "memory", "cc" \
		  _extra_clobber \
		  RSEQ_INJECT_CLOBBER \
		: _failure \
	); \
} while (0)

#define RSEQ_FINISH_FINAL_STORE_ASM() \
		"movq %[to_write_final], %[target_final]\n\t"

/* x86-64 is TSO */
#define RSEQ_FINISH_FINAL_STORE_RELEASE_ASM() \
		RSEQ_FINISH_FINAL_STORE_ASM()

#define RSEQ_FINISH_FINAL_STORE_INPUT(_target_final, _to_write_final) \
		, [to_write_final]"r"(_to_write_final), \
		[target_final]"m"(*(_target_final))

#define RSEQ_FINISH_SPECULATIVE_STORE_ASM() \
		"movq %[to_write_spec], %[target_spec]\n\t" \
		RSEQ_INJECT_ASM(4)

#define RSEQ_FINISH_SPECULATIVE_STORE_INPUT(_target_spec, _to_write_spec) \
		, [to_write_spec]"r"(_to_write_spec), \
		[target_spec]"m"(*(_target_spec))

/* TODO: implement a faster memcpy. */
#define RSEQ_FINISH_MEMCPY_STORE_ASM() \
		"test %[len_memcpy], %[len_memcpy]\n\t" \
		"jz 333f\n\t" \
		"222:\n\t" \
		"movb (%[to_write_memcpy]), %%al\n\t" \
		"movb %%al, (%[target_memcpy])\n\t" \
		"inc %[to_write_memcpy]\n\t" \
		"inc %[target_memcpy]\n\t" \
		"dec %[len_memcpy]\n\t" \
		"jnz 222b\n\t" \
		"333:\n\t" \
		RSEQ_INJECT_ASM(4)

#define RSEQ_FINISH_MEMCPY_STORE_INPUT(_target_memcpy, _to_write_memcpy, _len_memcpy) \
		, [to_write_memcpy]"r"(_to_write_memcpy), \
		[target_memcpy]"r"(_target_memcpy), \
		[len_memcpy]"r"(_len_memcpy), \
		[rseq_scratch0]"m"(rseq_scratch[0]), \
		[rseq_scratch1]"m"(rseq_scratch[1]), \
		[rseq_scratch2]"m"(rseq_scratch[2])

#define RSEQ_FINISH_MEMCPY_CLOBBER()	\
		, "rax"

#define RSEQ_FINISH_MEMCPY_SCRATCH() \
		uint64_t rseq_scratch[3];

/*
 * We need to save and restore those input registers so they can be
 * modified within the assembly.
 */
#define RSEQ_FINISH_MEMCPY_SETUP() \
		"movq %[to_write_memcpy], %[rseq_scratch0]\n\t" \
		"movq %[target_memcpy], %[rseq_scratch1]\n\t" \
		"movq %[len_memcpy], %[rseq_scratch2]\n\t"

#define RSEQ_FINISH_MEMCPY_TEARDOWN() \
		"movq %[rseq_scratch2], %[len_memcpy]\n\t" \
		"movq %[rseq_scratch1], %[target_memcpy]\n\t" \
		"movq %[rseq_scratch0], %[to_write_memcpy]\n\t"

#elif __i386__

/*
 * Support older 32-bit architectures that do not implement fence
 * instructions.
 */
#define smp_mb()	\
	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
#define smp_rmb()	\
	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
#define smp_wmb()	\
	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")

#define smp_load_acquire(p)						\
__extension__ ({							\
	__typeof(*p) ____p1 = READ_ONCE(*p);				\
	smp_mb();							\
	____p1;								\
})

#define smp_acquire__after_ctrl_dep()	smp_rmb()

#define smp_store_release(p, v)						\
do {									\
	smp_mb();							\
	WRITE_ONCE(*p, v);						\
} while (0)

#define has_fast_acquire_release()	0
#define has_single_copy_load_64()	0

/*
 * Use eax as scratch register and take memory operands as input to
 * lessen register pressure. Especially needed when compiling
 * do_rseq_memcpy() in O0.
 */
#define RSEQ_FINISH_ASM(_target_final, _to_write_final, _start_value, \
		_failure, _spec_store, _spec_input, \
		_final_store, _final_input, _extra_clobber, \
		_setup, _teardown, _scratch) \
do { \
	_scratch \
	__asm__ __volatile__ goto ( \
		".pushsection __rseq_table, \"aw\"\n\t" \
		".balign 32\n\t" \
		"3:\n\t" \
		".long 1f, 0x0, 2f, 0x0, 4f, 0x0, 0x0, 0x0\n\t" \
		".popsection\n\t" \
		"1:\n\t" \
		_setup \
		RSEQ_INJECT_ASM(1) \
		"movl $3b, %[rseq_cs]\n\t" \
		RSEQ_INJECT_ASM(2) \
		"movl %[start_event_counter], %%eax\n\t" \
		"cmpl %%eax, %[current_event_counter]\n\t" \
		"jnz 4f\n\t" \
		RSEQ_INJECT_ASM(3) \
		_spec_store \
		_final_store \
		"2:\n\t" \
		RSEQ_INJECT_ASM(5) \
		"movl $0, %[rseq_cs]\n\t" \
		_teardown \
		".pushsection __rseq_failure, \"a\"\n\t" \
		"4:\n\t" \
		"movl $0, %[rseq_cs]\n\t" \
		_teardown \
		"jmp %l[failure]\n\t" \
		".popsection\n\t" \
		: /* gcc asm goto does not allow outputs */ \
		: [start_event_counter]"m"((_start_value).event_counter), \
		  [current_event_counter]"m"((_start_value).rseqp->u.e.event_counter), \
		  [rseq_cs]"m"((_start_value).rseqp->rseq_cs) \
		  _spec_input \
		  _final_input \
		  RSEQ_INJECT_INPUT \
		: "memory", "cc", "eax" \
		  _extra_clobber \
		  RSEQ_INJECT_CLOBBER \
		: _failure \
	); \
} while (0)

#define RSEQ_FINISH_FINAL_STORE_ASM() \
		"movl %[to_write_final], %%eax\n\t" \
		"movl %%eax, %[target_final]\n\t"

#define RSEQ_FINISH_FINAL_STORE_RELEASE_ASM() \
		"lock; addl $0,0(%%esp)\n\t" \
		RSEQ_FINISH_FINAL_STORE_ASM()

#define RSEQ_FINISH_FINAL_STORE_INPUT(_target_final, _to_write_final) \
		, [to_write_final]"m"(_to_write_final), \
		[target_final]"m"(*(_target_final))

#define RSEQ_FINISH_SPECULATIVE_STORE_ASM() \
		"movl %[to_write_spec], %%eax\n\t" \
		"movl %%eax, %[target_spec]\n\t" \
		RSEQ_INJECT_ASM(4)

#define RSEQ_FINISH_SPECULATIVE_STORE_INPUT(_target_spec, _to_write_spec) \
		, [to_write_spec]"m"(_to_write_spec), \
		[target_spec]"m"(*(_target_spec))

/* TODO: implement a faster memcpy. */
#define RSEQ_FINISH_MEMCPY_STORE_ASM() \
		"movl %[len_memcpy], %%eax\n\t" \
		"test %%eax, %%eax\n\t" \
		"jz 333f\n\t" \
		"222:\n\t" \
		"movb (%[to_write_memcpy]), %%al\n\t" \
		"movb %%al, (%[target_memcpy])\n\t" \
		"inc %[to_write_memcpy]\n\t" \
		"inc %[target_memcpy]\n\t" \
		"decl %[rseq_scratch2]\n\t" \
		"jnz 222b\n\t" \
		"333:\n\t" \
		RSEQ_INJECT_ASM(4)

#define RSEQ_FINISH_MEMCPY_STORE_INPUT(_target_memcpy, _to_write_memcpy, _len_memcpy) \
		, [to_write_memcpy]"r"(_to_write_memcpy), \
		[target_memcpy]"r"(_target_memcpy), \
		[len_memcpy]"m"(_len_memcpy), \
		[rseq_scratch0]"m"(rseq_scratch[0]), \
		[rseq_scratch1]"m"(rseq_scratch[1]), \
		[rseq_scratch2]"m"(rseq_scratch[2])

#define RSEQ_FINISH_MEMCPY_CLOBBER()

#define RSEQ_FINISH_MEMCPY_SCRATCH() \
		uint32_t rseq_scratch[3];

/*
 * We need to save and restore those input registers so they can be
 * modified within the assembly.
 */
#define RSEQ_FINISH_MEMCPY_SETUP() \
		"movl %[to_write_memcpy], %[rseq_scratch0]\n\t" \
		"movl %[target_memcpy], %[rseq_scratch1]\n\t" \
		"movl %[len_memcpy], %%eax\n\t" \
		"movl %%eax, %[rseq_scratch2]\n\t"

#define RSEQ_FINISH_MEMCPY_TEARDOWN() \
		"movl %[rseq_scratch1], %[target_memcpy]\n\t" \
		"movl %[rseq_scratch0], %[to_write_memcpy]\n\t"

#endif
Commit	Line	Data
b54c5158 MD	1	/*
	2	* rseq-x86.h
	3	*
	4	* (C) Copyright 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	*
	6	* Permission is hereby granted, free of charge, to any person obtaining a copy
	7	* of this software and associated documentation files (the "Software"), to deal
	8	* in the Software without restriction, including without limitation the rights
	9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	10	* copies of the Software, and to permit persons to whom the Software is
	11	* furnished to do so, subject to the following conditions:
	12	*
	13	* The above copyright notice and this permission notice shall be included in
	14	* all copies or substantial portions of the Software.
	15	*
	16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	19	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	22	* SOFTWARE.
	23	*/
	24
	25	#ifdef __x86_64__
	26
	27	#define smp_mb() __asm__ __volatile__ ("mfence" : : : "memory")
	28	#define smp_rmb() barrier()
	29	#define smp_wmb() barrier()
	30
	31	#define smp_load_acquire(p) \
	32	__extension__ ({ \
	33	__typeof(p) ____p1 = READ_ONCE(p); \
	34	barrier(); \
	35	____p1; \
	36	})
	37
	38	#define smp_acquire__after_ctrl_dep() smp_rmb()
	39
	40	#define smp_store_release(p, v) \
	41	do { \
	42	barrier(); \
	43	WRITE_ONCE(*p, v); \
	44	} while (0)
	45
	46	#define has_fast_acquire_release() 1
	47	#define has_single_copy_load_64() 1
	48
	49	/*
	50	* The __rseq_table section can be used by debuggers to better handle
	51	* single-stepping through the restartable critical sections.
	52	*/
	53	#define RSEQ_FINISH_ASM(_target_final, _to_write_final, _start_value, \
	54	_failure, _spec_store, _spec_input, \
	55	_final_store, _final_input, _extra_clobber, \
	56	_setup, _teardown, _scratch) \
	57	do { \
	58	_scratch \
	59	__asm__ __volatile__ goto ( \
	60	".pushsection __rseq_table, \"aw\"\n\t" \
	61	".balign 32\n\t" \
	62	"3:\n\t" \
	63	".quad 1f, 2f, 4f, 0x0\n\t" \
	64	".popsection\n\t" \
65	"1:\n\t" \
66	_setup \
67	RSEQ_INJECT_ASM(1) \
68	"movq $3b, %[rseq_cs]\n\t" \
69	RSEQ_INJECT_ASM(2) \
70	"cmpl %[start_event_counter], %[current_event_counter]\n\t" \
71	"jnz 4f\n\t" \
72	RSEQ_INJECT_ASM(3) \
73	_spec_store \
74	_final_store \
75	"2:\n\t" \
76	RSEQ_INJECT_ASM(5) \
77	"movq $0, %[rseq_cs]\n\t" \
78	_teardown \
79	".pushsection __rseq_failure, \"a\"\n\t" \
80	"4:\n\t" \
81	"movq $0, %[rseq_cs]\n\t" \
82	_teardown \
83	"jmp %l[failure]\n\t" \
84	".popsection\n\t" \
85	: /* gcc asm goto does not allow outputs */ \
86	: [start_event_counter]"r"((_start_value).event_counter), \
87	[current_event_counter]"m"((_start_value).rseqp->u.e.event_counter), \
88	[rseq_cs]"m"((_start_value).rseqp->rseq_cs) \
89	_spec_input \
90	_final_input \
91	RSEQ_INJECT_INPUT \
92	: "memory", "cc" \
93	_extra_clobber \
94	RSEQ_INJECT_CLOBBER \
95	: _failure \
96	); \
97	} while (0)
98
99	#define RSEQ_FINISH_FINAL_STORE_ASM() \
100	"movq %[to_write_final], %[target_final]\n\t"
101
102	/* x86-64 is TSO */
103	#define RSEQ_FINISH_FINAL_STORE_RELEASE_ASM() \
104	RSEQ_FINISH_FINAL_STORE_ASM()
105
106	#define RSEQ_FINISH_FINAL_STORE_INPUT(_target_final, _to_write_final) \
107	, [to_write_final]"r"(_to_write_final), \
108	[target_final]"m"(*(_target_final))
109
110	#define RSEQ_FINISH_SPECULATIVE_STORE_ASM() \
111	"movq %[to_write_spec], %[target_spec]\n\t" \
112	RSEQ_INJECT_ASM(4)
113
114	#define RSEQ_FINISH_SPECULATIVE_STORE_INPUT(_target_spec, _to_write_spec) \
115	, [to_write_spec]"r"(_to_write_spec), \
116	[target_spec]"m"(*(_target_spec))
117
118	/* TODO: implement a faster memcpy. */
119	#define RSEQ_FINISH_MEMCPY_STORE_ASM() \
120	"test %[len_memcpy], %[len_memcpy]\n\t" \
121	"jz 333f\n\t" \
122	"222:\n\t" \
123	"movb (%[to_write_memcpy]), %%al\n\t" \
124	"movb %%al, (%[target_memcpy])\n\t" \
125	"inc %[to_write_memcpy]\n\t" \
126	"inc %[target_memcpy]\n\t" \
127	"dec %[len_memcpy]\n\t" \
128	"jnz 222b\n\t" \
129	"333:\n\t" \
130	RSEQ_INJECT_ASM(4)
131
132	#define RSEQ_FINISH_MEMCPY_STORE_INPUT(_target_memcpy, _to_write_memcpy, _len_memcpy) \
133	, [to_write_memcpy]"r"(_to_write_memcpy), \
134	[target_memcpy]"r"(_target_memcpy), \
135	[len_memcpy]"r"(_len_memcpy), \
136	[rseq_scratch0]"m"(rseq_scratch[0]), \
137	[rseq_scratch1]"m"(rseq_scratch[1]), \
138	[rseq_scratch2]"m"(rseq_scratch[2])
139
140	#define RSEQ_FINISH_MEMCPY_CLOBBER() \
141	, "rax"
142
143	#define RSEQ_FINISH_MEMCPY_SCRATCH() \
144	uint64_t rseq_scratch[3];
145
146	/*
147	* We need to save and restore those input registers so they can be
148	* modified within the assembly.
149	*/
150	#define RSEQ_FINISH_MEMCPY_SETUP() \
151	"movq %[to_write_memcpy], %[rseq_scratch0]\n\t" \
152	"movq %[target_memcpy], %[rseq_scratch1]\n\t" \
153	"movq %[len_memcpy], %[rseq_scratch2]\n\t"
154
155	#define RSEQ_FINISH_MEMCPY_TEARDOWN() \
156	"movq %[rseq_scratch2], %[len_memcpy]\n\t" \
157	"movq %[rseq_scratch1], %[target_memcpy]\n\t" \
158	"movq %[rseq_scratch0], %[to_write_memcpy]\n\t"
159
160	#elif __i386__
161
162	/*
163	* Support older 32-bit architectures that do not implement fence
164	* instructions.
165	*/
166	#define smp_mb() \
167	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
168	#define smp_rmb() \
169	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
170	#define smp_wmb() \
171	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
172
173	#define smp_load_acquire(p) \
174	__extension__ ({ \
175	__typeof(p) ____p1 = READ_ONCE(p); \
176	smp_mb(); \
177	____p1; \
178	})
179
180	#define smp_acquire__after_ctrl_dep() smp_rmb()
181
182	#define smp_store_release(p, v) \
183	do { \
184	smp_mb(); \
185	WRITE_ONCE(*p, v); \
186	} while (0)
187
188	#define has_fast_acquire_release() 0
189	#define has_single_copy_load_64() 0
190
191	/*
192	* Use eax as scratch register and take memory operands as input to
193	* lessen register pressure. Especially needed when compiling
194	* do_rseq_memcpy() in O0.
195	*/
196	#define RSEQ_FINISH_ASM(_target_final, _to_write_final, _start_value, \
197	_failure, _spec_store, _spec_input, \
198	_final_store, _final_input, _extra_clobber, \
199	_setup, _teardown, _scratch) \
200	do { \
201	_scratch \
202	__asm__ __volatile__ goto ( \
203	".pushsection __rseq_table, \"aw\"\n\t" \
204	".balign 32\n\t" \
205	"3:\n\t" \
206	".long 1f, 0x0, 2f, 0x0, 4f, 0x0, 0x0, 0x0\n\t" \
207	".popsection\n\t" \
208	"1:\n\t" \
209	_setup \
210	RSEQ_INJECT_ASM(1) \
211	"movl $3b, %[rseq_cs]\n\t" \
212	RSEQ_INJECT_ASM(2) \
213	"movl %[start_event_counter], %%eax\n\t" \
214	"cmpl %%eax, %[current_event_counter]\n\t" \
215	"jnz 4f\n\t" \
216	RSEQ_INJECT_ASM(3) \
217	_spec_store \
218	_final_store \
219	"2:\n\t" \
220	RSEQ_INJECT_ASM(5) \
221	"movl $0, %[rseq_cs]\n\t" \
222	_teardown \
223	".pushsection __rseq_failure, \"a\"\n\t" \
224	"4:\n\t" \
225	"movl $0, %[rseq_cs]\n\t" \
226	_teardown \
227	"jmp %l[failure]\n\t" \
228	".popsection\n\t" \
229	: /* gcc asm goto does not allow outputs */ \
230	: [start_event_counter]"m"((_start_value).event_counter), \
231	[current_event_counter]"m"((_start_value).rseqp->u.e.event_counter), \
232	[rseq_cs]"m"((_start_value).rseqp->rseq_cs) \
233	_spec_input \
234	_final_input \
235	RSEQ_INJECT_INPUT \
236	: "memory", "cc", "eax" \
237	_extra_clobber \
238	RSEQ_INJECT_CLOBBER \
239	: _failure \
240	); \
241	} while (0)
242
243	#define RSEQ_FINISH_FINAL_STORE_ASM() \
244	"movl %[to_write_final], %%eax\n\t" \
245	"movl %%eax, %[target_final]\n\t"
246
247	#define RSEQ_FINISH_FINAL_STORE_RELEASE_ASM() \
248	"lock; addl $0,0(%%esp)\n\t" \
249	RSEQ_FINISH_FINAL_STORE_ASM()
250
251	#define RSEQ_FINISH_FINAL_STORE_INPUT(_target_final, _to_write_final) \
252	, [to_write_final]"m"(_to_write_final), \
253	[target_final]"m"(*(_target_final))
254
255	#define RSEQ_FINISH_SPECULATIVE_STORE_ASM() \
256	"movl %[to_write_spec], %%eax\n\t" \
257	"movl %%eax, %[target_spec]\n\t" \
258	RSEQ_INJECT_ASM(4)
259
260	#define RSEQ_FINISH_SPECULATIVE_STORE_INPUT(_target_spec, _to_write_spec) \
261	, [to_write_spec]"m"(_to_write_spec), \
262	[target_spec]"m"(*(_target_spec))
263
264	/* TODO: implement a faster memcpy. */
265	#define RSEQ_FINISH_MEMCPY_STORE_ASM() \
266	"movl %[len_memcpy], %%eax\n\t" \
267	"test %%eax, %%eax\n\t" \
268	"jz 333f\n\t" \
269	"222:\n\t" \
270	"movb (%[to_write_memcpy]), %%al\n\t" \
271	"movb %%al, (%[target_memcpy])\n\t" \
272	"inc %[to_write_memcpy]\n\t" \
273	"inc %[target_memcpy]\n\t" \
274	"decl %[rseq_scratch2]\n\t" \
275	"jnz 222b\n\t" \
276	"333:\n\t" \
277	RSEQ_INJECT_ASM(4)
278
279	#define RSEQ_FINISH_MEMCPY_STORE_INPUT(_target_memcpy, _to_write_memcpy, _len_memcpy) \
280	, [to_write_memcpy]"r"(_to_write_memcpy), \
281	[target_memcpy]"r"(_target_memcpy), \
282	[len_memcpy]"m"(_len_memcpy), \
283	[rseq_scratch0]"m"(rseq_scratch[0]), \
284	[rseq_scratch1]"m"(rseq_scratch[1]), \
285	[rseq_scratch2]"m"(rseq_scratch[2])
286
287	#define RSEQ_FINISH_MEMCPY_CLOBBER()
288
289	#define RSEQ_FINISH_MEMCPY_SCRATCH() \
290	uint32_t rseq_scratch[3];
291
292	/*
293	* We need to save and restore those input registers so they can be
294	* modified within the assembly.
295	*/
296	#define RSEQ_FINISH_MEMCPY_SETUP() \
297	"movl %[to_write_memcpy], %[rseq_scratch0]\n\t" \
298	"movl %[target_memcpy], %[rseq_scratch1]\n\t" \
299	"movl %[len_memcpy], %%eax\n\t" \
300	"movl %%eax, %[rseq_scratch2]\n\t"
301
302	#define RSEQ_FINISH_MEMCPY_TEARDOWN() \
303	"movl %[rseq_scratch1], %[target_memcpy]\n\t" \
304	"movl %[rseq_scratch0], %[to_write_memcpy]\n\t"
305
306	#endif