xref: /openbmc/linux/arch/x86/include/asm/percpu.h (revision febe950d)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_PERCPU_H
3 #define _ASM_X86_PERCPU_H
4 
5 #ifdef CONFIG_X86_64
6 #define __percpu_seg		gs
7 #else
8 #define __percpu_seg		fs
9 #endif
10 
11 #ifdef __ASSEMBLY__
12 
13 #ifdef CONFIG_SMP
14 #define PER_CPU_VAR(var)	%__percpu_seg:var
15 #else /* ! SMP */
16 #define PER_CPU_VAR(var)	var
17 #endif	/* SMP */
18 
19 #ifdef CONFIG_X86_64_SMP
20 #define INIT_PER_CPU_VAR(var)  init_per_cpu__##var
21 #else
22 #define INIT_PER_CPU_VAR(var)  var
23 #endif
24 
25 #else /* ...!ASSEMBLY */
26 
27 #include <linux/kernel.h>
28 #include <linux/stringify.h>
29 
30 #ifdef CONFIG_SMP
31 #define __percpu_prefix		"%%"__stringify(__percpu_seg)":"
32 #define __my_cpu_offset		this_cpu_read(this_cpu_off)
33 
34 /*
35  * Compared to the generic __my_cpu_offset version, the following
36  * saves one instruction and avoids clobbering a temp register.
37  */
38 #define arch_raw_cpu_ptr(ptr)				\
39 ({							\
40 	unsigned long tcp_ptr__;			\
41 	asm ("add " __percpu_arg(1) ", %0"		\
42 	     : "=r" (tcp_ptr__)				\
43 	     : "m" (this_cpu_off), "0" (ptr));		\
44 	(typeof(*(ptr)) __kernel __force *)tcp_ptr__;	\
45 })
46 #else
47 #define __percpu_prefix		""
48 #endif
49 
50 #define __percpu_arg(x)		__percpu_prefix "%" #x
51 
52 /*
53  * Initialized pointers to per-cpu variables needed for the boot
54  * processor need to use these macros to get the proper address
55  * offset from __per_cpu_load on SMP.
56  *
57  * There also must be an entry in vmlinux_64.lds.S
58  */
59 #define DECLARE_INIT_PER_CPU(var) \
60        extern typeof(var) init_per_cpu_var(var)
61 
62 #ifdef CONFIG_X86_64_SMP
63 #define init_per_cpu_var(var)  init_per_cpu__##var
64 #else
65 #define init_per_cpu_var(var)  var
66 #endif
67 
68 /* For arch-specific code, we can use direct single-insn ops (they
69  * don't give an lvalue though). */
70 
71 #define __pcpu_type_1 u8
72 #define __pcpu_type_2 u16
73 #define __pcpu_type_4 u32
74 #define __pcpu_type_8 u64
75 
76 #define __pcpu_cast_1(val) ((u8)(((unsigned long) val) & 0xff))
77 #define __pcpu_cast_2(val) ((u16)(((unsigned long) val) & 0xffff))
78 #define __pcpu_cast_4(val) ((u32)(((unsigned long) val) & 0xffffffff))
79 #define __pcpu_cast_8(val) ((u64)(val))
80 
81 #define __pcpu_op1_1(op, dst) op "b " dst
82 #define __pcpu_op1_2(op, dst) op "w " dst
83 #define __pcpu_op1_4(op, dst) op "l " dst
84 #define __pcpu_op1_8(op, dst) op "q " dst
85 
86 #define __pcpu_op2_1(op, src, dst) op "b " src ", " dst
87 #define __pcpu_op2_2(op, src, dst) op "w " src ", " dst
88 #define __pcpu_op2_4(op, src, dst) op "l " src ", " dst
89 #define __pcpu_op2_8(op, src, dst) op "q " src ", " dst
90 
91 #define __pcpu_reg_1(mod, x) mod "q" (x)
92 #define __pcpu_reg_2(mod, x) mod "r" (x)
93 #define __pcpu_reg_4(mod, x) mod "r" (x)
94 #define __pcpu_reg_8(mod, x) mod "r" (x)
95 
96 #define __pcpu_reg_imm_1(x) "qi" (x)
97 #define __pcpu_reg_imm_2(x) "ri" (x)
98 #define __pcpu_reg_imm_4(x) "ri" (x)
99 #define __pcpu_reg_imm_8(x) "re" (x)
100 
101 #define percpu_to_op(size, qual, op, _var, _val)			\
102 do {									\
103 	__pcpu_type_##size pto_val__ = __pcpu_cast_##size(_val);	\
104 	if (0) {		                                        \
105 		typeof(_var) pto_tmp__;					\
106 		pto_tmp__ = (_val);					\
107 		(void)pto_tmp__;					\
108 	}								\
109 	asm qual(__pcpu_op2_##size(op, "%[val]", __percpu_arg([var]))	\
110 	    : [var] "+m" (_var)						\
111 	    : [val] __pcpu_reg_imm_##size(pto_val__));			\
112 } while (0)
113 
114 #define percpu_unary_op(size, qual, op, _var)				\
115 ({									\
116 	asm qual (__pcpu_op1_##size(op, __percpu_arg([var]))		\
117 	    : [var] "+m" (_var));					\
118 })
119 
120 /*
121  * Generate a percpu add to memory instruction and optimize code
122  * if one is added or subtracted.
123  */
124 #define percpu_add_op(size, qual, var, val)				\
125 do {									\
126 	const int pao_ID__ = (__builtin_constant_p(val) &&		\
127 			      ((val) == 1 || (val) == -1)) ?		\
128 				(int)(val) : 0;				\
129 	if (0) {							\
130 		typeof(var) pao_tmp__;					\
131 		pao_tmp__ = (val);					\
132 		(void)pao_tmp__;					\
133 	}								\
134 	if (pao_ID__ == 1)						\
135 		percpu_unary_op(size, qual, "inc", var);		\
136 	else if (pao_ID__ == -1)					\
137 		percpu_unary_op(size, qual, "dec", var);		\
138 	else								\
139 		percpu_to_op(size, qual, "add", var, val);		\
140 } while (0)
141 
142 #define percpu_from_op(size, qual, op, _var)				\
143 ({									\
144 	__pcpu_type_##size pfo_val__;					\
145 	asm qual (__pcpu_op2_##size(op, __percpu_arg([var]), "%[val]")	\
146 	    : [val] __pcpu_reg_##size("=", pfo_val__)			\
147 	    : [var] "m" (_var));					\
148 	(typeof(_var))(unsigned long) pfo_val__;			\
149 })
150 
151 #define percpu_stable_op(size, op, _var)				\
152 ({									\
153 	__pcpu_type_##size pfo_val__;					\
154 	asm(__pcpu_op2_##size(op, __percpu_arg(P[var]), "%[val]")	\
155 	    : [val] __pcpu_reg_##size("=", pfo_val__)			\
156 	    : [var] "p" (&(_var)));					\
157 	(typeof(_var))(unsigned long) pfo_val__;			\
158 })
159 
160 /*
161  * Add return operation
162  */
163 #define percpu_add_return_op(size, qual, _var, _val)			\
164 ({									\
165 	__pcpu_type_##size paro_tmp__ = __pcpu_cast_##size(_val);	\
166 	asm qual (__pcpu_op2_##size("xadd", "%[tmp]",			\
167 				     __percpu_arg([var]))		\
168 		  : [tmp] __pcpu_reg_##size("+", paro_tmp__),		\
169 		    [var] "+m" (_var)					\
170 		  : : "memory");					\
171 	(typeof(_var))(unsigned long) (paro_tmp__ + _val);		\
172 })
173 
174 /*
175  * xchg is implemented using cmpxchg without a lock prefix. xchg is
176  * expensive due to the implied lock prefix.  The processor cannot prefetch
177  * cachelines if xchg is used.
178  */
179 #define percpu_xchg_op(size, qual, _var, _nval)				\
180 ({									\
181 	__pcpu_type_##size pxo_old__;					\
182 	__pcpu_type_##size pxo_new__ = __pcpu_cast_##size(_nval);	\
183 	asm qual (__pcpu_op2_##size("mov", __percpu_arg([var]),		\
184 				    "%[oval]")				\
185 		  "\n1:\t"						\
186 		  __pcpu_op2_##size("cmpxchg", "%[nval]",		\
187 				    __percpu_arg([var]))		\
188 		  "\n\tjnz 1b"						\
189 		  : [oval] "=&a" (pxo_old__),				\
190 		    [var] "+m" (_var)					\
191 		  : [nval] __pcpu_reg_##size(, pxo_new__)		\
192 		  : "memory");						\
193 	(typeof(_var))(unsigned long) pxo_old__;			\
194 })
195 
196 /*
197  * cmpxchg has no such implied lock semantics as a result it is much
198  * more efficient for cpu local operations.
199  */
200 #define percpu_cmpxchg_op(size, qual, _var, _oval, _nval)		\
201 ({									\
202 	__pcpu_type_##size pco_old__ = __pcpu_cast_##size(_oval);	\
203 	__pcpu_type_##size pco_new__ = __pcpu_cast_##size(_nval);	\
204 	asm qual (__pcpu_op2_##size("cmpxchg", "%[nval]",		\
205 				    __percpu_arg([var]))		\
206 		  : [oval] "+a" (pco_old__),				\
207 		    [var] "+m" (_var)					\
208 		  : [nval] __pcpu_reg_##size(, pco_new__)		\
209 		  : "memory");						\
210 	(typeof(_var))(unsigned long) pco_old__;			\
211 })
212 
213 #if defined(CONFIG_X86_32) && !defined(CONFIG_UML)
214 #define percpu_cmpxchg64_op(size, qual, _var, _oval, _nval)		\
215 ({									\
216 	union {								\
217 		u64 var;						\
218 		struct {						\
219 			u32 low, high;					\
220 		};							\
221 	} old__, new__;							\
222 									\
223 	old__.var = _oval;						\
224 	new__.var = _nval;						\
225 									\
226 	asm qual (ALTERNATIVE("leal %P[var], %%esi; call this_cpu_cmpxchg8b_emu", \
227 			      "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \
228 		  : [var] "+m" (_var),					\
229 		    "+a" (old__.low),					\
230 		    "+d" (old__.high)					\
231 		  : "b" (new__.low),					\
232 		    "c" (new__.high)					\
233 		  : "memory", "esi");					\
234 									\
235 	old__.var;							\
236 })
237 
238 #define raw_cpu_cmpxchg64(pcp, oval, nval)	percpu_cmpxchg64_op(8,         , pcp, oval, nval)
239 #define this_cpu_cmpxchg64(pcp, oval, nval)	percpu_cmpxchg64_op(8, volatile, pcp, oval, nval)
240 #endif
241 
242 #ifdef CONFIG_X86_64
243 #define raw_cpu_cmpxchg64(pcp, oval, nval)	percpu_cmpxchg_op(8,         , pcp, oval, nval);
244 #define this_cpu_cmpxchg64(pcp, oval, nval)	percpu_cmpxchg_op(8, volatile, pcp, oval, nval);
245 
246 #define percpu_cmpxchg128_op(size, qual, _var, _oval, _nval)		\
247 ({									\
248 	union {								\
249 		u128 var;						\
250 		struct {						\
251 			u64 low, high;					\
252 		};							\
253 	} old__, new__;							\
254 									\
255 	old__.var = _oval;						\
256 	new__.var = _nval;						\
257 									\
258 	asm qual (ALTERNATIVE("leaq %P[var], %%rsi; call this_cpu_cmpxchg16b_emu", \
259 			      "cmpxchg16b " __percpu_arg([var]), X86_FEATURE_CX16) \
260 		  : [var] "+m" (_var),					\
261 		    "+a" (old__.low),					\
262 		    "+d" (old__.high)					\
263 		  : "b" (new__.low),					\
264 		    "c" (new__.high)					\
265 		  : "memory", "rsi");					\
266 									\
267 	old__.var;							\
268 })
269 
270 #define raw_cpu_cmpxchg128(pcp, oval, nval)	percpu_cmpxchg128_op(16,         , pcp, oval, nval)
271 #define this_cpu_cmpxchg128(pcp, oval, nval)	percpu_cmpxchg128_op(16, volatile, pcp, oval, nval)
272 #endif
273 
274 /*
275  * this_cpu_read() makes gcc load the percpu variable every time it is
276  * accessed while this_cpu_read_stable() allows the value to be cached.
277  * this_cpu_read_stable() is more efficient and can be used if its value
278  * is guaranteed to be valid across cpus.  The current users include
279  * get_current() and get_thread_info() both of which are actually
280  * per-thread variables implemented as per-cpu variables and thus
281  * stable for the duration of the respective task.
282  */
283 #define this_cpu_read_stable_1(pcp)	percpu_stable_op(1, "mov", pcp)
284 #define this_cpu_read_stable_2(pcp)	percpu_stable_op(2, "mov", pcp)
285 #define this_cpu_read_stable_4(pcp)	percpu_stable_op(4, "mov", pcp)
286 #define this_cpu_read_stable_8(pcp)	percpu_stable_op(8, "mov", pcp)
287 #define this_cpu_read_stable(pcp)	__pcpu_size_call_return(this_cpu_read_stable_, pcp)
288 
289 #define raw_cpu_read_1(pcp)		percpu_from_op(1, , "mov", pcp)
290 #define raw_cpu_read_2(pcp)		percpu_from_op(2, , "mov", pcp)
291 #define raw_cpu_read_4(pcp)		percpu_from_op(4, , "mov", pcp)
292 
293 #define raw_cpu_write_1(pcp, val)	percpu_to_op(1, , "mov", (pcp), val)
294 #define raw_cpu_write_2(pcp, val)	percpu_to_op(2, , "mov", (pcp), val)
295 #define raw_cpu_write_4(pcp, val)	percpu_to_op(4, , "mov", (pcp), val)
296 #define raw_cpu_add_1(pcp, val)		percpu_add_op(1, , (pcp), val)
297 #define raw_cpu_add_2(pcp, val)		percpu_add_op(2, , (pcp), val)
298 #define raw_cpu_add_4(pcp, val)		percpu_add_op(4, , (pcp), val)
299 #define raw_cpu_and_1(pcp, val)		percpu_to_op(1, , "and", (pcp), val)
300 #define raw_cpu_and_2(pcp, val)		percpu_to_op(2, , "and", (pcp), val)
301 #define raw_cpu_and_4(pcp, val)		percpu_to_op(4, , "and", (pcp), val)
302 #define raw_cpu_or_1(pcp, val)		percpu_to_op(1, , "or", (pcp), val)
303 #define raw_cpu_or_2(pcp, val)		percpu_to_op(2, , "or", (pcp), val)
304 #define raw_cpu_or_4(pcp, val)		percpu_to_op(4, , "or", (pcp), val)
305 
306 /*
307  * raw_cpu_xchg() can use a load-store since it is not required to be
308  * IRQ-safe.
309  */
310 #define raw_percpu_xchg_op(var, nval)					\
311 ({									\
312 	typeof(var) pxo_ret__ = raw_cpu_read(var);			\
313 	raw_cpu_write(var, (nval));					\
314 	pxo_ret__;							\
315 })
316 
317 #define raw_cpu_xchg_1(pcp, val)	raw_percpu_xchg_op(pcp, val)
318 #define raw_cpu_xchg_2(pcp, val)	raw_percpu_xchg_op(pcp, val)
319 #define raw_cpu_xchg_4(pcp, val)	raw_percpu_xchg_op(pcp, val)
320 
321 #define this_cpu_read_1(pcp)		percpu_from_op(1, volatile, "mov", pcp)
322 #define this_cpu_read_2(pcp)		percpu_from_op(2, volatile, "mov", pcp)
323 #define this_cpu_read_4(pcp)		percpu_from_op(4, volatile, "mov", pcp)
324 #define this_cpu_write_1(pcp, val)	percpu_to_op(1, volatile, "mov", (pcp), val)
325 #define this_cpu_write_2(pcp, val)	percpu_to_op(2, volatile, "mov", (pcp), val)
326 #define this_cpu_write_4(pcp, val)	percpu_to_op(4, volatile, "mov", (pcp), val)
327 #define this_cpu_add_1(pcp, val)	percpu_add_op(1, volatile, (pcp), val)
328 #define this_cpu_add_2(pcp, val)	percpu_add_op(2, volatile, (pcp), val)
329 #define this_cpu_add_4(pcp, val)	percpu_add_op(4, volatile, (pcp), val)
330 #define this_cpu_and_1(pcp, val)	percpu_to_op(1, volatile, "and", (pcp), val)
331 #define this_cpu_and_2(pcp, val)	percpu_to_op(2, volatile, "and", (pcp), val)
332 #define this_cpu_and_4(pcp, val)	percpu_to_op(4, volatile, "and", (pcp), val)
333 #define this_cpu_or_1(pcp, val)		percpu_to_op(1, volatile, "or", (pcp), val)
334 #define this_cpu_or_2(pcp, val)		percpu_to_op(2, volatile, "or", (pcp), val)
335 #define this_cpu_or_4(pcp, val)		percpu_to_op(4, volatile, "or", (pcp), val)
336 #define this_cpu_xchg_1(pcp, nval)	percpu_xchg_op(1, volatile, pcp, nval)
337 #define this_cpu_xchg_2(pcp, nval)	percpu_xchg_op(2, volatile, pcp, nval)
338 #define this_cpu_xchg_4(pcp, nval)	percpu_xchg_op(4, volatile, pcp, nval)
339 
340 #define raw_cpu_add_return_1(pcp, val)		percpu_add_return_op(1, , pcp, val)
341 #define raw_cpu_add_return_2(pcp, val)		percpu_add_return_op(2, , pcp, val)
342 #define raw_cpu_add_return_4(pcp, val)		percpu_add_return_op(4, , pcp, val)
343 #define raw_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(1, , pcp, oval, nval)
344 #define raw_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(2, , pcp, oval, nval)
345 #define raw_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(4, , pcp, oval, nval)
346 
347 #define this_cpu_add_return_1(pcp, val)		percpu_add_return_op(1, volatile, pcp, val)
348 #define this_cpu_add_return_2(pcp, val)		percpu_add_return_op(2, volatile, pcp, val)
349 #define this_cpu_add_return_4(pcp, val)		percpu_add_return_op(4, volatile, pcp, val)
350 #define this_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(1, volatile, pcp, oval, nval)
351 #define this_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(2, volatile, pcp, oval, nval)
352 #define this_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(4, volatile, pcp, oval, nval)
353 
354 /*
355  * Per cpu atomic 64 bit operations are only available under 64 bit.
356  * 32 bit must fall back to generic operations.
357  */
358 #ifdef CONFIG_X86_64
359 #define raw_cpu_read_8(pcp)			percpu_from_op(8, , "mov", pcp)
360 #define raw_cpu_write_8(pcp, val)		percpu_to_op(8, , "mov", (pcp), val)
361 #define raw_cpu_add_8(pcp, val)			percpu_add_op(8, , (pcp), val)
362 #define raw_cpu_and_8(pcp, val)			percpu_to_op(8, , "and", (pcp), val)
363 #define raw_cpu_or_8(pcp, val)			percpu_to_op(8, , "or", (pcp), val)
364 #define raw_cpu_add_return_8(pcp, val)		percpu_add_return_op(8, , pcp, val)
365 #define raw_cpu_xchg_8(pcp, nval)		raw_percpu_xchg_op(pcp, nval)
366 #define raw_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(8, , pcp, oval, nval)
367 
368 #define this_cpu_read_8(pcp)			percpu_from_op(8, volatile, "mov", pcp)
369 #define this_cpu_write_8(pcp, val)		percpu_to_op(8, volatile, "mov", (pcp), val)
370 #define this_cpu_add_8(pcp, val)		percpu_add_op(8, volatile, (pcp), val)
371 #define this_cpu_and_8(pcp, val)		percpu_to_op(8, volatile, "and", (pcp), val)
372 #define this_cpu_or_8(pcp, val)			percpu_to_op(8, volatile, "or", (pcp), val)
373 #define this_cpu_add_return_8(pcp, val)		percpu_add_return_op(8, volatile, pcp, val)
374 #define this_cpu_xchg_8(pcp, nval)		percpu_xchg_op(8, volatile, pcp, nval)
375 #define this_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(8, volatile, pcp, oval, nval)
376 #endif
377 
x86_this_cpu_constant_test_bit(unsigned int nr,const unsigned long __percpu * addr)378 static __always_inline bool x86_this_cpu_constant_test_bit(unsigned int nr,
379                         const unsigned long __percpu *addr)
380 {
381 	unsigned long __percpu *a =
382 		(unsigned long __percpu *)addr + nr / BITS_PER_LONG;
383 
384 #ifdef CONFIG_X86_64
385 	return ((1UL << (nr % BITS_PER_LONG)) & raw_cpu_read_8(*a)) != 0;
386 #else
387 	return ((1UL << (nr % BITS_PER_LONG)) & raw_cpu_read_4(*a)) != 0;
388 #endif
389 }
390 
x86_this_cpu_variable_test_bit(int nr,const unsigned long __percpu * addr)391 static inline bool x86_this_cpu_variable_test_bit(int nr,
392                         const unsigned long __percpu *addr)
393 {
394 	bool oldbit;
395 
396 	asm volatile("btl "__percpu_arg(2)",%1"
397 			CC_SET(c)
398 			: CC_OUT(c) (oldbit)
399 			: "m" (*(unsigned long __percpu *)addr), "Ir" (nr));
400 
401 	return oldbit;
402 }
403 
404 #define x86_this_cpu_test_bit(nr, addr)			\
405 	(__builtin_constant_p((nr))			\
406 	 ? x86_this_cpu_constant_test_bit((nr), (addr))	\
407 	 : x86_this_cpu_variable_test_bit((nr), (addr)))
408 
409 
410 #include <asm-generic/percpu.h>
411 
412 /* We can use this directly for local CPU (faster). */
413 DECLARE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off);
414 
415 #endif /* !__ASSEMBLY__ */
416 
417 #ifdef CONFIG_SMP
418 
419 /*
420  * Define the "EARLY_PER_CPU" macros.  These are used for some per_cpu
421  * variables that are initialized and accessed before there are per_cpu
422  * areas allocated.
423  */
424 
425 #define	DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)			\
426 	DEFINE_PER_CPU(_type, _name) = _initvalue;			\
427 	__typeof__(_type) _name##_early_map[NR_CPUS] __initdata =	\
428 				{ [0 ... NR_CPUS-1] = _initvalue };	\
429 	__typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
430 
431 #define DEFINE_EARLY_PER_CPU_READ_MOSTLY(_type, _name, _initvalue)	\
432 	DEFINE_PER_CPU_READ_MOSTLY(_type, _name) = _initvalue;		\
433 	__typeof__(_type) _name##_early_map[NR_CPUS] __initdata =	\
434 				{ [0 ... NR_CPUS-1] = _initvalue };	\
435 	__typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
436 
437 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)			\
438 	EXPORT_PER_CPU_SYMBOL(_name)
439 
440 #define DECLARE_EARLY_PER_CPU(_type, _name)			\
441 	DECLARE_PER_CPU(_type, _name);				\
442 	extern __typeof__(_type) *_name##_early_ptr;		\
443 	extern __typeof__(_type)  _name##_early_map[]
444 
445 #define DECLARE_EARLY_PER_CPU_READ_MOSTLY(_type, _name)		\
446 	DECLARE_PER_CPU_READ_MOSTLY(_type, _name);		\
447 	extern __typeof__(_type) *_name##_early_ptr;		\
448 	extern __typeof__(_type)  _name##_early_map[]
449 
450 #define	early_per_cpu_ptr(_name) (_name##_early_ptr)
451 #define	early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
452 #define	early_per_cpu(_name, _cpu) 				\
453 	*(early_per_cpu_ptr(_name) ?				\
454 		&early_per_cpu_ptr(_name)[_cpu] :		\
455 		&per_cpu(_name, _cpu))
456 
457 #else	/* !CONFIG_SMP */
458 #define	DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)		\
459 	DEFINE_PER_CPU(_type, _name) = _initvalue
460 
461 #define DEFINE_EARLY_PER_CPU_READ_MOSTLY(_type, _name, _initvalue)	\
462 	DEFINE_PER_CPU_READ_MOSTLY(_type, _name) = _initvalue
463 
464 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)			\
465 	EXPORT_PER_CPU_SYMBOL(_name)
466 
467 #define DECLARE_EARLY_PER_CPU(_type, _name)			\
468 	DECLARE_PER_CPU(_type, _name)
469 
470 #define DECLARE_EARLY_PER_CPU_READ_MOSTLY(_type, _name)		\
471 	DECLARE_PER_CPU_READ_MOSTLY(_type, _name)
472 
473 #define	early_per_cpu(_name, _cpu) per_cpu(_name, _cpu)
474 #define	early_per_cpu_ptr(_name) NULL
475 /* no early_per_cpu_map() */
476 
477 #endif	/* !CONFIG_SMP */
478 
479 #endif /* _ASM_X86_PERCPU_H */
480