[deliverable/linux.git] / arch / x86 / include / asm / alternative.h

#ifndef _ASM_X86_ALTERNATIVE_H
#define _ASM_X86_ALTERNATIVE_H

#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/stringify.h>
#include <asm/asm.h>
#include <asm/ptrace.h>

/*
 * Alternative inline assembly for SMP.
 *
 * The LOCK_PREFIX macro defined here replaces the LOCK and
 * LOCK_PREFIX macros used everywhere in the source tree.
 *
 * SMP alternatives use the same data structures as the other
 * alternatives and the X86_FEATURE_UP flag to indicate the case of a
 * UP system running a SMP kernel.  The existing apply_alternatives()
 * works fine for patching a SMP kernel for UP.
 *
 * The SMP alternative tables can be kept after boot and contain both
 * UP and SMP versions of the instructions to allow switching back to
 * SMP at runtime, when hotplugging in a new CPU, which is especially
 * useful in virtualized environments.
 *
 * The very common lock prefix is handled as special case in a
 * separate table which is a pure address list without replacement ptr
 * and size information.  That keeps the table sizes small.
 */

#ifdef CONFIG_SMP
#define LOCK_PREFIX_HERE \
		".pushsection .smp_locks,\"a\"\n"	\
		".balign 4\n"				\
		".long 671f - .\n" /* offset */		\
		".popsection\n"				\
		"671:"

#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; "

#else /* ! CONFIG_SMP */
#define LOCK_PREFIX_HERE ""
#define LOCK_PREFIX ""
#endif

struct alt_instr {
	s32 instr_offset;	/* original instruction */
	s32 repl_offset;	/* offset to replacement instruction */
	u16 cpuid;		/* cpuid bit set for replacement */
	u8  instrlen;		/* length of original instruction */
	u8  replacementlen;	/* length of new instruction, <= instrlen */
};

extern void alternative_instructions(void);
extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);

struct module;

#ifdef CONFIG_SMP
extern void alternatives_smp_module_add(struct module *mod, char *name,
					void *locks, void *locks_end,
					void *text, void *text_end);
extern void alternatives_smp_module_del(struct module *mod);
extern void alternatives_enable_smp(void);
extern int alternatives_text_reserved(void *start, void *end);
extern bool skip_smp_alternatives;
#else
static inline void alternatives_smp_module_add(struct module *mod, char *name,
					       void *locks, void *locks_end,
					       void *text, void *text_end) {}
static inline void alternatives_smp_module_del(struct module *mod) {}
static inline void alternatives_enable_smp(void) {}
static inline int alternatives_text_reserved(void *start, void *end)
{
	return 0;
}
#endif	/* CONFIG_SMP */

#define OLDINSTR(oldinstr)	"661:\n\t" oldinstr "\n662:\n"

#define b_replacement(number)	"663"#number
#define e_replacement(number)	"664"#number

#define alt_slen "662b-661b"
#define alt_rlen(number) e_replacement(number)"f-"b_replacement(number)"f"

#define ALTINSTR_ENTRY(feature, number)					      \
	" .long 661b - .\n"				/* label           */ \
	" .long " b_replacement(number)"f - .\n"	/* new instruction */ \
	" .word " __stringify(feature) "\n"		/* feature bit     */ \
	" .byte " alt_slen "\n"				/* source len      */ \
	" .byte " alt_rlen(number) "\n"			/* replacement len */

#define DISCARD_ENTRY(number)				/* rlen <= slen */    \
	" .byte 0xff + (" alt_rlen(number) ") - (" alt_slen ")\n"

#define ALTINSTR_REPLACEMENT(newinstr, feature, number)	/* replacement */     \
	b_replacement(number)":\n\t" newinstr "\n" e_replacement(number) ":\n\t"

/* alternative assembly primitive: */
#define ALTERNATIVE(oldinstr, newinstr, feature)			\
	OLDINSTR(oldinstr)						\
	".pushsection .altinstructions,\"a\"\n"				\
	ALTINSTR_ENTRY(feature, 1)					\
	".popsection\n"							\
	".pushsection .discard,\"aw\",@progbits\n"			\
	DISCARD_ENTRY(1)						\
	".popsection\n"							\
	".pushsection .altinstr_replacement, \"ax\"\n"			\
	ALTINSTR_REPLACEMENT(newinstr, feature, 1)			\
	".popsection"

#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
	OLDINSTR(oldinstr)						\
	".pushsection .altinstructions,\"a\"\n"				\
	ALTINSTR_ENTRY(feature1, 1)					\
	ALTINSTR_ENTRY(feature2, 2)					\
	".popsection\n"							\
	".pushsection .discard,\"aw\",@progbits\n"			\
	DISCARD_ENTRY(1)						\
	DISCARD_ENTRY(2)						\
	".popsection\n"							\
	".pushsection .altinstr_replacement, \"ax\"\n"			\
	ALTINSTR_REPLACEMENT(newinstr1, feature1, 1)			\
	ALTINSTR_REPLACEMENT(newinstr2, feature2, 2)			\
	".popsection"

/*
 * This must be included *after* the definition of ALTERNATIVE due to
 * <asm/arch_hweight.h>
 */
#include <asm/cpufeature.h>

/*
 * Alternative instructions for different CPU types or capabilities.
 *
 * This allows to use optimized instructions even on generic binary
 * kernels.
 *
 * length of oldinstr must be longer or equal the length of newinstr
 * It can be padded with nops as needed.
 *
 * For non barrier like inlines please define new variants
 * without volatile and memory clobber.
 */
#define alternative(oldinstr, newinstr, feature)			\
	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")

/*
 * Alternative inline assembly with input.
 *
 * Pecularities:
 * No memory clobber here.
 * Argument numbers start with 1.
 * Best is to use constraints that are fixed size (like (%1) ... "r")
 * If you use variable sized constraints like "m" or "g" in the
 * replacement make sure to pad to the worst case length.
 * Leaving an unused argument 0 to keep API compatibility.
 */
#define alternative_input(oldinstr, newinstr, feature, input...)	\
	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature)		\
		: : "i" (0), ## input)

/* Like alternative_input, but with a single output argument */
#define alternative_io(oldinstr, newinstr, feature, output, input...)	\
	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature)		\
		: output : "i" (0), ## input)

/* Like alternative_io, but for replacing a direct call with another one. */
#define alternative_call(oldfunc, newfunc, feature, output, input...)	\
	asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
		: output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)

/*
 * Like alternative_call, but there are two features and respective functions.
 * If CPU has feature2, function2 is used.
 * Otherwise, if CPU has feature1, function1 is used.
 * Otherwise, old function is used.
 */
#define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2,   \
			   output, input...)				      \
	asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
		"call %P[new2]", feature2)				      \
		: output : [old] "i" (oldfunc), [new1] "i" (newfunc1),	      \
		[new2] "i" (newfunc2), ## input)

/*
 * use this macro(s) if you need more than one output parameter
 * in alternative_io
 */
#define ASM_OUTPUT2(a...) a

/*
 * use this macro if you need clobbers but no inputs in
 * alternative_{input,io,call}()
 */
#define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr

struct paravirt_patch_site;
#ifdef CONFIG_PARAVIRT
void apply_paravirt(struct paravirt_patch_site *start,
		    struct paravirt_patch_site *end);
#else
static inline void apply_paravirt(struct paravirt_patch_site *start,
				  struct paravirt_patch_site *end)
{}
#define __parainstructions	NULL
#define __parainstructions_end	NULL
#endif

extern void *text_poke_early(void *addr, const void *opcode, size_t len);

/*
 * Clear and restore the kernel write-protection flag on the local CPU.
 * Allows the kernel to edit read-only pages.
 * Side-effect: any interrupt handler running between save and restore will have
 * the ability to write to read-only pages.
 *
 * Warning:
 * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
 * no thread can be preempted in the instructions being modified (no iret to an
 * invalid instruction possible) or if the instructions are changed from a
 * consistent state to another consistent state atomically.
 * On the local CPU you need to be protected again NMI or MCE handlers seeing an
 * inconsistent instruction while you patch.
 */
extern void *text_poke(void *addr, const void *opcode, size_t len);
extern int poke_int3_handler(struct pt_regs *regs);
extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);

#endif /* _ASM_X86_ALTERNATIVE_H */
Commit	Line	Data
1965aae3 PA	1	#ifndef _ASM_X86_ALTERNATIVE_H
1965aae3 PA	2	#define _ASM_X86_ALTERNATIVE_H
6b592570 PA	3
	4	#include <linux/types.h>
	5	#include <linux/stddef.h>
edc953fa	6	#include <linux/stringify.h>
6b592570	7	#include <asm/asm.h>
17f41571	8	#include <asm/ptrace.h>
6b592570 PA	9
	10	/*
	11	* Alternative inline assembly for SMP.
	12	*
	13	* The LOCK_PREFIX macro defined here replaces the LOCK and
	14	* LOCK_PREFIX macros used everywhere in the source tree.
	15	*
	16	* SMP alternatives use the same data structures as the other
	17	* alternatives and the X86_FEATURE_UP flag to indicate the case of a
	18	* UP system running a SMP kernel. The existing apply_alternatives()
	19	* works fine for patching a SMP kernel for UP.
	20	*
	21	* The SMP alternative tables can be kept after boot and contain both
	22	* UP and SMP versions of the instructions to allow switching back to
	23	* SMP at runtime, when hotplugging in a new CPU, which is especially
	24	* useful in virtualized environments.
	25	*
	26	* The very common lock prefix is handled as special case in a
	27	* separate table which is a pure address list without replacement ptr
	28	* and size information. That keeps the table sizes small.
	29	*/
	30
	31	#ifdef CONFIG_SMP
b3ac891b	32	#define LOCK_PREFIX_HERE \
9cebed42 PA	33	".pushsection .smp_locks,\"a\"\n" \
	34	".balign 4\n" \
	35	".long 671f - .\n" /* offset */ \
	36	".popsection\n" \
b3ac891b LB	37	"671:"
	38
	39	#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; "
6b592570 PA	40
6b592570 PA	41	#else /* ! CONFIG_SMP */
b701a47b	42	#define LOCK_PREFIX_HERE ""
6b592570 PA	43	#define LOCK_PREFIX ""
	44	#endif
	45
6b592570	46	struct alt_instr {
59e97e4d AL	47	s32 instr_offset; /* original instruction */
59e97e4d AL	48	s32 repl_offset; /* offset to replacement instruction */
83a7a2ad	49	u16 cpuid; /* cpuid bit set for replacement */
6b592570 PA	50	u8 instrlen; /* length of original instruction */
6b592570 PA	51	u8 replacementlen; /* length of new instruction, <= instrlen */
6b592570 PA	52	};
	53
	54	extern void alternative_instructions(void);
	55	extern void apply_alternatives(struct alt_instr start, struct alt_instr end);
	56
	57	struct module;
	58
	59	#ifdef CONFIG_SMP
	60	extern void alternatives_smp_module_add(struct module mod, char name,
	61	void locks, void locks_end,
	62	void text, void text_end);
	63	extern void alternatives_smp_module_del(struct module *mod);
816afe4f	64	extern void alternatives_enable_smp(void);
2cfa1978	65	extern int alternatives_text_reserved(void start, void end);
3fb82d56	66	extern bool skip_smp_alternatives;
6b592570 PA	67	#else
6b592570 PA	68	static inline void alternatives_smp_module_add(struct module mod, char name,
2ac1ea7c JP	69	void locks, void locks_end,
2ac1ea7c JP	70	void text, void text_end) {}
6b592570	71	static inline void alternatives_smp_module_del(struct module *mod) {}
816afe4f	72	static inline void alternatives_enable_smp(void) {}
2cfa1978 MH	73	static inline int alternatives_text_reserved(void start, void end)
	74	{
	75	return 0;
	76	}
6b592570 PA	77	#endif /* CONFIG_SMP */
6b592570 PA	78
954e482b FY	79	#define OLDINSTR(oldinstr) "661:\n\t" oldinstr "\n662:\n"
	80
	81	#define b_replacement(number) "663"#number
	82	#define e_replacement(number) "664"#number
	83
	84	#define alt_slen "662b-661b"
	85	#define alt_rlen(number) e_replacement(number)"f-"b_replacement(number)"f"
	86
	87	#define ALTINSTR_ENTRY(feature, number) \
	88	" .long 661b - .\n" /* label */ \
	89	" .long " b_replacement(number)"f - .\n" /* new instruction */ \
	90	" .word " __stringify(feature) "\n" /* feature bit */ \
	91	" .byte " alt_slen "\n" /* source len */ \
	92	" .byte " alt_rlen(number) "\n" /* replacement len */
	93
	94	#define DISCARD_ENTRY(number) /* rlen <= slen */ \
	95	" .byte 0xff + (" alt_rlen(number) ") - (" alt_slen ")\n"
	96
	97	#define ALTINSTR_REPLACEMENT(newinstr, feature, number) /* replacement */ \
	98	b_replacement(number)":\n\t" newinstr "\n" e_replacement(number) ":\n\t"
	99
edc953fa MD	100	/* alternative assembly primitive: */
edc953fa MD	101	#define ALTERNATIVE(oldinstr, newinstr, feature) \
954e482b	102	OLDINSTR(oldinstr) \
9cebed42	103	".pushsection .altinstructions,\"a\"\n" \
954e482b	104	ALTINSTR_ENTRY(feature, 1) \
9cebed42 PA	105	".popsection\n" \
9cebed42 PA	106	".pushsection .discard,\"aw\",@progbits\n" \
954e482b	107	DISCARD_ENTRY(1) \
9cebed42 PA	108	".popsection\n" \
9cebed42 PA	109	".pushsection .altinstr_replacement, \"ax\"\n" \
954e482b	110	ALTINSTR_REPLACEMENT(newinstr, feature, 1) \
9cebed42	111	".popsection"
954e482b FY	112
	113	#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
	114	OLDINSTR(oldinstr) \
9cebed42	115	".pushsection .altinstructions,\"a\"\n" \
954e482b FY	116	ALTINSTR_ENTRY(feature1, 1) \
954e482b FY	117	ALTINSTR_ENTRY(feature2, 2) \
9cebed42 PA	118	".popsection\n" \
9cebed42 PA	119	".pushsection .discard,\"aw\",@progbits\n" \
954e482b FY	120	DISCARD_ENTRY(1) \
954e482b FY	121	DISCARD_ENTRY(2) \
9cebed42 PA	122	".popsection\n" \
9cebed42 PA	123	".pushsection .altinstr_replacement, \"ax\"\n" \
954e482b FY	124	ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \
954e482b FY	125	ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
9cebed42	126	".popsection"
edc953fa	127
d61931d8 BP	128	/*
	129	* This must be included after the definition of ALTERNATIVE due to
	130	* <asm/arch_hweight.h>
	131	*/
	132	#include <asm/cpufeature.h>
	133
6b592570 PA	134	/*
	135	* Alternative instructions for different CPU types or capabilities.
	136	*
	137	* This allows to use optimized instructions even on generic binary
	138	* kernels.
	139	*
	140	* length of oldinstr must be longer or equal the length of newinstr
	141	* It can be padded with nops as needed.
	142	*
	143	* For non barrier like inlines please define new variants
	144	* without volatile and memory clobber.
	145	*/
	146	#define alternative(oldinstr, newinstr, feature) \
edc953fa	147	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")
6b592570 PA	148
	149	/*
	150	* Alternative inline assembly with input.
	151	*
	152	* Pecularities:
	153	* No memory clobber here.
	154	* Argument numbers start with 1.
	155	* Best is to use constraints that are fixed size (like (%1) ... "r")
	156	* If you use variable sized constraints like "m" or "g" in the
	157	* replacement make sure to pad to the worst case length.
edc953fa	158	* Leaving an unused argument 0 to keep API compatibility.
6b592570 PA	159	*/
6b592570 PA	160	#define alternative_input(oldinstr, newinstr, feature, input...) \
edc953fa MD	161	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
edc953fa MD	162	: : "i" (0), ## input)
6b592570 PA	163
	164	/* Like alternative_input, but with a single output argument */
	165	#define alternative_io(oldinstr, newinstr, feature, output, input...) \
edc953fa MD	166	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
edc953fa MD	167	: output : "i" (0), ## input)
6b592570	168
1b1d9258 JB	169	/* Like alternative_io, but for replacing a direct call with another one. */
	170	#define alternative_call(oldfunc, newfunc, feature, output, input...) \
	171	asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
	172	: output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
	173
954e482b FY	174	/*
	175	* Like alternative_call, but there are two features and respective functions.
	176	* If CPU has feature2, function2 is used.
	177	* Otherwise, if CPU has feature1, function1 is used.
	178	* Otherwise, old function is used.
	179	*/
	180	#define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \
	181	output, input...) \
	182	asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
	183	"call %P[new2]", feature2) \
	184	: output : [old] "i" (oldfunc), [new1] "i" (newfunc1), \
	185	[new2] "i" (newfunc2), ## input)
	186
6b592570 PA	187	/*
	188	* use this macro(s) if you need more than one output parameter
	189	* in alternative_io
	190	*/
1b1d9258	191	#define ASM_OUTPUT2(a...) a
6b592570	192
819165fb JB	193	/*
	194	* use this macro if you need clobbers but no inputs in
	195	* alternative_{input,io,call}()
	196	*/
	197	#define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr
	198
6b592570 PA	199	struct paravirt_patch_site;
	200	#ifdef CONFIG_PARAVIRT
	201	void apply_paravirt(struct paravirt_patch_site *start,
	202	struct paravirt_patch_site *end);
96a388de	203	#else
2ac1ea7c JP	204	static inline void apply_paravirt(struct paravirt_patch_site *start,
2ac1ea7c JP	205	struct paravirt_patch_site *end)
6b592570 PA	206	{}
	207	#define __parainstructions NULL
	208	#define __parainstructions_end NULL
96a388de	209	#endif
6b592570	210
fa6f2cc7 JB	211	extern void text_poke_early(void addr, const void *opcode, size_t len);
fa6f2cc7 JB	212
e587cadd MD	213	/*
	214	* Clear and restore the kernel write-protection flag on the local CPU.
	215	* Allows the kernel to edit read-only pages.
	216	* Side-effect: any interrupt handler running between save and restore will have
	217	* the ability to write to read-only pages.
	218	*
	219	* Warning:
	220	* Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
	221	* no thread can be preempted in the instructions being modified (no iret to an
	222	* invalid instruction possible) or if the instructions are changed from a
	223	* consistent state to another consistent state atomically.
e587cadd MD	224	* On the local CPU you need to be protected again NMI or MCE handlers seeing an
e587cadd MD	225	* inconsistent instruction while you patch.
e587cadd	226	*/
e587cadd	227	extern void text_poke(void addr, const void *opcode, size_t len);
17f41571	228	extern int poke_int3_handler(struct pt_regs *regs);
fd4363ff	229	extern void text_poke_bp(void addr, const void opcode, size_t len, void handler);
6b592570	230
1965aae3	231	#endif /* _ASM_X86_ALTERNATIVE_H */