WebSVN – Kolibri OS – Diff – /drivers/include/asm/alternative.h

 #ifndef _ASM_X86_ALTERNATIVE_H
 #define _ASM_X86_ALTERNATIVE_H
 #include
 #include
 #include
 #include
+#include
 /*
  * 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 */
+	u8  replacementlen;	/* length of new instruction */
+	u8  padlen;		/* length of build-time padding */
+} __packed;
-};
+/*
+ * Debug flag that can be tested to see whether alternative
+ * instructions were patched in already:
+ */
+extern int alternatives_patched;
 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 b_replacement(num)	"664"#num
+#define e_replacement(num)	"665"#num
 #define e_replacement(number)	"664"#number
+#define alt_end_marker		"663"
+#define alt_slen		"662b-661b"
+#define alt_pad_len		alt_end_marker"b-662b"
+#define alt_total_slen		alt_end_marker"b-661b"
+#define alt_rlen(num)		e_replacement(num)"f-"b_replacement(num)"f"
+#define __OLDINSTR(oldinstr, num)					\
+	"661:\n\t" oldinstr "\n662:\n"					\
+	".skip -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * "		\
+		"((" alt_rlen(num) ")-(" alt_slen ")),0x90\n"
+#define OLDINSTR(oldinstr, num)						\
+	__OLDINSTR(oldinstr, num)					\
+	alt_end_marker ":\n"
+/*
+ * max without conditionals. Idea adapted from:
+ * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
+ *
+ * The additional "-" is needed because gas works with s32s.
+ */
+#define alt_max_short(a, b)	"((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") - (" b ")))))"
+/*
+ * Pad the second replacement alternative with additional NOPs if it is
+ * additionally longer than the first replacement alternative.
+ */
+#define OLDINSTR_2(oldinstr, num1, num2) \
+	"661:\n\t" oldinstr "\n662:\n"								\
+	".skip -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * "	\
-#define alt_slen "662b-661b"
+		"(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")), 0x90\n"	\
-#define alt_rlen(number) e_replacement(number)"f-"b_replacement(number)"f"
+	alt_end_marker ":\n"
-#define ALTINSTR_ENTRY(feature, number)					      \
+#define ALTINSTR_ENTRY(feature, num)					      \
 	" .long 661b - .\n"				/* label           */ \
-	" .long " b_replacement(number)"f - .\n"	/* new instruction */ \
+	" .long " b_replacement(num)"f - .\n"		/* new instruction */ \
-	" .word " __stringify(feature) "\n"		/* feature bit     */ \
-	" .byte " alt_slen "\n"				/* source len      */ \
-	" .byte " alt_rlen(number) "\n"			/* replacement len */
+	" .word " __stringify(feature) "\n"		/* feature bit     */ \
+	" .byte " alt_total_slen "\n"			/* source len      */ \
-#define DISCARD_ENTRY(number)				/* rlen <= slen */    \
+	" .byte " alt_rlen(num) "\n"			/* replacement len */ \
-	" .byte 0xff + (" alt_rlen(number) ") - (" alt_slen ")\n"
+	" .byte " alt_pad_len "\n"			/* pad len */
-#define ALTINSTR_REPLACEMENT(newinstr, feature, number)	/* replacement */     \
+#define ALTINSTR_REPLACEMENT(newinstr, feature, num)	/* replacement */     \
-	b_replacement(number)":\n\t" newinstr "\n" e_replacement(number) ":\n\t"
+	b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t"
 /* alternative assembly primitive: */
 #define ALTERNATIVE(oldinstr, newinstr, feature)			\
-	OLDINSTR(oldinstr)						\
+	OLDINSTR(oldinstr, 1)						\
 	".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)						\
+	OLDINSTR_2(oldinstr, 1, 2)					\
 	".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
+ *
  */
 #include
 /*
  * 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")
+#define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
+	asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "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)
 /*
  * This is similar to alternative_input. But it has two features and
  * respective instructions.
+ *
  * If CPU has feature2, newinstr2 is used.
  * Otherwise, if CPU has feature1, newinstr1 is used.
  * Otherwise, oldinstr is used.
  */
 #define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2,	     \
 			   feature2, input...)				     \
 	asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1,	     \
 		newinstr2, feature2)					     \
 		: : "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 void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
 #endif /* _ASM_X86_ALTERNATIVE_H */

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(root)/drivers/include/asm/alternative.h – Rev 5270 → 6082