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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/riscv/include/asm/alternative-macros.h
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/* SPDX-License-Identifier: GPL-2.0 */

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#ifndef __ASM_ALTERNATIVE_MACROS_H

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#define __ASM_ALTERNATIVE_MACROS_H

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#ifdef CONFIG_RISCV_ALTERNATIVE

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#ifdef __ASSEMBLY__

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.macro ALT_ENTRY oldptr newptr vendor_id patch_id new_len

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	.4byte \oldptr - .

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	.4byte \newptr - .

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	.2byte \vendor_id

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	.2byte \new_len

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	.4byte \patch_id

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.endm

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.macro ALT_NEW_CONTENT vendor_id, patch_id, enable = 1, new_c

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	.if \enable

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	.pushsection .alternative, "a"

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	ALT_ENTRY 886b, 888f, \vendor_id, \patch_id, 889f - 888f

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	.popsection

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	.subsection 1

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888 :

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	.option push

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	.option norvc

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	.option norelax

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	\new_c

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	.option pop

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889 :

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	.org    . - (889b - 888b) + (887b - 886b)

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	.org    . - (887b - 886b) + (889b - 888b)

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	.previous

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	.endif

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.endm

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.macro ALTERNATIVE_CFG old_c, new_c, vendor_id, patch_id, enable

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886 :

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	.option push

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	.option norvc

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	.option norelax

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	\old_c

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	.option pop

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887 :

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	ALT_NEW_CONTENT \vendor_id, \patch_id, \enable, "\new_c"

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.endm

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.macro ALTERNATIVE_CFG_2 old_c, new_c_1, vendor_id_1, patch_id_1, enable_1,	\

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				new_c_2, vendor_id_2, patch_id_2, enable_2

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	ALTERNATIVE_CFG "\old_c", "\new_c_1", \vendor_id_1, \patch_id_1, \enable_1

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	ALT_NEW_CONTENT \vendor_id_2, \patch_id_2, \enable_2, "\new_c_2"

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.endm

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#define __ALTERNATIVE_CFG(...)		ALTERNATIVE_CFG __VA_ARGS__

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#define __ALTERNATIVE_CFG_2(...)	ALTERNATIVE_CFG_2 __VA_ARGS__

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#else /* !__ASSEMBLY__ */

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#include <asm/asm.h>

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#include <linux/stringify.h>

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#define ALT_ENTRY(oldptr, newptr, vendor_id, patch_id, newlen)		\

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	".4byte	((" oldptr ") - .) \n"					\

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	".4byte	((" newptr ") - .) \n"					\

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	".2byte	" vendor_id "\n"					\

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	".2byte " newlen "\n"						\

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	".4byte	" patch_id "\n"

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#define ALT_NEW_CONTENT(vendor_id, patch_id, enable, new_c)		\

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	".if " __stringify(enable) " == 1\n"				\

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	".pushsection .alternative, \"a\"\n"				\

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	ALT_ENTRY("886b", "888f", __stringify(vendor_id), __stringify(patch_id), "889f - 888f") \

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	".popsection\n"							\

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	".subsection 1\n"						\

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	"888 :\n"							\

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	".option push\n"						\

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	".option norvc\n"						\

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	".option norelax\n"						\

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	new_c "\n"							\

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	".option pop\n"							\

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	"889 :\n"							\

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	".org	. - (887b - 886b) + (889b - 888b)\n"			\

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	".org	. - (889b - 888b) + (887b - 886b)\n"			\

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	".previous\n"							\

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	".endif\n"

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#define __ALTERNATIVE_CFG(old_c, new_c, vendor_id, patch_id, enable)	\

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	"886 :\n"							\

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	".option push\n"						\

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	".option norvc\n"						\

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	".option norelax\n"						\

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	old_c "\n"							\

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	".option pop\n"							\

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	"887 :\n"							\

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	ALT_NEW_CONTENT(vendor_id, patch_id, enable, new_c)

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#define __ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, patch_id_1, enable_1,	\

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				   new_c_2, vendor_id_2, patch_id_2, enable_2)	\

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	__ALTERNATIVE_CFG(old_c, new_c_1, vendor_id_1, patch_id_1, enable_1)	\

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	ALT_NEW_CONTENT(vendor_id_2, patch_id_2, enable_2, new_c_2)

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#endif /* __ASSEMBLY__ */

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#define _ALTERNATIVE_CFG(old_c, new_c, vendor_id, patch_id, CONFIG_k)	\

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	__ALTERNATIVE_CFG(old_c, new_c, vendor_id, patch_id, IS_ENABLED(CONFIG_k))

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#define _ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, patch_id_1, CONFIG_k_1,		\

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				  new_c_2, vendor_id_2, patch_id_2, CONFIG_k_2)		\

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	__ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, patch_id_1, IS_ENABLED(CONFIG_k_1),	\

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				   new_c_2, vendor_id_2, patch_id_2, IS_ENABLED(CONFIG_k_2))

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#else /* CONFIG_RISCV_ALTERNATIVE */

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#ifdef __ASSEMBLY__

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.macro ALTERNATIVE_CFG old_c

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	\old_c

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.endm

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#define __ALTERNATIVE_CFG(old_c, ...)		ALTERNATIVE_CFG old_c

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#define __ALTERNATIVE_CFG_2(old_c, ...)		ALTERNATIVE_CFG old_c

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#else /* !__ASSEMBLY__ */

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#define __ALTERNATIVE_CFG(old_c, ...)		old_c "\n"

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#define __ALTERNATIVE_CFG_2(old_c, ...)		old_c "\n"

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#endif /* __ASSEMBLY__ */

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#define _ALTERNATIVE_CFG(old_c, ...)		__ALTERNATIVE_CFG(old_c)

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#define _ALTERNATIVE_CFG_2(old_c, ...)		__ALTERNATIVE_CFG_2(old_c)

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#endif /* CONFIG_RISCV_ALTERNATIVE */

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/*

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 * Usage:

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 *   ALTERNATIVE(old_content, new_content, vendor_id, patch_id, CONFIG_k)

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 * in the assembly code. Otherwise,

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 *   asm(ALTERNATIVE(old_content, new_content, vendor_id, patch_id, CONFIG_k));

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 *

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 * old_content: The old content which is probably replaced with new content.

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 * new_content: The new content.

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 * vendor_id: The CPU vendor ID.

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 * patch_id: The patch ID (erratum ID or cpufeature ID).

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 * CONFIG_k: The Kconfig of this patch ID. When Kconfig is disabled, the old

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 *	     content will always be executed.

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 */

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#define ALTERNATIVE(old_content, new_content, vendor_id, patch_id, CONFIG_k) \

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	_ALTERNATIVE_CFG(old_content, new_content, vendor_id, patch_id, CONFIG_k)

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/*

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 * A vendor wants to replace an old_content, but another vendor has used

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 * ALTERNATIVE() to patch its customized content at the same location. In

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 * this case, this vendor can create a new macro ALTERNATIVE_2() based

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 * on the following sample code and then replace ALTERNATIVE() with

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 * ALTERNATIVE_2() to append its customized content.

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 */

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#define ALTERNATIVE_2(old_content, new_content_1, vendor_id_1, patch_id_1, CONFIG_k_1,		\

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				   new_content_2, vendor_id_2, patch_id_2, CONFIG_k_2)		\

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	_ALTERNATIVE_CFG_2(old_content, new_content_1, vendor_id_1, patch_id_1, CONFIG_k_1,	\

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					new_content_2, vendor_id_2, patch_id_2, CONFIG_k_2)

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#endif

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