arch/riscv/include/asm/alternative-macros.h

root/arch/riscv/include/asm/alternative-macros.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_ALTERNATIVE_MACROS_H
#define __ASM_ALTERNATIVE_MACROS_H

#ifdef CONFIG_RISCV_ALTERNATIVE

#ifdef __ASSEMBLER__

.macro ALT_ENTRY oldptr newptr vendor_id patch_id new_len
        .4byte \oldptr - .
        .4byte \newptr - .
        .2byte \vendor_id
        .2byte \new_len
        .4byte \patch_id
.endm

.macro ALT_NEW_CONTENT vendor_id, patch_id, enable = 1, new_c
        .if \enable
        .pushsection .alternative, "a"
        ALT_ENTRY 886b, 888f, \vendor_id, \patch_id, 889f - 888f
        .popsection
        .subsection 1
888 :
        .option push
        .option norvc
        .option norelax
        \new_c
        .option pop
889 :
        .org    . - (889b - 888b) + (887b - 886b)
        .org    . - (887b - 886b) + (889b - 888b)
        .previous
        .endif
.endm

.macro ALTERNATIVE_CFG old_c, new_c, vendor_id, patch_id, enable
886 :
        .option push
        .option norvc
        .option norelax
        \old_c
        .option pop
887 :
        ALT_NEW_CONTENT \vendor_id, \patch_id, \enable, "\new_c"
.endm

.macro ALTERNATIVE_CFG_2 old_c, new_c_1, vendor_id_1, patch_id_1, enable_1,     \
                                new_c_2, vendor_id_2, patch_id_2, enable_2
        ALTERNATIVE_CFG "\old_c", "\new_c_1", \vendor_id_1, \patch_id_1, \enable_1
        ALT_NEW_CONTENT \vendor_id_2, \patch_id_2, \enable_2, "\new_c_2"
.endm

#define __ALTERNATIVE_CFG(...)          ALTERNATIVE_CFG __VA_ARGS__
#define __ALTERNATIVE_CFG_2(...)        ALTERNATIVE_CFG_2 __VA_ARGS__

#else /* !__ASSEMBLER__ */

#include <asm/asm.h>
#include <linux/stringify.h>

#define ALT_ENTRY(oldptr, newptr, vendor_id, patch_id, newlen)          \
        ".4byte ((" oldptr ") - .) \n"                                  \
        ".4byte ((" newptr ") - .) \n"                                  \
        ".2byte " vendor_id "\n"                                        \
        ".2byte " newlen "\n"                                           \
        ".4byte " patch_id "\n"

#define ALT_NEW_CONTENT(vendor_id, patch_id, enable, new_c)             \
        ".if " __stringify(enable) " == 1\n"                            \
        ".pushsection .alternative, \"a\"\n"                            \
        ALT_ENTRY("886b", "888f", __stringify(vendor_id), __stringify(patch_id), "889f - 888f") \
        ".popsection\n"                                                 \
        ".subsection 1\n"                                               \
        "888 :\n"                                                       \
        ".option push\n"                                                \
        ".option norvc\n"                                               \
        ".option norelax\n"                                             \
        new_c "\n"                                                      \
        ".option pop\n"                                                 \
        "889 :\n"                                                       \
        ".org   . - (887b - 886b) + (889b - 888b)\n"                    \
        ".org   . - (889b - 888b) + (887b - 886b)\n"                    \
        ".previous\n"                                                   \
        ".endif\n"

#define __ALTERNATIVE_CFG(old_c, new_c, vendor_id, patch_id, enable)    \
        "886 :\n"                                                       \
        ".option push\n"                                                \
        ".option norvc\n"                                               \
        ".option norelax\n"                                             \
        old_c "\n"                                                      \
        ".option pop\n"                                                 \
        "887 :\n"                                                       \
        ALT_NEW_CONTENT(vendor_id, patch_id, enable, new_c)

#define __ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, patch_id_1, enable_1,  \
                                   new_c_2, vendor_id_2, patch_id_2, enable_2)  \
        __ALTERNATIVE_CFG(old_c, new_c_1, vendor_id_1, patch_id_1, enable_1)    \
        ALT_NEW_CONTENT(vendor_id_2, patch_id_2, enable_2, new_c_2)

#endif /* __ASSEMBLER__ */

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

#define _ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, patch_id_1, CONFIG_k_1,         \
                                  new_c_2, vendor_id_2, patch_id_2, CONFIG_k_2)         \
        __ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, patch_id_1, IS_ENABLED(CONFIG_k_1),    \
                                   new_c_2, vendor_id_2, patch_id_2, IS_ENABLED(CONFIG_k_2))

#else /* CONFIG_RISCV_ALTERNATIVE */
#ifdef __ASSEMBLER__

.macro ALTERNATIVE_CFG old_c
        \old_c
.endm

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

#else /* !__ASSEMBLER__ */

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

#endif /* __ASSEMBLER__ */

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

#endif /* CONFIG_RISCV_ALTERNATIVE */

/*
 * Usage:
 *   ALTERNATIVE(old_content, new_content, vendor_id, patch_id, CONFIG_k)
 * in the assembly code. Otherwise,
 *   asm(ALTERNATIVE(old_content, new_content, vendor_id, patch_id, CONFIG_k));
 *
 * old_content: The old content which is probably replaced with new content.
 * new_content: The new content.
 * vendor_id: The CPU vendor ID.
 * patch_id: The patch ID (erratum ID or cpufeature ID).
 * CONFIG_k: The Kconfig of this patch ID. When Kconfig is disabled, the old
 *           content will always be executed.
 */
#define ALTERNATIVE(old_content, new_content, vendor_id, patch_id, CONFIG_k) \
        _ALTERNATIVE_CFG(old_content, new_content, vendor_id, patch_id, CONFIG_k)

/*
 * A vendor wants to replace an old_content, but another vendor has used
 * ALTERNATIVE() to patch its customized content at the same location. In
 * this case, this vendor can create a new macro ALTERNATIVE_2() based
 * on the following sample code and then replace ALTERNATIVE() with
 * ALTERNATIVE_2() to append its customized content.
 */
#define ALTERNATIVE_2(old_content, new_content_1, vendor_id_1, patch_id_1, CONFIG_k_1,          \
                                   new_content_2, vendor_id_2, patch_id_2, CONFIG_k_2)          \
        _ALTERNATIVE_CFG_2(old_content, new_content_1, vendor_id_1, patch_id_1, CONFIG_k_1,     \
                                        new_content_2, vendor_id_2, patch_id_2, CONFIG_k_2)

#endif
Linux
