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-rw-r--r--arch/loongarch/include/asm/alternative.h111
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diff --git a/arch/loongarch/include/asm/alternative.h b/arch/loongarch/include/asm/alternative.h
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+++ b/arch/loongarch/include/asm/alternative.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALTERNATIVE_H
+#define _ASM_ALTERNATIVE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/stringify.h>
+#include <asm/asm.h>
+
+struct alt_instr {
+ s32 instr_offset; /* offset to original instruction */
+ s32 replace_offset; /* offset to replacement instruction */
+ u16 feature; /* feature bit set for replacement */
+ u8 instrlen; /* length of original instruction */
+ u8 replacementlen; /* length of new instruction */
+} __packed;
+
+/*
+ * Debug flag that can be tested to see whether alternative
+ * instructions were patched in already:
+ */
+extern int alternatives_patched;
+extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
+
+extern void alternative_instructions(void);
+extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+
+#define b_replacement(num) "664"#num
+#define e_replacement(num) "665"#num
+
+#define alt_end_marker "663"
+#define alt_slen "662b-661b"
+#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" \
+ ".fill -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \
+ "((" alt_rlen(num) ")-(" alt_slen ")) / 4, 4, 0x03400000\n"
+
+#define OLDINSTR(oldinstr, num) \
+ __OLDINSTR(oldinstr, num) \
+ alt_end_marker ":\n"
+
+#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" \
+ ".fill -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \
+ "(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) / 4, " \
+ "4, 0x03400000\n" \
+ alt_end_marker ":\n"
+
+#define ALTINSTR_ENTRY(feature, num) \
+ " .long 661b - .\n" /* label */ \
+ " .long " b_replacement(num)"f - .\n" /* new instruction */ \
+ " .short " __stringify(feature) "\n" /* feature bit */ \
+ " .byte " alt_total_slen "\n" /* source len */ \
+ " .byte " alt_rlen(num) "\n" /* replacement len */
+
+#define ALTINSTR_REPLACEMENT(newinstr, feature, num) /* replacement */ \
+ b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t"
+
+/* alternative assembly primitive: */
+#define ALTERNATIVE(oldinstr, newinstr, feature) \
+ OLDINSTR(oldinstr, 1) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(feature, 1) \
+ ".popsection\n" \
+ ".subsection 1\n" \
+ ALTINSTR_REPLACEMENT(newinstr, feature, 1) \
+ ".previous\n"
+
+#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
+ OLDINSTR_2(oldinstr, 1, 2) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(feature1, 1) \
+ ALTINSTR_ENTRY(feature2, 2) \
+ ".popsection\n" \
+ ".subsection 1\n" \
+ ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \
+ ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
+ ".previous\n"
+
+/*
+ * 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"))
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_ALTERNATIVE_H */