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-rw-r--r--kernel/arch/arm64/include/asm/alternative.h44
1 files changed, 44 insertions, 0 deletions
diff --git a/kernel/arch/arm64/include/asm/alternative.h b/kernel/arch/arm64/include/asm/alternative.h
new file mode 100644
index 000000000..d261f01e2
--- /dev/null
+++ b/kernel/arch/arm64/include/asm/alternative.h
@@ -0,0 +1,44 @@
+#ifndef __ASM_ALTERNATIVE_H
+#define __ASM_ALTERNATIVE_H
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/stringify.h>
+
+struct alt_instr {
+ s32 orig_offset; /* offset to original instruction */
+ s32 alt_offset; /* offset to replacement instruction */
+ u16 cpufeature; /* cpufeature bit set for replacement */
+ u8 orig_len; /* size of original instruction(s) */
+ u8 alt_len; /* size of new instruction(s), <= orig_len */
+};
+
+void apply_alternatives_all(void);
+void apply_alternatives(void *start, size_t length);
+void free_alternatives_memory(void);
+
+#define ALTINSTR_ENTRY(feature) \
+ " .word 661b - .\n" /* label */ \
+ " .word 663f - .\n" /* new instruction */ \
+ " .hword " __stringify(feature) "\n" /* feature bit */ \
+ " .byte 662b-661b\n" /* source len */ \
+ " .byte 664f-663f\n" /* replacement len */
+
+/* alternative assembly primitive: */
+#define ALTERNATIVE(oldinstr, newinstr, feature) \
+ "661:\n\t" \
+ oldinstr "\n" \
+ "662:\n" \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(feature) \
+ ".popsection\n" \
+ ".pushsection .altinstr_replacement, \"a\"\n" \
+ "663:\n\t" \
+ newinstr "\n" \
+ "664:\n\t" \
+ ".popsection\n\t" \
+ ".if ((664b-663b) != (662b-661b))\n\t" \
+ " .error \"Alternatives instruction length mismatch\"\n\t"\
+ ".endif\n"
+
+#endif /* __ASM_ALTERNATIVE_H */