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-rw-r--r--arch/s390/include/asm/alternative.h120
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diff --git a/arch/s390/include/asm/alternative.h b/arch/s390/include/asm/alternative.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_S390_ALTERNATIVE_H
+#define _ASM_S390_ALTERNATIVE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/stringify.h>
+
+struct alt_instr {
+ s32 instr_offset; /* original instruction */
+ s32 repl_offset; /* offset to replacement instruction */
+ u16 facility; /* facility bit set for replacement */
+ u8 instrlen; /* length of original instruction */
+} __packed;
+
+void apply_alternative_instructions(void);
+void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+
+/*
+ * +---------------------------------+
+ * |661: |662:
+ * | oldinstr |
+ * +---------------------------------+
+ *
+ * .altinstr_replacement section
+ * +---------------------------------+
+ * |6641: |6651:
+ * | alternative instr 1 |
+ * +---------------------------------+
+ * |6642: |6652:
+ * | alternative instr 2 |
+ * +---------------------------------+
+ *
+ * .altinstructions section
+ * +---------------------------------+
+ * | alt_instr entries for each |
+ * | alternative instr |
+ * +---------------------------------+
+ */
+
+#define b_altinstr(num) "664"#num
+#define e_altinstr(num) "665"#num
+#define oldinstr_len "662b-661b"
+#define altinstr_len(num) e_altinstr(num)"b-"b_altinstr(num)"b"
+
+#define OLDINSTR(oldinstr) \
+ "661:\n\t" oldinstr "\n662:\n"
+
+#define ALTINSTR_ENTRY(facility, num) \
+ "\t.long 661b - .\n" /* old instruction */ \
+ "\t.long " b_altinstr(num)"b - .\n" /* alt instruction */ \
+ "\t.word " __stringify(facility) "\n" /* facility bit */ \
+ "\t.byte " oldinstr_len "\n" /* instruction len */ \
+ "\t.org . - (" oldinstr_len ") + (" altinstr_len(num) ")\n" \
+ "\t.org . - (" altinstr_len(num) ") + (" oldinstr_len ")\n"
+
+#define ALTINSTR_REPLACEMENT(altinstr, num) /* replacement */ \
+ b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n"
+
+/* alternative assembly primitive: */
+#define ALTERNATIVE(oldinstr, altinstr, facility) \
+ ".pushsection .altinstr_replacement, \"ax\"\n" \
+ ALTINSTR_REPLACEMENT(altinstr, 1) \
+ ".popsection\n" \
+ OLDINSTR(oldinstr) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(facility, 1) \
+ ".popsection\n"
+
+#define ALTERNATIVE_2(oldinstr, altinstr1, facility1, altinstr2, facility2)\
+ ".pushsection .altinstr_replacement, \"ax\"\n" \
+ ALTINSTR_REPLACEMENT(altinstr1, 1) \
+ ALTINSTR_REPLACEMENT(altinstr2, 2) \
+ ".popsection\n" \
+ OLDINSTR(oldinstr) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(facility1, 1) \
+ ALTINSTR_ENTRY(facility2, 2) \
+ ".popsection\n"
+
+/*
+ * Alternative instructions for different CPU types or capabilities.
+ *
+ * This allows to use optimized instructions even on generic binary
+ * kernels.
+ *
+ * oldinstr is padded with jump and nops at compile time if altinstr is
+ * longer. altinstr is padded with jump and nops at run-time during patching.
+ *
+ * For non barrier like inlines please define new variants
+ * without volatile and memory clobber.
+ */
+#define alternative(oldinstr, altinstr, facility) \
+ asm_inline volatile(ALTERNATIVE(oldinstr, altinstr, facility) : : : "memory")
+
+#define alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2) \
+ asm_inline volatile(ALTERNATIVE_2(oldinstr, altinstr1, facility1, \
+ altinstr2, facility2) ::: "memory")
+
+/* Alternative inline assembly with input. */
+#define alternative_input(oldinstr, newinstr, feature, input...) \
+ asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
+ : : input)
+
+/* Like alternative_input, but with a single output argument */
+#define alternative_io(oldinstr, altinstr, facility, output, input...) \
+ asm_inline volatile(ALTERNATIVE(oldinstr, altinstr, facility) \
+ : output : input)
+
+/* Use this macro if more than one output parameter is needed. */
+#define ASM_OUTPUT2(a...) a
+
+/* Use this macro if clobbers are needed without inputs. */
+#define ASM_NO_INPUT_CLOBBER(clobber...) : clobber
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_S390_ALTERNATIVE_H */