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-rw-r--r--arch/s390/include/asm/alternative.h149
1 files changed, 149 insertions, 0 deletions
diff --git a/arch/s390/include/asm/alternative.h b/arch/s390/include/asm/alternative.h
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+++ b/arch/s390/include/asm/alternative.h
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+#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 */
+ u8 replacementlen; /* length of new instruction */
+} __packed;
+
+void apply_alternative_instructions(void);
+void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+
+/*
+ * |661: |662: |6620 |663:
+ * +-----------+---------------------+
+ * | oldinstr | oldinstr_padding |
+ * | +----------+----------+
+ * | | | |
+ * | | >6 bytes |6/4/2 nops|
+ * | |6 bytes jg----------->
+ * +-----------+---------------------+
+ * ^^ static padding ^^
+ *
+ * .altinstr_replacement section
+ * +---------------------+-----------+
+ * |6641: |6651:
+ * | alternative instr 1 |
+ * +-----------+---------+- - - - - -+
+ * |6642: |6652: |
+ * | alternative instr 2 | padding
+ * +---------------------+- - - - - -+
+ * ^ runtime ^
+ *
+ * .altinstructions section
+ * +---------------------------------+
+ * | alt_instr entries for each |
+ * | alternative instr |
+ * +---------------------------------+
+ */
+
+#define b_altinstr(num) "664"#num
+#define e_altinstr(num) "665"#num
+
+#define e_oldinstr_pad_end "663"
+#define oldinstr_len "662b-661b"
+#define oldinstr_total_len e_oldinstr_pad_end"b-661b"
+#define altinstr_len(num) e_altinstr(num)"b-"b_altinstr(num)"b"
+#define oldinstr_pad_len(num) \
+ "-(((" altinstr_len(num) ")-(" oldinstr_len ")) > 0) * " \
+ "((" altinstr_len(num) ")-(" oldinstr_len "))"
+
+#define INSTR_LEN_SANITY_CHECK(len) \
+ ".if " len " > 254\n" \
+ "\t.error \"cpu alternatives does not support instructions " \
+ "blocks > 254 bytes\"\n" \
+ ".endif\n" \
+ ".if (" len ") %% 2\n" \
+ "\t.error \"cpu alternatives instructions length is odd\"\n" \
+ ".endif\n"
+
+#define OLDINSTR_PADDING(oldinstr, num) \
+ ".if " oldinstr_pad_len(num) " > 6\n" \
+ "\tjg " e_oldinstr_pad_end "f\n" \
+ "6620:\n" \
+ "\t.fill (" oldinstr_pad_len(num) " - (6620b-662b)) / 2, 2, 0x0700\n" \
+ ".else\n" \
+ "\t.fill " oldinstr_pad_len(num) " / 6, 6, 0xc0040000\n" \
+ "\t.fill " oldinstr_pad_len(num) " %% 6 / 4, 4, 0x47000000\n" \
+ "\t.fill " oldinstr_pad_len(num) " %% 6 %% 4 / 2, 2, 0x0700\n" \
+ ".endif\n"
+
+#define OLDINSTR(oldinstr, num) \
+ "661:\n\t" oldinstr "\n662:\n" \
+ OLDINSTR_PADDING(oldinstr, num) \
+ e_oldinstr_pad_end ":\n" \
+ INSTR_LEN_SANITY_CHECK(oldinstr_len)
+
+#define OLDINSTR_2(oldinstr, num1, num2) \
+ "661:\n\t" oldinstr "\n662:\n" \
+ ".if " altinstr_len(num1) " < " altinstr_len(num2) "\n" \
+ OLDINSTR_PADDING(oldinstr, num2) \
+ ".else\n" \
+ OLDINSTR_PADDING(oldinstr, num1) \
+ ".endif\n" \
+ e_oldinstr_pad_end ":\n" \
+ INSTR_LEN_SANITY_CHECK(oldinstr_len)
+
+#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_total_len "\n" /* source len */ \
+ "\t.byte " altinstr_len(num) "\n" /* alt instruction len */
+
+#define ALTINSTR_REPLACEMENT(altinstr, num) /* replacement */ \
+ b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n" \
+ INSTR_LEN_SANITY_CHECK(altinstr_len(num))
+
+/* alternative assembly primitive: */
+#define ALTERNATIVE(oldinstr, altinstr, facility) \
+ ".pushsection .altinstr_replacement, \"ax\"\n" \
+ ALTINSTR_REPLACEMENT(altinstr, 1) \
+ ".popsection\n" \
+ OLDINSTR(oldinstr, 1) \
+ ".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_2(oldinstr, 1, 2) \
+ ".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 volatile(ALTERNATIVE(oldinstr, altinstr, facility) : : : "memory")
+
+#define alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2) \
+ asm volatile(ALTERNATIVE_2(oldinstr, altinstr1, facility1, \
+ altinstr2, facility2) ::: "memory")
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_S390_ALTERNATIVE_H */