arch/s390/include/asm/alternative.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_S390_ALTERNATIVE_H
   3 #define _ASM_S390_ALTERNATIVE_H
   4
   5 #ifndef __ASSEMBLY__
   6
   7 #include <linux/types.h>
   8 #include <linux/stddef.h>
   9 #include <linux/stringify.h>
  10
  11 struct alt_instr {
  12         s32 instr_offset;       /* original instruction */
  13         s32 repl_offset;        /* offset to replacement instruction */
  14         u16 facility;           /* facility bit set for replacement */
  15         u8  instrlen;           /* length of original instruction */
  16 } __packed;
  17
  18 void apply_alternative_instructions(void);
  19 void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
  20
  21 /*
  22  * +---------------------------------+
  23  * |661:                             |662:
  24  * | oldinstr                        |
  25  * +---------------------------------+
  26  *
  27  * .altinstr_replacement section
  28  * +---------------------------------+
  29  * |6641:                            |6651:
  30  * | alternative instr 1             |
  31  * +---------------------------------+
  32  * |6642:                            |6652:
  33  * | alternative instr 2             |
  34  * +---------------------------------+
  35  *
  36  * .altinstructions section
  37  * +---------------------------------+
  38  * | alt_instr entries for each      |
  39  * | alternative instr               |
  40  * +---------------------------------+
  41  */
  42
  43 #define b_altinstr(num)         "664"#num
  44 #define e_altinstr(num)         "665"#num
  45 #define oldinstr_len            "662b-661b"
  46 #define altinstr_len(num)       e_altinstr(num)"b-"b_altinstr(num)"b"
  47
  48 #define OLDINSTR(oldinstr) \
  49         "661:\n\t" oldinstr "\n662:\n"
  50
  51 #define ALTINSTR_ENTRY(facility, num)                                   \
  52         "\t.long 661b - .\n"                    /* old instruction */   \
  53         "\t.long " b_altinstr(num)"b - .\n"     /* alt instruction */   \
  54         "\t.word " __stringify(facility) "\n"   /* facility bit    */   \
  55         "\t.byte " oldinstr_len "\n"            /* instruction len */   \
  56         "\t.org . - (" oldinstr_len ") + (" altinstr_len(num) ")\n"     \
  57         "\t.org . - (" altinstr_len(num) ") + (" oldinstr_len ")\n"
  58
  59 #define ALTINSTR_REPLACEMENT(altinstr, num)     /* replacement */       \
  60         b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n"
  61
  62 /* alternative assembly primitive: */
  63 #define ALTERNATIVE(oldinstr, altinstr, facility) \
  64         ".pushsection .altinstr_replacement, \"ax\"\n"                  \
  65         ALTINSTR_REPLACEMENT(altinstr, 1)                               \
  66         ".popsection\n"                                                 \
  67         OLDINSTR(oldinstr)                                              \
  68         ".pushsection .altinstructions,\"a\"\n"                         \
  69         ALTINSTR_ENTRY(facility, 1)                                     \
  70         ".popsection\n"
  71
  72 #define ALTERNATIVE_2(oldinstr, altinstr1, facility1, altinstr2, facility2)\
  73         ".pushsection .altinstr_replacement, \"ax\"\n"                  \
  74         ALTINSTR_REPLACEMENT(altinstr1, 1)                              \
  75         ALTINSTR_REPLACEMENT(altinstr2, 2)                              \
  76         ".popsection\n"                                                 \
  77         OLDINSTR(oldinstr)                                              \
  78         ".pushsection .altinstructions,\"a\"\n"                         \
  79         ALTINSTR_ENTRY(facility1, 1)                                    \
  80         ALTINSTR_ENTRY(facility2, 2)                                    \
  81         ".popsection\n"
  82
  83 /*
  84  * Alternative instructions for different CPU types or capabilities.
  85  *
  86  * This allows to use optimized instructions even on generic binary
  87  * kernels.
  88  *
  89  * oldinstr is padded with jump and nops at compile time if altinstr is
  90  * longer. altinstr is padded with jump and nops at run-time during patching.
  91  *
  92  * For non barrier like inlines please define new variants
  93  * without volatile and memory clobber.
  94  */
  95 #define alternative(oldinstr, altinstr, facility)                       \
  96         asm_inline volatile(ALTERNATIVE(oldinstr, altinstr, facility) : : : "memory")
  97
  98 #define alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2) \
  99         asm_inline volatile(ALTERNATIVE_2(oldinstr, altinstr1, facility1,   \
 100                                    altinstr2, facility2) ::: "memory")
 101
 102 /* Alternative inline assembly with input. */
 103 #define alternative_input(oldinstr, newinstr, feature, input...)        \
 104         asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature)   \
 105                 : : input)
 106
 107 /* Like alternative_input, but with a single output argument */
 108 #define alternative_io(oldinstr, altinstr, facility, output, input...)  \
 109         asm_inline volatile(ALTERNATIVE(oldinstr, altinstr, facility)   \
 110                 : output : input)
 111
 112 /* Use this macro if more than one output parameter is needed. */
 113 #define ASM_OUTPUT2(a...) a
 114
 115 /* Use this macro if clobbers are needed without inputs. */
 116 #define ASM_NO_INPUT_CLOBBER(clobber...) : clobber
 117
 118 #endif /* __ASSEMBLY__ */
 119
 120 #endif /* _ASM_S390_ALTERNATIVE_H */