1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_S390_ALTERNATIVE_H 3 #define _ASM_S390_ALTERNATIVE_H 4 5 /* 6 * Each alternative comes with a 32 bit feature field: 7 * union { 8 * u32 feature; 9 * struct { 10 * u32 ctx : 4; 11 * u32 type : 8; 12 * u32 data : 20; 13 * }; 14 * } 15 * 16 * @ctx is a bitfield, where only one bit must be set. Each bit defines 17 * in which context an alternative is supposed to be applied to the 18 * kernel image: 19 * 20 * - from the decompressor before the kernel itself is executed 21 * - from early kernel code from within the kernel 22 * 23 * @type is a number which defines the type and with that the type 24 * specific alternative patching. 25 * 26 * @data is additional type specific information which defines if an 27 * alternative should be applied. 28 */ 29 30 #define ALT_CTX_EARLY 1 31 #define ALT_CTX_LATE 2 32 #define ALT_CTX_ALL (ALT_CTX_EARLY | ALT_CTX_LATE) 33 34 #define ALT_TYPE_FACILITY 0 35 #define ALT_TYPE_FEATURE 1 36 #define ALT_TYPE_SPEC 2 37 38 #define ALT_DATA_SHIFT 0 39 #define ALT_TYPE_SHIFT 20 40 #define ALT_CTX_SHIFT 28 41 42 #define ALT_FACILITY(facility) (ALT_CTX_EARLY << ALT_CTX_SHIFT | \ 43 ALT_TYPE_FACILITY << ALT_TYPE_SHIFT | \ 44 (facility) << ALT_DATA_SHIFT) 45 46 #define ALT_FEATURE(feature) (ALT_CTX_EARLY << ALT_CTX_SHIFT | \ 47 ALT_TYPE_FEATURE << ALT_TYPE_SHIFT | \ 48 (feature) << ALT_DATA_SHIFT) 49 50 #define ALT_SPEC(facility) (ALT_CTX_LATE << ALT_CTX_SHIFT | \ 51 ALT_TYPE_SPEC << ALT_TYPE_SHIFT | \ 52 (facility) << ALT_DATA_SHIFT) 53 54 #ifndef __ASSEMBLY__ 55 56 #include <linux/types.h> 57 #include <linux/stddef.h> 58 #include <linux/stringify.h> 59 60 struct alt_instr { 61 s32 instr_offset; /* original instruction */ 62 s32 repl_offset; /* offset to replacement instruction */ 63 union { 64 u32 feature; /* feature required for replacement */ 65 struct { 66 u32 ctx : 4; /* context */ 67 u32 type : 8; /* type of alternative */ 68 u32 data : 20; /* patching information */ 69 }; 70 }; 71 u8 instrlen; /* length of original instruction */ 72 } __packed; 73 74 extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; 75 76 void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx); 77 78 static inline void apply_alternative_instructions(void) 79 { 80 __apply_alternatives(__alt_instructions, __alt_instructions_end, ALT_CTX_LATE); 81 } 82 83 static inline void apply_alternatives(struct alt_instr *start, struct alt_instr *end) 84 { 85 __apply_alternatives(start, end, ALT_CTX_ALL); 86 } 87 88 /* 89 * +---------------------------------+ 90 * |661: |662: 91 * | oldinstr | 92 * +---------------------------------+ 93 * 94 * .altinstr_replacement section 95 * +---------------------------------+ 96 * |6641: |6651: 97 * | alternative instr 1 | 98 * +---------------------------------+ 99 * |6642: |6652: 100 * | alternative instr 2 | 101 * +---------------------------------+ 102 * 103 * .altinstructions section 104 * +---------------------------------+ 105 * | alt_instr entries for each | 106 * | alternative instr | 107 * +---------------------------------+ 108 */ 109 110 #define b_altinstr(num) "664"#num 111 #define e_altinstr(num) "665"#num 112 #define oldinstr_len "662b-661b" 113 #define altinstr_len(num) e_altinstr(num)"b-"b_altinstr(num)"b" 114 115 #define OLDINSTR(oldinstr) \ 116 "661:\n\t" oldinstr "\n662:\n" 117 118 #define ALTINSTR_ENTRY(feature, num) \ 119 "\t.long 661b - .\n" /* old instruction */ \ 120 "\t.long " b_altinstr(num)"b - .\n" /* alt instruction */ \ 121 "\t.long " __stringify(feature) "\n" /* feature */ \ 122 "\t.byte " oldinstr_len "\n" /* instruction len */ \ 123 "\t.org . - (" oldinstr_len ") & 1\n" \ 124 "\t.org . - (" oldinstr_len ") + (" altinstr_len(num) ")\n" \ 125 "\t.org . - (" altinstr_len(num) ") + (" oldinstr_len ")\n" 126 127 #define ALTINSTR_REPLACEMENT(altinstr, num) /* replacement */ \ 128 b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n" 129 130 /* alternative assembly primitive: */ 131 #define ALTERNATIVE(oldinstr, altinstr, feature) \ 132 ".pushsection .altinstr_replacement, \"ax\"\n" \ 133 ALTINSTR_REPLACEMENT(altinstr, 1) \ 134 ".popsection\n" \ 135 OLDINSTR(oldinstr) \ 136 ".pushsection .altinstructions,\"a\"\n" \ 137 ALTINSTR_ENTRY(feature, 1) \ 138 ".popsection\n" 139 140 #define ALTERNATIVE_2(oldinstr, altinstr1, feature1, altinstr2, feature2)\ 141 ".pushsection .altinstr_replacement, \"ax\"\n" \ 142 ALTINSTR_REPLACEMENT(altinstr1, 1) \ 143 ALTINSTR_REPLACEMENT(altinstr2, 2) \ 144 ".popsection\n" \ 145 OLDINSTR(oldinstr) \ 146 ".pushsection .altinstructions,\"a\"\n" \ 147 ALTINSTR_ENTRY(feature1, 1) \ 148 ALTINSTR_ENTRY(feature2, 2) \ 149 ".popsection\n" 150 151 /* 152 * Alternative instructions for different CPU types or capabilities. 153 * 154 * This allows to use optimized instructions even on generic binary 155 * kernels. 156 * 157 * oldinstr is padded with jump and nops at compile time if altinstr is 158 * longer. altinstr is padded with jump and nops at run-time during patching. 159 * 160 * For non barrier like inlines please define new variants 161 * without volatile and memory clobber. 162 */ 163 #define alternative(oldinstr, altinstr, feature) \ 164 asm_inline volatile(ALTERNATIVE(oldinstr, altinstr, feature) : : : "memory") 165 166 #define alternative_2(oldinstr, altinstr1, feature1, altinstr2, feature2) \ 167 asm_inline volatile(ALTERNATIVE_2(oldinstr, altinstr1, feature1, \ 168 altinstr2, feature2) ::: "memory") 169 170 /* Alternative inline assembly with input. */ 171 #define alternative_input(oldinstr, newinstr, feature, input...) \ 172 asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ 173 : : input) 174 175 /* Like alternative_input, but with a single output argument */ 176 #define alternative_io(oldinstr, altinstr, feature, output, input...) \ 177 asm_inline volatile(ALTERNATIVE(oldinstr, altinstr, feature) \ 178 : output : input) 179 180 /* Use this macro if more than one output parameter is needed. */ 181 #define ASM_OUTPUT2(a...) a 182 183 /* Use this macro if clobbers are needed without inputs. */ 184 #define ASM_NO_INPUT_CLOBBER(clobber...) : clobber 185 186 #else /* __ASSEMBLY__ */ 187 188 /* 189 * Issue one struct alt_instr descriptor entry (need to put it into 190 * the section .altinstructions, see below). This entry contains 191 * enough information for the alternatives patching code to patch an 192 * instruction. See apply_alternatives(). 193 */ 194 .macro alt_entry orig_start, orig_end, alt_start, alt_end, feature 195 .long \orig_start - . 196 .long \alt_start - . 197 .long \feature 198 .byte \orig_end - \orig_start 199 .org . - ( \orig_end - \orig_start ) & 1 200 .org . - ( \orig_end - \orig_start ) + ( \alt_end - \alt_start ) 201 .org . - ( \alt_end - \alt_start ) + ( \orig_end - \orig_start ) 202 .endm 203 204 /* 205 * Define an alternative between two instructions. If @feature is 206 * present, early code in apply_alternatives() replaces @oldinstr with 207 * @newinstr. 208 */ 209 .macro ALTERNATIVE oldinstr, newinstr, feature 210 .pushsection .altinstr_replacement,"ax" 211 770: \newinstr 212 771: .popsection 213 772: \oldinstr 214 773: .pushsection .altinstructions,"a" 215 alt_entry 772b, 773b, 770b, 771b, \feature 216 .popsection 217 .endm 218 219 /* 220 * Define an alternative between two instructions. If @feature is 221 * present, early code in apply_alternatives() replaces @oldinstr with 222 * @newinstr. 223 */ 224 .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2 225 .pushsection .altinstr_replacement,"ax" 226 770: \newinstr1 227 771: \newinstr2 228 772: .popsection 229 773: \oldinstr 230 774: .pushsection .altinstructions,"a" 231 alt_entry 773b, 774b, 770b, 771b,\feature1 232 alt_entry 773b, 774b, 771b, 772b,\feature2 233 .popsection 234 .endm 235 236 #endif /* __ASSEMBLY__ */ 237 238 #endif /* _ASM_S390_ALTERNATIVE_H */ 239