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