| Martin Schwidefsky | fba9eb7 | 2018-03-19 18:07:31 +0100 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef _ASM_S390_ALTERNATIVE_ASM_H |
| 3 | #define _ASM_S390_ALTERNATIVE_ASM_H |
| 4 | |
| 5 | #ifdef __ASSEMBLY__ |
| 6 | |
| 7 | /* |
| 8 | * Check the length of an instruction sequence. The length may not be larger |
| 9 | * than 254 bytes and it has to be divisible by 2. |
| 10 | */ |
| 11 | .macro alt_len_check start,end |
| 12 | .if ( \end - \start ) > 254 |
| 13 | .error "cpu alternatives does not support instructions blocks > 254 bytes\n" |
| 14 | .endif |
| 15 | .if ( \end - \start ) % 2 |
| 16 | .error "cpu alternatives instructions length is odd\n" |
| 17 | .endif |
| 18 | .endm |
| 19 | |
| 20 | /* |
| 21 | * Issue one struct alt_instr descriptor entry (need to put it into |
| 22 | * the section .altinstructions, see below). This entry contains |
| 23 | * enough information for the alternatives patching code to patch an |
| 24 | * instruction. See apply_alternatives(). |
| 25 | */ |
| 26 | .macro alt_entry orig_start, orig_end, alt_start, alt_end, feature |
| 27 | .long \orig_start - . |
| 28 | .long \alt_start - . |
| 29 | .word \feature |
| 30 | .byte \orig_end - \orig_start |
| 31 | .byte \alt_end - \alt_start |
| 32 | .endm |
| 33 | |
| 34 | /* |
| 35 | * Fill up @bytes with nops. The macro emits 6-byte nop instructions |
| 36 | * for the bulk of the area, possibly followed by a 4-byte and/or |
| 37 | * a 2-byte nop if the size of the area is not divisible by 6. |
| 38 | */ |
| 39 | .macro alt_pad_fill bytes |
| 40 | .fill ( \bytes ) / 6, 6, 0xc0040000 |
| 41 | .fill ( \bytes ) % 6 / 4, 4, 0x47000000 |
| 42 | .fill ( \bytes ) % 6 % 4 / 2, 2, 0x0700 |
| 43 | .endm |
| 44 | |
| 45 | /* |
| 46 | * Fill up @bytes with nops. If the number of bytes is larger |
| 47 | * than 6, emit a jg instruction to branch over all nops, then |
| 48 | * fill an area of size (@bytes - 6) with nop instructions. |
| 49 | */ |
| 50 | .macro alt_pad bytes |
| 51 | .if ( \bytes > 0 ) |
| 52 | .if ( \bytes > 6 ) |
| 53 | jg . + \bytes |
| 54 | alt_pad_fill \bytes - 6 |
| 55 | .else |
| 56 | alt_pad_fill \bytes |
| 57 | .endif |
| 58 | .endif |
| 59 | .endm |
| 60 | |
| 61 | /* |
| 62 | * Define an alternative between two instructions. If @feature is |
| 63 | * present, early code in apply_alternatives() replaces @oldinstr with |
| 64 | * @newinstr. ".skip" directive takes care of proper instruction padding |
| 65 | * in case @newinstr is longer than @oldinstr. |
| 66 | */ |
| 67 | .macro ALTERNATIVE oldinstr, newinstr, feature |
| 68 | .pushsection .altinstr_replacement,"ax" |
| 69 | 770: \newinstr |
| 70 | 771: .popsection |
| 71 | 772: \oldinstr |
| 72 | 773: alt_len_check 770b, 771b |
| 73 | alt_len_check 772b, 773b |
| 74 | alt_pad ( ( 771b - 770b ) - ( 773b - 772b ) ) |
| 75 | 774: .pushsection .altinstructions,"a" |
| 76 | alt_entry 772b, 774b, 770b, 771b, \feature |
| 77 | .popsection |
| 78 | .endm |
| 79 | |
| 80 | /* |
| 81 | * Define an alternative between two instructions. If @feature is |
| 82 | * present, early code in apply_alternatives() replaces @oldinstr with |
| 83 | * @newinstr. ".skip" directive takes care of proper instruction padding |
| 84 | * in case @newinstr is longer than @oldinstr. |
| 85 | */ |
| 86 | .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2 |
| 87 | .pushsection .altinstr_replacement,"ax" |
| 88 | 770: \newinstr1 |
| 89 | 771: \newinstr2 |
| 90 | 772: .popsection |
| 91 | 773: \oldinstr |
| 92 | 774: alt_len_check 770b, 771b |
| 93 | alt_len_check 771b, 772b |
| 94 | alt_len_check 773b, 774b |
| 95 | .if ( 771b - 770b > 772b - 771b ) |
| 96 | alt_pad ( ( 771b - 770b ) - ( 774b - 773b ) ) |
| 97 | .else |
| 98 | alt_pad ( ( 772b - 771b ) - ( 774b - 773b ) ) |
| 99 | .endif |
| 100 | 775: .pushsection .altinstructions,"a" |
| 101 | alt_entry 773b, 775b, 770b, 771b,\feature1 |
| 102 | alt_entry 773b, 775b, 771b, 772b,\feature2 |
| 103 | .popsection |
| 104 | .endm |
| 105 | |
| 106 | #endif /* __ASSEMBLY__ */ |
| 107 | |
| 108 | #endif /* _ASM_S390_ALTERNATIVE_ASM_H */ |