| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _ASM_S390_ALTERNATIVE_ASM_H |
| #define _ASM_S390_ALTERNATIVE_ASM_H |
| |
| #ifdef __ASSEMBLY__ |
| |
| /* |
| * Check the length of an instruction sequence. The length may not be larger |
| * than 254 bytes and it has to be divisible by 2. |
| */ |
| .macro alt_len_check start,end |
| .if ( \end - \start ) > 254 |
| .error "cpu alternatives does not support instructions blocks > 254 bytes\n" |
| .endif |
| .if ( \end - \start ) % 2 |
| .error "cpu alternatives instructions length is odd\n" |
| .endif |
| .endm |
| |
| /* |
| * Issue one struct alt_instr descriptor entry (need to put it into |
| * the section .altinstructions, see below). This entry contains |
| * enough information for the alternatives patching code to patch an |
| * instruction. See apply_alternatives(). |
| */ |
| .macro alt_entry orig_start, orig_end, alt_start, alt_end, feature |
| .long \orig_start - . |
| .long \alt_start - . |
| .word \feature |
| .byte \orig_end - \orig_start |
| .byte \alt_end - \alt_start |
| .endm |
| |
| /* |
| * Fill up @bytes with nops. The macro emits 6-byte nop instructions |
| * for the bulk of the area, possibly followed by a 4-byte and/or |
| * a 2-byte nop if the size of the area is not divisible by 6. |
| */ |
| .macro alt_pad_fill bytes |
| .fill ( \bytes ) / 6, 6, 0xc0040000 |
| .fill ( \bytes ) % 6 / 4, 4, 0x47000000 |
| .fill ( \bytes ) % 6 % 4 / 2, 2, 0x0700 |
| .endm |
| |
| /* |
| * Fill up @bytes with nops. If the number of bytes is larger |
| * than 6, emit a jg instruction to branch over all nops, then |
| * fill an area of size (@bytes - 6) with nop instructions. |
| */ |
| .macro alt_pad bytes |
| .if ( \bytes > 0 ) |
| .if ( \bytes > 6 ) |
| jg . + \bytes |
| alt_pad_fill \bytes - 6 |
| .else |
| alt_pad_fill \bytes |
| .endif |
| .endif |
| .endm |
| |
| /* |
| * Define an alternative between two instructions. If @feature is |
| * present, early code in apply_alternatives() replaces @oldinstr with |
| * @newinstr. ".skip" directive takes care of proper instruction padding |
| * in case @newinstr is longer than @oldinstr. |
| */ |
| .macro ALTERNATIVE oldinstr, newinstr, feature |
| .pushsection .altinstr_replacement,"ax" |
| 770: \newinstr |
| 771: .popsection |
| 772: \oldinstr |
| 773: alt_len_check 770b, 771b |
| alt_len_check 772b, 773b |
| alt_pad ( ( 771b - 770b ) - ( 773b - 772b ) ) |
| 774: .pushsection .altinstructions,"a" |
| alt_entry 772b, 774b, 770b, 771b, \feature |
| .popsection |
| .endm |
| |
| /* |
| * Define an alternative between two instructions. If @feature is |
| * present, early code in apply_alternatives() replaces @oldinstr with |
| * @newinstr. ".skip" directive takes care of proper instruction padding |
| * in case @newinstr is longer than @oldinstr. |
| */ |
| .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2 |
| .pushsection .altinstr_replacement,"ax" |
| 770: \newinstr1 |
| 771: \newinstr2 |
| 772: .popsection |
| 773: \oldinstr |
| 774: alt_len_check 770b, 771b |
| alt_len_check 771b, 772b |
| alt_len_check 773b, 774b |
| .if ( 771b - 770b > 772b - 771b ) |
| alt_pad ( ( 771b - 770b ) - ( 774b - 773b ) ) |
| .else |
| alt_pad ( ( 772b - 771b ) - ( 774b - 773b ) ) |
| .endif |
| 775: .pushsection .altinstructions,"a" |
| alt_entry 773b, 775b, 770b, 771b,\feature1 |
| alt_entry 773b, 775b, 771b, 772b,\feature2 |
| .popsection |
| .endm |
| |
| #endif /* __ASSEMBLY__ */ |
| |
| #endif /* _ASM_S390_ALTERNATIVE_ASM_H */ |
