1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_S390_ALTERNATIVE_ASM_H
3 #define _ASM_S390_ALTERNATIVE_ASM_H
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.
11 .macro alt_len_check start,end
12 .if ( \end - \start ) > 254
13 .error "cpu alternatives does not support instructions blocks > 254 bytes\n"
15 .if ( \end - \start ) % 2
16 .error "cpu alternatives instructions length is odd\n"
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().
26 .macro alt_entry orig_start, orig_end, alt_start, alt_end, feature
30 .byte \orig_end - \orig_start
31 .byte \alt_end - \alt_start
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.
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
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.
54 alt_pad_fill \bytes - 6
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.
67 .macro ALTERNATIVE oldinstr, newinstr, feature
68 .pushsection .altinstr_replacement,"ax"
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
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.
86 .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
87 .pushsection .altinstr_replacement,"ax"
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 ) )
98 alt_pad ( ( 772b - 771b ) - ( 774b - 773b ) )
100 775: .pushsection .altinstructions,"a"
101 alt_entry 773b, 775b, 770b, 771b,\feature1
102 alt_entry 773b, 775b, 771b, 772b,\feature2
106 #endif /* __ASSEMBLY__ */
108 #endif /* _ASM_S390_ALTERNATIVE_ASM_H */