H. Peter Anvin | 76f3075 | 2012-09-21 12:43:09 -0700 | [diff] [blame] | 1 | #ifndef _ASM_X86_ALTERNATIVE_ASM_H |
| 2 | #define _ASM_X86_ALTERNATIVE_ASM_H |
| 3 | |
Adrian Bunk | 7e02cb9 | 2007-10-17 18:04:38 +0200 | [diff] [blame] | 4 | #ifdef __ASSEMBLY__ |
| 5 | |
Jan Beulich | 99063c0 | 2009-11-27 15:06:16 +0000 | [diff] [blame] | 6 | #include <asm/asm.h> |
Adrian Bunk | 7e02cb9 | 2007-10-17 18:04:38 +0200 | [diff] [blame] | 7 | |
| 8 | #ifdef CONFIG_SMP |
| 9 | .macro LOCK_PREFIX |
Eric Dumazet | ceb7b40 | 2012-01-03 17:35:40 +0100 | [diff] [blame] | 10 | 672: lock |
H. Peter Anvin | 9cebed4 | 2012-09-21 12:43:08 -0700 | [diff] [blame] | 11 | .pushsection .smp_locks,"a" |
Jan Beulich | 5967ed8 | 2010-04-21 16:08:14 +0100 | [diff] [blame] | 12 | .balign 4 |
Eric Dumazet | ceb7b40 | 2012-01-03 17:35:40 +0100 | [diff] [blame] | 13 | .long 672b - . |
H. Peter Anvin | 9cebed4 | 2012-09-21 12:43:08 -0700 | [diff] [blame] | 14 | .popsection |
Adrian Bunk | 7e02cb9 | 2007-10-17 18:04:38 +0200 | [diff] [blame] | 15 | .endm |
| 16 | #else |
| 17 | .macro LOCK_PREFIX |
| 18 | .endm |
| 19 | #endif |
| 20 | |
Borislav Petkov | 5b673a4 | 2015-04-04 16:40:45 +0200 | [diff] [blame] | 21 | /* |
| 22 | * Issue one struct alt_instr descriptor entry (need to put it into |
| 23 | * the section .altinstructions, see below). This entry contains |
| 24 | * enough information for the alternatives patching code to patch an |
| 25 | * instruction. See apply_alternatives(). |
| 26 | */ |
Borislav Petkov | 4332195 | 2014-12-27 10:41:52 +0100 | [diff] [blame] | 27 | .macro altinstruction_entry orig alt feature orig_len alt_len pad_len |
Andy Lutomirski | 59e97e4 | 2011-07-13 09:24:10 -0400 | [diff] [blame] | 28 | .long \orig - . |
| 29 | .long \alt - . |
Fenghua Yu | 9072d11 | 2011-05-17 15:29:13 -0700 | [diff] [blame] | 30 | .word \feature |
| 31 | .byte \orig_len |
| 32 | .byte \alt_len |
Borislav Petkov | 4332195 | 2014-12-27 10:41:52 +0100 | [diff] [blame] | 33 | .byte \pad_len |
| 34 | .endm |
| 35 | |
Borislav Petkov | 5b673a4 | 2015-04-04 16:40:45 +0200 | [diff] [blame] | 36 | /* |
| 37 | * Define an alternative between two instructions. If @feature is |
| 38 | * present, early code in apply_alternatives() replaces @oldinstr with |
| 39 | * @newinstr. ".skip" directive takes care of proper instruction padding |
| 40 | * in case @newinstr is longer than @oldinstr. |
| 41 | */ |
Borislav Petkov | 4332195 | 2014-12-27 10:41:52 +0100 | [diff] [blame] | 42 | .macro ALTERNATIVE oldinstr, newinstr, feature |
| 43 | 140: |
| 44 | \oldinstr |
| 45 | 141: |
| 46 | .skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90 |
| 47 | 142: |
| 48 | |
| 49 | .pushsection .altinstructions,"a" |
| 50 | altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b |
| 51 | .popsection |
| 52 | |
| 53 | .pushsection .altinstr_replacement,"ax" |
| 54 | 143: |
| 55 | \newinstr |
| 56 | 144: |
| 57 | .popsection |
| 58 | .endm |
| 59 | |
Borislav Petkov | dbe4058 | 2015-04-04 15:34:43 +0200 | [diff] [blame] | 60 | #define old_len 141b-140b |
| 61 | #define new_len1 144f-143f |
| 62 | #define new_len2 145f-144f |
| 63 | |
| 64 | /* |
Mathias Krause | fb6da44 | 2017-10-05 20:30:12 +0200 | [diff] [blame] | 65 | * gas compatible max based on the idea from: |
Borislav Petkov | dbe4058 | 2015-04-04 15:34:43 +0200 | [diff] [blame] | 66 | * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax |
Mathias Krause | fb6da44 | 2017-10-05 20:30:12 +0200 | [diff] [blame] | 67 | * |
| 68 | * The additional "-" is needed because gas uses a "true" value of -1. |
Borislav Petkov | dbe4058 | 2015-04-04 15:34:43 +0200 | [diff] [blame] | 69 | */ |
| 70 | #define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b))))) |
| 71 | |
Borislav Petkov | 5b673a4 | 2015-04-04 16:40:45 +0200 | [diff] [blame] | 72 | |
| 73 | /* |
| 74 | * Same as ALTERNATIVE macro above but for two alternatives. If CPU |
| 75 | * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has |
| 76 | * @feature2, it replaces @oldinstr with @feature2. |
| 77 | */ |
Borislav Petkov | 4332195 | 2014-12-27 10:41:52 +0100 | [diff] [blame] | 78 | .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2 |
| 79 | 140: |
| 80 | \oldinstr |
| 81 | 141: |
Borislav Petkov | dbe4058 | 2015-04-04 15:34:43 +0200 | [diff] [blame] | 82 | .skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \ |
| 83 | (alt_max_short(new_len1, new_len2) - (old_len)),0x90 |
Borislav Petkov | 4332195 | 2014-12-27 10:41:52 +0100 | [diff] [blame] | 84 | 142: |
| 85 | |
| 86 | .pushsection .altinstructions,"a" |
| 87 | altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b |
| 88 | altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b |
| 89 | .popsection |
| 90 | |
| 91 | .pushsection .altinstr_replacement,"ax" |
| 92 | 143: |
| 93 | \newinstr1 |
| 94 | 144: |
| 95 | \newinstr2 |
| 96 | 145: |
| 97 | .popsection |
Fenghua Yu | 9072d11 | 2011-05-17 15:29:13 -0700 | [diff] [blame] | 98 | .endm |
| 99 | |
Adrian Bunk | 7e02cb9 | 2007-10-17 18:04:38 +0200 | [diff] [blame] | 100 | #endif /* __ASSEMBLY__ */ |
H. Peter Anvin | 76f3075 | 2012-09-21 12:43:09 -0700 | [diff] [blame] | 101 | |
| 102 | #endif /* _ASM_X86_ALTERNATIVE_ASM_H */ |