diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/alternative-asm.h | 14 | ||||
| -rw-r--r-- | arch/x86/include/asm/alternative.h | 16 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 4 |
3 files changed, 26 insertions, 8 deletions
diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h index 524bddce0b76..bdf02eeee765 100644 --- a/arch/x86/include/asm/alternative-asm.h +++ b/arch/x86/include/asm/alternative-asm.h @@ -45,12 +45,22 @@ .popsection .endm +#define old_len 141b-140b +#define new_len1 144f-143f +#define new_len2 145f-144f + +/* + * max without conditionals. Idea adapted from: + * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax + */ +#define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b))))) + .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2 140: \oldinstr 141: - .skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90 - .skip -(((145f-144f)-(144f-143f)-(141b-140b)) > 0) * ((145f-144f)-(144f-143f)-(141b-140b)),0x90 + .skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \ + (alt_max_short(new_len1, new_len2) - (old_len)),0x90 142: .pushsection .altinstructions,"a" diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 5aef6a97d80e..ba32af062f61 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -96,13 +96,21 @@ static inline int alternatives_text_reserved(void *start, void *end) alt_end_marker ":\n" /* + * max without conditionals. Idea adapted from: + * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax + * + * The additional "-" is needed because gas works with s32s. + */ +#define alt_max_short(a, b) "((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") - (" b ")))))" + +/* * Pad the second replacement alternative with additional NOPs if it is * additionally longer than the first replacement alternative. */ -#define OLDINSTR_2(oldinstr, num1, num2) \ - __OLDINSTR(oldinstr, num1) \ - ".skip -(((" alt_rlen(num2) ")-(" alt_rlen(num1) ")-(662b-661b)) > 0) * " \ - "((" alt_rlen(num2) ")-(" alt_rlen(num1) ")-(662b-661b)),0x90\n" \ +#define OLDINSTR_2(oldinstr, num1, num2) \ + "661:\n\t" oldinstr "\n662:\n" \ + ".skip -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \ + "(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")), 0x90\n" \ alt_end_marker ":\n" #define ALTINSTR_ENTRY(feature, num) \ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 5c993c94255e..7c4ad005d7a0 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -369,11 +369,11 @@ void __init_or_module apply_alternatives(struct alt_instr *start, continue; } - DPRINTK("feat: %d*32+%d, old: (%p, len: %d), repl: (%p, len: %d)", + DPRINTK("feat: %d*32+%d, old: (%p, len: %d), repl: (%p, len: %d), pad: %d", a->cpuid >> 5, a->cpuid & 0x1f, instr, a->instrlen, - replacement, a->replacementlen); + replacement, a->replacementlen, a->padlen); DUMP_BYTES(instr, a->instrlen, "%p: old_insn: ", instr); DUMP_BYTES(replacement, a->replacementlen, "%p: rpl_insn: ", replacement); |