diff options
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 89de61243272..37596a417094 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -432,6 +432,11 @@ static int alt_replace_call(u8 *instr, u8 *insn_buff, struct alt_instr *a) return 5; } +static inline u8 * instr_va(struct alt_instr *i) +{ + return (u8 *)&i->instr_offset + i->instr_offset; +} + /* * Replace instructions with better alternatives for this CPU type. This runs * before SMP is initialized to avoid SMP problems with self modifying code. @@ -447,7 +452,7 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, { u8 insn_buff[MAX_PATCH_LEN]; u8 *instr, *replacement; - struct alt_instr *a; + struct alt_instr *a, *b; DPRINTK(ALT, "alt table %px, -> %px", start, end); @@ -473,7 +478,18 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, for (a = start; a < end; a++) { int insn_buff_sz = 0; - instr = (u8 *)&a->instr_offset + a->instr_offset; + /* + * In case of nested ALTERNATIVE()s the outer alternative might + * add more padding. To ensure consistent patching find the max + * padding for all alt_instr entries for this site (nested + * alternatives result in consecutive entries). + */ + for (b = a+1; b < end && instr_va(b) == instr_va(a); b++) { + u8 len = max(a->instrlen, b->instrlen); + a->instrlen = b->instrlen = len; + } + + instr = instr_va(a); replacement = (u8 *)&a->repl_offset + a->repl_offset; BUG_ON(a->instrlen > sizeof(insn_buff)); BUG_ON(a->cpuid >= (NCAPINTS + NBUGINTS) * 32); |