diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 3b46a894c204..d513c9761f34 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -1157,10 +1157,37 @@ void arch_uprobe_optimize(struct arch_uprobe *auprobe, unsigned long vaddr) mmap_write_unlock(mm); } -static bool can_optimize(struct arch_uprobe *auprobe, unsigned long vaddr) +static bool insn_is_nop(struct insn *insn) { - if (memcmp(&auprobe->insn, x86_nops[5], 5)) + return insn->opcode.nbytes == 1 && insn->opcode.bytes[0] == 0x90; +} + +static bool insn_is_nopl(struct insn *insn) +{ + if (insn->opcode.nbytes != 2) return false; + + if (insn->opcode.bytes[0] != 0x0f || insn->opcode.bytes[1] != 0x1f) + return false; + + if (!insn->modrm.nbytes) + return false; + + if (X86_MODRM_REG(insn->modrm.bytes[0]) != 0) + return false; + + /* 0f 1f /0 - NOPL */ + return true; +} + +static bool can_optimize(struct insn *insn, unsigned long vaddr) +{ + if (!insn->x86_64 || insn->length != 5) + return false; + + if (!insn_is_nop(insn) && !insn_is_nopl(insn)) + return false; + /* We can't do cross page atomic writes yet. */ return PAGE_SIZE - (vaddr & ~PAGE_MASK) >= 5; } @@ -1177,7 +1204,7 @@ static void riprel_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) { } -static bool can_optimize(struct arch_uprobe *auprobe, unsigned long vaddr) +static bool can_optimize(struct insn *insn, unsigned long vaddr) { return false; } @@ -1539,15 +1566,15 @@ static int push_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) */ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long addr) { - struct insn insn; u8 fix_ip_or_call = UPROBE_FIX_IP; + struct insn insn; int ret; ret = uprobe_init_insn(auprobe, &insn, is_64bit_mm(mm)); if (ret) return ret; - if (can_optimize(auprobe, addr)) + if (can_optimize(&insn, addr)) set_bit(ARCH_UPROBE_FLAG_CAN_OPTIMIZE, &auprobe->flags); ret = branch_setup_xol_ops(auprobe, &insn);