x86: introduce REX prefix helper for kprobes (9930927f) · Commits · 戴 / test

arch/x86/kernel/kprobes.c

+19 −8

Original line number	Diff line number	Diff line
		@@ -170,6 +170,19 @@ static void __kprobes set_jmp_op(void from, void to)
		jop->op = RELATIVEJUMP_INSTRUCTION;
		}

		/*
		* Check for the REX prefix which can only exist on X86_64
		* X86_32 always returns 0
		*/
		static int __kprobes is_REX_prefix(kprobe_opcode_t *insn)
		{
		#ifdef CONFIG_X86_64
		if ((*insn & 0xf0) == 0x40)
		return 1;
		#endif
		return 0;
		}

		/*
		* Returns non-zero if opcode is boostable.
		* RIP relative instructions are adjusted at copying time in 64 bits mode
		@@ -239,14 +252,14 @@ static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
		case 0x9d: /* popf/popfd */
		return 1;
		}
		#ifdef CONFIG_X86_64

		/*
		* on 64 bit x86, 0x40-0x4f are prefixes so we need to look
		* on X86_64, 0x40-0x4f are REX prefixes so we need to look
		* at the next byte instead.. but of course not recurse infinitely
		*/
		if (insn >= 0x40 && insn <= 0x4f)
		if (is_REX_prefix(insn))
		return is_IF_modifier(++insn);
		#endif

		return 0;
		}

		@@ -284,7 +297,7 @@ static void __kprobes fix_riprel(struct kprobe *p)
		}

		/* Skip REX instruction prefix. */
		if ((*insn & 0xf0) == 0x40)
		if (is_REX_prefix(insn))
		++insn;

		if (*insn == 0x0f) {
		@@ -748,11 +761,9 @@ static void __kprobes resume_execution(struct kprobe *p,
		unsigned long orig_ip = (unsigned long)p->addr;
		kprobe_opcode_t *insn = p->ainsn.insn;

		#ifdef CONFIG_X86_64
		/skip the REX prefix/
		if (insn >= 0x40 && insn <= 0x4f)
		if (is_REX_prefix(insn))
		insn++;
		#endif

		regs->flags &= ~X86_EFLAGS_TF;
		switch (*insn) {