ARM: kprobes: Decode 16-bit Thumb BX and BLX instructions (a9c3c29e) · Commits · 戴 / test

arch/arm/kernel/kprobes-thumb.c

+37 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,31 @@
		*/
		#define current_cond(cpsr) ((cpsr >> 12) & 0xf)

		/*
		* Return the PC value for a probe in thumb code.
		* This is the address of the probed instruction plus 4.
		* We subtract one because the address will have bit zero set to indicate
		* a pointer to thumb code.
		*/
		static inline unsigned long __kprobes thumb_probe_pc(struct kprobe *p)
		{
		return (unsigned long)p->addr - 1 + 4;
		}

		static void __kprobes
		t16_simulate_bxblx(struct kprobe p, struct pt_regs regs)
		{
		kprobe_opcode_t insn = p->opcode;
		unsigned long pc = thumb_probe_pc(p);
		int rm = (insn >> 3) & 0xf;
		unsigned long rmv = (rm == 15) ? pc : regs->uregs[rm];

		if (insn & (1 << 7)) /* BLX ? */
		regs->ARM_lr = (unsigned long)p->addr + 2;

		bx_write_pc(rmv, regs);
		}

		static unsigned long __kprobes
		t16_emulate_loregs(struct kprobe p, struct pt_regs regs)
		{
		@@ -131,6 +156,18 @@ const union decode_item kprobe_decode_thumb16_table[] = {
		/* MVN (register) 0100 0011 10xx xxxx */
		DECODE_EMULATE (0xfc00, 0x4000, t16_emulate_loregs_noitrwflags),

		/*
		* Special data instructions and branch and exchange
		* 0100 01xx xxxx xxxx
		*/

		/* BLX pc 0100 0111 1111 1xxx */
		DECODE_REJECT (0xfff8, 0x47f8),

		/* BX (register) 0100 0111 0xxx xxxx */
		/* BLX (register) 0100 0111 1xxx xxxx */
		DECODE_SIMULATE (0xff00, 0x4700, t16_simulate_bxblx),

		/*
		* Miscellaneous 16-bit instructions
		* 1011 xxxx xxxx xxxx