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Commit 8dd7cfbe authored by Jon Medhurst's avatar Jon Medhurst Committed by Nicolas Pitre
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ARM: kprobes: Fix emulation of SXTB16, SXTB, SXTH, UXTB16, UXTB and UXTH instructions 



These sign extension instructions are encoded as extend-and-add
instructions where the register to add is specified as r15. The decoding
routines weren't checking for this and were using the incorrect
emulation code, giving incorrect results.

Signed-off-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Signed-off-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 780b5c11

arch/arm/kernel/kprobes-decode.c

+12 −2
Original line number Diff line number Diff line
@@ -1390,19 +1390,29 @@ space_cccc_0110__1(kprobe_opcode_t insn, struct arch_specific_insn *asi) 
		return prep_emulate_rd12rn16rm0_wflags(insn, asi);



	/* SXTAB16   : cccc 0110 1000 xxxx xxxx xxxx 0111 xxxx :   */

	/* SXTB      : cccc 0110 1010 xxxx xxxx xxxx 0111 xxxx :   */

	/* SXTB16    : cccc 0110 1000 1111 xxxx xxxx 0111 xxxx :   */

	/* ???       : cccc 0110 1001 xxxx xxxx xxxx 0111 xxxx :   */

	/* SXTAB     : cccc 0110 1010 xxxx xxxx xxxx 0111 xxxx :   */

	/* SXTB      : cccc 0110 1010 1111 xxxx xxxx 0111 xxxx :   */

	/* SXTAH     : cccc 0110 1011 xxxx xxxx xxxx 0111 xxxx :   */

	/* SXTH      : cccc 0110 1011 1111 xxxx xxxx 0111 xxxx :   */

	/* UXTAB16   : cccc 0110 1100 xxxx xxxx xxxx 0111 xxxx :   */

	/* UXTB16    : cccc 0110 1100 1111 xxxx xxxx 0111 xxxx :   */

	/* ???       : cccc 0110 1101 xxxx xxxx xxxx 0111 xxxx :   */

	/* UXTAB     : cccc 0110 1110 xxxx xxxx xxxx 0111 xxxx :   */

	/* UXTB      : cccc 0110 1110 1111 xxxx xxxx 0111 xxxx :   */

	/* UXTAH     : cccc 0110 1111 xxxx xxxx xxxx 0111 xxxx :   */

	/* UXTH      : cccc 0110 1111 1111 xxxx xxxx 0111 xxxx :   */

	if ((insn & 0x0f8000f0) == 0x06800070) {

		if ((insn & 0x00300000) == 0x00100000)

			return INSN_REJECTED;	/* Unallocated space */



		if ((insn & 0x000f0000) == 0x000f0000) {

			return prep_emulate_rd12rm0(insn, asi);

		} else {

			return prep_emulate_rd12rn16rm0_wflags(insn, asi);

		}

	}



	/* Other instruction encodings aren't yet defined */

	return INSN_REJECTED;