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Commit f39ca8b4 authored by Jon Medhurst's avatar Jon Medhurst Committed by Tixy
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ARM: kprobes: Decode 32-bit Thumb hint instructions 



For hints which may have observable effects, like SEV (send event), we
use kprobe_emulate_none which emulates the hint by executing the
original instruction.

For NOP we simulate the instruction using kprobe_simulate_nop, which
does nothing. As probes execute with interrupts disabled this is also
used for hints which may block for an indefinite time, like WFE (wait
for event).

Signed-off-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 0a188ccb

arch/arm/kernel/kprobes-thumb.c

+27 −1
Original line number Diff line number Diff line
@@ -37,6 +37,32 @@ static inline unsigned long __kprobes thumb_probe_pc(struct kprobe *p) 
	return (unsigned long)p->addr - 1 + 4;

}



static const union decode_item t32_table_1111_0xxx___1[] = {

	/* Branches and miscellaneous control				*/



	/* YIELD		1111 0011 1010 xxxx 10x0 x000 0000 0001 */

	DECODE_OR	(0xfff0d7ff, 0xf3a08001),

	/* SEV			1111 0011 1010 xxxx 10x0 x000 0000 0100 */

	DECODE_EMULATE	(0xfff0d7ff, 0xf3a08004, kprobe_emulate_none),

	/* NOP			1111 0011 1010 xxxx 10x0 x000 0000 0000 */

	/* WFE			1111 0011 1010 xxxx 10x0 x000 0000 0010 */

	/* WFI			1111 0011 1010 xxxx 10x0 x000 0000 0011 */

	DECODE_SIMULATE	(0xfff0d7fc, 0xf3a08000, kprobe_simulate_nop),



	DECODE_END

};



const union decode_item kprobe_decode_thumb32_table[] = {



	/*

	 * Branches and miscellaneous control

	 *			1111 0xxx xxxx xxxx 1xxx xxxx xxxx xxxx

	 */

	DECODE_TABLE	(0xf8008000, 0xf0008000, t32_table_1111_0xxx___1),



	DECODE_END

};



static void __kprobes

t16_simulate_bxblx(struct kprobe *p, struct pt_regs *regs)

{
@@ -551,5 +577,5 @@ thumb32_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) 
{

	asi->insn_singlestep = thumb32_singlestep;

	asi->insn_check_cc = thumb_check_cc;

	return INSN_REJECTED;

	return kprobe_decode_insn(insn, asi, kprobe_decode_thumb32_table, true);

}