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Commit 83803d97 authored by Wang Nan's avatar Wang Nan Committed by Jon Medhurst
Browse files

ARM: kprobes: introduces checker 



This patch introdces 'checker' to decoding phase, and calls checkers
when instruction decoding. This allows further decoding for specific
instructions.  This patch introduces a stub call of checkers in kprobe
arch_prepare_kprobe() as an example and for further expansion.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Reviewed-by: default avatarJon Medhurst <tixy@linaro.org>
Reviewed-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarJon Medhurst <tixy@linaro.org>
parent 832607e7

arch/arm/probes/decode-arm.c

+3 −2
Original line number Diff line number Diff line
@@ -726,10 +726,11 @@ static void __kprobes arm_singlestep(probes_opcode_t insn, 
 */

enum probes_insn __kprobes

arm_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,

		       bool emulate, const union decode_action *actions)

		       bool emulate, const union decode_action *actions,

		       const struct decode_checker *checkers[])

{

	asi->insn_singlestep = arm_singlestep;

	asi->insn_check_cc = probes_condition_checks[insn>>28];

	return probes_decode_insn(insn, asi, probes_decode_arm_table, false,

				  emulate, actions);

				  emulate, actions, checkers);

}

arch/arm/probes/decode-arm.h

+2 −1
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ extern const union decode_item probes_decode_arm_table[]; 


enum probes_insn arm_probes_decode_insn(probes_opcode_t,

		struct arch_probes_insn *, bool emulate,

		const union decode_action *actions);

		const union decode_action *actions,

		const struct decode_checker *checkers[]);



#endif

arch/arm/probes/decode-thumb.c

+6 −4
Original line number Diff line number Diff line
@@ -863,20 +863,22 @@ static void __kprobes thumb32_singlestep(probes_opcode_t opcode, 


enum probes_insn __kprobes

thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,

			   bool emulate, const union decode_action *actions)

			   bool emulate, const union decode_action *actions,

			   const struct decode_checker *checkers[])

{

	asi->insn_singlestep = thumb16_singlestep;

	asi->insn_check_cc = thumb_check_cc;

	return probes_decode_insn(insn, asi, probes_decode_thumb16_table, true,

				  emulate, actions);

				  emulate, actions, checkers);

}



enum probes_insn __kprobes

thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,

			   bool emulate, const union decode_action *actions)

			   bool emulate, const union decode_action *actions,

			   const struct decode_checker *checkers[])

{

	asi->insn_singlestep = thumb32_singlestep;

	asi->insn_check_cc = thumb_check_cc;

	return probes_decode_insn(insn, asi, probes_decode_thumb32_table, true,

				  emulate, actions);

				  emulate, actions, checkers);

}

arch/arm/probes/decode-thumb.h

+4 −2
Original line number Diff line number Diff line
@@ -91,9 +91,11 @@ extern const union decode_item probes_decode_thumb16_table[]; 


enum probes_insn __kprobes

thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,

		bool emulate, const union decode_action *actions);

		bool emulate, const union decode_action *actions,

		const struct decode_checker *checkers[]);

enum probes_insn __kprobes

thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,

		bool emulate, const union decode_action *actions);

		bool emulate, const union decode_action *actions,

		const struct decode_checker *checkers[]);



#endif

arch/arm/probes/decode.c

+54 −6
Original line number Diff line number Diff line
@@ -342,6 +342,31 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = { 
	[DECODE_TYPE_REJECT]	= sizeof(struct decode_reject)

};



static int run_checkers(const struct decode_checker *checkers[],

		int action, probes_opcode_t insn,

		struct arch_probes_insn *asi,

		const struct decode_header *h)

{

	const struct decode_checker **p;



	if (!checkers)

		return INSN_GOOD;



	p = checkers;

	while (*p != NULL) {

		int retval;

		probes_check_t *checker_func = (*p)[action].checker;



		retval = INSN_GOOD;

		if (checker_func)

			retval = checker_func(insn, asi, h);

		if (retval == INSN_REJECTED)

			return retval;

		p++;

	}

	return INSN_GOOD;

}



/*

 * probes_decode_insn operates on data tables in order to decode an ARM

 * architecture instruction onto which a kprobe has been placed.
@@ -388,11 +413,17 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = { 
int __kprobes

probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,

		   const union decode_item *table, bool thumb,

		   bool emulate, const union decode_action *actions)

		   bool emulate, const union decode_action *actions,

		   const struct decode_checker *checkers[])

{

	const struct decode_header *h = (struct decode_header *)table;

	const struct decode_header *next;

	bool matched = false;

	/*

	 * @insn can be modified by decode_regs. Save its original

	 * value for checkers.

	 */

	probes_opcode_t origin_insn = insn;



	if (emulate)

		insn = prepare_emulated_insn(insn, asi, thumb);
@@ -422,24 +453,41 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, 
		}



		case DECODE_TYPE_CUSTOM: {

			int err;

			struct decode_custom *d = (struct decode_custom *)h;

			return actions[d->decoder.action].decoder(insn, asi, h);

			int action = d->decoder.action;



			err = run_checkers(checkers, action, origin_insn, asi, h);

			if (err == INSN_REJECTED)

				return INSN_REJECTED;

			return actions[action].decoder(insn, asi, h);

		}



		case DECODE_TYPE_SIMULATE: {

			int err;

			struct decode_simulate *d = (struct decode_simulate *)h;

			asi->insn_handler = actions[d->handler.action].handler;

			int action = d->handler.action;



			err = run_checkers(checkers, action, origin_insn, asi, h);

			if (err == INSN_REJECTED)

				return INSN_REJECTED;

			asi->insn_handler = actions[action].handler;

			return INSN_GOOD_NO_SLOT;

		}



		case DECODE_TYPE_EMULATE: {

			int err;

			struct decode_emulate *d = (struct decode_emulate *)h;

			int action = d->handler.action;



			err = run_checkers(checkers, action, origin_insn, asi, h);

			if (err == INSN_REJECTED)

				return INSN_REJECTED;



			if (!emulate)

				return actions[d->handler.action].decoder(insn,

					asi, h);

				return actions[action].decoder(insn, asi, h);



			asi->insn_handler = actions[d->handler.action].handler;

			asi->insn_handler = actions[action].handler;

			set_emulated_insn(insn, asi, thumb);

			return INSN_GOOD;

		}