Commit a5403183 authored by Anil S Keshavamurthy's avatar Anil S Keshavamurthy Committed by Linus Torvalds
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[PATCH] Kprobes IA64: arch_prepare_kprobes() cleanup 



arch_prepare_kprobes() was doing lots of functionality
in just one single function. This patch
attempts to clean up arch_prepare_kprobes() by moving
specific sub task to the following (new)functions
1)valid_kprobe_addr() -->> validate the given kprobe address
2)get_kprobe_inst(slot..)->> Retrives the instruction for a given slot from the bundle
3)prepare_break_inst() -->> Prepares break instruction within the bundle
	3a)update_kprobe_inst_flag()-->>Updates the internal flags, required
			for proper emulation of the instruction at later
			point in time.

Signed-off-by: default avatarAnil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 13608d64

arch/ia64/kernel/kprobes.c

+121 −70
Original line number Diff line number Diff line
@@ -81,60 +81,17 @@ static enum instruction_type bundle_encoding[32][3] = { 
  { u, u, u },  			/* 1F */

};



int arch_prepare_kprobe(struct kprobe *p)

/*

 * In this function we check to see if the instruction

 * is IP relative instruction and update the kprobe

 * inst flag accordingly

 */

static void update_kprobe_inst_flag(uint template, uint  slot, uint major_opcode,

	unsigned long kprobe_inst, struct kprobe *p)

{

	unsigned long addr = (unsigned long) p->addr;

	unsigned long *bundle_addr = (unsigned long *)(addr & ~0xFULL);

	unsigned long slot = addr & 0xf;

	unsigned long template;

 	unsigned long major_opcode = 0;

 	unsigned long lx_type_inst = 0;

 	unsigned long kprobe_inst = 0;

	bundle_t *bundle = &p->ainsn.insn.bundle;



	memcpy(&p->opcode.bundle, bundle_addr, sizeof(bundle_t));

	memcpy(&p->ainsn.insn.bundle, bundle_addr, sizeof(bundle_t));



	p->ainsn.inst_flag = 0;

	p->ainsn.target_br_reg = 0;



 	template = bundle->quad0.template;



	if (((bundle_encoding[template][1] == L) && slot > 1) || (slot > 2)) {

		printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",

				addr);

		return -EINVAL;

	}



 	if (slot == 1 && bundle_encoding[template][1] == L) {

 		lx_type_inst = 1;

  		slot = 2;

 	}



	switch (slot) {

	case 0:

 		major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);

 		kprobe_inst = bundle->quad0.slot0;

		bundle->quad0.slot0 = BREAK_INST | (0x3f & kprobe_inst);

		break;

	case 1:

 		major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);

 		kprobe_inst = (bundle->quad0.slot1_p0 |

 				(bundle->quad1.slot1_p1 << (64-46)));

		bundle->quad0.slot1_p0 = BREAK_INST | (0x3f & kprobe_inst);

		bundle->quad1.slot1_p1 = (BREAK_INST >> (64-46));

		break;

	case 2:

 		major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);

 		kprobe_inst = bundle->quad1.slot2;

		bundle->quad1.slot2 = BREAK_INST | (0x3f & kprobe_inst);

		break;

	}



 	/*

 	 * Look for IP relative Branches, IP relative call or

 	 * IP relative predicate instructions

 	 */

	if (bundle_encoding[template][slot] == B) {

		switch (major_opcode) {

		  case INDIRECT_CALL_OPCODE:
@@ -150,22 +107,116 @@ int arch_prepare_kprobe(struct kprobe *p) 
 			p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;

 			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);

 			break;

 			default:

 				/* Do nothing */

 				break;

		}

 	} else if (lx_type_inst) {

 	} else if (bundle_encoding[template][slot] == X) {

		switch (major_opcode) {

		  case LONG_CALL_OPCODE:

			p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;

			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);

		  break;

 			default:

 				/* Do nothing */

		}

	}

	return;

}



/*

 * In this function we override the bundle with

 * the break instruction at the given slot.

 */

static void prepare_break_inst(uint template, uint  slot, uint major_opcode,

	unsigned long kprobe_inst, struct kprobe *p)

{

	unsigned long break_inst = BREAK_INST;

	bundle_t *bundle = &p->ainsn.insn.bundle;



	/*

	 * Copy the original kprobe_inst qualifying predicate(qp)

	 * to the break instruction

	 */

	break_inst |= (0x3f & kprobe_inst);



	switch (slot) {

	  case 0:

		bundle->quad0.slot0 = break_inst;

		break;

	  case 1:

		bundle->quad0.slot1_p0 = break_inst;

		bundle->quad1.slot1_p1 = break_inst >> (64-46);

		break;

	  case 2:

		bundle->quad1.slot2 = break_inst;

		break;

	}



	/*

	 * Update the instruction flag, so that we can

	 * emulate the instruction properly after we

	 * single step on original instruction

	 */

	update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);

}



static inline void get_kprobe_inst(bundle_t *bundle, uint slot,

	       	unsigned long *kprobe_inst, uint *major_opcode)

{

	unsigned long kprobe_inst_p0, kprobe_inst_p1;

	unsigned int template;



	template = bundle->quad0.template;



	switch (slot) {

	  case 0:

 		*major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);

 		*kprobe_inst = bundle->quad0.slot0;

		break;

	  case 1:

 		*major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);

  		kprobe_inst_p0 = bundle->quad0.slot1_p0;

  		kprobe_inst_p1 = bundle->quad1.slot1_p1;

  		*kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));

		break;

	  case 2:

 		*major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);

 		*kprobe_inst = bundle->quad1.slot2;

		break;

	}

}



static int valid_kprobe_addr(int template, int slot, unsigned long addr)

{

	if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {

		printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",

				addr);

		return -EINVAL;

	}

	return 0;

}



int arch_prepare_kprobe(struct kprobe *p)

{

	unsigned long addr = (unsigned long) p->addr;

	unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);

	unsigned long kprobe_inst=0;

	unsigned int slot = addr & 0xf, template, major_opcode = 0;

	bundle_t *bundle = &p->ainsn.insn.bundle;



	memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));

	memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));



 	template = bundle->quad0.template;



	if(valid_kprobe_addr(template, slot, addr))

		return -EINVAL;



	/* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */

 	if (slot == 1 && bundle_encoding[template][1] == L)

  		slot++;



	/* Get kprobe_inst and major_opcode from the bundle */

	get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);



	prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);



	return 0;

}

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