Commit cd2675bf authored by Anil S Keshavamurthy's avatar Anil S Keshavamurthy Committed by Linus Torvalds
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[PATCH] Kprobes/IA64: support kprobe on branch/call instructions 



This patch is required to support kprobe on branch/call instructions.

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 b2761dc2

arch/ia64/kernel/kprobes.c

+116 −15
Original line number Diff line number Diff line
@@ -120,25 +120,75 @@ void arch_arm_kprobe(struct kprobe *p) 
	unsigned long arm_addr = 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;



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

   	p->ainsn.inst_flag = 0;

   	p->ainsn.target_br_reg = 0;



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

    	template = bundle.quad0.template;

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

    	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;

		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;

		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;

		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:

    				p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;

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

    				break;

    			case IP_RELATIVE_PREDICT_OPCODE:

    			case IP_RELATIVE_BRANCH_OPCODE:

    				p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;

    				break;

    			case IP_RELATIVE_CALL_OPCODE:

    				p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;

    				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) {

    		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 */

    				break;

    		}

    	}



 	/* Flush icache for the instruction at the emulated address */

	flush_icache_range((unsigned long)&p->ainsn.insn.bundle,
@@ -170,23 +220,74 @@ void arch_remove_kprobe(struct kprobe *p) 
 * We are resuming execution after a single step fault, so the pt_regs

 * structure reflects the register state after we executed the instruction

 * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust

 * the ip to point back to the original stack address, and if we see that

 * the slot has incremented back to zero, then we need to point to the next

 * slot location.

 * the ip to point back to the original stack address. To set the IP address

 * to original stack address, handle the case where we need to fixup the

 * relative IP address and/or fixup branch register.

 */

static void resume_execution(struct kprobe *p, struct pt_regs *regs)

{

	unsigned long bundle = (unsigned long)p->addr & ~0xFULL;

  	unsigned long bundle_addr = ((unsigned long) (&p->ainsn.insn.bundle)) & ~0xFULL;

  	unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;

 	unsigned long template;

 	int slot = ((unsigned long)p->addr & 0xf);



	template = p->opcode.bundle.quad0.template;



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

 		slot = 2;



	if (p->ainsn.inst_flag) {



		if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {

			/* Fix relative IP address */

 			regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;

		}



		if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {

		/*

	 * TODO: Handle cases where kprobe was inserted on a branch instruction

		 * Fix target branch register, software convention is

		 * to use either b0 or b6 or b7, so just checking

		 * only those registers

		 */

			switch (p->ainsn.target_br_reg) {

			case 0:

				if ((regs->b0 == bundle_addr) ||

					(regs->b0 == bundle_addr + 0x10)) {

					regs->b0 = (regs->b0 - bundle_addr) +

						resume_addr;

				}

				break;

			case 6:

				if ((regs->b6 == bundle_addr) ||

					(regs->b6 == bundle_addr + 0x10)) {

					regs->b6 = (regs->b6 - bundle_addr) +

						resume_addr;

				}

				break;

			case 7:

				if ((regs->b7 == bundle_addr) ||

					(regs->b7 == bundle_addr + 0x10)) {

					regs->b7 = (regs->b7 - bundle_addr) +

						resume_addr;

				}

				break;

			} /* end switch */

		}

		goto turn_ss_off;

	}



	if (!ia64_psr(regs)->ri)

		regs->cr_iip = bundle + 0x10;

	else

		regs->cr_iip = bundle;

	if (slot == 2) {

 		if (regs->cr_iip == bundle_addr + 0x10) {

 			regs->cr_iip = resume_addr + 0x10;

 		}

 	} else {

 		if (regs->cr_iip == bundle_addr) {

 			regs->cr_iip = resume_addr;

 		}

 	}



turn_ss_off:

  	/* Turn off Single Step bit */

  	ia64_psr(regs)->ss = 0;

}

include/asm-ia64/kprobes.h

+16 −1
Original line number Diff line number Diff line
@@ -44,6 +44,17 @@ typedef struct _bundle { 


#define JPROBE_ENTRY(pentry)	(kprobe_opcode_t *)pentry



#define SLOT0_OPCODE_SHIFT	(37)

#define SLOT1_p1_OPCODE_SHIFT	(37 - (64-46))

#define SLOT2_OPCODE_SHIFT 	(37)



#define INDIRECT_CALL_OPCODE		(1)

#define IP_RELATIVE_CALL_OPCODE		(5)

#define IP_RELATIVE_BRANCH_OPCODE	(4)

#define IP_RELATIVE_PREDICT_OPCODE	(7)

#define LONG_BRANCH_OPCODE		(0xC)

#define LONG_CALL_OPCODE		(0xD)



typedef struct kprobe_opcode {

	bundle_t bundle;

} kprobe_opcode_t;
@@ -55,8 +66,12 @@ struct fnptr { 


/* Architecture specific copy of original instruction*/

struct arch_specific_insn {

	/* copy of the original instruction */

	/* copy of the instruction to be emulated */

	kprobe_opcode_t insn;

 #define INST_FLAG_FIX_RELATIVE_IP_ADDR		1

 #define INST_FLAG_FIX_BRANCH_REG		2

 	unsigned long inst_flag;

 	unsigned short target_br_reg;

};



/* ia64 does not need this */