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Commit 708de8f1 authored by Anil S Keshavamurthy's avatar Anil S Keshavamurthy Committed by Linus Torvalds
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[PATCH] Kprobes IA64: safe register kprobe 



The current kprobes does not yet handle register kprobes on some of the
following kind of instruction which needs to be emulated in a special way.

1) mov r1=ip
2) chk -- Speculation check instruction

This patch attempts to fail register_kprobes() when user tries to insert
kprobes on the above kind of instruction.

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 1674eafc

arch/ia64/kernel/kprobes.c

+45 −0
Original line number Diff line number Diff line
@@ -119,6 +119,48 @@ static void update_kprobe_inst_flag(uint template, uint slot, uint major_opcode 
	return;

}



/*

 * In this function we check to see if the instruction

 * on which we are inserting kprobe is supported.

 * Returns 0 if supported

 * Returns -EINVAL if unsupported

 */

static int unsupported_inst(uint template, uint  slot, uint major_opcode,

	unsigned long kprobe_inst, struct kprobe *p)

{

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



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

		switch (major_opcode) {

			case 0x0: //I_UNIT_MISC_OPCODE:

			/*

			 * Check for Integer speculation instruction

			 * - Bit 33-35 to be equal to 0x1

			 */

			if (((kprobe_inst >> 33) & 0x7) == 1) {

				printk(KERN_WARNING

					"Kprobes on speculation inst at <0x%lx> not supported\n",

					addr);

				return -EINVAL;

			}



			/*

			 * IP relative mov instruction

			 *  - Bit 27-35 to be equal to 0x30

			 */

			if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {

				printk(KERN_WARNING

					"Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",

					addr);

				return -EINVAL;



			}

		}

	}

	return 0;

}





/*

 * In this function we check to see if the instruction

 * (qp) cmpx.crel.ctype p1,p2=r2,r3
@@ -254,6 +296,9 @@ int arch_prepare_kprobe(struct kprobe *p) 
	/* Get kprobe_inst and major_opcode from the bundle */

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



	if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))

			return -EINVAL;



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



	return 0;