/* * Jprobe specific operations * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright (C) Intel Corporation, 2005 * * 2005-May Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy * <anil.s.keshavamurthy@intel.com> initial implementation * * Jprobes (a.k.a. "jump probes" which is built on-top of kprobes) allow a * probe to be inserted into the beginning of a function call. The fundamental * difference between a jprobe and a kprobe is the jprobe handler is executed * in the same context as the target function, while the kprobe handlers * are executed in interrupt context. * * For jprobes we initially gain control by placing a break point in the * first instruction of the targeted function. When we catch that specific * break, we: * * set the return address to our jprobe_inst_return() function * * jump to the jprobe handler function * * Since we fixed up the return address, the jprobe handler will return to our * jprobe_inst_return() function, giving us control again. At this point we * are back in the parents frame marker, so we do yet another call to our * jprobe_break() function to fix up the frame marker as it would normally * exist in the target function. * * Our jprobe_return function then transfers control back to kprobes.c by * executing a break instruction using one of our reserved numbers. When we * catch that break in kprobes.c, we continue like we do for a normal kprobe * by single stepping the emulated instruction, and then returning execution * to the correct location. */ #include <asm/asmmacro.h> #include <asm/break.h> /* * void jprobe_break(void) */ .section .kprobes.text, "ax" ENTRY(jprobe_break) break.m __IA64_BREAK_JPROBE END(jprobe_break) /* * void jprobe_inst_return(void) */ GLOBAL_ENTRY(jprobe_inst_return) br.call.sptk.many b0=jprobe_break END(jprobe_inst_return) GLOBAL_ENTRY(invalidate_stacked_regs) movl r16=invalidate_restore_cfm ;; mov b6=r16 ;; br.ret.sptk.many b6 ;; invalidate_restore_cfm: mov r16=ar.rsc ;; mov ar.rsc=r0 ;; loadrs ;; mov ar.rsc=r16 ;; br.cond.sptk.many rp END(invalidate_stacked_regs) GLOBAL_ENTRY(flush_register_stack) // flush dirty regs to backing store (must be first in insn group) flushrs ;; br.ret.sptk.many rp END(flush_register_stack)