| /* |
| * 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> |
| |
| /* |
| * void jprobe_break(void) |
| */ |
| .section .kprobes.text, "ax" |
| ENTRY(jprobe_break) |
| break.m 0x80300 |
| END(jprobe_break) |
| |
| /* |
| * void jprobe_inst_return(void) |
| */ |
| GLOBAL_ENTRY(jprobe_inst_return) |
| br.call.sptk.many b0=jprobe_break |
| END(jprobe_inst_return) |
