From b2761dc262b428475890fffd979687051beb12ba Mon Sep 17 00:00:00 2001 From: Anil S Keshavamurthy Date: Thu, 23 Jun 2005 00:09:28 -0700 Subject: [PATCH] Kprobes/IA64: architecture specific JProbes support This patch adds IA64 architecture specific JProbes support on top of Kprobes Signed-off-by: Anil S Keshavamurthy Signed-off-by: Rusty Lynch Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/ia64/kernel/jprobes.S | 61 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 arch/ia64/kernel/jprobes.S (limited to 'arch/ia64/kernel/jprobes.S') diff --git a/arch/ia64/kernel/jprobes.S b/arch/ia64/kernel/jprobes.S new file mode 100644 index 000000000000..b7fa3ccd2b0f --- /dev/null +++ b/arch/ia64/kernel/jprobes.S @@ -0,0 +1,61 @@ +/* + * 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 and Anil S Keshavamurthy + * 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 + + /* + * void jprobe_break(void) + */ +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) -- cgit v1.2.3