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Diffstat (limited to 'arch/ia64/kernel/jprobes.S')
-rw-r--r-- | arch/ia64/kernel/jprobes.S | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/arch/ia64/kernel/jprobes.S b/arch/ia64/kernel/jprobes.S new file mode 100644 index 000000000..f69389c7b --- /dev/null +++ b/arch/ia64/kernel/jprobes.S @@ -0,0 +1,90 @@ +/* + * 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) + |