projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| b2761dc2 AK |
1 | /* |
| 2 | * Jprobe specific operations | |
| 3 | * | |
| 4 | * This program is free software; you can redistribute it and/or modify | |
| 5 | * it under the terms of the GNU General Public License as published by | |
| 6 | * the Free Software Foundation; either version 2 of the License, or | |
| 7 | * (at your option) any later version. | |
| 8 | * | |
| 9 | * This program is distributed in the hope that it will be useful, | |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 | * GNU General Public License for more details. | |
| 13 | * | |
| 14 | * You should have received a copy of the GNU General Public License | |
| 15 | * along with this program; if not, write to the Free Software | |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
| 17 | * | |
| 18 | * Copyright (C) Intel Corporation, 2005 | |
| 19 | * | |
| 20 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy | |
| 21 | * <anil.s.keshavamurthy@intel.com> initial implementation | |
| 22 | * | |
| 23 | * Jprobes (a.k.a. "jump probes" which is built on-top of kprobes) allow a | |
| 24 | * probe to be inserted into the beginning of a function call. The fundamental | |
| 25 | * difference between a jprobe and a kprobe is the jprobe handler is executed | |
| 26 | * in the same context as the target function, while the kprobe handlers | |
| 27 | * are executed in interrupt context. | |
| 28 | * | |
| 29 | * For jprobes we initially gain control by placing a break point in the | |
| 30 | * first instruction of the targeted function. When we catch that specific | |
| 31 | * break, we: | |
| 32 | * * set the return address to our jprobe_inst_return() function | |
| 33 | * * jump to the jprobe handler function | |
| 34 | * | |
| 35 | * Since we fixed up the return address, the jprobe handler will return to our | |
| 36 | * jprobe_inst_return() function, giving us control again. At this point we | |
| 37 | * are back in the parents frame marker, so we do yet another call to our | |
| 38 | * jprobe_break() function to fix up the frame marker as it would normally | |
| 39 | * exist in the target function. | |
| 40 | * | |
| 41 | * Our jprobe_return function then transfers control back to kprobes.c by | |
| 42 | * executing a break instruction using one of our reserved numbers. When we | |
| 43 | * catch that break in kprobes.c, we continue like we do for a normal kprobe | |
| 44 | * by single stepping the emulated instruction, and then returning execution | |
| 45 | * to the correct location. | |
| 46 | */ | |
| 47 | #include <asm/asmmacro.h> | |
| 7f30491c | 48 | #include <asm/break.h> |
| b2761dc2 AK |
49 | |
| 50 | /* | |
| 51 | * void jprobe_break(void) | |
| 52 | */ | |
| 1f7ad57b | 53 | .section .kprobes.text, "ax" |
| b2761dc2 | 54 | ENTRY(jprobe_break) |
| 08ed38b6 | 55 | break.m __IA64_BREAK_JPROBE |
| b2761dc2 AK |
56 | END(jprobe_break) |
| 57 | ||
| 58 | /* | |
| 59 | * void jprobe_inst_return(void) | |
| 60 | */ | |
| 61 | GLOBAL_ENTRY(jprobe_inst_return) | |
| 62 | br.call.sptk.many b0=jprobe_break | |
| 63 | END(jprobe_inst_return) | |
| d3ef1f5a ZY |
64 | |
| 65 | GLOBAL_ENTRY(invalidate_stacked_regs) | |
| 66 | movl r16=invalidate_restore_cfm | |
| 67 | ;; | |
| 68 | mov b6=r16 | |
| 69 | ;; | |
| 70 | br.ret.sptk.many b6 | |
| 71 | ;; | |
| 72 | invalidate_restore_cfm: | |
| 73 | mov r16=ar.rsc | |
| 74 | ;; | |
| 75 | mov ar.rsc=r0 | |
| 76 | ;; | |
| 77 | loadrs | |
| 78 | ;; | |
| 79 | mov ar.rsc=r16 | |
| 80 | ;; | |
| 81 | br.cond.sptk.many rp | |
| 82 | END(invalidate_stacked_regs) | |
| 83 | ||
| 84 | GLOBAL_ENTRY(flush_register_stack) | |
| 85 | // flush dirty regs to backing store (must be first in insn group) | |
| 86 | flushrs | |
| 87 | ;; | |
| 88 | br.ret.sptk.many rp | |
| 89 | END(flush_register_stack) | |
| 90 |