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