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When jprobe is hit, the function parameters of the original function should be saved before jprobe handler is executed, and restored it after jprobe handler is executed, because jprobe handler might change the register values due to tail call optimization by the gcc. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
90 lines
2.9 KiB
ArmAsm
90 lines
2.9 KiB
ArmAsm
/*
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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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/*
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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 0x80300
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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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