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a5447fb9b3
The "Changing Execution Path" section in the Documentation/kprobes.txt said: Since kprobes can probe into a running kernel code, it can change the register set, including instruction pointer. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Cc: Arnd Bergmann <arnd@arndb.de>
212 lines
3.5 KiB
ArmAsm
212 lines
3.5 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
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#include <linux/linkage.h>
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#include <asm/ftrace.h>
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#include <abi/entry.h>
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#include <asm/asm-offsets.h>
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/*
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* csky-gcc with -pg will put the following asm after prologue:
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* push r15
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* jsri _mcount
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*
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* stack layout after mcount_enter in _mcount():
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*
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* current sp => 0:+-------+
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* | a0-a3 | -> must save all argument regs
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* +16:+-------+
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* | lr | -> _mcount lr (instrumente function's pc)
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* +20:+-------+
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* | fp=r8 | -> instrumented function fp
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* +24:+-------+
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* | plr | -> instrumented function lr (parent's pc)
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* +-------+
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*/
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.macro mcount_enter
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subi sp, 24
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stw a0, (sp, 0)
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stw a1, (sp, 4)
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stw a2, (sp, 8)
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stw a3, (sp, 12)
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stw lr, (sp, 16)
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stw r8, (sp, 20)
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.endm
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.macro mcount_exit
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ldw a0, (sp, 0)
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ldw a1, (sp, 4)
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ldw a2, (sp, 8)
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ldw a3, (sp, 12)
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ldw t1, (sp, 16)
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ldw r8, (sp, 20)
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ldw lr, (sp, 24)
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addi sp, 28
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jmp t1
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.endm
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.macro mcount_enter_regs
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subi sp, 8
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stw lr, (sp, 0)
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stw r8, (sp, 4)
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SAVE_REGS_FTRACE
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.endm
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.macro mcount_exit_regs
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RESTORE_REGS_FTRACE
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subi sp, 152
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ldw t1, (sp, 4)
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addi sp, 152
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ldw r8, (sp, 4)
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ldw lr, (sp, 8)
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addi sp, 12
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jmp t1
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.endm
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.macro save_return_regs
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subi sp, 16
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stw a0, (sp, 0)
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stw a1, (sp, 4)
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stw a2, (sp, 8)
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stw a3, (sp, 12)
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.endm
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.macro restore_return_regs
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mov lr, a0
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ldw a0, (sp, 0)
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ldw a1, (sp, 4)
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ldw a2, (sp, 8)
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ldw a3, (sp, 12)
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addi sp, 16
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.endm
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.macro nop32_stub
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nop32
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nop32
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nop32
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.endm
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ENTRY(ftrace_stub)
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jmp lr
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END(ftrace_stub)
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#ifndef CONFIG_DYNAMIC_FTRACE
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ENTRY(_mcount)
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mcount_enter
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/* r26 is link register, only used with jsri translation */
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lrw r26, ftrace_trace_function
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ldw r26, (r26, 0)
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lrw a1, ftrace_stub
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cmpne r26, a1
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bf skip_ftrace
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mov a0, lr
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subi a0, 4
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ldw a1, (sp, 24)
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lrw a2, function_trace_op
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ldw a2, (a2, 0)
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jsr r26
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#ifndef CONFIG_FUNCTION_GRAPH_TRACER
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skip_ftrace:
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mcount_exit
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#else
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skip_ftrace:
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lrw a0, ftrace_graph_return
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ldw a0, (a0, 0)
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lrw a1, ftrace_stub
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cmpne a0, a1
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bt ftrace_graph_caller
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lrw a0, ftrace_graph_entry
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ldw a0, (a0, 0)
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lrw a1, ftrace_graph_entry_stub
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cmpne a0, a1
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bt ftrace_graph_caller
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mcount_exit
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#endif
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END(_mcount)
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#else /* CONFIG_DYNAMIC_FTRACE */
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ENTRY(_mcount)
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mov t1, lr
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ldw lr, (sp, 0)
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addi sp, 4
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jmp t1
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ENDPROC(_mcount)
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ENTRY(ftrace_caller)
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mcount_enter
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ldw a0, (sp, 16)
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subi a0, 4
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ldw a1, (sp, 24)
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lrw a2, function_trace_op
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ldw a2, (a2, 0)
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nop
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GLOBAL(ftrace_call)
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nop32_stub
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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nop
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GLOBAL(ftrace_graph_call)
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nop32_stub
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#endif
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mcount_exit
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ENDPROC(ftrace_caller)
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ENTRY(ftrace_graph_caller)
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mov a0, sp
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addi a0, 24
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ldw a1, (sp, 16)
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subi a1, 4
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mov a2, r8
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lrw r26, prepare_ftrace_return
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jsr r26
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mcount_exit
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END(ftrace_graph_caller)
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ENTRY(return_to_handler)
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save_return_regs
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mov a0, r8
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jsri ftrace_return_to_handler
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restore_return_regs
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jmp lr
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END(return_to_handler)
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
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ENTRY(ftrace_regs_caller)
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mcount_enter_regs
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lrw t1, PT_FRAME_SIZE
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add t1, sp
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ldw a0, (t1, 0)
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subi a0, 4
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ldw a1, (t1, 8)
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lrw a2, function_trace_op
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ldw a2, (a2, 0)
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mov a3, sp
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nop
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GLOBAL(ftrace_regs_call)
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nop32_stub
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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nop
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GLOBAL(ftrace_graph_regs_call)
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nop32_stub
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#endif
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mcount_exit_regs
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ENDPROC(ftrace_regs_caller)
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#endif /* CONFIG_DYNAMIC_FTRACE */
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