51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
// 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/ftrace.h>
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#include <linux/uaccess.h>
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
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unsigned long frame_pointer)
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{
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unsigned long return_hooker = (unsigned long)&return_to_handler;
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unsigned long old;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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old = *parent;
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if (!function_graph_enter(old, self_addr,
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*(unsigned long *)frame_pointer, parent)) {
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/*
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* For csky-gcc function has sub-call:
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* subi sp, sp, 8
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* stw r8, (sp, 0)
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* mov r8, sp
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* st.w r15, (sp, 0x4)
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* push r15
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* jl _mcount
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* We only need set *parent for resume
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*
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* For csky-gcc function has no sub-call:
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* subi sp, sp, 4
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* stw r8, (sp, 0)
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* mov r8, sp
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* push r15
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* jl _mcount
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* We need set *parent and *(frame_pointer + 4) for resume,
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* because lr is resumed twice.
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*/
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*parent = return_hooker;
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frame_pointer += 4;
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if (*(unsigned long *)frame_pointer == old)
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*(unsigned long *)frame_pointer = return_hooker;
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}
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}
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#endif
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/* _mcount is defined in abi's mcount.S */
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extern void _mcount(void);
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EXPORT_SYMBOL(_mcount);
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