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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long frame_pointer)
{
unsigned long return_hooker = (unsigned long)&return_to_handler;
unsigned long old;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
old = *parent;
if (!function_graph_enter(old, self_addr,
*(unsigned long *)frame_pointer, parent)) {
/*
* For csky-gcc function has sub-call:
* subi sp, sp, 8
* stw r8, (sp, 0)
* mov r8, sp
* st.w r15, (sp, 0x4)
* push r15
* jl _mcount
* We only need set *parent for resume
*
* For csky-gcc function has no sub-call:
* subi sp, sp, 4
* stw r8, (sp, 0)
* mov r8, sp
* push r15
* jl _mcount
* We need set *parent and *(frame_pointer + 4) for resume,
* because lr is resumed twice.
*/
*parent = return_hooker;
frame_pointer += 4;
if (*(unsigned long *)frame_pointer == old)
*(unsigned long *)frame_pointer = return_hooker;
}
}
#endif
/* _mcount is defined in abi's mcount.S */
extern void _mcount(void);
EXPORT_SYMBOL(_mcount);
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