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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2022 Loongson Technology Corporation Limited
*/
#include <linux/init.h>
#include <linux/ftrace.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <asm/asm.h>
#include <asm/asm-offsets.h>
#include <asm/cacheflush.h>
#include <asm/inst.h>
#include <asm/loongarch.h>
#include <asm/syscall.h>
#include <asm-generic/sections.h>
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
* As `call _mcount` follows LoongArch psABI, ra-saved operation and
* stack operation can be found before this insn.
*/
static int ftrace_get_parent_ra_addr(unsigned long insn_addr, int *ra_off)
{
int limit = 32;
union loongarch_instruction *insn;
insn = (union loongarch_instruction *)insn_addr;
do {
insn--;
limit--;
if (is_ra_save_ins(insn))
*ra_off = -((1 << 12) - insn->reg2i12_format.immediate);
} while (!is_stack_alloc_ins(insn) && limit);
if (!limit)
return -EINVAL;
return 0;
}
void prepare_ftrace_return(unsigned long self_addr,
unsigned long callsite_sp, unsigned long old)
{
int ra_off;
unsigned long return_hooker = (unsigned long)&return_to_handler;
if (unlikely(ftrace_graph_is_dead()))
return;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
if (ftrace_get_parent_ra_addr(self_addr, &ra_off))
goto out;
if (!function_graph_enter(old, self_addr, 0, NULL))
*(unsigned long *)(callsite_sp + ra_off) = return_hooker;
return;
out:
ftrace_graph_stop();
WARN_ON(1);
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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