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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/loongarch/kernel/mcount.S
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/* SPDX-License-Identifier: GPL-2.0 */

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/*

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 * LoongArch specific _mcount support

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 *

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 * Copyright (C) 2022 Loongson Technology Corporation Limited

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 */

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#include <linux/export.h>

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#include <asm/ftrace.h>

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#include <asm/regdef.h>

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#include <asm/stackframe.h>

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	.text

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#define MCOUNT_S0_OFFSET	(0)

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#define MCOUNT_RA_OFFSET	(SZREG)

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#define MCOUNT_STACK_SIZE	(2 * SZREG)

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	.macro MCOUNT_SAVE_REGS

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	PTR_ADDI	sp, sp, -MCOUNT_STACK_SIZE

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	PTR_S		s0, sp, MCOUNT_S0_OFFSET

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	PTR_S		ra, sp, MCOUNT_RA_OFFSET

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	move		s0, a0

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	.endm

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	.macro MCOUNT_RESTORE_REGS

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	move		a0, s0

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	PTR_L		ra, sp, MCOUNT_RA_OFFSET

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	PTR_L		s0, sp, MCOUNT_S0_OFFSET

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	PTR_ADDI	sp, sp, MCOUNT_STACK_SIZE

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	.endm

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SYM_FUNC_START(_mcount)

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	la.pcrel	t1, ftrace_stub

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	la.pcrel	t2, ftrace_trace_function	/* Prepare t2 for (1) */

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	PTR_L		t2, t2, 0

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	beq		t1, t2, fgraph_trace

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	MCOUNT_SAVE_REGS

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	move		a0, ra				/* arg0: self return address */

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	move		a1, s0				/* arg1: parent's return address */

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	jirl		ra, t2, 0			/* (1) call *ftrace_trace_function */

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	MCOUNT_RESTORE_REGS

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fgraph_trace:

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#ifdef CONFIG_FUNCTION_GRAPH_TRACER

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	la.pcrel	t1, ftrace_stub

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	la.pcrel	t3, ftrace_graph_return

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	PTR_L		t3, t3, 0

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	bne		t1, t3, ftrace_graph_caller

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	la.pcrel	t1, ftrace_graph_entry_stub

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	la.pcrel	t3, ftrace_graph_entry

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	PTR_L		t3, t3, 0

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	bne		t1, t3, ftrace_graph_caller

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#endif

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SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL)

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	jr		ra

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#ifdef CONFIG_FUNCTION_GRAPH_TRACER

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SYM_INNER_LABEL(ftrace_graph_func, SYM_L_GLOBAL)

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	bl		ftrace_stub

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#endif

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SYM_FUNC_END(_mcount)

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EXPORT_SYMBOL(_mcount)

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#ifdef CONFIG_FUNCTION_GRAPH_TRACER

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SYM_FUNC_START(ftrace_graph_caller)

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	MCOUNT_SAVE_REGS

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	PTR_ADDI	a0, ra, -4			/* arg0: Callsite self return addr */

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	PTR_ADDI	a1, sp, MCOUNT_STACK_SIZE	/* arg1: Callsite sp */

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	move		a2, s0				/* arg2: Callsite parent ra */

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	bl		prepare_ftrace_return

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	MCOUNT_RESTORE_REGS

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	jr		ra

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SYM_FUNC_END(ftrace_graph_caller)

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SYM_FUNC_START(return_to_handler)

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	/* Save return value regs */

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	PTR_ADDI	sp, sp, -PT_SIZE

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	PTR_S		a0, sp, PT_R4

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	PTR_S		a1, sp, PT_R5

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	PTR_S		zero, sp, PT_R22

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	move		a0, sp

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	bl		ftrace_return_to_handler

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	/* Restore the real parent address: a0 -> ra */

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	move		ra, a0

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	/* Restore return value regs */

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	PTR_L		a0, sp, PT_R4

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	PTR_L		a1, sp, PT_R5

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	PTR_ADDI	sp, sp, PT_SIZE

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	jr		ra

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SYM_FUNC_END(return_to_handler)

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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

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