mcount.S

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * LoongArch specific _mcount support
  4 *
  5 * Copyright (C) 2022 Loongson Technology Corporation Limited
  6 */
  7
  8#include <linux/export.h>
  9#include <asm/ftrace.h>
 10#include <asm/regdef.h>
 11#include <asm/stackframe.h>
 12
 13	.text
 14
 15#define MCOUNT_S0_OFFSET	(0)
 16#define MCOUNT_RA_OFFSET	(SZREG)
 17#define MCOUNT_STACK_SIZE	(2 * SZREG)
 18
 19	.macro MCOUNT_SAVE_REGS
 20	PTR_ADDI	sp, sp, -MCOUNT_STACK_SIZE
 21	PTR_S		s0, sp, MCOUNT_S0_OFFSET
 22	PTR_S		ra, sp, MCOUNT_RA_OFFSET
 23	move		s0, a0
 24	.endm
 25
 26	.macro MCOUNT_RESTORE_REGS
 27	move		a0, s0
 28	PTR_L		ra, sp, MCOUNT_RA_OFFSET
 29	PTR_L		s0, sp, MCOUNT_S0_OFFSET
 30	PTR_ADDI	sp, sp, MCOUNT_STACK_SIZE
 31	.endm
 32
 33SYM_FUNC_START(_mcount)
 34	la.pcrel	t1, ftrace_stub
 35	la.pcrel	t2, ftrace_trace_function	/* Prepare t2 for (1) */
 36	PTR_L		t2, t2, 0
 37	beq		t1, t2, fgraph_trace
 38
 39	MCOUNT_SAVE_REGS
 40
 41	move		a0, ra				/* arg0: self return address */
 42	move		a1, s0				/* arg1: parent's return address */
 43	jirl		ra, t2, 0			/* (1) call *ftrace_trace_function */
 44
 45	MCOUNT_RESTORE_REGS
 46
 47fgraph_trace:
 48#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 49	la.pcrel	t1, ftrace_stub
 50	la.pcrel	t3, ftrace_graph_return
 51	PTR_L		t3, t3, 0
 52	bne		t1, t3, ftrace_graph_caller
 53	la.pcrel	t1, ftrace_graph_entry_stub
 54	la.pcrel	t3, ftrace_graph_entry
 55	PTR_L		t3, t3, 0
 56	bne		t1, t3, ftrace_graph_caller
 57#endif
 58
 59SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL)
 60	jr		ra
 61#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 62SYM_INNER_LABEL(ftrace_graph_func, SYM_L_GLOBAL)
 63	bl		ftrace_stub
 64#endif
 65SYM_FUNC_END(_mcount)
 66EXPORT_SYMBOL(_mcount)
 67
 68#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 69SYM_FUNC_START(ftrace_graph_caller)
 70	MCOUNT_SAVE_REGS
 71
 72	PTR_ADDI	a0, ra, -4			/* arg0: Callsite self return addr */
 73	PTR_ADDI	a1, sp, MCOUNT_STACK_SIZE	/* arg1: Callsite sp */
 74	move		a2, s0				/* arg2: Callsite parent ra */
 75	bl		prepare_ftrace_return
 76
 77	MCOUNT_RESTORE_REGS
 78	jr		ra
 79SYM_FUNC_END(ftrace_graph_caller)
 80
 81SYM_FUNC_START(return_to_handler)
 82	/* Save return value regs */
 83	PTR_ADDI	sp, sp, -PT_SIZE
 84	PTR_S		a0, sp, PT_R4
 85	PTR_S		a1, sp, PT_R5
 86	PTR_S		zero, sp, PT_R22
 87
 88	move		a0, sp
 89	bl		ftrace_return_to_handler
 90
 91	/* Restore the real parent address: a0 -> ra */
 92	move		ra, a0
 93
 94	/* Restore return value regs */
 95	PTR_L		a0, sp, PT_R4
 96	PTR_L		a1, sp, PT_R5
 97	PTR_ADDI	sp, sp, PT_SIZE
 98
 99	jr		ra
100SYM_FUNC_END(return_to_handler)
101#endif /* CONFIG_FUNCTION_GRAPH_TRACER */