summaryrefslogtreecommitdiff
path: root/arch/riscv/kernel/mcount.S
blob: 5721624886a1cc8f0af054da3bec133b53de0381 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2017 Andes Technology Corporation */

#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/asm.h>
#include <asm/csr.h>
#include <asm/unistd.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm-generic/export.h>
#include <asm/ftrace.h>

	.text

	.macro SAVE_ABI_STATE
	addi	sp, sp, -16
	sd	s0, 0(sp)
	sd	ra, 8(sp)
	addi	s0, sp, 16
	.endm

	/*
	 * The call to ftrace_return_to_handler would overwrite the return
	 * register if a0 was not saved.
	 */
	.macro SAVE_RET_ABI_STATE
	addi	sp, sp, -32
	sd	s0, 16(sp)
	sd	ra, 24(sp)
	sd	a0, 8(sp)
	addi	s0, sp, 32
	.endm

	.macro RESTORE_ABI_STATE
	ld	ra, 8(sp)
	ld	s0, 0(sp)
	addi	sp, sp, 16
	.endm

	.macro RESTORE_RET_ABI_STATE
	ld	ra, 24(sp)
	ld	s0, 16(sp)
	ld	a0, 8(sp)
	addi	sp, sp, 32
	.endm

ENTRY(ftrace_stub)
#ifdef CONFIG_DYNAMIC_FTRACE
       .global _mcount
       .set    _mcount, ftrace_stub
#endif
	ret
ENDPROC(ftrace_stub)

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(return_to_handler)
/*
 * On implementing the frame point test, the ideal way is to compare the
 * s0 (frame pointer, if enabled) on entry and the sp (stack pointer) on return.
 * However, the psABI of variable-length-argument functions does not allow this.
 *
 * So alternatively we check the *old* frame pointer position, that is, the
 * value stored in -16(s0) on entry, and the s0 on return.
 */
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
	mv	t6, s0
#endif
	SAVE_RET_ABI_STATE
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
	mv	a0, t6
#endif
	call	ftrace_return_to_handler
	mv	a1, a0
	RESTORE_RET_ABI_STATE
	jalr	a1
ENDPROC(return_to_handler)
EXPORT_SYMBOL(return_to_handler)
#endif

#ifndef CONFIG_DYNAMIC_FTRACE
ENTRY(_mcount)
	la	t4, ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	la	t0, ftrace_graph_return
	ld	t1, 0(t0)
	bne	t1, t4, do_ftrace_graph_caller

	la	t3, ftrace_graph_entry
	ld	t2, 0(t3)
	la	t6, ftrace_graph_entry_stub
	bne	t2, t6, do_ftrace_graph_caller
#endif
	la	t3, ftrace_trace_function
	ld	t5, 0(t3)
	bne	t5, t4, do_trace
	ret

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
 * A pseudo representation for the function graph tracer:
 * prepare_to_return(&ra_to_caller_of_caller, ra_to_caller)
 */
do_ftrace_graph_caller:
	addi	a0, s0, -8
	mv	a1, ra
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
	ld	a2, -16(s0)
#endif
	SAVE_ABI_STATE
	call	prepare_ftrace_return
	RESTORE_ABI_STATE
	ret
#endif

/*
 * A pseudo representation for the function tracer:
 * (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller)
 */
do_trace:
	ld	a1, -8(s0)
	mv	a0, ra

	SAVE_ABI_STATE
	jalr	t5
	RESTORE_ABI_STATE
	ret
ENDPROC(_mcount)
#endif
EXPORT_SYMBOL(_mcount)