1/* SPDX-License-Identifier: GPL-2.0 */
2/* Copyright (C) 2017 Andes Technology Corporation */
3
4#include <linux/init.h>
5#include <linux/linkage.h>
6#include <asm/asm.h>
7#include <asm/csr.h>
8#include <asm/unistd.h>
9#include <asm/thread_info.h>
10#include <asm/asm-offsets.h>
11#include <asm-generic/export.h>
12#include <asm/ftrace.h>
13
14	.text
15
16	.macro SAVE_ABI_STATE
17	addi	sp, sp, -16
18	sd	s0, 0(sp)
19	sd	ra, 8(sp)
20	addi	s0, sp, 16
21	.endm
22
23	/*
24	 * The call to ftrace_return_to_handler would overwrite the return
25	 * register if a0 was not saved.
26	 */
27	.macro SAVE_RET_ABI_STATE
28	addi	sp, sp, -32
29	sd	s0, 16(sp)
30	sd	ra, 24(sp)
31	sd	a0, 8(sp)
32	addi	s0, sp, 32
33	.endm
34
35	.macro RESTORE_ABI_STATE
36	ld	ra, 8(sp)
37	ld	s0, 0(sp)
38	addi	sp, sp, 16
39	.endm
40
41	.macro RESTORE_RET_ABI_STATE
42	ld	ra, 24(sp)
43	ld	s0, 16(sp)
44	ld	a0, 8(sp)
45	addi	sp, sp, 32
46	.endm
47
48ENTRY(ftrace_stub)
49#ifdef CONFIG_DYNAMIC_FTRACE
50       .global MCOUNT_NAME
51       .set    MCOUNT_NAME, ftrace_stub
52#endif
53	ret
54ENDPROC(ftrace_stub)
55
56#ifdef CONFIG_FUNCTION_GRAPH_TRACER
57ENTRY(return_to_handler)
58/*
59 * On implementing the frame point test, the ideal way is to compare the
60 * s0 (frame pointer, if enabled) on entry and the sp (stack pointer) on return.
61 * However, the psABI of variable-length-argument functions does not allow this.
62 *
63 * So alternatively we check the *old* frame pointer position, that is, the
64 * value stored in -16(s0) on entry, and the s0 on return.
65 */
66#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
67	mv	t6, s0
68#endif
69	SAVE_RET_ABI_STATE
70#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
71	mv	a0, t6
72#endif
73	call	ftrace_return_to_handler
74	mv	a1, a0
75	RESTORE_RET_ABI_STATE
76	jalr	a1
77ENDPROC(return_to_handler)
78#endif
79
80#ifndef CONFIG_DYNAMIC_FTRACE
81ENTRY(MCOUNT_NAME)
82	la	t4, ftrace_stub
83#ifdef CONFIG_FUNCTION_GRAPH_TRACER
84	la	t0, ftrace_graph_return
85	ld	t1, 0(t0)
86	bne	t1, t4, do_ftrace_graph_caller
87
88	la	t3, ftrace_graph_entry
89	ld	t2, 0(t3)
90	la	t6, ftrace_graph_entry_stub
91	bne	t2, t6, do_ftrace_graph_caller
92#endif
93	la	t3, ftrace_trace_function
94	ld	t5, 0(t3)
95	bne	t5, t4, do_trace
96	ret
97
98#ifdef CONFIG_FUNCTION_GRAPH_TRACER
99/*
100 * A pseudo representation for the function graph tracer:
101 * prepare_to_return(&ra_to_caller_of_caller, ra_to_caller)
102 */
103do_ftrace_graph_caller:
104	addi	a0, s0, -8
105	mv	a1, ra
106#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
107	ld	a2, -16(s0)
108#endif
109	SAVE_ABI_STATE
110	call	prepare_ftrace_return
111	RESTORE_ABI_STATE
112	ret
113#endif
114
115/*
116 * A pseudo representation for the function tracer:
117 * (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller)
118 */
119do_trace:
120	ld	a1, -8(s0)
121	mv	a0, ra
122
123	SAVE_ABI_STATE
124	jalr	t5
125	RESTORE_ABI_STATE
126	ret
127ENDPROC(MCOUNT_NAME)
128#endif
129EXPORT_SYMBOL(MCOUNT_NAME)
130