1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 2022 Loongson Technology Corporation Limited
4 */
5
6#include <asm/ftrace.h>
7#include <asm/regdef.h>
8#include <asm/stackframe.h>
9
10	.text
11/*
12 * Due to -fpatchable-function-entry=2: the compiler inserted 2 NOPs before the
13 * regular C function prologue. When PC arrived here, the last 2 instructions
14 * are as follows:
15 * 	move		t0, ra
16 * 	bl		callsite (for modules, callsite is a tramplione)
17 *
18 * modules trampoline is as follows:
19 * 	lu12i.w		t1, callsite[31:12]
20 * 	lu32i.d		t1, callsite[51:32]
21 * 	lu52i.d		t1, t1, callsite[63:52]
22 * 	jirl		zero, t1, callsite[11:0] >> 2
23 *
24 * See arch/loongarch/kernel/ftrace_dyn.c for details. Here, pay attention to
25 * that the T series regs are available and safe because each C functions
26 * follows the LoongArch's psABI as well.
27 */
28
29	.macro  ftrace_regs_entry allregs=0
30	PTR_ADDI	sp, sp, -PT_SIZE
31	PTR_S		t0, sp, PT_R1  /* Save parent ra at PT_R1(RA) */
32	PTR_S		a0, sp, PT_R4
33	PTR_S		a1, sp, PT_R5
34	PTR_S		a2, sp, PT_R6
35	PTR_S		a3, sp, PT_R7
36	PTR_S		a4, sp, PT_R8
37	PTR_S		a5, sp, PT_R9
38	PTR_S		a6, sp, PT_R10
39	PTR_S		a7, sp, PT_R11
40	PTR_S		fp, sp, PT_R22
41	.if \allregs
42	PTR_S		tp, sp, PT_R2
43	PTR_S		t0, sp, PT_R12
44	PTR_S		t2, sp, PT_R14
45	PTR_S		t3, sp, PT_R15
46	PTR_S		t4, sp, PT_R16
47	PTR_S		t5, sp, PT_R17
48	PTR_S		t6, sp, PT_R18
49	PTR_S		t7, sp, PT_R19
50	PTR_S		t8, sp, PT_R20
51	PTR_S		u0, sp, PT_R21
52	PTR_S		s0, sp, PT_R23
53	PTR_S		s1, sp, PT_R24
54	PTR_S		s2, sp, PT_R25
55	PTR_S		s3, sp, PT_R26
56	PTR_S		s4, sp, PT_R27
57	PTR_S		s5, sp, PT_R28
58	PTR_S		s6, sp, PT_R29
59	PTR_S		s7, sp, PT_R30
60	PTR_S		s8, sp, PT_R31
61	/* Clear it for later use as a flag sometimes. */
62	PTR_S		zero, sp, PT_R0
63	.endif
64	PTR_S		ra, sp, PT_ERA /* Save trace function ra at PT_ERA */
65	move		t1, zero
66	PTR_S		t1, sp, PT_R13
67	PTR_ADDI	t8, sp, PT_SIZE
68	PTR_S		t8, sp, PT_R3
69	.endm
70
71SYM_FUNC_START(ftrace_stub)
72	jr		ra
73SYM_FUNC_END(ftrace_stub)
74
75SYM_CODE_START(ftrace_common)
76	UNWIND_HINT_UNDEFINED
77	PTR_ADDI	a0, ra, -8	/* arg0: ip */
78	move		a1, t0		/* arg1: parent_ip */
79	la.pcrel	t1, function_trace_op
80	PTR_L		a2, t1, 0	/* arg2: op */
81	move		a3, sp		/* arg3: regs */
82
83SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
84	bl		ftrace_stub
85#ifdef CONFIG_FUNCTION_GRAPH_TRACER
86SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL)
87	nop				/* b ftrace_graph_caller */
88#endif
89
90/*
91 * As we didn't use S series regs in this assmembly code and all calls
92 * are C function which will save S series regs by themselves, there is
93 * no need to restore S series regs. The T series is available and safe
94 * at the callsite, so there is no need to restore the T series regs.
95 */
96ftrace_common_return:
97	PTR_L		ra, sp, PT_R1
98	PTR_L		a0, sp, PT_R4
99	PTR_L		a1, sp, PT_R5
100	PTR_L		a2, sp, PT_R6
101	PTR_L		a3, sp, PT_R7
102	PTR_L		a4, sp, PT_R8
103	PTR_L		a5, sp, PT_R9
104	PTR_L		a6, sp, PT_R10
105	PTR_L		a7, sp, PT_R11
106	PTR_L		fp, sp, PT_R22
107	PTR_L		t0, sp, PT_ERA
108	PTR_L		t1, sp, PT_R13
109	PTR_ADDI	sp, sp, PT_SIZE
110	bnez		t1, .Ldirect
111	jr		t0
112.Ldirect:
113	jr		t1
114SYM_CODE_END(ftrace_common)
115
116SYM_CODE_START(ftrace_caller)
117	UNWIND_HINT_UNDEFINED
118	ftrace_regs_entry allregs=0
119	b		ftrace_common
120SYM_CODE_END(ftrace_caller)
121
122#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
123SYM_CODE_START(ftrace_regs_caller)
124	UNWIND_HINT_UNDEFINED
125	ftrace_regs_entry allregs=1
126	b		ftrace_common
127SYM_CODE_END(ftrace_regs_caller)
128#endif
129
130#ifdef CONFIG_FUNCTION_GRAPH_TRACER
131SYM_CODE_START(ftrace_graph_caller)
132	UNWIND_HINT_UNDEFINED
133	PTR_L		a0, sp, PT_ERA
134	PTR_ADDI	a0, a0, -8	/* arg0: self_addr */
135	PTR_ADDI	a1, sp, PT_R1	/* arg1: parent */
136	bl		prepare_ftrace_return
137	b		ftrace_common_return
138SYM_CODE_END(ftrace_graph_caller)
139
140SYM_CODE_START(return_to_handler)
141	UNWIND_HINT_UNDEFINED
142	/* Save return value regs */
143	PTR_ADDI	sp, sp, -FGRET_REGS_SIZE
144	PTR_S		a0, sp, FGRET_REGS_A0
145	PTR_S		a1, sp, FGRET_REGS_A1
146	PTR_S		zero, sp, FGRET_REGS_FP
147
148	move		a0, sp
149	bl		ftrace_return_to_handler
150	move		ra, a0
151
152	/* Restore return value regs */
153	PTR_L		a0, sp, FGRET_REGS_A0
154	PTR_L		a1, sp, FGRET_REGS_A1
155	PTR_ADDI	sp, sp, FGRET_REGS_SIZE
156
157	jr		ra
158SYM_CODE_END(return_to_handler)
159#endif
160
161#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
162SYM_CODE_START(ftrace_stub_direct_tramp)
163	UNWIND_HINT_UNDEFINED
164	jr		t0
165SYM_CODE_END(ftrace_stub_direct_tramp)
166#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
167