1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 2022 Loongson Technology Corporation Limited
4 */
5
6#include <asm/export.h>
7#include <asm/ftrace.h>
8#include <asm/regdef.h>
9#include <asm/stackframe.h>
10
11	.text
12/*
13 * Due to -fpatchable-function-entry=2: the compiler inserted 2 NOPs before the
14 * regular C function prologue. When PC arrived here, the last 2 instructions
15 * are as follows:
16 * 	move		t0, ra
17 * 	bl		callsite (for modules, callsite is a tramplione)
18 *
19 * modules trampoline is as follows:
20 * 	lu12i.w		t1, callsite[31:12]
21 * 	lu32i.d		t1, callsite[51:32]
22 * 	lu52i.d		t1, t1, callsite[63:52]
23 * 	jirl		zero, t1, callsite[11:0] >> 2
24 *
25 * See arch/loongarch/kernel/ftrace_dyn.c for details. Here, pay attention to
26 * that the T series regs are available and safe because each C functions
27 * follows the LoongArch's psABI as well.
28 */
29
30	.macro  ftrace_regs_entry allregs=0
31	PTR_ADDI	sp, sp, -PT_SIZE
32	PTR_S		t0, sp, PT_R1  /* Save parent ra at PT_R1(RA) */
33	PTR_S		a0, sp, PT_R4
34	PTR_S		a1, sp, PT_R5
35	PTR_S		a2, sp, PT_R6
36	PTR_S		a3, sp, PT_R7
37	PTR_S		a4, sp, PT_R8
38	PTR_S		a5, sp, PT_R9
39	PTR_S		a6, sp, PT_R10
40	PTR_S		a7, sp, PT_R11
41	PTR_S		fp, sp, PT_R22
42	.if \allregs
43	PTR_S		tp, sp, PT_R2
44	PTR_S		t0, sp, PT_R12
45	PTR_S		t2, sp, PT_R14
46	PTR_S		t3, sp, PT_R15
47	PTR_S		t4, sp, PT_R16
48	PTR_S		t5, sp, PT_R17
49	PTR_S		t6, sp, PT_R18
50	PTR_S		t7, sp, PT_R19
51	PTR_S		t8, sp, PT_R20
52	PTR_S		u0, sp, PT_R21
53	PTR_S		s0, sp, PT_R23
54	PTR_S		s1, sp, PT_R24
55	PTR_S		s2, sp, PT_R25
56	PTR_S		s3, sp, PT_R26
57	PTR_S		s4, sp, PT_R27
58	PTR_S		s5, sp, PT_R28
59	PTR_S		s6, sp, PT_R29
60	PTR_S		s7, sp, PT_R30
61	PTR_S		s8, sp, PT_R31
62	/* Clear it for later use as a flag sometimes. */
63	PTR_S		zero, sp, PT_R0
64	.endif
65	PTR_S		ra, sp, PT_ERA /* Save trace function ra at PT_ERA */
66	move		t1, zero
67	PTR_S		t1, sp, PT_R13
68	PTR_ADDI	t8, sp, PT_SIZE
69	PTR_S		t8, sp, PT_R3
70	.endm
71
72SYM_FUNC_START(ftrace_stub)
73	jr		ra
74SYM_FUNC_END(ftrace_stub)
75
76SYM_CODE_START(ftrace_common)
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	ftrace_regs_entry allregs=0
118	b		ftrace_common
119SYM_CODE_END(ftrace_caller)
120
121#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
122SYM_CODE_START(ftrace_regs_caller)
123	ftrace_regs_entry allregs=1
124	b		ftrace_common
125SYM_CODE_END(ftrace_regs_caller)
126#endif
127
128#ifdef CONFIG_FUNCTION_GRAPH_TRACER
129SYM_CODE_START(ftrace_graph_caller)
130	PTR_L		a0, sp, PT_ERA
131	PTR_ADDI	a0, a0, -8	/* arg0: self_addr */
132	PTR_ADDI	a1, sp, PT_R1	/* arg1: parent */
133	bl		prepare_ftrace_return
134	b		ftrace_common_return
135SYM_CODE_END(ftrace_graph_caller)
136
137SYM_CODE_START(return_to_handler)
138	/* Save return value regs */
139	PTR_ADDI	sp, sp, -FGRET_REGS_SIZE
140	PTR_S		a0, sp, FGRET_REGS_A0
141	PTR_S		a1, sp, FGRET_REGS_A1
142	PTR_S		zero, sp, FGRET_REGS_FP
143
144	move		a0, sp
145	bl		ftrace_return_to_handler
146	move		ra, a0
147
148	/* Restore return value regs */
149	PTR_L		a0, sp, FGRET_REGS_A0
150	PTR_L		a1, sp, FGRET_REGS_A1
151	PTR_ADDI	sp, sp, FGRET_REGS_SIZE
152
153	jr		ra
154SYM_CODE_END(return_to_handler)
155#endif
156
157#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
158SYM_CODE_START(ftrace_stub_direct_tramp)
159	jr		t0
160SYM_CODE_END(ftrace_stub_direct_tramp)
161#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
162