1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2017 Steven Rostedt, VMware
4 */
5
6 #include <linux/export.h>
7 #include <linux/linkage.h>
8 #include <asm/page_types.h>
9 #include <asm/segment.h>
10 #include <asm/ftrace.h>
11 #include <asm/nospec-branch.h>
12 #include <asm/frame.h>
13 #include <asm/asm-offsets.h>
14
15 #ifdef CONFIG_FRAME_POINTER
16 # define MCOUNT_FRAME 1
17 #else
18 # define MCOUNT_FRAME 0
19 #endif
20
21 SYM_FUNC_START(__fentry__)
22 RET
23 SYM_FUNC_END(__fentry__)
24 EXPORT_SYMBOL(__fentry__)
25
26 SYM_CODE_START(ftrace_caller)
27
28 #ifdef CONFIG_FRAME_POINTER
29 /*
30 * Frame pointers are of ip followed b
31 * Since fentry is an immediate jump,
32 * parent-ip, function-ip. We need to
33 * parent-ip followed by ebp.
34 */
35 pushl 4(%esp)
36 pushl %ebp
37 movl %esp, %ebp
38 pushl 2*4(%esp)
39
40 /* For mcount, the function ip is dire
41 pushl %ebp
42 movl %esp, %ebp
43 #endif
44 pushl %eax
45 pushl %ecx
46 pushl %edx
47 pushl $0
48
49 #ifdef CONFIG_FRAME_POINTER
50 /* Load parent ebp into edx */
51 movl 4*4(%esp), %edx
52 #else
53 /* There's no frame pointer, load the
54 lea 4*4(%esp), %edx
55 #endif
56
57 movl (MCOUNT_FRAME+4)*4(%esp), %eax
58 /* Get the parent ip */
59 movl 4(%edx), %edx
60
61 movl function_trace_op, %ecx
62 subl $MCOUNT_INSN_SIZE, %eax
63
64 .globl ftrace_call
65 ftrace_call:
66 call ftrace_stub
67
68 addl $4, %esp
69 popl %edx
70 popl %ecx
71 popl %eax
72 #ifdef CONFIG_FRAME_POINTER
73 popl %ebp
74 addl $4,%esp
75 popl %ebp
76 addl $4, %esp
77 #endif
78 .Lftrace_ret:
79 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
80 .globl ftrace_graph_call
81 ftrace_graph_call:
82 jmp ftrace_stub
83 #endif
84
85 /* This is weak to keep gas from relaxing the
86 SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK)
87 RET
88 SYM_CODE_END(ftrace_caller)
89
90 SYM_CODE_START(ftrace_regs_caller)
91 /*
92 * We're here from an mcount/fentry CA
93 *
94 * <previous context>
95 * RET-IP
96 *
97 * The purpose of this function is to
98 * environment with a stack frame like
99 *
100 * <previous context>
101 * gap / RET-IP
102 * gap
103 * gap
104 * gap
105 * pt_regs
106 *
107 * We do _NOT_ restore: ss, flags, cs,
108 */
109 subl $3*4, %esp # RET-IP + 3 g
110 pushl %ss # ss
111 pushl %esp # points at ss
112 addl $5*4, (%esp) # make it po
113 pushfl # flags
114 pushl $__KERNEL_CS # cs
115 pushl 7*4(%esp) # ip <- RET-IP
116 pushl $0 # orig_eax
117
118 pushl %gs
119 pushl %fs
120 pushl %es
121 pushl %ds
122
123 pushl %eax
124 pushl %ebp
125 pushl %edi
126 pushl %esi
127 pushl %edx
128 pushl %ecx
129 pushl %ebx
130
131 ENCODE_FRAME_POINTER
132
133 movl PT_EIP(%esp), %eax # 1st
134 subl $MCOUNT_INSN_SIZE, %eax
135 movl 21*4(%esp), %edx # 2nd
136 movl function_trace_op, %ecx # 3rd
137 pushl %esp # 4th
138
139 SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL
140 call ftrace_stub
141
142 addl $4, %esp # skip
143
144 /* place IP below the new SP */
145 movl PT_OLDESP(%esp), %eax
146 movl PT_EIP(%esp), %ecx
147 movl %ecx, -4(%eax)
148
149 /* place EAX below that */
150 movl PT_EAX(%esp), %ecx
151 movl %ecx, -8(%eax)
152
153 popl %ebx
154 popl %ecx
155 popl %edx
156 popl %esi
157 popl %edi
158 popl %ebp
159
160 lea -8(%eax), %esp
161 popl %eax
162
163 jmp .Lftrace_ret
164 SYM_CODE_END(ftrace_regs_caller)
165
166 SYM_FUNC_START(ftrace_stub_direct_tramp)
167 CALL_DEPTH_ACCOUNT
168 RET
169 SYM_FUNC_END(ftrace_stub_direct_tramp)
170
171 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
172 SYM_CODE_START(ftrace_graph_caller)
173 pushl %eax
174 pushl %ecx
175 pushl %edx
176 movl 3*4(%esp), %eax
177 /* Even with frame pointers, fentry do
178 lea 4*4(%esp), %edx
179 movl $0, %ecx
180 subl $MCOUNT_INSN_SIZE, %eax
181 call prepare_ftrace_return
182 popl %edx
183 popl %ecx
184 popl %eax
185 RET
186 SYM_CODE_END(ftrace_graph_caller)
187
188 .globl return_to_handler
189 return_to_handler:
190 pushl $0
191 pushl %edx
192 pushl %eax
193 movl %esp, %eax
194 call ftrace_return_to_handler
195 movl %eax, %ecx
196 popl %eax
197 popl %edx
198 addl $4, %esp # skip
199 JMP_NOSPEC ecx
200 #endif
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