xref: /openbmc/linux/arch/arm64/include/asm/ftrace.h (revision 801b27e8)
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * arch/arm64/include/asm/ftrace.h
4  *
5  * Copyright (C) 2013 Linaro Limited
6  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
7  */
8 #ifndef __ASM_FTRACE_H
9 #define __ASM_FTRACE_H
10 
11 #include <asm/insn.h>
12 
13 #define HAVE_FUNCTION_GRAPH_FP_TEST
14 
15 /*
16  * HAVE_FUNCTION_GRAPH_RET_ADDR_PTR means that the architecture can provide a
17  * "return address pointer" which can be used to uniquely identify a return
18  * address which has been overwritten.
19  *
20  * On arm64 we use the address of the caller's frame record, which remains the
21  * same for the lifetime of the instrumented function, unlike the return
22  * address in the LR.
23  */
24 #define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
25 
26 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
27 #define ARCH_SUPPORTS_FTRACE_OPS 1
28 #else
29 #define MCOUNT_ADDR		((unsigned long)_mcount)
30 #endif
31 
32 /* The BL at the callsite's adjusted rec->ip */
33 #define MCOUNT_INSN_SIZE	AARCH64_INSN_SIZE
34 
35 #define FTRACE_PLT_IDX		0
36 #define NR_FTRACE_PLTS		1
37 
38 /*
39  * Currently, gcc tends to save the link register after the local variables
40  * on the stack. This causes the max stack tracer to report the function
41  * frame sizes for the wrong functions. By defining
42  * ARCH_FTRACE_SHIFT_STACK_TRACER, it will tell the stack tracer to expect
43  * to find the return address on the stack after the local variables have
44  * been set up.
45  *
46  * Note, this may change in the future, and we will need to deal with that
47  * if it were to happen.
48  */
49 #define ARCH_FTRACE_SHIFT_STACK_TRACER 1
50 
51 #ifndef __ASSEMBLY__
52 #include <linux/compat.h>
53 
54 extern void _mcount(unsigned long);
55 extern void *return_address(unsigned int);
56 
57 struct dyn_arch_ftrace {
58 	/* No extra data needed for arm64 */
59 };
60 
61 extern unsigned long ftrace_graph_call;
62 
63 extern void return_to_handler(void);
64 
65 unsigned long ftrace_call_adjust(unsigned long addr);
66 
67 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
68 struct dyn_ftrace;
69 struct ftrace_ops;
70 
71 #define arch_ftrace_get_regs(regs) NULL
72 
73 /*
74  * Note: sizeof(struct ftrace_regs) must be a multiple of 16 to ensure correct
75  * stack alignment
76  */
77 struct ftrace_regs {
78 	/* x0 - x8 */
79 	unsigned long regs[9];
80 
81 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
82 	unsigned long direct_tramp;
83 #else
84 	unsigned long __unused;
85 #endif
86 
87 	unsigned long fp;
88 	unsigned long lr;
89 
90 	unsigned long sp;
91 	unsigned long pc;
92 };
93 
94 static __always_inline unsigned long
95 ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs)
96 {
97 	return fregs->pc;
98 }
99 
100 static __always_inline void
101 ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
102 				    unsigned long pc)
103 {
104 	fregs->pc = pc;
105 }
106 
107 static __always_inline unsigned long
108 ftrace_regs_get_stack_pointer(const struct ftrace_regs *fregs)
109 {
110 	return fregs->sp;
111 }
112 
113 static __always_inline unsigned long
114 ftrace_regs_get_argument(struct ftrace_regs *fregs, unsigned int n)
115 {
116 	if (n < 8)
117 		return fregs->regs[n];
118 	return 0;
119 }
120 
121 static __always_inline unsigned long
122 ftrace_regs_get_return_value(const struct ftrace_regs *fregs)
123 {
124 	return fregs->regs[0];
125 }
126 
127 static __always_inline void
128 ftrace_regs_set_return_value(struct ftrace_regs *fregs,
129 			     unsigned long ret)
130 {
131 	fregs->regs[0] = ret;
132 }
133 
134 static __always_inline void
135 ftrace_override_function_with_return(struct ftrace_regs *fregs)
136 {
137 	fregs->pc = fregs->lr;
138 }
139 
140 int ftrace_regs_query_register_offset(const char *name);
141 
142 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
143 #define ftrace_init_nop ftrace_init_nop
144 
145 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
146 		       struct ftrace_ops *op, struct ftrace_regs *fregs);
147 #define ftrace_graph_func ftrace_graph_func
148 
149 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
150 static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs,
151 						 unsigned long addr)
152 {
153 	/*
154 	 * The ftrace trampoline will return to this address instead of the
155 	 * instrumented function.
156 	 */
157 	fregs->direct_tramp = addr;
158 }
159 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
160 
161 #endif
162 
163 #define ftrace_return_address(n) return_address(n)
164 
165 /*
166  * Because AArch32 mode does not share the same syscall table with AArch64,
167  * tracing compat syscalls may result in reporting bogus syscalls or even
168  * hang-up, so just do not trace them.
169  * See kernel/trace/trace_syscalls.c
170  *
171  * x86 code says:
172  * If the user really wants these, then they should use the
173  * raw syscall tracepoints with filtering.
174  */
175 #define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
176 static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
177 {
178 	return is_compat_task();
179 }
180 
181 #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
182 
183 static inline bool arch_syscall_match_sym_name(const char *sym,
184 					       const char *name)
185 {
186 	/*
187 	 * Since all syscall functions have __arm64_ prefix, we must skip it.
188 	 * However, as we described above, we decided to ignore compat
189 	 * syscalls, so we don't care about __arm64_compat_ prefix here.
190 	 */
191 	return !strcmp(sym + 8, name);
192 }
193 #endif /* ifndef __ASSEMBLY__ */
194 
195 #ifndef __ASSEMBLY__
196 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
197 struct fgraph_ret_regs {
198 	/* x0 - x7 */
199 	unsigned long regs[8];
200 
201 	unsigned long fp;
202 	unsigned long __unused;
203 };
204 
205 static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
206 {
207 	return ret_regs->regs[0];
208 }
209 
210 static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
211 {
212 	return ret_regs->fp;
213 }
214 
215 void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
216 			   unsigned long frame_pointer);
217 
218 #endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER  */
219 #endif
220 
221 #endif /* __ASM_FTRACE_H */
222