xref: /linux/arch/riscv/include/asm/ftrace.h (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (C) 2017 Andes Technology Corporation */
3 
4 #ifndef _ASM_RISCV_FTRACE_H
5 #define _ASM_RISCV_FTRACE_H
6 
7 /*
8  * The graph frame test is not possible if CONFIG_FRAME_POINTER is not enabled.
9  * Check arch/riscv/kernel/mcount.S for detail.
10  */
11 #if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER)
12 #define HAVE_FUNCTION_GRAPH_FP_TEST
13 #endif
14 
15 #define ARCH_SUPPORTS_FTRACE_OPS 1
16 #ifndef __ASSEMBLY__
17 
18 extern void *return_address(unsigned int level);
19 
20 #define ftrace_return_address(n) return_address(n)
21 
22 void _mcount(void);
ftrace_call_adjust(unsigned long addr)23 static inline unsigned long ftrace_call_adjust(unsigned long addr)
24 {
25 	return addr;
26 }
27 
28 /*
29  * Let's do like x86/arm64 and ignore the compat syscalls.
30  */
31 #define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
arch_trace_is_compat_syscall(struct pt_regs * regs)32 static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
33 {
34 	return is_compat_task();
35 }
36 
37 #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
arch_syscall_match_sym_name(const char * sym,const char * name)38 static inline bool arch_syscall_match_sym_name(const char *sym,
39 					       const char *name)
40 {
41 	/*
42 	 * Since all syscall functions have __riscv_ prefix, we must skip it.
43 	 * However, as we described above, we decided to ignore compat
44 	 * syscalls, so we don't care about __riscv_compat_ prefix here.
45 	 */
46 	return !strcmp(sym + 8, name);
47 }
48 
49 struct dyn_arch_ftrace {
50 };
51 #endif
52 
53 #ifdef CONFIG_DYNAMIC_FTRACE
54 /*
55  * A general call in RISC-V is a pair of insts:
56  * 1) auipc: setting high-20 pc-related bits to ra register
57  * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to
58  *          return address (original pc + 4)
59  *
60  *<ftrace enable>:
61  * 0: auipc  t0/ra, 0x?
62  * 4: jalr   t0/ra, ?(t0/ra)
63  *
64  *<ftrace disable>:
65  * 0: nop
66  * 4: nop
67  *
68  * Dynamic ftrace generates probes to call sites, so we must deal with
69  * both auipc and jalr at the same time.
70  */
71 
72 #define MCOUNT_ADDR		((unsigned long)_mcount)
73 #define JALR_SIGN_MASK		(0x00000800)
74 #define JALR_OFFSET_MASK	(0x00000fff)
75 #define AUIPC_OFFSET_MASK	(0xfffff000)
76 #define AUIPC_PAD		(0x00001000)
77 #define JALR_SHIFT		20
78 #define JALR_RA			(0x000080e7)
79 #define AUIPC_RA		(0x00000097)
80 #define JALR_T0			(0x000282e7)
81 #define AUIPC_T0		(0x00000297)
82 #define NOP4			(0x00000013)
83 
84 #define to_jalr_t0(offset)						\
85 	(((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_T0)
86 
87 #define to_auipc_t0(offset)						\
88 	((offset & JALR_SIGN_MASK) ?					\
89 	(((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_T0) :	\
90 	((offset & AUIPC_OFFSET_MASK) | AUIPC_T0))
91 
92 #define make_call_t0(caller, callee, call)				\
93 do {									\
94 	unsigned int offset =						\
95 		(unsigned long) callee - (unsigned long) caller;	\
96 	call[0] = to_auipc_t0(offset);					\
97 	call[1] = to_jalr_t0(offset);					\
98 } while (0)
99 
100 #define to_jalr_ra(offset)						\
101 	(((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_RA)
102 
103 #define to_auipc_ra(offset)						\
104 	((offset & JALR_SIGN_MASK) ?					\
105 	(((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_RA) :	\
106 	((offset & AUIPC_OFFSET_MASK) | AUIPC_RA))
107 
108 #define make_call_ra(caller, callee, call)				\
109 do {									\
110 	unsigned int offset =						\
111 		(unsigned long) callee - (unsigned long) caller;	\
112 	call[0] = to_auipc_ra(offset);					\
113 	call[1] = to_jalr_ra(offset);					\
114 } while (0)
115 
116 /*
117  * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here.
118  */
119 #define MCOUNT_INSN_SIZE 8
120 
121 #ifndef __ASSEMBLY__
122 struct dyn_ftrace;
123 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
124 #define ftrace_init_nop ftrace_init_nop
125 
126 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
127 #define arch_ftrace_get_regs(regs) NULL
128 struct ftrace_ops;
129 struct ftrace_regs {
130 	unsigned long epc;
131 	unsigned long ra;
132 	unsigned long sp;
133 	unsigned long s0;
134 	unsigned long t1;
135 	union {
136 		unsigned long args[8];
137 		struct {
138 			unsigned long a0;
139 			unsigned long a1;
140 			unsigned long a2;
141 			unsigned long a3;
142 			unsigned long a4;
143 			unsigned long a5;
144 			unsigned long a6;
145 			unsigned long a7;
146 		};
147 	};
148 };
149 
ftrace_regs_get_instruction_pointer(const struct ftrace_regs * fregs)150 static __always_inline unsigned long ftrace_regs_get_instruction_pointer(const struct ftrace_regs
151 									 *fregs)
152 {
153 	return fregs->epc;
154 }
155 
ftrace_regs_set_instruction_pointer(struct ftrace_regs * fregs,unsigned long pc)156 static __always_inline void ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
157 								unsigned long pc)
158 {
159 	fregs->epc = pc;
160 }
161 
ftrace_regs_get_stack_pointer(const struct ftrace_regs * fregs)162 static __always_inline unsigned long ftrace_regs_get_stack_pointer(const struct ftrace_regs *fregs)
163 {
164 	return fregs->sp;
165 }
166 
ftrace_regs_get_argument(struct ftrace_regs * fregs,unsigned int n)167 static __always_inline unsigned long ftrace_regs_get_argument(struct ftrace_regs *fregs,
168 							      unsigned int n)
169 {
170 	if (n < 8)
171 		return fregs->args[n];
172 	return 0;
173 }
174 
ftrace_regs_get_return_value(const struct ftrace_regs * fregs)175 static __always_inline unsigned long ftrace_regs_get_return_value(const struct ftrace_regs *fregs)
176 {
177 	return fregs->a0;
178 }
179 
ftrace_regs_set_return_value(struct ftrace_regs * fregs,unsigned long ret)180 static __always_inline void ftrace_regs_set_return_value(struct ftrace_regs *fregs,
181 							 unsigned long ret)
182 {
183 	fregs->a0 = ret;
184 }
185 
ftrace_override_function_with_return(struct ftrace_regs * fregs)186 static __always_inline void ftrace_override_function_with_return(struct ftrace_regs *fregs)
187 {
188 	fregs->epc = fregs->ra;
189 }
190 
191 int ftrace_regs_query_register_offset(const char *name);
192 
193 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
194 		       struct ftrace_ops *op, struct ftrace_regs *fregs);
195 #define ftrace_graph_func ftrace_graph_func
196 
arch_ftrace_set_direct_caller(struct ftrace_regs * fregs,unsigned long addr)197 static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs, unsigned long addr)
198 {
199 	fregs->t1 = addr;
200 }
201 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */
202 
203 #endif /* __ASSEMBLY__ */
204 
205 #endif /* CONFIG_DYNAMIC_FTRACE */
206 
207 #ifndef __ASSEMBLY__
208 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
209 struct fgraph_ret_regs {
210 	unsigned long a1;
211 	unsigned long a0;
212 	unsigned long s0;
213 	unsigned long ra;
214 };
215 
fgraph_ret_regs_return_value(struct fgraph_ret_regs * ret_regs)216 static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
217 {
218 	return ret_regs->a0;
219 }
220 
fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs * ret_regs)221 static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
222 {
223 	return ret_regs->s0;
224 }
225 #endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
226 #endif
227 
228 #endif /* _ASM_RISCV_FTRACE_H */
229