summaryrefslogtreecommitdiffstats
path: root/arch/riscv/include/asm/ftrace.h
blob: 15055f9df4daa1e4250c8a37c64193bf5c943ee3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2017 Andes Technology Corporation */

#ifndef _ASM_RISCV_FTRACE_H
#define _ASM_RISCV_FTRACE_H

/*
 * The graph frame test is not possible if CONFIG_FRAME_POINTER is not enabled.
 * Check arch/riscv/kernel/mcount.S for detail.
 */
#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER)
#define HAVE_FUNCTION_GRAPH_FP_TEST
#endif
#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR

/*
 * Clang prior to 13 had "mcount" instead of "_mcount":
 * https://reviews.llvm.org/D98881
 */
#if defined(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION >= 130000
#define MCOUNT_NAME _mcount
#else
#define MCOUNT_NAME mcount
#endif

#define ARCH_SUPPORTS_FTRACE_OPS 1
#ifndef __ASSEMBLY__

extern void *return_address(unsigned int level);

#define ftrace_return_address(n) return_address(n)

void MCOUNT_NAME(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
	return addr;
}

/*
 * Let's do like x86/arm64 and ignore the compat syscalls.
 */
#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
{
	return is_compat_task();
}

#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
static inline bool arch_syscall_match_sym_name(const char *sym,
					       const char *name)
{
	/*
	 * Since all syscall functions have __riscv_ prefix, we must skip it.
	 * However, as we described above, we decided to ignore compat
	 * syscalls, so we don't care about __riscv_compat_ prefix here.
	 */
	return !strcmp(sym + 8, name);
}

struct dyn_arch_ftrace {
};
#endif

#ifdef CONFIG_DYNAMIC_FTRACE
/*
 * A general call in RISC-V is a pair of insts:
 * 1) auipc: setting high-20 pc-related bits to ra register
 * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to
 *          return address (original pc + 4)
 *
 *<ftrace enable>:
 * 0: auipc  t0/ra, 0x?
 * 4: jalr   t0/ra, ?(t0/ra)
 *
 *<ftrace disable>:
 * 0: nop
 * 4: nop
 *
 * Dynamic ftrace generates probes to call sites, so we must deal with
 * both auipc and jalr at the same time.
 */

#define MCOUNT_ADDR		((unsigned long)MCOUNT_NAME)
#define JALR_SIGN_MASK		(0x00000800)
#define JALR_OFFSET_MASK	(0x00000fff)
#define AUIPC_OFFSET_MASK	(0xfffff000)
#define AUIPC_PAD		(0x00001000)
#define JALR_SHIFT		20
#define JALR_RA			(0x000080e7)
#define AUIPC_RA		(0x00000097)
#define JALR_T0			(0x000282e7)
#define AUIPC_T0		(0x00000297)
#define NOP4			(0x00000013)

#define to_jalr_t0(offset)						\
	(((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_T0)

#define to_auipc_t0(offset)						\
	((offset & JALR_SIGN_MASK) ?					\
	(((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_T0) :	\
	((offset & AUIPC_OFFSET_MASK) | AUIPC_T0))

#define make_call_t0(caller, callee, call)				\
do {									\
	unsigned int offset =						\
		(unsigned long) callee - (unsigned long) caller;	\
	call[0] = to_auipc_t0(offset);					\
	call[1] = to_jalr_t0(offset);					\
} while (0)

#define to_jalr_ra(offset)						\
	(((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_RA)

#define to_auipc_ra(offset)						\
	((offset & JALR_SIGN_MASK) ?					\
	(((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_RA) :	\
	((offset & AUIPC_OFFSET_MASK) | AUIPC_RA))

#define make_call_ra(caller, callee, call)				\
do {									\
	unsigned int offset =						\
		(unsigned long) callee - (unsigned long) caller;	\
	call[0] = to_auipc_ra(offset);					\
	call[1] = to_jalr_ra(offset);					\
} while (0)

/*
 * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here.
 */
#define MCOUNT_INSN_SIZE 8

#ifndef __ASSEMBLY__
struct dyn_ftrace;
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
#define ftrace_init_nop ftrace_init_nop

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
struct ftrace_ops;
struct ftrace_regs;
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
		       struct ftrace_ops *op, struct ftrace_regs *fregs);
#define ftrace_graph_func ftrace_graph_func

static inline void __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)
{
		regs->t1 = addr;
}
#define arch_ftrace_set_direct_caller(fregs, addr) \
	__arch_ftrace_set_direct_caller(&(fregs)->regs, addr)
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */

#endif /* __ASSEMBLY__ */

#endif /* CONFIG_DYNAMIC_FTRACE */

#ifndef __ASSEMBLY__
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
struct fgraph_ret_regs {
	unsigned long a1;
	unsigned long a0;
	unsigned long s0;
	unsigned long ra;
};

static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
{
	return ret_regs->a0;
}

static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
{
	return ret_regs->s0;
}
#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
#endif

#endif /* _ASM_RISCV_FTRACE_H */