xref: /openbmc/linux/arch/riscv/include/asm/ftrace.h (revision b737eecd)
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 #define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
15 
16 #define ARCH_SUPPORTS_FTRACE_OPS 1
17 #ifndef __ASSEMBLY__
18 void _mcount(void);
19 static inline unsigned long ftrace_call_adjust(unsigned long addr)
20 {
21 	return addr;
22 }
23 
24 struct dyn_arch_ftrace {
25 };
26 #endif
27 
28 #ifdef CONFIG_DYNAMIC_FTRACE
29 /*
30  * A general call in RISC-V is a pair of insts:
31  * 1) auipc: setting high-20 pc-related bits to ra register
32  * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to
33  *          return address (original pc + 4)
34  *
35  * Dynamic ftrace generates probes to call sites, so we must deal with
36  * both auipc and jalr at the same time.
37  */
38 
39 #define MCOUNT_ADDR		((unsigned long)_mcount)
40 #define JALR_SIGN_MASK		(0x00000800)
41 #define JALR_OFFSET_MASK	(0x00000fff)
42 #define AUIPC_OFFSET_MASK	(0xfffff000)
43 #define AUIPC_PAD		(0x00001000)
44 #define JALR_SHIFT		20
45 #define JALR_BASIC		(0x000080e7)
46 #define AUIPC_BASIC		(0x00000097)
47 #define NOP4			(0x00000013)
48 
49 #define make_call(caller, callee, call)					\
50 do {									\
51 	call[0] = to_auipc_insn((unsigned int)((unsigned long)callee -	\
52 				(unsigned long)caller));		\
53 	call[1] = to_jalr_insn((unsigned int)((unsigned long)callee -	\
54 			       (unsigned long)caller));			\
55 } while (0)
56 
57 #define to_jalr_insn(offset)						\
58 	(((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_BASIC)
59 
60 #define to_auipc_insn(offset)						\
61 	((offset & JALR_SIGN_MASK) ?					\
62 	(((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_BASIC) :	\
63 	((offset & AUIPC_OFFSET_MASK) | AUIPC_BASIC))
64 
65 /*
66  * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here.
67  */
68 #define MCOUNT_INSN_SIZE 8
69 
70 #ifndef __ASSEMBLY__
71 struct dyn_ftrace;
72 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
73 #define ftrace_init_nop ftrace_init_nop
74 #endif
75 
76 #endif
77 
78 #endif /* _ASM_RISCV_FTRACE_H */
79