arch/riscv/include/asm/ftrace.h

   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
  19 extern void *return_address(unsigned int level);
  20
  21 #define ftrace_return_address(n) return_address(n)
  22
  23 void _mcount(void);
  24 static inline unsigned long ftrace_call_adjust(unsigned long addr)
  25 {
  26         return addr;
  27 }
  28
  29 /*
  30  * Let's do like x86/arm64 and ignore the compat syscalls.
  31  */
  32 #define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
  33 static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
  34 {
  35         return is_compat_task();
  36 }
  37
  38 #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
  39 static inline bool arch_syscall_match_sym_name(const char *sym,
  40                                                const char *name)
  41 {
  42         /*
  43          * Since all syscall functions have __riscv_ prefix, we must skip it.
  44          * However, as we described above, we decided to ignore compat
  45          * syscalls, so we don't care about __riscv_compat_ prefix here.
  46          */
  47         return !strcmp(sym + 8, name);
  48 }
  49
  50 struct dyn_arch_ftrace {
  51 };
  52 #endif
  53
  54 #ifdef CONFIG_DYNAMIC_FTRACE
  55 /*
  56  * A general call in RISC-V is a pair of insts:
  57  * 1) auipc: setting high-20 pc-related bits to ra register
  58  * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to
  59  *          return address (original pc + 4)
  60  *
  61  *<ftrace enable>:
  62  * 0: auipc  t0/ra, 0x?
  63  * 4: jalr   t0/ra, ?(t0/ra)
  64  *
  65  *<ftrace disable>:
  66  * 0: nop
  67  * 4: nop
  68  *
  69  * Dynamic ftrace generates probes to call sites, so we must deal with
  70  * both auipc and jalr at the same time.
  71  */
  72
  73 #define MCOUNT_ADDR             ((unsigned long)_mcount)
  74 #define JALR_SIGN_MASK          (0x00000800)
  75 #define JALR_OFFSET_MASK        (0x00000fff)
  76 #define AUIPC_OFFSET_MASK       (0xfffff000)
  77 #define AUIPC_PAD               (0x00001000)
  78 #define JALR_SHIFT              20
  79 #define JALR_RA                 (0x000080e7)
  80 #define AUIPC_RA                (0x00000097)
  81 #define JALR_T0                 (0x000282e7)
  82 #define AUIPC_T0                (0x00000297)
  83 #define NOP4                    (0x00000013)
  84
  85 #define to_jalr_t0(offset)                                              \
  86         (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_T0)
  87
  88 #define to_auipc_t0(offset)                                             \
  89         ((offset & JALR_SIGN_MASK) ?                                    \
  90         (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_T0) :       \
  91         ((offset & AUIPC_OFFSET_MASK) | AUIPC_T0))
  92
  93 #define make_call_t0(caller, callee, call)                              \
  94 do {                                                                    \
  95         unsigned int offset =                                           \
  96                 (unsigned long) callee - (unsigned long) caller;        \
  97         call[0] = to_auipc_t0(offset);                                  \
  98         call[1] = to_jalr_t0(offset);                                   \
  99 } while (0)
 100
 101 #define to_jalr_ra(offset)                                              \
 102         (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_RA)
 103
 104 #define to_auipc_ra(offset)                                             \
 105         ((offset & JALR_SIGN_MASK) ?                                    \
 106         (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_RA) :       \
 107         ((offset & AUIPC_OFFSET_MASK) | AUIPC_RA))
 108
 109 #define make_call_ra(caller, callee, call)                              \
 110 do {                                                                    \
 111         unsigned int offset =                                           \
 112                 (unsigned long) callee - (unsigned long) caller;        \
 113         call[0] = to_auipc_ra(offset);                                  \
 114         call[1] = to_jalr_ra(offset);                                   \
 115 } while (0)
 116
 117 /*
 118  * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here.
 119  */
 120 #define MCOUNT_INSN_SIZE 8
 121
 122 #ifndef __ASSEMBLY__
 123 struct dyn_ftrace;
 124 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 125 #define ftrace_init_nop ftrace_init_nop
 126
 127 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 128 struct ftrace_ops;
 129 struct ftrace_regs;
 130 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 131                        struct ftrace_ops *op, struct ftrace_regs *fregs);
 132 #define ftrace_graph_func ftrace_graph_func
 133
 134 static inline void __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)
 135 {
 136                 regs->t1 = addr;
 137 }
 138 #define arch_ftrace_set_direct_caller(fregs, addr) \
 139         __arch_ftrace_set_direct_caller(&(fregs)->regs, addr)
 140 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 141
 142 #endif /* __ASSEMBLY__ */
 143
 144 #endif /* CONFIG_DYNAMIC_FTRACE */
 145
 146 #ifndef __ASSEMBLY__
 147 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 148 struct fgraph_ret_regs {
 149         unsigned long a1;
 150         unsigned long a0;
 151         unsigned long s0;
 152         unsigned long ra;
 153 };
 154
 155 static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
 156 {
 157         return ret_regs->a0;
 158 }
 159
 160 static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
 161 {
 162         return ret_regs->s0;
 163 }
 164 #endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
 165 #endif
 166
 167 #endif /* _ASM_RISCV_FTRACE_H */