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
  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);
  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
  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
  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
 150 static __always_inline unsigned long ftrace_regs_get_instruction_pointer(const struct ftrace_regs
 151                                                                          *fregs)
 152 {
 153         return fregs->epc;
 154 }
 155
 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
 162 static __always_inline unsigned long ftrace_regs_get_stack_pointer(const struct ftrace_regs *fregs)
 163 {
 164         return fregs->sp;
 165 }
 166
 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
 175 static __always_inline unsigned long ftrace_regs_get_return_value(const struct ftrace_regs *fregs)
 176 {
 177         return fregs->a0;
 178 }
 179
 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
 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
 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
 216 static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
 217 {
 218         return ret_regs->a0;
 219 }
 220
 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 */