arch/nds32/kernel/ftrace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/ftrace.h>
   4 #include <linux/uaccess.h>
   5 #include <asm/cacheflush.h>
   6
   7 #ifndef CONFIG_DYNAMIC_FTRACE
   8 extern void (*ftrace_trace_function)(unsigned long, unsigned long,
   9                                      struct ftrace_ops*, struct ftrace_regs*);
  10 extern void ftrace_graph_caller(void);
  11
  12 noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
  13                                   struct ftrace_ops *op, struct ftrace_regs *fregs)
  14 {
  15         __asm__ ("");  /* avoid to optimize as pure function */
  16 }
  17
  18 noinline void _mcount(unsigned long parent_ip)
  19 {
  20         /* save all state by the compiler prologue */
  21
  22         unsigned long ip = (unsigned long)__builtin_return_address(0);
  23
  24         if (ftrace_trace_function != ftrace_stub)
  25                 ftrace_trace_function(ip - MCOUNT_INSN_SIZE, parent_ip,
  26                                       NULL, NULL);
  27
  28 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  29         if (ftrace_graph_return != (trace_func_graph_ret_t)ftrace_stub
  30             || ftrace_graph_entry != ftrace_graph_entry_stub)
  31                 ftrace_graph_caller();
  32 #endif
  33
  34         /* restore all state by the compiler epilogue */
  35 }
  36 EXPORT_SYMBOL(_mcount);
  37
  38 #else /* CONFIG_DYNAMIC_FTRACE */
  39
  40 noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
  41                                   struct ftrace_ops *op, struct ftrace_regs *fregs)
  42 {
  43         __asm__ ("");  /* avoid to optimize as pure function */
  44 }
  45
  46 noinline void __naked _mcount(unsigned long parent_ip)
  47 {
  48         __asm__ ("");  /* avoid to optimize as pure function */
  49 }
  50 EXPORT_SYMBOL(_mcount);
  51
  52 #define XSTR(s) STR(s)
  53 #define STR(s) #s
  54 void _ftrace_caller(unsigned long parent_ip)
  55 {
  56         /* save all state needed by the compiler prologue */
  57
  58         /*
  59          * prepare arguments for real tracing function
  60          * first  arg : __builtin_return_address(0) - MCOUNT_INSN_SIZE
  61          * second arg : parent_ip
  62          */
  63         __asm__ __volatile__ (
  64                 "move $r1, %0                              \n\t"
  65                 "addi $r0, %1, #-" XSTR(MCOUNT_INSN_SIZE) "\n\t"
  66                 :
  67                 : "r" (parent_ip), "r" (__builtin_return_address(0)));
  68
  69         /* a placeholder for the call to a real tracing function */
  70         __asm__ __volatile__ (
  71                 "ftrace_call:           \n\t"
  72                 "nop                    \n\t"
  73                 "nop                    \n\t"
  74                 "nop                    \n\t");
  75
  76 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  77         /* a placeholder for the call to ftrace_graph_caller */
  78         __asm__ __volatile__ (
  79                 "ftrace_graph_call:     \n\t"
  80                 "nop                    \n\t"
  81                 "nop                    \n\t"
  82                 "nop                    \n\t");
  83 #endif
  84         /* restore all state needed by the compiler epilogue */
  85 }
  86
  87 static unsigned long gen_sethi_insn(unsigned long addr)
  88 {
  89         unsigned long opcode = 0x46000000;
  90         unsigned long imm = addr >> 12;
  91         unsigned long rt_num = 0xf << 20;
  92
  93         return ENDIAN_CONVERT(opcode | rt_num | imm);
  94 }
  95
  96 static unsigned long gen_ori_insn(unsigned long addr)
  97 {
  98         unsigned long opcode = 0x58000000;
  99         unsigned long imm = addr & 0x0000fff;
 100         unsigned long rt_num = 0xf << 20;
 101         unsigned long ra_num = 0xf << 15;
 102
 103         return ENDIAN_CONVERT(opcode | rt_num | ra_num | imm);
 104 }
 105
 106 static unsigned long gen_jral_insn(unsigned long addr)
 107 {
 108         unsigned long opcode = 0x4a000001;
 109         unsigned long rt_num = 0x1e << 20;
 110         unsigned long rb_num = 0xf << 10;
 111
 112         return ENDIAN_CONVERT(opcode | rt_num | rb_num);
 113 }
 114
 115 static void ftrace_gen_call_insn(unsigned long *call_insns,
 116                                  unsigned long addr)
 117 {
 118         call_insns[0] = gen_sethi_insn(addr); /* sethi $r15, imm20u       */
 119         call_insns[1] = gen_ori_insn(addr);   /* ori   $r15, $r15, imm15u */
 120         call_insns[2] = gen_jral_insn(addr);  /* jral  $lp,  $r15         */
 121 }
 122
 123 static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
 124                                 unsigned long *new_insn, bool validate)
 125 {
 126         unsigned long orig_insn[3];
 127
 128         if (validate) {
 129                 if (copy_from_kernel_nofault(orig_insn, (void *)pc,
 130                                 MCOUNT_INSN_SIZE))
 131                         return -EFAULT;
 132                 if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE))
 133                         return -EINVAL;
 134         }
 135
 136         if (copy_to_kernel_nofault((void *)pc, new_insn, MCOUNT_INSN_SIZE))
 137                 return -EPERM;
 138
 139         return 0;
 140 }
 141
 142 static int ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
 143                               unsigned long *new_insn, bool validate)
 144 {
 145         int ret;
 146
 147         ret = __ftrace_modify_code(pc, old_insn, new_insn, validate);
 148         if (ret)
 149                 return ret;
 150
 151         flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
 152
 153         return ret;
 154 }
 155
 156 int ftrace_update_ftrace_func(ftrace_func_t func)
 157 {
 158         unsigned long pc = (unsigned long)&ftrace_call;
 159         unsigned long old_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 160         unsigned long new_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 161
 162         if (func != ftrace_stub)
 163                 ftrace_gen_call_insn(new_insn, (unsigned long)func);
 164
 165         return ftrace_modify_code(pc, old_insn, new_insn, false);
 166 }
 167
 168 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 169 {
 170         unsigned long pc = rec->ip;
 171         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 172         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 173
 174         ftrace_gen_call_insn(call_insn, addr);
 175
 176         return ftrace_modify_code(pc, nop_insn, call_insn, true);
 177 }
 178
 179 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 180                     unsigned long addr)
 181 {
 182         unsigned long pc = rec->ip;
 183         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 184         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 185
 186         ftrace_gen_call_insn(call_insn, addr);
 187
 188         return ftrace_modify_code(pc, call_insn, nop_insn, true);
 189 }
 190 #endif /* CONFIG_DYNAMIC_FTRACE */
 191
 192 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 193 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 194                            unsigned long frame_pointer)
 195 {
 196         unsigned long return_hooker = (unsigned long)&return_to_handler;
 197         unsigned long old;
 198
 199         if (unlikely(atomic_read(&current->tracing_graph_pause)))
 200                 return;
 201
 202         old = *parent;
 203
 204         if (!function_graph_enter(old, self_addr, frame_pointer, NULL))
 205                 *parent = return_hooker;
 206 }
 207
 208 noinline void ftrace_graph_caller(void)
 209 {
 210         unsigned long *parent_ip =
 211                 (unsigned long *)(__builtin_frame_address(2) - 4);
 212
 213         unsigned long selfpc =
 214                 (unsigned long)(__builtin_return_address(1) - MCOUNT_INSN_SIZE);
 215
 216         unsigned long frame_pointer =
 217                 (unsigned long)__builtin_frame_address(3);
 218
 219         prepare_ftrace_return(parent_ip, selfpc, frame_pointer);
 220 }
 221
 222 extern unsigned long ftrace_return_to_handler(unsigned long frame_pointer);
 223 void __naked return_to_handler(void)
 224 {
 225         __asm__ __volatile__ (
 226                 /* save state needed by the ABI     */
 227                 "smw.adm $r0,[$sp],$r1,#0x0  \n\t"
 228
 229                 /* get original return address      */
 230                 "move $r0, $fp               \n\t"
 231                 "bal ftrace_return_to_handler\n\t"
 232                 "move $lp, $r0               \n\t"
 233
 234                 /* restore state needed by the ABI  */
 235                 "lmw.bim $r0,[$sp],$r1,#0x0  \n\t");
 236 }
 237
 238 #ifdef CONFIG_DYNAMIC_FTRACE
 239 extern unsigned long ftrace_graph_call;
 240
 241 static int ftrace_modify_graph_caller(bool enable)
 242 {
 243         unsigned long pc = (unsigned long)&ftrace_graph_call;
 244         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 245         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 246
 247         ftrace_gen_call_insn(call_insn, (unsigned long)ftrace_graph_caller);
 248
 249         if (enable)
 250                 return ftrace_modify_code(pc, nop_insn, call_insn, true);
 251         else
 252                 return ftrace_modify_code(pc, call_insn, nop_insn, true);
 253 }
 254
 255 int ftrace_enable_ftrace_graph_caller(void)
 256 {
 257         return ftrace_modify_graph_caller(true);
 258 }
 259
 260 int ftrace_disable_ftrace_graph_caller(void)
 261 {
 262         return ftrace_modify_graph_caller(false);
 263 }
 264 #endif /* CONFIG_DYNAMIC_FTRACE */
 265
 266 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 267
 268
 269 #ifdef CONFIG_TRACE_IRQFLAGS
 270 noinline void __trace_hardirqs_off(void)
 271 {
 272         trace_hardirqs_off();
 273 }
 274 noinline void __trace_hardirqs_on(void)
 275 {
 276         trace_hardirqs_on();
 277 }
 278 #endif /* CONFIG_TRACE_IRQFLAGS */