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 pt_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 pt_regs *regs)
  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 pt_regs *regs)
  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 int __init ftrace_dyn_arch_init(void)
  88 {
  89         return 0;
  90 }
  91
  92 static unsigned long gen_sethi_insn(unsigned long addr)
  93 {
  94         unsigned long opcode = 0x46000000;
  95         unsigned long imm = addr >> 12;
  96         unsigned long rt_num = 0xf << 20;
  97
  98         return ENDIAN_CONVERT(opcode | rt_num | imm);
  99 }
 100
 101 static unsigned long gen_ori_insn(unsigned long addr)
 102 {
 103         unsigned long opcode = 0x58000000;
 104         unsigned long imm = addr & 0x0000fff;
 105         unsigned long rt_num = 0xf << 20;
 106         unsigned long ra_num = 0xf << 15;
 107
 108         return ENDIAN_CONVERT(opcode | rt_num | ra_num | imm);
 109 }
 110
 111 static unsigned long gen_jral_insn(unsigned long addr)
 112 {
 113         unsigned long opcode = 0x4a000001;
 114         unsigned long rt_num = 0x1e << 20;
 115         unsigned long rb_num = 0xf << 10;
 116
 117         return ENDIAN_CONVERT(opcode | rt_num | rb_num);
 118 }
 119
 120 static void ftrace_gen_call_insn(unsigned long *call_insns,
 121                                  unsigned long addr)
 122 {
 123         call_insns[0] = gen_sethi_insn(addr); /* sethi $r15, imm20u       */
 124         call_insns[1] = gen_ori_insn(addr);   /* ori   $r15, $r15, imm15u */
 125         call_insns[2] = gen_jral_insn(addr);  /* jral  $lp,  $r15         */
 126 }
 127
 128 static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
 129                                 unsigned long *new_insn, bool validate)
 130 {
 131         unsigned long orig_insn[3];
 132
 133         if (validate) {
 134                 if (probe_kernel_read(orig_insn, (void *)pc, MCOUNT_INSN_SIZE))
 135                         return -EFAULT;
 136                 if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE))
 137                         return -EINVAL;
 138         }
 139
 140         if (probe_kernel_write((void *)pc, new_insn, MCOUNT_INSN_SIZE))
 141                 return -EPERM;
 142
 143         return 0;
 144 }
 145
 146 static int ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
 147                               unsigned long *new_insn, bool validate)
 148 {
 149         int ret;
 150
 151         ret = __ftrace_modify_code(pc, old_insn, new_insn, validate);
 152         if (ret)
 153                 return ret;
 154
 155         flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
 156
 157         return ret;
 158 }
 159
 160 int ftrace_update_ftrace_func(ftrace_func_t func)
 161 {
 162         unsigned long pc = (unsigned long)&ftrace_call;
 163         unsigned long old_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 164         unsigned long new_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 165
 166         if (func != ftrace_stub)
 167                 ftrace_gen_call_insn(new_insn, (unsigned long)func);
 168
 169         return ftrace_modify_code(pc, old_insn, new_insn, false);
 170 }
 171
 172 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 173 {
 174         unsigned long pc = rec->ip;
 175         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 176         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 177
 178         ftrace_gen_call_insn(call_insn, addr);
 179
 180         return ftrace_modify_code(pc, nop_insn, call_insn, true);
 181 }
 182
 183 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 184                     unsigned long addr)
 185 {
 186         unsigned long pc = rec->ip;
 187         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 188         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 189
 190         ftrace_gen_call_insn(call_insn, addr);
 191
 192         return ftrace_modify_code(pc, call_insn, nop_insn, true);
 193 }
 194 #endif /* CONFIG_DYNAMIC_FTRACE */
 195
 196 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 197 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 198                            unsigned long frame_pointer)
 199 {
 200         unsigned long return_hooker = (unsigned long)&return_to_handler;
 201         unsigned long old;
 202
 203         if (unlikely(atomic_read(&current->tracing_graph_pause)))
 204                 return;
 205
 206         old = *parent;
 207
 208         if (!function_graph_enter(old, self_addr, frame_pointer, NULL))
 209                 *parent = return_hooker;
 210 }
 211
 212 noinline void ftrace_graph_caller(void)
 213 {
 214         unsigned long *parent_ip =
 215                 (unsigned long *)(__builtin_frame_address(2) - 4);
 216
 217         unsigned long selfpc =
 218                 (unsigned long)(__builtin_return_address(1) - MCOUNT_INSN_SIZE);
 219
 220         unsigned long frame_pointer =
 221                 (unsigned long)__builtin_frame_address(3);
 222
 223         prepare_ftrace_return(parent_ip, selfpc, frame_pointer);
 224 }
 225
 226 extern unsigned long ftrace_return_to_handler(unsigned long frame_pointer);
 227 void __naked return_to_handler(void)
 228 {
 229         __asm__ __volatile__ (
 230                 /* save state needed by the ABI     */
 231                 "smw.adm $r0,[$sp],$r1,#0x0  \n\t"
 232
 233                 /* get original return address      */
 234                 "move $r0, $fp               \n\t"
 235                 "bal ftrace_return_to_handler\n\t"
 236                 "move $lp, $r0               \n\t"
 237
 238                 /* restore state nedded by the ABI  */
 239                 "lmw.bim $r0,[$sp],$r1,#0x0  \n\t");
 240 }
 241
 242 #ifdef CONFIG_DYNAMIC_FTRACE
 243 extern unsigned long ftrace_graph_call;
 244
 245 static int ftrace_modify_graph_caller(bool enable)
 246 {
 247         unsigned long pc = (unsigned long)&ftrace_graph_call;
 248         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 249         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 250
 251         ftrace_gen_call_insn(call_insn, (unsigned long)ftrace_graph_caller);
 252
 253         if (enable)
 254                 return ftrace_modify_code(pc, nop_insn, call_insn, true);
 255         else
 256                 return ftrace_modify_code(pc, call_insn, nop_insn, true);
 257 }
 258
 259 int ftrace_enable_ftrace_graph_caller(void)
 260 {
 261         return ftrace_modify_graph_caller(true);
 262 }
 263
 264 int ftrace_disable_ftrace_graph_caller(void)
 265 {
 266         return ftrace_modify_graph_caller(false);
 267 }
 268 #endif /* CONFIG_DYNAMIC_FTRACE */
 269
 270 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 271
 272
 273 #ifdef CONFIG_TRACE_IRQFLAGS
 274 noinline void __trace_hardirqs_off(void)
 275 {
 276         trace_hardirqs_off();
 277 }
 278 noinline void __trace_hardirqs_on(void)
 279 {
 280         trace_hardirqs_on();
 281 }
 282 #endif /* CONFIG_TRACE_IRQFLAGS */