ptrace_h.c

   1 /*
   2  *    ptrace cpu depend helper functions
   3  *
   4  *  Copyright 2003, 2015 Yoshinori Sato <ysato@users.sourceforge.jp>
   5  *
   6  * This file is subject to the terms and conditions of the GNU General
   7  * Public License.  See the file COPYING in the main directory of
   8  * this archive for more details.
   9  */
  10
  11 #include <linux/linkage.h>
  12 #include <linux/sched/signal.h>
  13 #include <asm/ptrace.h>
  14
  15 #define BREAKINST 0x5730 /* trapa #3 */
  16
  17 /* disable singlestep */
  18 void user_disable_single_step(struct task_struct *child)
  19 {
  20         if ((long)child->thread.breakinfo.addr != -1L) {
  21                 *(child->thread.breakinfo.addr) = child->thread.breakinfo.inst;
  22                 child->thread.breakinfo.addr = (unsigned short *)-1L;
  23         }
  24 }
  25
  26 /* calculate next pc */
  27 enum jump_type {none,    /* normal instruction */
  28                 jabs,    /* absolute address jump */
  29                 ind,     /* indirect address jump */
  30                 ret,     /* return to subrutine */
  31                 reg,     /* register indexed jump */
  32                 relb,    /* pc relative jump (byte offset) */
  33                 relw,    /* pc relative jump (word offset) */
  34                };
  35
  36 /* opcode decode table define
  37    ptn: opcode pattern
  38    msk: opcode bitmask
  39    len: instruction length (<0 next table index)
  40    jmp: jump operation mode */
  41 struct optable {
  42         unsigned char bitpattern;
  43         unsigned char bitmask;
  44         signed char length;
  45         signed char type;
  46 } __packed __aligned(1);
  47
  48 #define OPTABLE(ptn, msk, len, jmp)     \
  49         {                               \
  50                 .bitpattern = ptn,      \
  51                 .bitmask    = msk,      \
  52                 .length     = len,      \
  53                 .type       = jmp,      \
  54         }
  55
  56 static const struct optable optable_0[] = {
  57         OPTABLE(0x00, 0xff,  1, none), /* 0x00 */
  58         OPTABLE(0x01, 0xff, -1, none), /* 0x01 */
  59         OPTABLE(0x02, 0xfe,  1, none), /* 0x02-0x03 */
  60         OPTABLE(0x04, 0xee,  1, none), /* 0x04-0x05/0x14-0x15 */
  61         OPTABLE(0x06, 0xfe,  1, none), /* 0x06-0x07 */
  62         OPTABLE(0x08, 0xea,  1, none), /* 0x08-0x09/0x0c-0x0d/0x18-0x19/0x1c-0x1d */
  63         OPTABLE(0x0a, 0xee,  1, none), /* 0x0a-0x0b/0x1a-0x1b */
  64         OPTABLE(0x0e, 0xee,  1, none), /* 0x0e-0x0f/0x1e-0x1f */
  65         OPTABLE(0x10, 0xfc,  1, none), /* 0x10-0x13 */
  66         OPTABLE(0x16, 0xfe,  1, none), /* 0x16-0x17 */
  67         OPTABLE(0x20, 0xe0,  1, none), /* 0x20-0x3f */
  68         OPTABLE(0x40, 0xf0,  1, relb), /* 0x40-0x4f */
  69         OPTABLE(0x50, 0xfc,  1, none), /* 0x50-0x53 */
  70         OPTABLE(0x54, 0xfd,  1, ret), /* 0x54/0x56 */
  71         OPTABLE(0x55, 0xff,  1, relb), /* 0x55 */
  72         OPTABLE(0x57, 0xff,  1, none), /* 0x57 */
  73         OPTABLE(0x58, 0xfb,  2, relw), /* 0x58/0x5c */
  74         OPTABLE(0x59, 0xfb,  1, reg), /* 0x59/0x5b */
  75         OPTABLE(0x5a, 0xfb,  2, jabs), /* 0x5a/0x5e */
  76         OPTABLE(0x5b, 0xfb,  2, ind), /* 0x5b/0x5f */
  77         OPTABLE(0x60, 0xe8,  1, none), /* 0x60-0x67/0x70-0x77 */
  78         OPTABLE(0x68, 0xfa,  1, none), /* 0x68-0x69/0x6c-0x6d */
  79         OPTABLE(0x6a, 0xfe, -2, none), /* 0x6a-0x6b */
  80         OPTABLE(0x6e, 0xfe,  2, none), /* 0x6e-0x6f */
  81         OPTABLE(0x78, 0xff,  4, none), /* 0x78 */
  82         OPTABLE(0x79, 0xff,  2, none), /* 0x79 */
  83         OPTABLE(0x7a, 0xff,  3, none), /* 0x7a */
  84         OPTABLE(0x7b, 0xff,  2, none), /* 0x7b */
  85         OPTABLE(0x7c, 0xfc,  2, none), /* 0x7c-0x7f */
  86         OPTABLE(0x80, 0x80,  1, none), /* 0x80-0xff */
  87 };
  88
  89 static const struct optable optable_1[] = {
  90         OPTABLE(0x00, 0xff, -3, none), /* 0x0100 */
  91         OPTABLE(0x40, 0xf0, -3, none), /* 0x0140-0x14f */
  92         OPTABLE(0x80, 0xf0,  1, none), /* 0x0180-0x018f */
  93         OPTABLE(0xc0, 0xc0,  2, none), /* 0x01c0-0x01ff */
  94 };
  95
  96 static const struct optable optable_2[] = {
  97         OPTABLE(0x00, 0x20,  2, none), /* 0x6a0?/0x6a8?/0x6b0?/0x6b8? */
  98         OPTABLE(0x20, 0x20,  3, none), /* 0x6a2?/0x6aa?/0x6b2?/0x6ba? */
  99 };
 100
 101 static const struct optable optable_3[] = {
 102         OPTABLE(0x69, 0xfb,  2, none), /* 0x010069/0x01006d/014069/0x01406d */
 103         OPTABLE(0x6b, 0xff, -4, none), /* 0x01006b/0x01406b */
 104         OPTABLE(0x6f, 0xff,  3, none), /* 0x01006f/0x01406f */
 105         OPTABLE(0x78, 0xff,  5, none), /* 0x010078/0x014078 */
 106 };
 107
 108 static const struct optable optable_4[] = {
 109 /* 0x0100690?/0x01006d0?/0140690?/0x01406d0?/
 110    0x0100698?/0x01006d8?/0140698?/0x01406d8? */
 111         OPTABLE(0x00, 0x78, 3, none),
 112 /* 0x0100692?/0x01006d2?/0140692?/0x01406d2?/
 113    0x010069a?/0x01006da?/014069a?/0x01406da? */
 114         OPTABLE(0x20, 0x78, 4, none),
 115 };
 116
 117 static const struct optables_list {
 118         const struct optable *ptr;
 119         int size;
 120 } optables[] = {
 121 #define OPTABLES(no)                                                   \
 122         {                                                              \
 123                 .ptr  = optable_##no,                                  \
 124                 .size = sizeof(optable_##no) / sizeof(struct optable), \
 125         }
 126         OPTABLES(0),
 127         OPTABLES(1),
 128         OPTABLES(2),
 129         OPTABLES(3),
 130         OPTABLES(4),
 131
 132 };
 133
 134 const unsigned char condmask[] = {
 135         0x00, 0x40, 0x01, 0x04, 0x02, 0x08, 0x10, 0x20
 136 };
 137
 138 static int isbranch(struct task_struct *task, int reson)
 139 {
 140         unsigned char cond = h8300_get_reg(task, PT_CCR);
 141
 142         /* encode complex conditions */
 143         /* B4: N^V
 144            B5: Z|(N^V)
 145            B6: C|Z */
 146         __asm__("bld #3,%w0\n\t"
 147                 "bxor #1,%w0\n\t"
 148                 "bst #4,%w0\n\t"
 149                 "bor #2,%w0\n\t"
 150                 "bst #5,%w0\n\t"
 151                 "bld #2,%w0\n\t"
 152                 "bor #0,%w0\n\t"
 153                 "bst #6,%w0\n\t"
 154                 : "=&r"(cond) : "0"(cond) : "cc");
 155         cond &= condmask[reson >> 1];
 156         if (!(reson & 1))
 157                 return cond == 0;
 158         else
 159                 return cond != 0;
 160 }
 161
 162 static unsigned short *decode(struct task_struct *child,
 163                               const struct optable *op,
 164                               char *fetch_p, unsigned short *pc,
 165                               unsigned char inst)
 166 {
 167         unsigned long addr;
 168         unsigned long *sp;
 169         int regno;
 170
 171         switch (op->type) {
 172         case none:
 173                 return (unsigned short *)pc + op->length;
 174         case jabs:
 175                 addr = *(unsigned long *)pc;
 176                 return (unsigned short *)(addr & 0x00ffffff);
 177         case ind:
 178                 addr = *pc & 0xff;
 179                 return (unsigned short *)(*(unsigned long *)addr);
 180         case ret:
 181                 sp = (unsigned long *)h8300_get_reg(child, PT_USP);
 182                 /* user stack frames
 183                    |   er0  | temporary saved
 184                    +--------+
 185                    |   exp  | exception stack frames
 186                    +--------+
 187                    | ret pc | userspace return address
 188                 */
 189                 return (unsigned short *)(*(sp+2) & 0x00ffffff);
 190         case reg:
 191                 regno = (*pc >> 4) & 0x07;
 192                 if (regno == 0)
 193                         addr = h8300_get_reg(child, PT_ER0);
 194                 else
 195                         addr = h8300_get_reg(child, regno-1 + PT_ER1);
 196                 return (unsigned short *)addr;
 197         case relb:
 198                 if (inst == 0x55 || isbranch(child, inst & 0x0f))
 199                         pc = (unsigned short *)((unsigned long)pc +
 200                                                 ((signed char)(*fetch_p)));
 201                 return pc+1; /* skip myself */
 202         case relw:
 203                 if (inst == 0x5c || isbranch(child, (*fetch_p & 0xf0) >> 4))
 204                         pc = (unsigned short *)((unsigned long)pc +
 205                                                 ((signed short)(*(pc+1))));
 206                 return pc+2; /* skip myself */
 207         default:
 208                 return NULL;
 209         }
 210 }
 211
 212 static unsigned short *nextpc(struct task_struct *child, unsigned short *pc)
 213 {
 214         const struct optable *op;
 215         unsigned char *fetch_p;
 216         int op_len;
 217         unsigned char inst;
 218
 219         op = optables[0].ptr;
 220         op_len = optables[0].size;
 221         fetch_p = (unsigned char *)pc;
 222         inst = *fetch_p++;
 223         do {
 224                 if ((inst & op->bitmask) == op->bitpattern) {
 225                         if (op->length < 0) {
 226                                 op = optables[-op->length].ptr;
 227                                 op_len = optables[-op->length].size + 1;
 228                                 inst = *fetch_p++;
 229                         } else
 230                                 return decode(child, op, fetch_p, pc, inst);
 231                 } else
 232                         op++;
 233         } while (--op_len > 0);
 234         return NULL;
 235 }
 236
 237 /* Set breakpoint(s) to simulate a single step from the current PC.  */
 238
 239 void user_enable_single_step(struct task_struct *child)
 240 {
 241         unsigned short *next;
 242
 243         next = nextpc(child, (unsigned short *)h8300_get_reg(child, PT_PC));
 244         child->thread.breakinfo.addr = next;
 245         child->thread.breakinfo.inst = *next;
 246         *next = BREAKINST;
 247 }
 248
 249 asmlinkage void trace_trap(unsigned long bp)
 250 {
 251         if ((unsigned long)current->thread.breakinfo.addr == bp) {
 252                 user_disable_single_step(current);
 253                 force_sig(SIGTRAP);
 254         } else
 255                 force_sig(SIGILL);
 256 }