arch/s390/kernel/uprobes.c

   1 /*
   2  *  User-space Probes (UProbes) for s390
   3  *
   4  *    Copyright IBM Corp. 2014
   5  *    Author(s): Jan Willeke,
   6  */
   7
   8 #include <linux/kprobes.h>
   9 #include <linux/uaccess.h>
  10 #include <linux/uprobes.h>
  11 #include <linux/compat.h>
  12 #include <linux/kdebug.h>
  13 #include <asm/switch_to.h>
  14 #include <asm/facility.h>
  15 #include <asm/dis.h>
  16 #include "entry.h"
  17
  18 #define UPROBE_TRAP_NR  UINT_MAX
  19
  20 int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
  21                              unsigned long addr)
  22 {
  23         return probe_is_prohibited_opcode(auprobe->insn);
  24 }
  25
  26 int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
  27 {
  28         if (psw_bits(regs->psw).eaba == PSW_AMODE_24BIT)
  29                 return -EINVAL;
  30         if (!is_compat_task() && psw_bits(regs->psw).eaba == PSW_AMODE_31BIT)
  31                 return -EINVAL;
  32         clear_pt_regs_flag(regs, PIF_PER_TRAP);
  33         auprobe->saved_per = psw_bits(regs->psw).r;
  34         auprobe->saved_int_code = regs->int_code;
  35         regs->int_code = UPROBE_TRAP_NR;
  36         regs->psw.addr = current->utask->xol_vaddr;
  37         set_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
  38         update_cr_regs(current);
  39         return 0;
  40 }
  41
  42 bool arch_uprobe_xol_was_trapped(struct task_struct *tsk)
  43 {
  44         struct pt_regs *regs = task_pt_regs(tsk);
  45
  46         if (regs->int_code != UPROBE_TRAP_NR)
  47                 return true;
  48         return false;
  49 }
  50
  51 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
  52 {
  53         int fixup = probe_get_fixup_type(auprobe->insn);
  54         struct uprobe_task *utask = current->utask;
  55
  56         clear_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
  57         update_cr_regs(current);
  58         psw_bits(regs->psw).r = auprobe->saved_per;
  59         regs->int_code = auprobe->saved_int_code;
  60
  61         if (fixup & FIXUP_PSW_NORMAL)
  62                 regs->psw.addr += utask->vaddr - utask->xol_vaddr;
  63         if (fixup & FIXUP_RETURN_REGISTER) {
  64                 int reg = (auprobe->insn[0] & 0xf0) >> 4;
  65
  66                 regs->gprs[reg] += utask->vaddr - utask->xol_vaddr;
  67         }
  68         if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
  69                 int ilen = insn_length(auprobe->insn[0] >> 8);
  70
  71                 if (regs->psw.addr - utask->xol_vaddr == ilen)
  72                         regs->psw.addr = utask->vaddr + ilen;
  73         }
  74         /* If per tracing was active generate trap */
  75         if (regs->psw.mask & PSW_MASK_PER)
  76                 do_per_trap(regs);
  77         return 0;
  78 }
  79
  80 int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
  81                                  void *data)
  82 {
  83         struct die_args *args = data;
  84         struct pt_regs *regs = args->regs;
  85
  86         if (!user_mode(regs))
  87                 return NOTIFY_DONE;
  88         if (regs->int_code & 0x200) /* Trap during transaction */
  89                 return NOTIFY_DONE;
  90         switch (val) {
  91         case DIE_BPT:
  92                 if (uprobe_pre_sstep_notifier(regs))
  93                         return NOTIFY_STOP;
  94                 break;
  95         case DIE_SSTEP:
  96                 if (uprobe_post_sstep_notifier(regs))
  97                         return NOTIFY_STOP;
  98         default:
  99                 break;
 100         }
 101         return NOTIFY_DONE;
 102 }
 103
 104 void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 105 {
 106         clear_thread_flag(TIF_UPROBE_SINGLESTEP);
 107         regs->int_code = auprobe->saved_int_code;
 108         regs->psw.addr = current->utask->vaddr;
 109 }
 110
 111 unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
 112                                                 struct pt_regs *regs)
 113 {
 114         unsigned long orig;
 115
 116         orig = regs->gprs[14];
 117         regs->gprs[14] = trampoline;
 118         return orig;
 119 }
 120
 121 /* Instruction Emulation */
 122
 123 static void adjust_psw_addr(psw_t *psw, unsigned long len)
 124 {
 125         psw->addr = __rewind_psw(*psw, -len);
 126 }
 127
 128 #define EMU_ILLEGAL_OP          1
 129 #define EMU_SPECIFICATION       2
 130 #define EMU_ADDRESSING          3
 131
 132 #define emu_load_ril(ptr, output)                       \
 133 ({                                                      \
 134         unsigned int mask = sizeof(*(ptr)) - 1;         \
 135         __typeof__(*(ptr)) input;                       \
 136         int __rc = 0;                                   \
 137                                                         \
 138         if (!test_facility(34))                         \
 139                 __rc = EMU_ILLEGAL_OP;                  \
 140         else if ((u64 __force)ptr & mask)               \
 141                 __rc = EMU_SPECIFICATION;               \
 142         else if (get_user(input, ptr))                  \
 143                 __rc = EMU_ADDRESSING;                  \
 144         else                                            \
 145                 *(output) = input;                      \
 146         __rc;                                           \
 147 })
 148
 149 #define emu_store_ril(ptr, input)                       \
 150 ({                                                      \
 151         unsigned int mask = sizeof(*(ptr)) - 1;         \
 152         int __rc = 0;                                   \
 153                                                         \
 154         if (!test_facility(34))                         \
 155                 __rc = EMU_ILLEGAL_OP;                  \
 156         else if ((u64 __force)ptr & mask)               \
 157                 __rc = EMU_SPECIFICATION;               \
 158         else if (put_user(*(input), ptr))               \
 159                 __rc = EMU_ADDRESSING;                  \
 160         __rc;                                           \
 161 })
 162
 163 #define emu_cmp_ril(regs, ptr, cmp)                     \
 164 ({                                                      \
 165         unsigned int mask = sizeof(*(ptr)) - 1;         \
 166         __typeof__(*(ptr)) input;                       \
 167         int __rc = 0;                                   \
 168                                                         \
 169         if (!test_facility(34))                         \
 170                 __rc = EMU_ILLEGAL_OP;                  \
 171         else if ((u64 __force)ptr & mask)               \
 172                 __rc = EMU_SPECIFICATION;               \
 173         else if (get_user(input, ptr))                  \
 174                 __rc = EMU_ADDRESSING;                  \
 175         else if (input > *(cmp))                        \
 176                 psw_bits((regs)->psw).cc = 1;           \
 177         else if (input < *(cmp))                        \
 178                 psw_bits((regs)->psw).cc = 2;           \
 179         else                                            \
 180                 psw_bits((regs)->psw).cc = 0;           \
 181         __rc;                                           \
 182 })
 183
 184 struct insn_ril {
 185         u8 opc0;
 186         u8 reg  : 4;
 187         u8 opc1 : 4;
 188         s32 disp;
 189 } __packed;
 190
 191 union split_register {
 192         u64 u64;
 193         u32 u32[2];
 194         u16 u16[4];
 195         s64 s64;
 196         s32 s32[2];
 197         s16 s16[4];
 198 };
 199
 200 /*
 201  * pc relative instructions are emulated, since parameters may not be
 202  * accessible from the xol area due to range limitations.
 203  */
 204 static void handle_insn_ril(struct arch_uprobe *auprobe, struct pt_regs *regs)
 205 {
 206         union split_register *rx;
 207         struct insn_ril *insn;
 208         unsigned int ilen;
 209         void *uptr;
 210         int rc = 0;
 211
 212         insn = (struct insn_ril *) &auprobe->insn;
 213         rx = (union split_register *) &regs->gprs[insn->reg];
 214         uptr = (void *)(regs->psw.addr + (insn->disp * 2));
 215         ilen = insn_length(insn->opc0);
 216
 217         switch (insn->opc0) {
 218         case 0xc0:
 219                 switch (insn->opc1) {
 220                 case 0x00: /* larl */
 221                         rx->u64 = (unsigned long)uptr;
 222                         break;
 223                 }
 224                 break;
 225         case 0xc4:
 226                 switch (insn->opc1) {
 227                 case 0x02: /* llhrl */
 228                         rc = emu_load_ril((u16 __user *)uptr, &rx->u32[1]);
 229                         break;
 230                 case 0x04: /* lghrl */
 231                         rc = emu_load_ril((s16 __user *)uptr, &rx->u64);
 232                         break;
 233                 case 0x05: /* lhrl */
 234                         rc = emu_load_ril((s16 __user *)uptr, &rx->u32[1]);
 235                         break;
 236                 case 0x06: /* llghrl */
 237                         rc = emu_load_ril((u16 __user *)uptr, &rx->u64);
 238                         break;
 239                 case 0x08: /* lgrl */
 240                         rc = emu_load_ril((u64 __user *)uptr, &rx->u64);
 241                         break;
 242                 case 0x0c: /* lgfrl */
 243                         rc = emu_load_ril((s32 __user *)uptr, &rx->u64);
 244                         break;
 245                 case 0x0d: /* lrl */
 246                         rc = emu_load_ril((u32 __user *)uptr, &rx->u32[1]);
 247                         break;
 248                 case 0x0e: /* llgfrl */
 249                         rc = emu_load_ril((u32 __user *)uptr, &rx->u64);
 250                         break;
 251                 case 0x07: /* sthrl */
 252                         rc = emu_store_ril((u16 __user *)uptr, &rx->u16[3]);
 253                         break;
 254                 case 0x0b: /* stgrl */
 255                         rc = emu_store_ril((u64 __user *)uptr, &rx->u64);
 256                         break;
 257                 case 0x0f: /* strl */
 258                         rc = emu_store_ril((u32 __user *)uptr, &rx->u32[1]);
 259                         break;
 260                 }
 261                 break;
 262         case 0xc6:
 263                 switch (insn->opc1) {
 264                 case 0x02: /* pfdrl */
 265                         if (!test_facility(34))
 266                                 rc = EMU_ILLEGAL_OP;
 267                         break;
 268                 case 0x04: /* cghrl */
 269                         rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s64);
 270                         break;
 271                 case 0x05: /* chrl */
 272                         rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s32[1]);
 273                         break;
 274                 case 0x06: /* clghrl */
 275                         rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u64);
 276                         break;
 277                 case 0x07: /* clhrl */
 278                         rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u32[1]);
 279                         break;
 280                 case 0x08: /* cgrl */
 281                         rc = emu_cmp_ril(regs, (s64 __user *)uptr, &rx->s64);
 282                         break;
 283                 case 0x0a: /* clgrl */
 284                         rc = emu_cmp_ril(regs, (u64 __user *)uptr, &rx->u64);
 285                         break;
 286                 case 0x0c: /* cgfrl */
 287                         rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s64);
 288                         break;
 289                 case 0x0d: /* crl */
 290                         rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s32[1]);
 291                         break;
 292                 case 0x0e: /* clgfrl */
 293                         rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u64);
 294                         break;
 295                 case 0x0f: /* clrl */
 296                         rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
 297                         break;
 298                 }
 299                 break;
 300         }
 301         adjust_psw_addr(&regs->psw, ilen);
 302         switch (rc) {
 303         case EMU_ILLEGAL_OP:
 304                 regs->int_code = ilen << 16 | 0x0001;
 305                 do_report_trap(regs, SIGILL, ILL_ILLOPC, NULL);
 306                 break;
 307         case EMU_SPECIFICATION:
 308                 regs->int_code = ilen << 16 | 0x0006;
 309                 do_report_trap(regs, SIGILL, ILL_ILLOPC , NULL);
 310                 break;
 311         case EMU_ADDRESSING:
 312                 regs->int_code = ilen << 16 | 0x0005;
 313                 do_report_trap(regs, SIGSEGV, SEGV_MAPERR, NULL);
 314                 break;
 315         }
 316 }
 317
 318 bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 319 {
 320         if ((psw_bits(regs->psw).eaba == PSW_AMODE_24BIT) ||
 321             ((psw_bits(regs->psw).eaba == PSW_AMODE_31BIT) &&
 322              !is_compat_task())) {
 323                 regs->psw.addr = __rewind_psw(regs->psw, UPROBE_SWBP_INSN_SIZE);
 324                 do_report_trap(regs, SIGILL, ILL_ILLADR, NULL);
 325                 return true;
 326         }
 327         if (probe_is_insn_relative_long(auprobe->insn)) {
 328                 handle_insn_ril(auprobe, regs);
 329                 return true;
 330         }
 331         return false;
 332 }