arch/powerpc/kernel/signal.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Common signal handling code for both 32 and 64 bits
   4  *
   5  *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation
   6  *    Extracted from signal_32.c and signal_64.c
   7  */
   8
   9 #include <linux/resume_user_mode.h>
  10 #include <linux/signal.h>
  11 #include <linux/uprobes.h>
  12 #include <linux/key.h>
  13 #include <linux/context_tracking.h>
  14 #include <linux/livepatch.h>
  15 #include <linux/syscalls.h>
  16 #include <asm/hw_breakpoint.h>
  17 #include <linux/uaccess.h>
  18 #include <asm/switch_to.h>
  19 #include <asm/unistd.h>
  20 #include <asm/debug.h>
  21 #include <asm/tm.h>
  22
  23 #include "signal.h"
  24
  25 #ifdef CONFIG_VSX
  26 unsigned long copy_fpr_to_user(void __user *to,
  27                                struct task_struct *task)
  28 {
  29         u64 buf[ELF_NFPREG];
  30         int i;
  31
  32         /* save FPR copy to local buffer then write to the thread_struct */
  33         for (i = 0; i < (ELF_NFPREG - 1) ; i++)
  34                 buf[i] = task->thread.TS_FPR(i);
  35         buf[i] = task->thread.fp_state.fpscr;
  36         return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
  37 }
  38
  39 unsigned long copy_fpr_from_user(struct task_struct *task,
  40                                  void __user *from)
  41 {
  42         u64 buf[ELF_NFPREG];
  43         int i;
  44
  45         if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
  46                 return 1;
  47         for (i = 0; i < (ELF_NFPREG - 1) ; i++)
  48                 task->thread.TS_FPR(i) = buf[i];
  49         task->thread.fp_state.fpscr = buf[i];
  50
  51         return 0;
  52 }
  53
  54 unsigned long copy_vsx_to_user(void __user *to,
  55                                struct task_struct *task)
  56 {
  57         u64 buf[ELF_NVSRHALFREG];
  58         int i;
  59
  60         /* save FPR copy to local buffer then write to the thread_struct */
  61         for (i = 0; i < ELF_NVSRHALFREG; i++)
  62                 buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
  63         return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
  64 }
  65
  66 unsigned long copy_vsx_from_user(struct task_struct *task,
  67                                  void __user *from)
  68 {
  69         u64 buf[ELF_NVSRHALFREG];
  70         int i;
  71
  72         if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
  73                 return 1;
  74         for (i = 0; i < ELF_NVSRHALFREG ; i++)
  75                 task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
  76         return 0;
  77 }
  78
  79 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
  80 unsigned long copy_ckfpr_to_user(void __user *to,
  81                                   struct task_struct *task)
  82 {
  83         u64 buf[ELF_NFPREG];
  84         int i;
  85
  86         /* save FPR copy to local buffer then write to the thread_struct */
  87         for (i = 0; i < (ELF_NFPREG - 1) ; i++)
  88                 buf[i] = task->thread.TS_CKFPR(i);
  89         buf[i] = task->thread.ckfp_state.fpscr;
  90         return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
  91 }
  92
  93 unsigned long copy_ckfpr_from_user(struct task_struct *task,
  94                                           void __user *from)
  95 {
  96         u64 buf[ELF_NFPREG];
  97         int i;
  98
  99         if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
 100                 return 1;
 101         for (i = 0; i < (ELF_NFPREG - 1) ; i++)
 102                 task->thread.TS_CKFPR(i) = buf[i];
 103         task->thread.ckfp_state.fpscr = buf[i];
 104
 105         return 0;
 106 }
 107
 108 unsigned long copy_ckvsx_to_user(void __user *to,
 109                                   struct task_struct *task)
 110 {
 111         u64 buf[ELF_NVSRHALFREG];
 112         int i;
 113
 114         /* save FPR copy to local buffer then write to the thread_struct */
 115         for (i = 0; i < ELF_NVSRHALFREG; i++)
 116                 buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
 117         return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
 118 }
 119
 120 unsigned long copy_ckvsx_from_user(struct task_struct *task,
 121                                           void __user *from)
 122 {
 123         u64 buf[ELF_NVSRHALFREG];
 124         int i;
 125
 126         if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
 127                 return 1;
 128         for (i = 0; i < ELF_NVSRHALFREG ; i++)
 129                 task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
 130         return 0;
 131 }
 132 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
 133 #endif
 134
 135 /* Log an error when sending an unhandled signal to a process. Controlled
 136  * through debug.exception-trace sysctl.
 137  */
 138
 139 int show_unhandled_signals = 1;
 140
 141 unsigned long get_min_sigframe_size(void)
 142 {
 143         if (IS_ENABLED(CONFIG_PPC64))
 144                 return get_min_sigframe_size_64();
 145         else
 146                 return get_min_sigframe_size_32();
 147 }
 148
 149 #ifdef CONFIG_COMPAT
 150 unsigned long get_min_sigframe_size_compat(void)
 151 {
 152         return get_min_sigframe_size_32();
 153 }
 154 #endif
 155
 156 /*
 157  * Allocate space for the signal frame
 158  */
 159 static unsigned long get_tm_stackpointer(struct task_struct *tsk);
 160
 161 void __user *get_sigframe(struct ksignal *ksig, struct task_struct *tsk,
 162                           size_t frame_size, int is_32)
 163 {
 164         unsigned long oldsp, newsp;
 165         unsigned long sp = get_tm_stackpointer(tsk);
 166
 167         /* Default to using normal stack */
 168         if (is_32)
 169                 oldsp = sp & 0x0ffffffffUL;
 170         else
 171                 oldsp = sp;
 172         oldsp = sigsp(oldsp, ksig);
 173         newsp = (oldsp - frame_size) & ~0xFUL;
 174
 175         return (void __user *)newsp;
 176 }
 177
 178 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
 179                                   int has_handler)
 180 {
 181         unsigned long ret = regs->gpr[3];
 182         int restart = 1;
 183
 184         /* syscall ? */
 185         if (!trap_is_syscall(regs))
 186                 return;
 187
 188         if (trap_norestart(regs))
 189                 return;
 190
 191         /* error signalled ? */
 192         if (trap_is_scv(regs)) {
 193                 /* 32-bit compat mode sign extend? */
 194                 if (!IS_ERR_VALUE(ret))
 195                         return;
 196                 ret = -ret;
 197         } else if (!(regs->ccr & 0x10000000)) {
 198                 return;
 199         }
 200
 201         switch (ret) {
 202         case ERESTART_RESTARTBLOCK:
 203         case ERESTARTNOHAND:
 204                 /* ERESTARTNOHAND means that the syscall should only be
 205                  * restarted if there was no handler for the signal, and since
 206                  * we only get here if there is a handler, we dont restart.
 207                  */
 208                 restart = !has_handler;
 209                 break;
 210         case ERESTARTSYS:
 211                 /* ERESTARTSYS means to restart the syscall if there is no
 212                  * handler or the handler was registered with SA_RESTART
 213                  */
 214                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
 215                 break;
 216         case ERESTARTNOINTR:
 217                 /* ERESTARTNOINTR means that the syscall should be
 218                  * called again after the signal handler returns.
 219                  */
 220                 break;
 221         default:
 222                 return;
 223         }
 224         if (restart) {
 225                 if (ret == ERESTART_RESTARTBLOCK)
 226                         regs->gpr[0] = __NR_restart_syscall;
 227                 else
 228                         regs->gpr[3] = regs->orig_gpr3;
 229                 regs_add_return_ip(regs, -4);
 230                 regs->result = 0;
 231         } else {
 232                 if (trap_is_scv(regs)) {
 233                         regs->result = -EINTR;
 234                         regs->gpr[3] = -EINTR;
 235                 } else {
 236                         regs->result = -EINTR;
 237                         regs->gpr[3] = EINTR;
 238                         regs->ccr |= 0x10000000;
 239                 }
 240         }
 241 }
 242
 243 static void do_signal(struct task_struct *tsk)
 244 {
 245         sigset_t *oldset = sigmask_to_save();
 246         struct ksignal ksig = { .sig = 0 };
 247         int ret;
 248
 249         BUG_ON(tsk != current);
 250
 251         get_signal(&ksig);
 252
 253         /* Is there any syscall restart business here ? */
 254         check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);
 255
 256         if (ksig.sig <= 0) {
 257                 /* No signal to deliver -- put the saved sigmask back */
 258                 restore_saved_sigmask();
 259                 set_trap_norestart(tsk->thread.regs);
 260                 return;               /* no signals delivered */
 261         }
 262
 263         /*
 264          * Reenable the DABR before delivering the signal to
 265          * user space. The DABR will have been cleared if it
 266          * triggered inside the kernel.
 267          */
 268         if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) {
 269                 int i;
 270
 271                 for (i = 0; i < nr_wp_slots(); i++) {
 272                         if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
 273                                 __set_breakpoint(i, &tsk->thread.hw_brk[i]);
 274                 }
 275         }
 276
 277         /* Re-enable the breakpoints for the signal stack */
 278         thread_change_pc(tsk, tsk->thread.regs);
 279
 280         rseq_signal_deliver(&ksig, tsk->thread.regs);
 281
 282         if (is_32bit_task()) {
 283                 if (ksig.ka.sa.sa_flags & SA_SIGINFO)
 284                         ret = handle_rt_signal32(&ksig, oldset, tsk);
 285                 else
 286                         ret = handle_signal32(&ksig, oldset, tsk);
 287         } else {
 288                 ret = handle_rt_signal64(&ksig, oldset, tsk);
 289         }
 290
 291         set_trap_norestart(tsk->thread.regs);
 292         signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
 293 }
 294
 295 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 296 {
 297         if (thread_info_flags & _TIF_UPROBE)
 298                 uprobe_notify_resume(regs);
 299
 300         if (thread_info_flags & _TIF_PATCH_PENDING)
 301                 klp_update_patch_state(current);
 302
 303         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
 304                 BUG_ON(regs != current->thread.regs);
 305                 do_signal(current);
 306         }
 307
 308         if (thread_info_flags & _TIF_NOTIFY_RESUME)
 309                 resume_user_mode_work(regs);
 310 }
 311
 312 static unsigned long get_tm_stackpointer(struct task_struct *tsk)
 313 {
 314         /* When in an active transaction that takes a signal, we need to be
 315          * careful with the stack.  It's possible that the stack has moved back
 316          * up after the tbegin.  The obvious case here is when the tbegin is
 317          * called inside a function that returns before a tend.  In this case,
 318          * the stack is part of the checkpointed transactional memory state.
 319          * If we write over this non transactionally or in suspend, we are in
 320          * trouble because if we get a tm abort, the program counter and stack
 321          * pointer will be back at the tbegin but our in memory stack won't be
 322          * valid anymore.
 323          *
 324          * To avoid this, when taking a signal in an active transaction, we
 325          * need to use the stack pointer from the checkpointed state, rather
 326          * than the speculated state.  This ensures that the signal context
 327          * (written tm suspended) will be written below the stack required for
 328          * the rollback.  The transaction is aborted because of the treclaim,
 329          * so any memory written between the tbegin and the signal will be
 330          * rolled back anyway.
 331          *
 332          * For signals taken in non-TM or suspended mode, we use the
 333          * normal/non-checkpointed stack pointer.
 334          */
 335         struct pt_regs *regs = tsk->thread.regs;
 336         unsigned long ret = regs->gpr[1];
 337
 338 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 339         BUG_ON(tsk != current);
 340
 341         if (MSR_TM_ACTIVE(regs->msr)) {
 342                 preempt_disable();
 343                 tm_reclaim_current(TM_CAUSE_SIGNAL);
 344                 if (MSR_TM_TRANSACTIONAL(regs->msr))
 345                         ret = tsk->thread.ckpt_regs.gpr[1];
 346
 347                 /*
 348                  * If we treclaim, we must clear the current thread's TM bits
 349                  * before re-enabling preemption. Otherwise we might be
 350                  * preempted and have the live MSR[TS] changed behind our back
 351                  * (tm_recheckpoint_new_task() would recheckpoint). Besides, we
 352                  * enter the signal handler in non-transactional state.
 353                  */
 354                 regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK);
 355                 preempt_enable();
 356         }
 357 #endif
 358         return ret;
 359 }
 360
 361 static const char fm32[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %08lx lr %08lx\n";
 362 static const char fm64[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %016lx lr %016lx\n";
 363
 364 void signal_fault(struct task_struct *tsk, struct pt_regs *regs,
 365                   const char *where, void __user *ptr)
 366 {
 367         if (show_unhandled_signals)
 368                 printk_ratelimited(regs->msr & MSR_64BIT ? fm64 : fm32, tsk->comm,
 369                                    task_pid_nr(tsk), where, ptr, regs->nip, regs->link);
 370 }