LXR linux/arch/unicore32/kernel/signal.c

   1/*
   2 * linux/arch/unicore32/kernel/signal.c
   3 *
   4 * Code specific to PKUnity SoC and UniCore ISA
   5 *
   6 * Copyright (C) 2001-2010 GUAN Xue-tao
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12#include <linux/errno.h>
  13#include <linux/signal.h>
  14#include <linux/personality.h>
  15#include <linux/uaccess.h>
  16#include <linux/tracehook.h>
  17#include <linux/elf.h>
  18#include <linux/unistd.h>
  19
  20#include <asm/cacheflush.h>
  21#include <asm/ucontext.h>
  22
  23/*
  24 * For UniCore syscalls, we encode the syscall number into the instruction.
  25 */
  26#define SWI_SYS_SIGRETURN       (0xff000000) /* error number for new abi */
  27#define SWI_SYS_RT_SIGRETURN    (0xff000000 | (__NR_rt_sigreturn))
  28#define SWI_SYS_RESTART         (0xff000000 | (__NR_restart_syscall))
  29
  30#define KERN_SIGRETURN_CODE     (KUSER_VECPAGE_BASE + 0x00000500)
  31#define KERN_RESTART_CODE       (KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
  32
  33const unsigned long sigreturn_codes[3] = {
  34        SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
  35};
  36
  37const unsigned long syscall_restart_code[2] = {
  38        SWI_SYS_RESTART,        /* swi  __NR_restart_syscall */
  39        0x69efc004,             /* ldr  pc, [sp], #4 */
  40};
  41
  42/*
  43 * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
  44 */
  45struct sigframe {
  46        struct ucontext uc;
  47        unsigned long retcode[2];
  48};
  49
  50struct rt_sigframe {
  51        struct siginfo info;
  52        struct sigframe sig;
  53};
  54
  55static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
  56{
  57        sigset_t set;
  58        int err;
  59
  60        err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
  61        if (err == 0)
  62                set_current_blocked(&set);
  63
  64        err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
  65        err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
  66        err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
  67        err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
  68        err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
  69        err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
  70        err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
  71        err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
  72        err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
  73        err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
  74        err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
  75        err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
  76        err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
  77        err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
  78        err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
  79        err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
  80        err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
  81        err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
  82        err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
  83        err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
  84        err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
  85        err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
  86        err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
  87        err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
  88        err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
  89        err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
  90        err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
  91        err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
  92        err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
  93        err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
  94        err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
  95        err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
  96        err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
  97
  98        err |= !valid_user_regs(regs);
  99
 100        return err;
 101}
 102
 103asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
 104{
 105        struct rt_sigframe __user *frame;
 106
 107        /* Always make any pending restarted system calls return -EINTR */
 108        current->restart_block.fn = do_no_restart_syscall;
 109
 110        /*
 111         * Since we stacked the signal on a 64-bit boundary,
 112         * then 'sp' should be word aligned here.  If it's
 113         * not, then the user is trying to mess with us.
 114         */
 115        if (regs->UCreg_sp & 7)
 116                goto badframe;
 117
 118        frame = (struct rt_sigframe __user *)regs->UCreg_sp;
 119
 120        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 121                goto badframe;
 122
 123        if (restore_sigframe(regs, &frame->sig))
 124                goto badframe;
 125
 126        if (restore_altstack(&frame->sig.uc.uc_stack))
 127                goto badframe;
 128
 129        return regs->UCreg_00;
 130
 131badframe:
 132        force_sig(SIGSEGV, current);
 133        return 0;
 134}
 135
 136static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
 137                sigset_t *set)
 138{
 139        int err = 0;
 140
 141        err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
 142        err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
 143        err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
 144        err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
 145        err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
 146        err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
 147        err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
 148        err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
 149        err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
 150        err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
 151        err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
 152        err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
 153        err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
 154        err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
 155        err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
 156        err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
 157        err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
 158        err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
 159        err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
 160        err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
 161        err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
 162        err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
 163        err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
 164        err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
 165        err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
 166        err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
 167        err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
 168        err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
 169        err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
 170        err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
 171        err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 172        err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 173        err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 174
 175        err |= __put_user(current->thread.trap_no,
 176                        &sf->uc.uc_mcontext.trap_no);
 177        err |= __put_user(current->thread.error_code,
 178                        &sf->uc.uc_mcontext.error_code);
 179        err |= __put_user(current->thread.address,
 180                        &sf->uc.uc_mcontext.fault_address);
 181        err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
 182
 183        err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 184
 185        return err;
 186}
 187
 188static inline void __user *get_sigframe(struct k_sigaction *ka,
 189                struct pt_regs *regs, int framesize)
 190{
 191        unsigned long sp = regs->UCreg_sp;
 192        void __user *frame;
 193
 194        /*
 195         * This is the X/Open sanctioned signal stack switching.
 196         */
 197        if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 198                sp = current->sas_ss_sp + current->sas_ss_size;
 199
 200        /*
 201         * ATPCS B01 mandates 8-byte alignment
 202         */
 203        frame = (void __user *)((sp - framesize) & ~7);
 204
 205        /*
 206         * Check that we can actually write to the signal frame.
 207         */
 208        if (!access_ok(VERIFY_WRITE, frame, framesize))
 209                frame = NULL;
 210
 211        return frame;
 212}
 213
 214static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 215             unsigned long __user *rc, void __user *frame, int usig)
 216{
 217        unsigned long handler = (unsigned long)ka->sa.sa_handler;
 218        unsigned long retcode;
 219        unsigned long asr = regs->UCreg_asr & ~PSR_f;
 220
 221        unsigned int idx = 0;
 222
 223        if (ka->sa.sa_flags & SA_SIGINFO)
 224                idx += 1;
 225
 226        if (__put_user(sigreturn_codes[idx],   rc) ||
 227            __put_user(sigreturn_codes[idx+1], rc+1))
 228                return 1;
 229
 230        retcode = KERN_SIGRETURN_CODE + (idx << 2);
 231
 232        regs->UCreg_00 = usig;
 233        regs->UCreg_sp = (unsigned long)frame;
 234        regs->UCreg_lr = retcode;
 235        regs->UCreg_pc = handler;
 236        regs->UCreg_asr = asr;
 237
 238        return 0;
 239}
 240
 241static int setup_frame(struct ksignal *ksig, sigset_t *set,
 242                       struct pt_regs *regs)
 243{
 244        struct sigframe __user *frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
 245        int err = 0;
 246
 247        if (!frame)
 248                return 1;
 249
 250        /*
 251         * Set uc.uc_flags to a value which sc.trap_no would never have.
 252         */
 253        err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
 254
 255        err |= setup_sigframe(frame, regs, set);
 256        if (err == 0)
 257                err |= setup_return(regs, &ksig->ka, frame->retcode, frame,
 258                                    ksig->sig);
 259
 260        return err;
 261}
 262
 263static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 264                          struct pt_regs *regs)
 265{
 266        struct rt_sigframe __user *frame =
 267                        get_sigframe(&ksig->ka, regs, sizeof(*frame));
 268        int err = 0;
 269
 270        if (!frame)
 271                return 1;
 272
 273        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 274
 275        err |= __put_user(0, &frame->sig.uc.uc_flags);
 276        err |= __put_user(NULL, &frame->sig.uc.uc_link);
 277        err |= __save_altstack(&frame->sig.uc.uc_stack, regs->UCreg_sp);
 278        err |= setup_sigframe(&frame->sig, regs, set);
 279        if (err == 0)
 280                err |= setup_return(regs, &ksig->ka, frame->sig.retcode, frame,
 281                                    ksig->sig);
 282
 283        if (err == 0) {
 284                /*
 285                 * For realtime signals we must also set the second and third
 286                 * arguments for the signal handler.
 287                 */
 288                regs->UCreg_01 = (unsigned long)&frame->info;
 289                regs->UCreg_02 = (unsigned long)&frame->sig.uc;
 290        }
 291
 292        return err;
 293}
 294
 295static inline void setup_syscall_restart(struct pt_regs *regs)
 296{
 297        regs->UCreg_00 = regs->UCreg_ORIG_00;
 298        regs->UCreg_pc -= 4;
 299}
 300
 301/*
 302 * OK, we're invoking a handler
 303 */
 304static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
 305                          int syscall)
 306{
 307        struct thread_info *thread = current_thread_info();
 308        sigset_t *oldset = sigmask_to_save();
 309        int usig = ksig->sig;
 310        int ret;
 311
 312        /*
 313         * If we were from a system call, check for system call restarting...
 314         */
 315        if (syscall) {
 316                switch (regs->UCreg_00) {
 317                case -ERESTART_RESTARTBLOCK:
 318                case -ERESTARTNOHAND:
 319                        regs->UCreg_00 = -EINTR;
 320                        break;
 321                case -ERESTARTSYS:
 322                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 323                                regs->UCreg_00 = -EINTR;
 324                                break;
 325                        }
 326                        /* fallthrough */
 327                case -ERESTARTNOINTR:
 328                        setup_syscall_restart(regs);
 329                }
 330        }
 331
 332        /*
 333         * Set up the stack frame
 334         */
 335        if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 336                ret = setup_rt_frame(ksig, oldset, regs);
 337        else
 338                ret = setup_frame(ksig, oldset, regs);
 339
 340        /*
 341         * Check that the resulting registers are actually sane.
 342         */
 343        ret |= !valid_user_regs(regs);
 344
 345        signal_setup_done(ret, ksig, 0);
 346}
 347
 348/*
 349 * Note that 'init' is a special process: it doesn't get signals it doesn't
 350 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 351 * mistake.
 352 *
 353 * Note that we go through the signals twice: once to check the signals that
 354 * the kernel can handle, and then we build all the user-level signal handling
 355 * stack-frames in one go after that.
 356 */
 357static void do_signal(struct pt_regs *regs, int syscall)
 358{
 359        struct ksignal ksig;
 360
 361        /*
 362         * We want the common case to go fast, which
 363         * is why we may in certain cases get here from
 364         * kernel mode. Just return without doing anything
 365         * if so.
 366         */
 367        if (!user_mode(regs))
 368                return;
 369
 370        if (get_signal(&ksig)) {
 371                handle_signal(&ksig, regs, syscall);
 372                return;
 373        }
 374
 375        /*
 376         * No signal to deliver to the process - restart the syscall.
 377         */
 378        if (syscall) {
 379                if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
 380                                u32 __user *usp;
 381
 382                                regs->UCreg_sp -= 4;
 383                                usp = (u32 __user *)regs->UCreg_sp;
 384
 385                                if (put_user(regs->UCreg_pc, usp) == 0) {
 386                                        regs->UCreg_pc = KERN_RESTART_CODE;
 387                                } else {
 388                                        regs->UCreg_sp += 4;
 389                                        force_sigsegv(0, current);
 390                                }
 391                }
 392                if (regs->UCreg_00 == -ERESTARTNOHAND ||
 393                    regs->UCreg_00 == -ERESTARTSYS ||
 394                    regs->UCreg_00 == -ERESTARTNOINTR) {
 395                        setup_syscall_restart(regs);
 396                }
 397        }
 398        /* If there's no signal to deliver, we just put the saved
 399         * sigmask back.
 400         */
 401        restore_saved_sigmask();
 402}
 403
 404asmlinkage void do_notify_resume(struct pt_regs *regs,
 405                unsigned int thread_flags, int syscall)
 406{
 407        if (thread_flags & _TIF_SIGPENDING)
 408                do_signal(regs, syscall);
 409
 410        if (thread_flags & _TIF_NOTIFY_RESUME) {
 411                clear_thread_flag(TIF_NOTIFY_RESUME);
 412                tracehook_notify_resume(regs);
 413        }
 414}
 415
 416/*
 417 * Copy signal return handlers into the vector page, and
 418 * set sigreturn to be a pointer to these.
 419 */
 420void __init early_signal_init(void)
 421{
 422        memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
 423                        sigreturn_codes, sizeof(sigreturn_codes));
 424        memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
 425                        syscall_restart_code, sizeof(syscall_restart_code));
 426        /* Need not to flush icache, since early_trap_init will do it last. */
 427}
 428