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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/arch/unicore32/kernel/signal.c
   4 *
   5 * Code specific to PKUnity SoC and UniCore ISA
   6 *
   7 * Copyright (C) 2001-2010 GUAN Xue-tao
   8 */
   9#include <linux/errno.h>
  10#include <linux/signal.h>
  11#include <linux/personality.h>
  12#include <linux/uaccess.h>
  13#include <linux/tracehook.h>
  14#include <linux/elf.h>
  15#include <linux/unistd.h>
  16
  17#include <asm/cacheflush.h>
  18#include <asm/ucontext.h>
  19
  20/*
  21 * For UniCore syscalls, we encode the syscall number into the instruction.
  22 */
  23#define SWI_SYS_SIGRETURN       (0xff000000) /* error number for new abi */
  24#define SWI_SYS_RT_SIGRETURN    (0xff000000 | (__NR_rt_sigreturn))
  25#define SWI_SYS_RESTART         (0xff000000 | (__NR_restart_syscall))
  26
  27#define KERN_SIGRETURN_CODE     (KUSER_VECPAGE_BASE + 0x00000500)
  28#define KERN_RESTART_CODE       (KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
  29
  30const unsigned long sigreturn_codes[3] = {
  31        SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
  32};
  33
  34const unsigned long syscall_restart_code[2] = {
  35        SWI_SYS_RESTART,        /* swi  __NR_restart_syscall */
  36        0x69efc004,             /* ldr  pc, [sp], #4 */
  37};
  38
  39/*
  40 * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
  41 */
  42struct sigframe {
  43        struct ucontext uc;
  44        unsigned long retcode[2];
  45};
  46
  47struct rt_sigframe {
  48        struct siginfo info;
  49        struct sigframe sig;
  50};
  51
  52static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
  53{
  54        sigset_t set;
  55        int err;
  56
  57        err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
  58        if (err == 0)
  59                set_current_blocked(&set);
  60
  61        err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
  62        err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
  63        err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
  64        err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
  65        err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
  66        err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
  67        err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
  68        err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
  69        err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
  70        err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
  71        err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
  72        err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
  73        err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
  74        err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
  75        err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
  76        err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
  77        err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
  78        err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
  79        err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
  80        err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
  81        err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
  82        err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
  83        err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
  84        err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
  85        err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
  86        err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
  87        err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
  88        err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
  89        err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
  90        err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
  91        err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
  92        err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
  93        err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
  94
  95        err |= !valid_user_regs(regs);
  96
  97        return err;
  98}
  99
 100asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
 101{
 102        struct rt_sigframe __user *frame;
 103
 104        /* Always make any pending restarted system calls return -EINTR */
 105        current->restart_block.fn = do_no_restart_syscall;
 106
 107        /*
 108         * Since we stacked the signal on a 64-bit boundary,
 109         * then 'sp' should be word aligned here.  If it's
 110         * not, then the user is trying to mess with us.
 111         */
 112        if (regs->UCreg_sp & 7)
 113                goto badframe;
 114
 115        frame = (struct rt_sigframe __user *)regs->UCreg_sp;
 116
 117        if (!access_ok(frame, sizeof(*frame)))
 118                goto badframe;
 119
 120        if (restore_sigframe(regs, &frame->sig))
 121                goto badframe;
 122
 123        if (restore_altstack(&frame->sig.uc.uc_stack))
 124                goto badframe;
 125
 126        return regs->UCreg_00;
 127
 128badframe:
 129        force_sig(SIGSEGV);
 130        return 0;
 131}
 132
 133static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
 134                sigset_t *set)
 135{
 136        int err = 0;
 137
 138        err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
 139        err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
 140        err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
 141        err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
 142        err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
 143        err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
 144        err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
 145        err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
 146        err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
 147        err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
 148        err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
 149        err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
 150        err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
 151        err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
 152        err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
 153        err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
 154        err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
 155        err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
 156        err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
 157        err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
 158        err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
 159        err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
 160        err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
 161        err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
 162        err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
 163        err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
 164        err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
 165        err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
 166        err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
 167        err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
 168        err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 169        err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 170        err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 171
 172        err |= __put_user(current->thread.trap_no,
 173                        &sf->uc.uc_mcontext.trap_no);
 174        err |= __put_user(current->thread.error_code,
 175                        &sf->uc.uc_mcontext.error_code);
 176        err |= __put_user(current->thread.address,
 177                        &sf->uc.uc_mcontext.fault_address);
 178        err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
 179
 180        err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 181
 182        return err;
 183}
 184
 185static inline void __user *get_sigframe(struct k_sigaction *ka,
 186                struct pt_regs *regs, int framesize)
 187{
 188        unsigned long sp = regs->UCreg_sp;
 189        void __user *frame;
 190
 191        /*
 192         * This is the X/Open sanctioned signal stack switching.
 193         */
 194        if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 195                sp = current->sas_ss_sp + current->sas_ss_size;
 196
 197        /*
 198         * ATPCS B01 mandates 8-byte alignment
 199         */
 200        frame = (void __user *)((sp - framesize) & ~7);
 201
 202        /*
 203         * Check that we can actually write to the signal frame.
 204         */
 205        if (!access_ok(frame, framesize))
 206                frame = NULL;
 207
 208        return frame;
 209}
 210
 211static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 212             unsigned long __user *rc, void __user *frame, int usig)
 213{
 214        unsigned long handler = (unsigned long)ka->sa.sa_handler;
 215        unsigned long retcode;
 216        unsigned long asr = regs->UCreg_asr & ~PSR_f;
 217
 218        unsigned int idx = 0;
 219
 220        if (ka->sa.sa_flags & SA_SIGINFO)
 221                idx += 1;
 222
 223        if (__put_user(sigreturn_codes[idx],   rc) ||
 224            __put_user(sigreturn_codes[idx+1], rc+1))
 225                return 1;
 226
 227        retcode = KERN_SIGRETURN_CODE + (idx << 2);
 228
 229        regs->UCreg_00 = usig;
 230        regs->UCreg_sp = (unsigned long)frame;
 231        regs->UCreg_lr = retcode;
 232        regs->UCreg_pc = handler;
 233        regs->UCreg_asr = asr;
 234
 235        return 0;
 236}
 237
 238static int setup_frame(struct ksignal *ksig, sigset_t *set,
 239                       struct pt_regs *regs)
 240{
 241        struct sigframe __user *frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
 242        int err = 0;
 243
 244        if (!frame)
 245                return 1;
 246
 247        /*
 248         * Set uc.uc_flags to a value which sc.trap_no would never have.
 249         */
 250        err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
 251
 252        err |= setup_sigframe(frame, regs, set);
 253        if (err == 0)
 254                err |= setup_return(regs, &ksig->ka, frame->retcode, frame,
 255                                    ksig->sig);
 256
 257        return err;
 258}
 259
 260static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 261                          struct pt_regs *regs)
 262{
 263        struct rt_sigframe __user *frame =
 264                        get_sigframe(&ksig->ka, regs, sizeof(*frame));
 265        int err = 0;
 266
 267        if (!frame)
 268                return 1;
 269
 270        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 271
 272        err |= __put_user(0, &frame->sig.uc.uc_flags);
 273        err |= __put_user(NULL, &frame->sig.uc.uc_link);
 274        err |= __save_altstack(&frame->sig.uc.uc_stack, regs->UCreg_sp);
 275        err |= setup_sigframe(&frame->sig, regs, set);
 276        if (err == 0)
 277                err |= setup_return(regs, &ksig->ka, frame->sig.retcode, frame,
 278                                    ksig->sig);
 279
 280        if (err == 0) {
 281                /*
 282                 * For realtime signals we must also set the second and third
 283                 * arguments for the signal handler.
 284                 */
 285                regs->UCreg_01 = (unsigned long)&frame->info;
 286                regs->UCreg_02 = (unsigned long)&frame->sig.uc;
 287        }
 288
 289        return err;
 290}
 291
 292static inline void setup_syscall_restart(struct pt_regs *regs)
 293{
 294        regs->UCreg_00 = regs->UCreg_ORIG_00;
 295        regs->UCreg_pc -= 4;
 296}
 297
 298/*
 299 * OK, we're invoking a handler
 300 */
 301static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
 302                          int syscall)
 303{
 304        struct thread_info *thread = current_thread_info();
 305        sigset_t *oldset = sigmask_to_save();
 306        int usig = ksig->sig;
 307        int ret;
 308
 309        /*
 310         * If we were from a system call, check for system call restarting...
 311         */
 312        if (syscall) {
 313                switch (regs->UCreg_00) {
 314                case -ERESTART_RESTARTBLOCK:
 315                case -ERESTARTNOHAND:
 316                        regs->UCreg_00 = -EINTR;
 317                        break;
 318                case -ERESTARTSYS:
 319                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 320                                regs->UCreg_00 = -EINTR;
 321                                break;
 322                        }
 323                        /* fallthrough */
 324                case -ERESTARTNOINTR:
 325                        setup_syscall_restart(regs);
 326                }
 327        }
 328
 329        /*
 330         * Set up the stack frame
 331         */
 332        if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 333                ret = setup_rt_frame(ksig, oldset, regs);
 334        else
 335                ret = setup_frame(ksig, oldset, regs);
 336
 337        /*
 338         * Check that the resulting registers are actually sane.
 339         */
 340        ret |= !valid_user_regs(regs);
 341
 342        signal_setup_done(ret, ksig, 0);
 343}
 344
 345/*
 346 * Note that 'init' is a special process: it doesn't get signals it doesn't
 347 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 348 * mistake.
 349 *
 350 * Note that we go through the signals twice: once to check the signals that
 351 * the kernel can handle, and then we build all the user-level signal handling
 352 * stack-frames in one go after that.
 353 */
 354static void do_signal(struct pt_regs *regs, int syscall)
 355{
 356        struct ksignal ksig;
 357
 358        /*
 359         * We want the common case to go fast, which
 360         * is why we may in certain cases get here from
 361         * kernel mode. Just return without doing anything
 362         * if so.
 363         */
 364        if (!user_mode(regs))
 365                return;
 366
 367        if (get_signal(&ksig)) {
 368                handle_signal(&ksig, regs, syscall);
 369                return;
 370        }
 371
 372        /*
 373         * No signal to deliver to the process - restart the syscall.
 374         */
 375        if (syscall) {
 376                if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
 377                                u32 __user *usp;
 378
 379                                regs->UCreg_sp -= 4;
 380                                usp = (u32 __user *)regs->UCreg_sp;
 381
 382                                if (put_user(regs->UCreg_pc, usp) == 0) {
 383                                        regs->UCreg_pc = KERN_RESTART_CODE;
 384                                } else {
 385                                        regs->UCreg_sp += 4;
 386                                        force_sigsegv(0);
 387                                }
 388                }
 389                if (regs->UCreg_00 == -ERESTARTNOHAND ||
 390                    regs->UCreg_00 == -ERESTARTSYS ||
 391                    regs->UCreg_00 == -ERESTARTNOINTR) {
 392                        setup_syscall_restart(regs);
 393                }
 394        }
 395        /* If there's no signal to deliver, we just put the saved
 396         * sigmask back.
 397         */
 398        restore_saved_sigmask();
 399}
 400
 401asmlinkage void do_notify_resume(struct pt_regs *regs,
 402                unsigned int thread_flags, int syscall)
 403{
 404        if (thread_flags & _TIF_SIGPENDING)
 405                do_signal(regs, syscall);
 406
 407        if (thread_flags & _TIF_NOTIFY_RESUME) {
 408                clear_thread_flag(TIF_NOTIFY_RESUME);
 409                tracehook_notify_resume(regs);
 410        }
 411}
 412
 413/*
 414 * Copy signal return handlers into the vector page, and
 415 * set sigreturn to be a pointer to these.
 416 */
 417void __init early_signal_init(void)
 418{
 419        memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
 420                        sigreturn_codes, sizeof(sigreturn_codes));
 421        memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
 422                        syscall_restart_code, sizeof(syscall_restart_code));
 423        /* Need not to flush icache, since early_trap_init will do it last. */
 424}
 425