text: /*
   * Copyright (C) 1991, 1992  Linus Torvalds
   * Copyright 2010 Tilera Corporation. All Rights Reserved.
   *
   *   This program is free software; you can redistribute it and/or
   *   modify it under the terms of the GNU General Public License
   *   as published by the Free Software Foundation, version 2.
   *
   *   This program is distributed in the hope that it will be useful, but
   *   WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
   *   NON INFRINGEMENT.  See the GNU General Public License for
   *   more details.
   */
  
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/smp.h>
  #include <linux/kernel.h>
  #include <linux/signal.h>
  #include <linux/errno.h>
  #include <linux/wait.h>
  #include <linux/unistd.h>
  #include <linux/stddef.h>
  #include <linux/personality.h>
  #include <linux/suspend.h>
  #include <linux/ptrace.h>
  #include <linux/elf.h>
  #include <linux/compat.h>
  #include <linux/syscalls.h>
  #include <linux/uaccess.h>
  #include <asm/processor.h>
  #include <asm/ucontext.h>
  #include <asm/sigframe.h>
  #include <asm/syscalls.h>
  #include <asm/vdso.h>
  #include <arch/interrupts.h>
  
  #define DEBUG_SIG 0
  
  /*
   * Do a signal return; undo the signal stack.
   */
  
  int restore_sigcontext(struct pt_regs *regs,
  		       struct sigcontext __user *sc)
  {
  	int err = 0;
  	int i;
  
  	/* Always make any pending restarted system calls return -EINTR */
  	current_thread_info()->restart_block.fn = do_no_restart_syscall;
  
  	/*
  	 * Enforce that sigcontext is like pt_regs, and doesn't mess
  	 * up our stack alignment rules.
  	 */
  	BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
  	BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
  
  	for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
  		err |= __get_user(regs->regs[i], &sc->gregs[i]);
  
  	/* Ensure that the PL is always set to USER_PL. */
  	regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
  
  	regs->faultnum = INT_SWINT_1_SIGRETURN;
  
  	return err;
  }
  
  void signal_fault(const char *type, struct pt_regs *regs,
  		  void __user *frame, int sig)
  {
  	trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
  	force_sigsegv(sig, current);
  }
  
  /* The assembly shim for this function arranges to ignore the return value. */
  SYSCALL_DEFINE0(rt_sigreturn)
  {
  	struct pt_regs *regs = current_pt_regs();
  	struct rt_sigframe __user *frame =
  		(struct rt_sigframe __user *)(regs->sp);
  	sigset_t set;
  
  	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  		goto badframe;
  	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  		goto badframe;
  
  	set_current_blocked(&set);
  
  	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  		goto badframe;
  
  	if (restore_altstack(&frame->uc.uc_stack))
  		goto badframe;
  
  	return 0;
  
  badframe:
  	signal_fault("bad sigreturn frame", regs, frame, 0);
  	return 0;
  }
  
  /*
   * Set up a signal frame.
   */
  
  int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
  {
  	int i, err = 0;
  
  	for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
  		err |= __put_user(regs->regs[i], &sc->gregs[i]);
  
  	return err;
  }
  
  /*
   * Determine which stack to use..
   */
  static inline void __user *get_sigframe(struct k_sigaction *ka,
  					struct pt_regs *regs,
  					size_t frame_size)
  {
  	unsigned long sp;
  
  	/* Default to using normal stack */
  	sp = regs->sp;
  
  	/*
  	 * If we are on the alternate signal stack and would overflow
  	 * it, don't.  Return an always-bogus address instead so we
  	 * will die with SIGSEGV.
  	 */
  	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
  		return (void __user __force *)-1UL;
  
  	/* This is the X/Open sanctioned signal stack switching.  */
  	if (ka->sa.sa_flags & SA_ONSTACK) {
  		if (sas_ss_flags(sp) == 0)
  			sp = current->sas_ss_sp + current->sas_ss_size;
  	}
  
  	sp -= frame_size;
  	/*
  	 * Align the stack pointer according to the TILE ABI,
  	 * i.e. so that on function entry (sp & 15) == 0.
  	 */
  	sp &= -16UL;
  	return (void __user *) sp;
  }
  
  static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  			   sigset_t *set, struct pt_regs *regs)
  {
  	unsigned long restorer;
  	struct rt_sigframe __user *frame;
  	int err = 0;
  	int usig;
  
  	frame = get_sigframe(ka, regs, sizeof(*frame));
  
  	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
  		goto give_sigsegv;
  
  	usig = current_thread_info()->exec_domain
  		&& current_thread_info()->exec_domain->signal_invmap
  		&& sig < 32
  		? current_thread_info()->exec_domain->signal_invmap[sig]
  		: sig;
  
  	/* Always write at least the signal number for the stack backtracer. */
  	if (ka->sa.sa_flags & SA_SIGINFO) {
  		/* At sigreturn time, restore the callee-save registers too. */
  		err |= copy_siginfo_to_user(&frame->info, info);
  		regs->flags |= PT_FLAGS_RESTORE_REGS;
  	} else {
  		err |= __put_user(info->si_signo, &frame->info.si_signo);
  	}
  
  	/* Create the ucontext.  */
  	err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
  	err |= __put_user(0, &frame->uc.uc_flags);
  	err |= __put_user(NULL, &frame->uc.uc_link);
  	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
  	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
  	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
  	if (err)
  		goto give_sigsegv;
  
  	restorer = VDSO_SYM(&__vdso_rt_sigreturn);
  	if (ka->sa.sa_flags & SA_RESTORER)
  		restorer = (unsigned long) ka->sa.sa_restorer;
  
  	/*
  	 * Set up registers for signal handler.
  	 * Registers that we don't modify keep the value they had from
  	 * user-space at the time we took the signal.
  	 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
  	 * since some things rely on this (e.g. glibc's debug/segfault.c).
  	 */
  	regs->pc = (unsigned long) ka->sa.sa_handler;
  	regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
  	regs->sp = (unsigned long) frame;
  	regs->lr = restorer;
  	regs->regs[0] = (unsigned long) usig;
  	regs->regs[1] = (unsigned long) &frame->info;
  	regs->regs[2] = (unsigned long) &frame->uc;
  	regs->flags |= PT_FLAGS_CALLER_SAVES;
  	return 0;
  
  give_sigsegv:
  	signal_fault("bad setup frame", regs, frame, sig);
  	return -EFAULT;
  }
  
  /*
   * OK, we're invoking a handler
   */
  
  static void handle_signal(unsigned long sig, siginfo_t *info,
  			 struct k_sigaction *ka,
  			 struct pt_regs *regs)
  {
  	sigset_t *oldset = sigmask_to_save();
  	int ret;
  
  	/* Are we from a system call? */
  	if (regs->faultnum == INT_SWINT_1) {
  		/* If so, check system call restarting.. */
  		switch (regs->regs[0]) {
  		case -ERESTART_RESTARTBLOCK:
  		case -ERESTARTNOHAND:
  			regs->regs[0] = -EINTR;
  			break;
  
  		case -ERESTARTSYS:
  			if (!(ka->sa.sa_flags & SA_RESTART)) {
  				regs->regs[0] = -EINTR;
  				break;
  			}
  			/* fallthrough */
  		case -ERESTARTNOINTR:
  			/* Reload caller-saves to restore r0..r5 and r10. */
  			regs->flags |= PT_FLAGS_CALLER_SAVES;
  			regs->regs[0] = regs->orig_r0;
  			regs->pc -= 8;
  		}
  	}
  
  	/* Set up the stack frame */
  #ifdef CONFIG_COMPAT
  	if (is_compat_task())
  		ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
  	else
  #endif
  		ret = setup_rt_frame(sig, ka, info, oldset, regs);
  	if (ret)
  		return;
  	signal_delivered(sig, info, ka, regs,
  			test_thread_flag(TIF_SINGLESTEP));
  }
  
  /*
   * Note that 'init' is a special process: it doesn't get signals it doesn't
   * want to handle. Thus you cannot kill init even with a SIGKILL even by
   * mistake.
   */
  void do_signal(struct pt_regs *regs)
  {
  	siginfo_t info;
  	int signr;
  	struct k_sigaction ka;
  
  	/*
  	 * i386 will check if we're coming from kernel mode and bail out
  	 * here.  In my experience this just turns weird crashes into
  	 * weird spin-hangs.  But if we find a case where this seems
  	 * helpful, we can reinstate the check on "!user_mode(regs)".
  	 */
  
  	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
  	if (signr > 0) {
  		/* Whee! Actually deliver the signal.  */
  		handle_signal(signr, &info, &ka, regs);
  		goto done;
  	}
  
  	/* Did we come from a system call? */
  	if (regs->faultnum == INT_SWINT_1) {
  		/* Restart the system call - no handlers present */
  		switch (regs->regs[0]) {
  		case -ERESTARTNOHAND:
  		case -ERESTARTSYS:
  		case -ERESTARTNOINTR:
  			regs->flags |= PT_FLAGS_CALLER_SAVES;
  			regs->regs[0] = regs->orig_r0;
  			regs->pc -= 8;
  			break;
  
  		case -ERESTART_RESTARTBLOCK:
  			regs->flags |= PT_FLAGS_CALLER_SAVES;
  			regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
  			regs->pc -= 8;
  			break;
  		}
  	}
  
  	/* If there's no signal to deliver, just put the saved sigmask back. */
  	restore_saved_sigmask();
  
  done:
  	/* Avoid double syscall restart if there are nested signals. */
  	regs->faultnum = INT_SWINT_1_SIGRETURN;
  }
  
  int show_unhandled_signals = 1;
  
  static int __init crashinfo(char *str)
  {
  	const char *word;
  
  	if (*str == '\0')
  		show_unhandled_signals = 2;
  	else if (*str != '=' || kstrtoint(++str, 0, &show_unhandled_signals) != 0)
  		return 0;
  
  	switch (show_unhandled_signals) {
  	case 0:
  		word = "No";
  		break;
  	case 1:
  		word = "One-line";
  		break;
  	default:
  		word = "Detailed";
  		break;
  	}
  	pr_info("%s crash reports will be generated on the console\n", word);
  	return 1;
  }
  __setup("crashinfo", crashinfo);
  
  static void dump_mem(void __user *address)
  {
  	void __user *addr;
  	enum { region_size = 256, bytes_per_line = 16 };
  	int i, j, k;
  	int found_readable_mem = 0;
  
  	pr_err("\n");
  	if (!access_ok(VERIFY_READ, address, 1)) {
  		pr_err("Not dumping at address 0x%lx (kernel address)\n",
  		       (unsigned long)address);
  		return;
  	}
  
  	addr = (void __user *)
  		(((unsigned long)address & -bytes_per_line) - region_size/2);
  	if (addr > address)
  		addr = NULL;
  	for (i = 0; i < region_size;
  	     addr += bytes_per_line, i += bytes_per_line) {
  		unsigned char buf[bytes_per_line];
  		char line[100];
  		if (copy_from_user(buf, addr, bytes_per_line))
  			continue;
  		if (!found_readable_mem) {
  			pr_err("Dumping memory around address 0x%lx:\n",
  			       (unsigned long)address);
  			found_readable_mem = 1;
  		}
  		j = sprintf(line, REGFMT":", (unsigned long)addr);
  		for (k = 0; k < bytes_per_line; ++k)
  			j += sprintf(&line[j], " %02x", buf[k]);
  		pr_err("%s\n", line);
  	}
  	if (!found_readable_mem)
  		pr_err("No readable memory around address 0x%lx\n",
  		       (unsigned long)address);
  }
  
  void trace_unhandled_signal(const char *type, struct pt_regs *regs,
  			    unsigned long address, int sig)
  {
  	struct task_struct *tsk = current;
  
  	if (show_unhandled_signals == 0)
  		return;
  
  	/* If the signal is handled, don't show it here. */
  	if (!is_global_init(tsk)) {
  		void __user *handler =
  			tsk->sighand->action[sig-1].sa.sa_handler;
  		if (handler != SIG_IGN && handler != SIG_DFL)
  			return;
  	}
  
  	/* Rate-limit the one-line output, not the detailed output. */
  	if (show_unhandled_signals <= 1 && !printk_ratelimit())
  		return;
  
  	printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
  	       task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
  	       tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
  
  	print_vma_addr(KERN_CONT " in ", regs->pc);
  
  	printk(KERN_CONT "\n");
  
  	if (show_unhandled_signals > 1) {
  		switch (sig) {
  		case SIGILL:
  		case SIGFPE:
  		case SIGSEGV:
  		case SIGBUS:
  			pr_err("User crash: signal %d,"
  			       " trap %ld, address 0x%lx\n",
  			       sig, regs->faultnum, address);
  			show_regs(regs);
  			dump_mem((void __user *)address);
  			break;
  		default:
  			pr_err("User crash: signal %d, trap %ld\n",
  			       sig, regs->faultnum);
  			break;
  		}
  	}
  }
  