unicore32 core architecture: signals handling

/*

 * linux/arch/unicore32/include/asm/sigcontext.h

 *

 * Code specific to PKUnity SoC and UniCore ISA

 *

 * Copyright (C) 2001-2010 GUAN Xue-tao

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#ifndef __UNICORE_SIGCONTEXT_H__

#define __UNICORE_SIGCONTEXT_H__

#include <asm/ptrace.h>

/*

 * Signal context structure - contains all info to do with the state

 * before the signal handler was invoked.  Note: only add new entries

 * to the end of the structure.

 */

struct sigcontext {

	unsigned long trap_no;

	unsigned long error_code;

	unsigned long oldmask;

	unsigned long fault_address;

	struct pt_regs regs;

};

#endif

/*

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

 *

 * Code specific to PKUnity SoC and UniCore ISA

 *

 * Copyright (C) 2001-2010 GUAN Xue-tao

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#include <linux/errno.h>

#include <linux/signal.h>

#include <linux/personality.h>

#include <linux/freezer.h>

#include <linux/uaccess.h>

#include <linux/tracehook.h>

#include <linux/elf.h>

#include <linux/unistd.h>

#include <asm/cacheflush.h>

#include <asm/ucontext.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

/*

 * For UniCore syscalls, we encode the syscall number into the instruction.

 */

#define SWI_SYS_SIGRETURN	(0xff000000) /* error number for new abi */

#define SWI_SYS_RT_SIGRETURN	(0xff000000 | (__NR_rt_sigreturn))

#define SWI_SYS_RESTART		(0xff000000 | (__NR_restart_syscall))

#define KERN_SIGRETURN_CODE	(KUSER_VECPAGE_BASE + 0x00000500)

#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))

const unsigned long sigreturn_codes[3] = {

	SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,

};

const unsigned long syscall_restart_code[2] = {

	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */

	0x69efc004,		/* ldr	pc, [sp], #4 */

};

/*

 * Do a signal return; undo the signal stack.  These are aligned to 64-bit.

 */

struct sigframe {

	struct ucontext uc;

	unsigned long retcode[2];

};

struct rt_sigframe {

	struct siginfo info;

	struct sigframe sig;

};

static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)

{

	sigset_t set;

	int err;

	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));

	if (err == 0) {

		sigdelsetmask(&set, ~_BLOCKABLE);

		spin_lock_irq(&current->sighand->siglock);

		current->blocked = set;

		recalc_sigpending();

		spin_unlock_irq(&current->sighand->siglock);

	}

	err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);

	err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);

	err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);

	err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);

	err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);

	err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);

	err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);

	err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);

	err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);

	err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);

	err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);

	err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);

	err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);

	err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);

	err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);

	err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);

	err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);

	err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);

	err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);

	err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);

	err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);

	err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);

	err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);

	err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);

	err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);

	err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);

	err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);

	err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);

	err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);

	err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);

	err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);

	err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);

	err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);

	err |= !valid_user_regs(regs);

	return err;

}

asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)

{

	struct rt_sigframe __user *frame;

	/* Always make any pending restarted system calls return -EINTR */

	current_thread_info()->restart_block.fn = do_no_restart_syscall;

	/*

	 * Since we stacked the signal on a 64-bit boundary,

	 * then 'sp' should be word aligned here.  If it's

	 * not, then the user is trying to mess with us.

	 */

	if (regs->UCreg_sp & 7)

		goto badframe;

	frame = (struct rt_sigframe __user *)regs->UCreg_sp;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))

		goto badframe;

	if (restore_sigframe(regs, &frame->sig))

		goto badframe;

	if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)

			== -EFAULT)

		goto badframe;

	return regs->UCreg_00;

badframe:

	force_sig(SIGSEGV, current);

	return 0;

}

static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,

		sigset_t *set)

{

	int err = 0;

	err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);

	err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);

	err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);

	err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);

	err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);

	err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);

	err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);

	err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);

	err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);

	err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);

	err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);

	err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);

	err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);

	err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);

	err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);

	err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);

	err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);

	err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);

	err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);

	err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);

	err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);

	err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);

	err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);

	err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);

	err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);

	err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);

	err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);

	err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);

	err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);

	err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);

	err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);

	err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);

	err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);

	err |= __put_user(current->thread.trap_no,

			&sf->uc.uc_mcontext.trap_no);

	err |= __put_user(current->thread.error_code,

			&sf->uc.uc_mcontext.error_code);

	err |= __put_user(current->thread.address,

			&sf->uc.uc_mcontext.fault_address);

	err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);

	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));

	return err;

}

static inline void __user *get_sigframe(struct k_sigaction *ka,

		struct pt_regs *regs, int framesize)

{

	unsigned long sp = regs->UCreg_sp;

	void __user *frame;

	/*

	 * This is the X/Open sanctioned signal stack switching.

	 */

	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))

		sp = current->sas_ss_sp + current->sas_ss_size;

	/*

	 * ATPCS B01 mandates 8-byte alignment

	 */

	frame = (void __user *)((sp - framesize) & ~7);

	/*

	 * Check that we can actually write to the signal frame.

	 */

	if (!access_ok(VERIFY_WRITE, frame, framesize))

		frame = NULL;

	return frame;

}

static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,

	     unsigned long __user *rc, void __user *frame, int usig)

{

	unsigned long handler = (unsigned long)ka->sa.sa_handler;

	unsigned long retcode;

	unsigned long asr = regs->UCreg_asr & ~PSR_f;

	unsigned int idx = 0;

	if (ka->sa.sa_flags & SA_SIGINFO)

		idx += 1;

	if (__put_user(sigreturn_codes[idx],   rc) ||

	    __put_user(sigreturn_codes[idx+1], rc+1))

		return 1;

	retcode = KERN_SIGRETURN_CODE + (idx << 2);

	regs->UCreg_00 = usig;

	regs->UCreg_sp = (unsigned long)frame;

	regs->UCreg_lr = retcode;

	regs->UCreg_pc = handler;

	regs->UCreg_asr = asr;

	return 0;

}

static int setup_frame(int usig, struct k_sigaction *ka,

		sigset_t *set, struct pt_regs *regs)

{

	struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));

	int err = 0;

	if (!frame)

		return 1;

	/*

	 * Set uc.uc_flags to a value which sc.trap_no would never have.

	 */

	err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);

	err |= setup_sigframe(frame, regs, set);

	if (err == 0)

		err |= setup_return(regs, ka, frame->retcode, frame, usig);

	return err;

}

static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,

	       sigset_t *set, struct pt_regs *regs)

{

	struct rt_sigframe __user *frame =

			get_sigframe(ka, regs, sizeof(*frame));

	stack_t stack;

	int err = 0;

	if (!frame)

		return 1;

	err |= copy_siginfo_to_user(&frame->info, info);

	err |= __put_user(0, &frame->sig.uc.uc_flags);

	err |= __put_user(NULL, &frame->sig.uc.uc_link);

	memset(&stack, 0, sizeof(stack));

	stack.ss_sp = (void __user *)current->sas_ss_sp;

	stack.ss_flags = sas_ss_flags(regs->UCreg_sp);

	stack.ss_size = current->sas_ss_size;

	err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));

	err |= setup_sigframe(&frame->sig, regs, set);

	if (err == 0)

		err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);

	if (err == 0) {

		/*

		 * For realtime signals we must also set the second and third

		 * arguments for the signal handler.

		 */

		regs->UCreg_01 = (unsigned long)&frame->info;

		regs->UCreg_02 = (unsigned long)&frame->sig.uc;

	}

	return err;

}

static inline void setup_syscall_restart(struct pt_regs *regs)

{

	regs->UCreg_00 = regs->UCreg_ORIG_00;

	regs->UCreg_pc -= 4;

}

/*

 * OK, we're invoking a handler

 */

static int handle_signal(unsigned long sig, struct k_sigaction *ka,

	      siginfo_t *info, sigset_t *oldset,

	      struct pt_regs *regs, int syscall)

{

	struct thread_info *thread = current_thread_info();

	struct task_struct *tsk = current;

	int usig = sig;

	int ret;

	/*

	 * If we were from a system call, check for system call restarting...

	 */

	if (syscall) {

		switch (regs->UCreg_00) {

		case -ERESTART_RESTARTBLOCK:

		case -ERESTARTNOHAND:

			regs->UCreg_00 = -EINTR;

			break;

		case -ERESTARTSYS:

			if (!(ka->sa.sa_flags & SA_RESTART)) {

				regs->UCreg_00 = -EINTR;

				break;

			}

			/* fallthrough */

		case -ERESTARTNOINTR:

			setup_syscall_restart(regs);

		}

	}

	/*

	 * translate the signal

	 */

	if (usig < 32 && thread->exec_domain

			&& thread->exec_domain->signal_invmap)

		usig = thread->exec_domain->signal_invmap[usig];

	/*

	 * Set up the stack frame

	 */

	if (ka->sa.sa_flags & SA_SIGINFO)

		ret = setup_rt_frame(usig, ka, info, oldset, regs);

	else

		ret = setup_frame(usig, ka, oldset, regs);

	/*

	 * Check that the resulting registers are actually sane.

	 */

	ret |= !valid_user_regs(regs);

	if (ret != 0) {

		force_sigsegv(sig, tsk);

		return ret;

	}

	/*

	 * Block the signal if we were successful.

	 */

	spin_lock_irq(&tsk->sighand->siglock);

	sigorsets(&tsk->blocked, &tsk->blocked,

		  &ka->sa.sa_mask);

	if (!(ka->sa.sa_flags & SA_NODEFER))

		sigaddset(&tsk->blocked, sig);

	recalc_sigpending();

	spin_unlock_irq(&tsk->sighand->siglock);

	return 0;

}

/*

 * 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.

 *

 * Note that we go through the signals twice: once to check the signals that

 * the kernel can handle, and then we build all the user-level signal handling

 * stack-frames in one go after that.

 */

static void do_signal(struct pt_regs *regs, int syscall)

{

	struct k_sigaction ka;

	siginfo_t info;

	int signr;

	/*

	 * We want the common case to go fast, which

	 * is why we may in certain cases get here from

	 * kernel mode. Just return without doing anything

	 * if so.

	 */

	if (!user_mode(regs))

		return;

	if (try_to_freeze())

		goto no_signal;

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

	if (signr > 0) {

		sigset_t *oldset;

		if (test_thread_flag(TIF_RESTORE_SIGMASK))

			oldset = &current->saved_sigmask;

		else

			oldset = &current->blocked;

		if (handle_signal(signr, &ka, &info, oldset, regs, syscall)

				== 0) {

			/*

			 * A signal was successfully delivered; the saved

			 * sigmask will have been stored in the signal frame,

			 * and will be restored by sigreturn, so we can simply

			 * clear the TIF_RESTORE_SIGMASK flag.

			 */

			if (test_thread_flag(TIF_RESTORE_SIGMASK))

				clear_thread_flag(TIF_RESTORE_SIGMASK);

		}

		return;

	}

 no_signal:

	/*

	 * No signal to deliver to the process - restart the syscall.

	 */

	if (syscall) {

		if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {

				u32 __user *usp;

				regs->UCreg_sp -= 4;

				usp = (u32 __user *)regs->UCreg_sp;

				if (put_user(regs->UCreg_pc, usp) == 0) {

					regs->UCreg_pc = KERN_RESTART_CODE;

				} else {

					regs->UCreg_sp += 4;

					force_sigsegv(0, current);

				}

		}

		if (regs->UCreg_00 == -ERESTARTNOHAND ||

		    regs->UCreg_00 == -ERESTARTSYS ||

		    regs->UCreg_00 == -ERESTARTNOINTR) {

			setup_syscall_restart(regs);

		}

		/* If there's no signal to deliver, we just put the saved

		 * sigmask back.

		 */

		if (test_thread_flag(TIF_RESTORE_SIGMASK)) {

			clear_thread_flag(TIF_RESTORE_SIGMASK);

			sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);

		}

	}

}

asmlinkage void do_notify_resume(struct pt_regs *regs,

		unsigned int thread_flags, int syscall)

{

	if (thread_flags & _TIF_SIGPENDING)

		do_signal(regs, syscall);

	if (thread_flags & _TIF_NOTIFY_RESUME) {

		clear_thread_flag(TIF_NOTIFY_RESUME);

		tracehook_notify_resume(regs);

		if (current->replacement_session_keyring)

			key_replace_session_keyring();

	}

}

/*

 * Copy signal return handlers into the vector page, and

 * set sigreturn to be a pointer to these.

 */

void __init early_signal_init(void)

{

	memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),

			sigreturn_codes, sizeof(sigreturn_codes));

	memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),

			syscall_restart_code, sizeof(syscall_restart_code));

	/* Need not to flush icache, since early_trap_init will do it last. */

}