signal.c

底层驱动开发

/*
 *  linux/arch/arm/kernel/signal.c
 *
 *  Copyright (C) 1995-2002 Russell King
 *
 * 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/config.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/personality.h>

#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>

#include "ptrace.h"
#include "signal.h"

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

/*
 * For ARM syscalls, we encode the syscall number into the instruction.
 */
#define SWI_SYS_SIGRETURN	(0xef000000|(__NR_sigreturn))
#define SWI_SYS_RT_SIGRETURN	(0xef000000|(__NR_rt_sigreturn))

/*
 * For Thumb syscalls, we pass the syscall number via r7.  We therefore
 * need two 16-bit instructions.
 */
#define SWI_THUMB_SIGRETURN	(0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
#define SWI_THUMB_RT_SIGRETURN	(0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))

const unsigned long sigreturn_codes[4] = {
	SWI_SYS_SIGRETURN,	SWI_THUMB_SIGRETURN,
	SWI_SYS_RT_SIGRETURN,	SWI_THUMB_RT_SIGRETURN
};

static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);

/*
 * atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
{
	sigset_t saveset;

	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	regs->ARM_r0 = -EINTR;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs, 0))
			return regs->ARM_r0;
	}
}

asmlinkage int
sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
{
	sigset_t saveset, newset;

	/* XXX: Don't preclude handling different sized sigset_t's. */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (copy_from_user(&newset, unewset, sizeof(newset)))
		return -EFAULT;
	sigdelsetmask(&newset, ~_BLOCKABLE);

	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	current->blocked = newset;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	regs->ARM_r0 = -EINTR;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs, 0))
			return regs->ARM_r0;
	}
}

asmlinkage int 
sys_sigaction(int sig, const struct old_sigaction __user *act,
	      struct old_sigaction __user *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	if (act) {
		old_sigset_t mask;
		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
			return -EFAULT;
		__get_user(new_ka.sa.sa_flags, &act->sa_flags);
		__get_user(mask, &act->sa_mask);
		siginitset(&new_ka.sa.sa_mask, mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
			return -EFAULT;
		__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
		__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return ret;
}

#ifdef CONFIG_IWMMXT

/* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
#define IWMMXT_STORAGE_SIZE	(0x98 + 8)
#define IWMMXT_MAGIC0		0x12ef842a
#define IWMMXT_MAGIC1		0x1c07ca71

struct iwmmxt_sigframe {
	unsigned long	magic0;
	unsigned long	magic1;
	unsigned long	storage[0x98/4];
};

static int page_present(struct mm_struct *mm, void __user *uptr, int wr)
{
	unsigned long addr = (unsigned long)uptr;
	pgd_t *pgd = pgd_offset(mm, addr);
	if (pgd_present(*pgd)) {
		pmd_t *pmd = pmd_offset(pgd, addr);
		if (pmd_present(*pmd)) {
			pte_t *pte = pte_offset_map(pmd, addr);
			return (pte_present(*pte) && (!wr || pte_write(*pte)));
		}
	}
	return 0;
}

static int copy_locked(void __user *uptr, void *kptr, size_t size, int write,
		       void (*copyfn)(void *, void __user *))
{
	unsigned char v, __user *userptr = uptr;
	int err = 0;

	do {
		struct mm_struct *mm;

		if (write) {
			__put_user_error(0, userptr, err);
			__put_user_error(0, userptr + size - 1, err);
		} else {
			__get_user_error(v, userptr, err);
			__get_user_error(v, userptr + size - 1, err);
		}

		if (err)
			break;

		mm = current->mm;
		spin_lock(&mm->page_table_lock);
		if (page_present(mm, userptr, write) &&
		    page_present(mm, userptr + size - 1, write)) {
		    	copyfn(kptr, uptr);
		} else
			err = 1;
		spin_unlock(&mm->page_table_lock);
	} while (err);

	return err;
}

static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
{
	int err = 0;

	/* the iWMMXt context must be 64 bit aligned */
	WARN_ON((unsigned long)frame & 7);

	__put_user_error(IWMMXT_MAGIC0, &frame->magic0, err);
	__put_user_error(IWMMXT_MAGIC1, &frame->magic1, err);

	/*
	 * iwmmxt_task_copy() doesn't check user permissions.
	 * Let's do a dummy write on the upper boundary to ensure
	 * access to user mem is OK all way up.
	 */
	err |= copy_locked(&frame->storage, current_thread_info(),
			   sizeof(frame->storage), 1, iwmmxt_task_copy);
	return err;
}

static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
{
	unsigned long magic0, magic1;
	int err = 0;

	/* the iWMMXt context is 64 bit aligned */
	WARN_ON((unsigned long)frame & 7);

	/*
	 * Validate iWMMXt context signature.
	 * Also, iwmmxt_task_restore() doesn't check user permissions.
	 * Let's do a dummy write on the upper boundary to ensure
	 * access to user mem is OK all way up.
	 */
	__get_user_error(magic0, &frame->magic0, err);
	__get_user_error(magic1, &frame->magic1, err);
	if (!err && magic0 == IWMMXT_MAGIC0 && magic1 == IWMMXT_MAGIC1)
		err = copy_locked(&frame->storage, current_thread_info(),
				  sizeof(frame->storage), 0, iwmmxt_task_restore);
	return err;
}

#endif

/*
 * Auxiliary signal frame.  This saves stuff like FP state.
 * The layout of this structure is not part of the user ABI.
 */
struct aux_sigframe {
#ifdef CONFIG_IWMMXT
	struct iwmmxt_sigframe	iwmmxt;
#endif
#ifdef CONFIG_VFP
	union vfp_state		vfp;
#endif
};

/*
 * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 */
struct sigframe {
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS-1];
	unsigned long retcode;
	struct aux_sigframe aux __attribute__((aligned(8)));
};

struct rt_sigframe {
	struct siginfo __user *pinfo;
	void __user *puc;
	struct siginfo info;
	struct ucontext uc;
	unsigned long retcode;
	struct aux_sigframe aux __attribute__((aligned(8)));
};

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
		   struct aux_sigframe __user *aux)
{
	int err = 0;

	__get_user_error(regs->ARM_r0, &sc->arm_r0, err);
	__get_user_error(regs->ARM_r1, &sc->arm_r1, err);
	__get_user_error(regs->ARM_r2, &sc->arm_r2, err);
	__get_user_error(regs->ARM_r3, &sc->arm_r3, err);
	__get_user_error(regs->ARM_r4, &sc->arm_r4, err);
	__get_user_error(regs->ARM_r5, &sc->arm_r5, err);
	__get_user_error(regs->ARM_r6, &sc->arm_r6, err);
	__get_user_error(regs->ARM_r7, &sc->arm_r7, err);
	__get_user_error(regs->ARM_r8, &sc->arm_r8, err);
	__get_user_error(regs->ARM_r9, &sc->arm_r9, err);
	__get_user_error(regs->ARM_r10, &sc->arm_r10, err);
	__get_user_error(regs->ARM_fp, &sc->arm_fp, err);
	__get_user_error(regs->ARM_ip, &sc->arm_ip, err);
	__get_user_error(regs->ARM_sp, &sc->arm_sp, err);
	__get_user_error(regs->ARM_lr, &sc->arm_lr, err);
	__get_user_error(regs->ARM_pc, &sc->arm_pc, err);
	__get_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);

	err |= !valid_user_regs(regs);

#ifdef CONFIG_IWMMXT
	if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
		err |= restore_iwmmxt_context(&aux->iwmmxt);
#endif
#ifdef CONFIG_VFP
//	if (err == 0)
//		err |= vfp_restore_state(&aux->vfp);
#endif

	return err;
}

asmlinkage int sys_sigreturn(struct pt_regs *regs)
{
	struct sigframe __user *frame;
	sigset_t set;

	/* 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->ARM_sp & 7)
		goto badframe;

	frame = (struct sigframe __user *)regs->ARM_sp;

	if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
		goto badframe;
	if (__get_user(set.sig[0], &frame->sc.oldmask)
	    || (_NSIG_WORDS > 1
	        && __copy_from_user(&set.sig[1], &frame->extramask,
				    sizeof(frame->extramask))))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->sc, &frame->aux))
		goto badframe;

	/* Send SIGTRAP if we're single-stepping */
	if (current->ptrace & PT_SINGLESTEP) {
		ptrace_cancel_bpt(current);
		send_sig(SIGTRAP, current, 1);
	}

	return regs->ARM_r0;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
	struct rt_sigframe __user *frame;
	sigset_t set;

	/* 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->ARM_sp & 7)
		goto badframe;

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

	if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
		goto badframe;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &frame->aux))