signal32.c

来自「优龙2410linux2.6.8内核源代码」· C语言 代码 · 共 998 行 · 第 1/2 页

/*
 * signal32.c: Support 32bit signal syscalls.
 *
 * Copyright (C) 2001 IBM
 * Copyright (C) 1997,1998 Jakub Jelinek ([e-mail])
 * Copyright (C) 1997 David S. Miller ([e-mail])
 *
 * These routines maintain argument size conversion between 32bit and 64bit
 * environment.
 *
 *      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; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/mm.h> 
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/errno.h>
#include <linux/elf.h>
#include <linux/compat.h>
#include <asm/ppc32.h>
#include <asm/uaccess.h>
#include <asm/ppcdebug.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>

#define DEBUG_SIG 0

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

#define GP_REGS_SIZE32	min(sizeof(elf_gregset_t32), sizeof(struct pt_regs32))

/*
 * When we have signals to deliver, we set up on the
 * user stack, going down from the original stack pointer:
 *	a sigregs32 struct
 *	a sigcontext32 struct
 *	a gap of __SIGNAL_FRAMESIZE32 bytes
 *
 * Each of these things must be a multiple of 16 bytes in size.
 *
 */
struct sigregs32 {
	struct mcontext32	mctx;		/* all the register values */
	/*
	 * Programs using the rs6000/xcoff abi can save up to 19 gp
	 * regs and 18 fp regs below sp before decrementing it.
	 */
	int			abigap[56];
};

/* We use the mc_pad field for the signal return trampoline. */
#define tramp	mc_pad

/*
 *  When we have rt signals to deliver, we set up on the
 *  user stack, going down from the original stack pointer:
 *	one rt_sigframe32 struct (siginfo + ucontext + ABI gap)
 *	a gap of __SIGNAL_FRAMESIZE32+16 bytes
 *  (the +16 is to get the siginfo and ucontext32 in the same
 *  positions as in older kernels).
 *
 *  Each of these things must be a multiple of 16 bytes in size.
 *
 */
struct rt_sigframe32 {
	struct compat_siginfo	info;
	struct ucontext32	uc;
	/*
	 * Programs using the rs6000/xcoff abi can save up to 19 gp
	 * regs and 18 fp regs below sp before decrementing it.
	 */
	int			abigap[56];
};


/*
 * Common utility functions used by signal and context support
 *
 */

/*
 * Restore the user process's signal mask
 * (implemented in signal.c)
 */
extern void restore_sigmask(sigset_t *set);

/*
 * Functions for flipping sigsets (thanks to brain dead generic
 * implementation that makes things simple for little endian only
 */
static inline void compat_from_sigset(compat_sigset_t *compat, sigset_t *set)
{
	switch (_NSIG_WORDS) {
	case 4: compat->sig[5] = set->sig[3] & 0xffffffffull ;
		compat->sig[7] = set->sig[3] >> 32; 
	case 3: compat->sig[4] = set->sig[2] & 0xffffffffull ;
		compat->sig[5] = set->sig[2] >> 32; 
	case 2: compat->sig[2] = set->sig[1] & 0xffffffffull ;
		compat->sig[3] = set->sig[1] >> 32; 
	case 1: compat->sig[0] = set->sig[0] & 0xffffffffull ;
		compat->sig[1] = set->sig[0] >> 32; 
	}
}

static inline void sigset_from_compat(sigset_t *set, compat_sigset_t *compat)
{
	switch (_NSIG_WORDS) {
	case 4: set->sig[3] = compat->sig[6] | (((long)compat->sig[7]) << 32);
	case 3: set->sig[2] = compat->sig[4] | (((long)compat->sig[5]) << 32);
	case 2: set->sig[1] = compat->sig[2] | (((long)compat->sig[3]) << 32);
	case 1: set->sig[0] = compat->sig[0] | (((long)compat->sig[1]) << 32);
	}
}


/*
 * Save the current user registers on the user stack.
 * We only save the altivec registers if the process has used
 * altivec instructions at some point.
 */
static int save_user_regs(struct pt_regs *regs, struct mcontext32 __user *frame, int sigret)
{
	elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
	int i, err = 0;

	/* Make sure floating point registers are stored in regs */
	flush_fp_to_thread(current);

	/* save general and floating-point registers */
	for (i = 0; i <= PT_RESULT; i ++)
		err |= __put_user((unsigned int)gregs[i], &frame->mc_gregs[i]);
	err |= __copy_to_user(&frame->mc_fregs, current->thread.fpr,
			      ELF_NFPREG * sizeof(double));
	if (err)
		return 1;

	current->thread.fpscr = 0;	/* turn off all fp exceptions */

#ifdef CONFIG_ALTIVEC
	/* save altivec registers */
	if (current->thread.used_vr) {
		flush_altivec_to_thread(current);
		if (__copy_to_user(&frame->mc_vregs, current->thread.vr,
				   ELF_NVRREG32 * sizeof(vector128)))
			return 1;
		/* set MSR_VEC in the saved MSR value to indicate that
		   frame->mc_vregs contains valid data */
		if (__put_user(regs->msr | MSR_VEC, &frame->mc_gregs[PT_MSR]))
			return 1;
	}
	/* else assert((regs->msr & MSR_VEC) == 0) */

	/* We always copy to/from vrsave, it's 0 if we don't have or don't
	 * use altivec. Since VSCR only contains 32 bits saved in the least
	 * significant bits of a vector, we "cheat" and stuff VRSAVE in the
	 * most significant bits of that same vector. --BenH
	 */
	if (__put_user(current->thread.vrsave, (u32 __user *)&frame->mc_vregs[32]))
		return 1;
#endif /* CONFIG_ALTIVEC */

	if (sigret) {
		/* Set up the sigreturn trampoline: li r0,sigret; sc */
		if (__put_user(0x38000000UL + sigret, &frame->tramp[0])
		    || __put_user(0x44000002UL, &frame->tramp[1]))
			return 1;
		flush_icache_range((unsigned long) &frame->tramp[0],
				   (unsigned long) &frame->tramp[2]);
	}

	return 0;
}

/*
 * Restore the current user register values from the user stack,
 * (except for MSR).
 */
static long restore_user_regs(struct pt_regs *regs,
			      struct mcontext32 __user *sr, int sig)
{
	elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
	int i;
	long err = 0;
	unsigned int save_r2;
#ifdef CONFIG_ALTIVEC
	unsigned long msr;
#endif

	/*
	 * restore general registers but not including MSR or SOFTE. Also
	 * take care of keeping r2 (TLS) intact if not a signal
	 */
	if (!sig)
		save_r2 = (unsigned int)regs->gpr[2];
	for (i = 0; i <= PT_RESULT; i++) {
		if ((i == PT_MSR) || (i == PT_SOFTE))
			continue;
		err |= __get_user(gregs[i], &sr->mc_gregs[i]);
	}
	if (!sig)
		regs->gpr[2] = (unsigned long) save_r2;
	if (err)
		return 1;

	/* force the process to reload the FP registers from
	   current->thread when it next does FP instructions */
	regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1);
	if (__copy_from_user(current->thread.fpr, &sr->mc_fregs,
			     sizeof(sr->mc_fregs)))
		return 1;

#ifdef CONFIG_ALTIVEC
	/* force the process to reload the altivec registers from
	   current->thread when it next does altivec instructions */
	regs->msr &= ~MSR_VEC;
	if (!__get_user(msr, &sr->mc_gregs[PT_MSR]) && (msr & MSR_VEC) != 0) {
		/* restore altivec registers from the stack */
		if (__copy_from_user(current->thread.vr, &sr->mc_vregs,
				     sizeof(sr->mc_vregs)))
			return 1;
	} else if (current->thread.used_vr)
		memset(&current->thread.vr, 0, ELF_NVRREG32 * sizeof(vector128));

	/* Always get VRSAVE back */
	if (__get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32]))
		return 1;
#endif /* CONFIG_ALTIVEC */

	return 0;
}


/*
 *  Start of nonRT signal support
 *
 *     sigset_t is 32 bits for non-rt signals
 *
 *  System Calls
 *       sigaction                sys32_sigaction
 *       sigreturn                sys32_sigreturn
 *
 *  Note sigsuspend has no special 32 bit routine - uses the 64 bit routine
 *
 *  Other routines
 *        setup_frame32
 */

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
long sys32_sigsuspend(old_sigset_t mask, int p2, int p3, int p4, int p6, int p7,
	       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->result = -EINTR;
	regs->gpr[3] = EINTR;
	regs->ccr |= 0x10000000;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal32(&saveset, regs))
			/*
			 * If a signal handler needs to be called,
			 * do_signal32() has set R3 to the signal number (the
			 * first argument of the signal handler), so don't
			 * overwrite that with EINTR !
			 * In the other cases, do_signal32() doesn't touch 
			 * R3, so it's still set to -EINTR (see above).
			 */
			return regs->gpr[3];
	}
}

long sys32_sigaction(int sig, struct old_sigaction32 __user *act,
		struct old_sigaction32 __user *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;
	
	if (sig < 0)
		sig = -sig;

	if (act) {
		compat_old_sigset_t mask;
		compat_uptr_t handler, restorer;

		if (get_user(handler, &act->sa_handler) ||
		    __get_user(restorer, &act->sa_restorer) ||
		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
		    __get_user(mask, &act->sa_mask))
			return -EFAULT;
		new_ka.sa.sa_handler = compat_ptr(handler);
		new_ka.sa.sa_restorer = compat_ptr(restorer);
		siginitset(&new_ka.sa.sa_mask, mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		if (put_user((long)old_ka.sa.sa_handler, &oact->sa_handler) ||
		    __put_user((long)old_ka.sa.sa_restorer, &oact->sa_restorer) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
			return -EFAULT;
	}

	return ret;
}



/*
 *  Start of RT signal support
 *
 *     sigset_t is 64 bits for rt signals
 *
 *  System Calls
 *       sigaction                sys32_rt_sigaction
 *       sigpending               sys32_rt_sigpending
 *       sigprocmask              sys32_rt_sigprocmask
 *       sigreturn                sys32_rt_sigreturn
 *       sigtimedwait             sys32_rt_sigtimedwait
 *       sigqueueinfo             sys32_rt_sigqueueinfo
 *       sigsuspend               sys32_rt_sigsuspend
 *
 *  Other routines
 *        setup_rt_frame32
 *        copy_siginfo_to_user32
 *        siginfo32to64
 */


long sys32_rt_sigaction(int sig, const struct sigaction32 __user *act,
		struct sigaction32 __user *oact, size_t sigsetsize)
{
	struct k_sigaction new_ka, old_ka;
	int ret;
	compat_sigset_t set32;

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

	if (act) {
		compat_uptr_t handler;

		ret = get_user(handler, &act->sa_handler);
		new_ka.sa.sa_handler = compat_ptr(handler);
		ret |= __copy_from_user(&set32, &act->sa_mask,
					sizeof(compat_sigset_t));
		sigset_from_compat(&new_ka.sa.sa_mask, &set32);
		ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
		if (ret)
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		compat_from_sigset(&set32, &old_ka.sa.sa_mask);
		ret = put_user((long)old_ka.sa.sa_handler, &oact->sa_handler);
		ret |= __copy_to_user(&oact->sa_mask, &set32,
				      sizeof(compat_sigset_t));
		ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
	}
	return ret;
}

/*
 * Note: it is necessary to treat how as an unsigned int, with the
 * corresponding cast to a signed int to insure that the proper
 * conversion (sign extension) between the register representation
 * of a signed int (msr in 32-bit mode) and the register representation
 * of a signed int (msr in 64-bit mode) is performed.
 */
long sys32_rt_sigprocmask(u32 how, compat_sigset_t __user *set,
		compat_sigset_t __user *oset, size_t sigsetsize)
{
	sigset_t s;
	sigset_t __user *up;
	compat_sigset_t s32;
	int ret;
	mm_segment_t old_fs = get_fs();

	if (set) {
		if (copy_from_user (&s32, set, sizeof(compat_sigset_t)))
			return -EFAULT;    
		sigset_from_compat(&s, &s32);
	}
	
	set_fs(KERNEL_DS);
	/* This is valid because of the set_fs() */
	up = (sigset_t __user *) &s;
	ret = sys_rt_sigprocmask((int)how, set ? up : NULL, oset ? up : NULL,
				 sigsetsize); 
	set_fs(old_fs);
	if (ret)
		return ret;
	if (oset) {
		compat_from_sigset(&s32, &s);
		if (copy_to_user (oset, &s32, sizeof(compat_sigset_t)))
			return -EFAULT;
	}
	return 0;
}

long sys32_rt_sigpending(compat_sigset_t __user *set, compat_size_t sigsetsize)
{
	sigset_t s;
	compat_sigset_t s32;
	int ret;
	mm_segment_t old_fs = get_fs();

	set_fs(KERNEL_DS);
	/* The __user pointer cast is valid because of the set_fs() */
	ret = sys_rt_sigpending((sigset_t __user *) &s, sigsetsize);
	set_fs(old_fs);
	if (!ret) {
		compat_from_sigset(&s32, &s);
		if (copy_to_user (set, &s32, sizeof(compat_sigset_t)))
			return -EFAULT;
	}
	return ret;
}


static long copy_siginfo_to_user32(compat_siginfo_t __user *d, siginfo_t *s)
{
	long err;

	if (!access_ok (VERIFY_WRITE, d, sizeof(*d)))
		return -EFAULT;

	/* If you change siginfo_t structure, please be sure
	 * this code is fixed accordingly.
	 * It should never copy any pad contained in the structure
	 * to avoid security leaks, but must copy the generic
	 * 3 ints plus the relevant union member.
	 * This routine must convert siginfo from 64bit to 32bit as well
	 * at the same time.
	 */
	err = __put_user(s->si_signo, &d->si_signo);
	err |= __put_user(s->si_errno, &d->si_errno);
	err |= __put_user((short)s->si_code, &d->si_code);
	if (s->si_code < 0)
		err |= __copy_to_user(&d->_sifields._pad, &s->_sifields._pad,
				      SI_PAD_SIZE32);
	else switch(s->si_code >> 16) {
	case __SI_CHLD >> 16:
		err |= __put_user(s->si_pid, &d->si_pid);
		err |= __put_user(s->si_uid, &d->si_uid);
		err |= __put_user(s->si_utime, &d->si_utime);
		err |= __put_user(s->si_stime, &d->si_stime);
		err |= __put_user(s->si_status, &d->si_status);
		break;
	case __SI_FAULT >> 16:
		err |= __put_user((unsigned int)(unsigned long)s->si_addr,
				  &d->si_addr);
		break;
	case __SI_POLL >> 16:
	case __SI_TIMER >> 16:
		err |= __put_user(s->si_band, &d->si_band);
		err |= __put_user(s->si_fd, &d->si_fd);
		break;
	case __SI_RT >> 16: /* This is not generated by the kernel as of now.  */
	case __SI_MESGQ >> 16:
		err |= __put_user(s->si_int, &d->si_int);
		/* fallthrough */
	case __SI_KILL >> 16:
	default:
		err |= __put_user(s->si_pid, &d->si_pid);
		err |= __put_user(s->si_uid, &d->si_uid);
		break;
	}
	return err;
}

long sys32_rt_sigtimedwait(compat_sigset_t __user *uthese, compat_siginfo_t __user *uinfo,
		struct compat_timespec __user *uts, compat_size_t sigsetsize)
{
	sigset_t s;
	compat_sigset_t s32;
	struct timespec t;
	int ret;
	mm_segment_t old_fs = get_fs();