signal.c

内核linux2.4.20,可跟rtlinux3.2打补丁 组成实时linux系统,编译内核

/*
 *  linux/arch/parisc/kernel/signal.c: Architecture-specific signal
 *  handling support.
 *
 *  Copyright (C) 2000 David Huggins-Daines <[e-mail]>
 *  Copyright (C) 2000 Linuxcare, Inc.
 *
 *  Based on the ia64, i386, and alpha versions.
 *
 *  Like the IA-64, we are a recent enough port (we are *starting*
 *  with glibc2.2) that we do not need to support the old non-realtime
 *  Linux signals.  Therefore we don't.  HP/UX signals will go in
 *  arch/parisc/hpux/signal.c when we figure out how to do them.
 */

#include <linux/version.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/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>

#define DEBUG_SIG 0

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

extern long sys_wait4 (int, int *, int, struct rusage *);
int do_signal(sigset_t *oldset, struct pt_regs *regs, int in_syscall);

int copy_siginfo_to_user(siginfo_t *to, siginfo_t *from)
{
	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
		return -EFAULT;
	if (from->si_code < 0)
		return __copy_to_user(to, from, sizeof(siginfo_t));
	else {
		int err;

		/*
		 * 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.
		 */
		err = __put_user(from->si_signo, &to->si_signo);
		err |= __put_user(from->si_errno, &to->si_errno);
		err |= __put_user((short)from->si_code, &to->si_code);
		switch (from->si_code >> 16) {
		      case __SI_FAULT >> 16:
			/* FIXME: should we put the interruption code here? */
		      case __SI_POLL >> 16:
			err |= __put_user(from->si_addr, &to->si_addr);
			break;
		      case __SI_CHLD >> 16:
			err |= __put_user(from->si_utime, &to->si_utime);
			err |= __put_user(from->si_stime, &to->si_stime);
			err |= __put_user(from->si_status, &to->si_status);
		      default:
			err |= __put_user(from->si_uid, &to->si_uid);
			err |= __put_user(from->si_pid, &to->si_pid);
			break;
		      /* case __SI_RT: This is not generated by the kernel as of now.  */
		}
		return err;
	}
}

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
#ifdef __LP64__
#include "sys32.h"
#endif

asmlinkage int
sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, struct pt_regs *regs)
{
	sigset_t saveset, newset;
#ifdef __LP64__
	/* XXX FIXME -- assumes 32-bit user app! */
	sigset_t32 newset32;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t32))
		return -EINVAL;

	if (copy_from_user(&newset32, (sigset_t32 *)unewset, sizeof(newset32)))
		return -EFAULT;

	newset.sig[0] = newset32.sig[0] | ((unsigned long)newset32.sig[1] << 32);
#else

	/* 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;
#endif
	sigdelsetmask(&newset, ~_BLOCKABLE);

	spin_lock_irq(&current->sigmask_lock);
	saveset = current->blocked;
	current->blocked = newset;
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	regs->gr[28] = -EINTR;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs, 1))
			return -EINTR;
	}
}

/*
 * Do a signal return - restore sigcontext.
 */

struct rt_sigframe {
	unsigned int tramp[4];
	struct siginfo info;
	struct ucontext uc;
};

/* Trampoline for calling rt_sigreturn() */
#define INSN_LDI_R25_0	 0x34190000 /* ldi  0,%r25 (in_syscall=0) */
#define INSN_LDI_R25_1	 0x34190002 /* ldi  1,%r25 (in_syscall=1) */
#define INSN_LDI_R20	 0x3414015a /* ldi  __NR_rt_sigreturn,%r20 */
#define INSN_BLE_SR2_R0  0xe4008200 /* be,l 0x100(%sr2,%r0),%sr0,%r31 */
#define INSN_NOP	 0x80000240 /* nop */
/* For debugging */
#define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */

/*
 * The 32-bit ABI wants at least 48 bytes for a function call frame:
 * 16 bytes for arg0-arg3, and 32 bytes for magic (the only part of
 * which Linux/parisc uses is sp-20 for the saved return pointer...)
 * Then, the stack pointer must be rounded to a cache line (64 bytes).
 */
#define PARISC_RT_SIGFRAME_SIZE					\
	(((sizeof(struct rt_sigframe) + 48) + 63) & -64)

static long
restore_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
{
	long err = 0;

	err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
	err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
	err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
	err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
	err |= __get_user(regs->sar, &sc->sc_sar);

#if DEBUG_SIG
	printk("restore_sigcontext: r28 is %ld\n", regs->gr[28]);
#endif
	return err;
}

void
sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
{
	struct rt_sigframe *frame;
	struct siginfo si;
	sigset_t set;
	unsigned long usp = regs->gr[30];

	/* Unwind the user stack to get the rt_sigframe structure. */
	frame = (struct rt_sigframe *)
		(usp - PARISC_RT_SIGFRAME_SIZE);
#if DEBUG_SIG
	printk("in sys_rt_sigreturn, frame is %p\n", frame);
#endif

	/* Verify that it's a good sigcontext before using it */
	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto give_sigsegv;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto give_sigsegv;

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

	/* Good thing we saved the old gr[30], eh? */
	if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
		goto give_sigsegv;

#if DEBUG_SIG
	printk("usp: %#08lx stack %p",
	       usp, &frame->uc.uc_stack);
#endif

	/* I don't know why everyone else assumes they can call this
           with a pointer to a stack_t on the kernel stack.  That
           makes no sense.  Anyway we'll do it like m68k, since we
           also are using segmentation in the same way as them. */
	if (do_sigaltstack(&frame->uc.uc_stack, NULL, usp) == -EFAULT)
		goto give_sigsegv;

	/* If we are on the syscall path IAOQ will not be restored, and
	 * if we are on the interrupt path we must not corrupt gr31.
	 */
	if (in_syscall)
		regs->gr[31] = regs->iaoq[0];
#if DEBUG_SIG
	printk("returning to %#lx\n", regs->iaoq[0]);
	printk("in sys_rt_sigreturn:\n");
	show_regs(regs);
#endif
	return;

give_sigsegv:
#if DEBUG_SIG
	printk("fuckup in sys_rt_sigreturn, sending SIGSEGV\n");
#endif
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = &frame->uc;
	force_sig_info(SIGSEGV, &si, current);
	return;
}

/*
 * Set up a signal frame.
 */

static inline void *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
		sp = current->sas_ss_sp + current->sas_ss_size;

	return (void *) sp; /* Stacks grow up.  Fun. */
}

static long
setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, int in_syscall)
		 
{
	unsigned long flags = 0;
	long err = 0;

	if (on_sig_stack((unsigned long) sc))
		flags |= PARISC_SC_FLAG_ONSTACK;
	if (in_syscall) {
		flags |= PARISC_SC_FLAG_IN_SYSCALL;
		/* regs->iaoq is undefined in the syscall return path */
		err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
		err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
#if DEBUG_SIG
		printk("setup_sigcontext: iaoq %#lx/%#lx\n", regs->gr[31], regs->gr[31]);
#endif
	} else {
		err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
		err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
#if DEBUG_SIG
		printk("setup_sigcontext: iaoq %#lx/%#lx\n", regs->iaoq[0], regs->iaoq[1]);
#endif
	}

	err |= __put_user(flags, &sc->sc_flags);
	err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
	err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
	err |= __put_user(regs->sar, &sc->sc_sar);
#if DEBUG_SIG
	printk("setup_sigcontext: r28 is %ld\n", regs->gr[28]);
#endif

	return err;
}

static long
setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
	       sigset_t *set, struct pt_regs *regs, int in_syscall)
{
	struct rt_sigframe *frame;
	unsigned long rp, usp, haddr;
	struct siginfo si;
	int err = 0;

	usp = regs->gr[30];
	/* access_ok is broken, so do a simplistic "are we stomping on
           kernel space" assertion. */
	if (usp > PAGE_OFFSET) {
		printk("setup_rt_frame: called on kernel space (usp=%#lx),  NOW YOU MUST DIE!!!\n",
		       usp);
		show_regs(regs);
		while(1);
	}
		
	frame = get_sigframe(ka, usp, sizeof(*frame));
	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

#if DEBUG_SIG
	printk("setup_rt_frame 1: frame %p info %p\n", frame, info);
#endif

	err |= __copy_to_user(&frame->info, info, sizeof(siginfo_t));
	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= __put_user(sas_ss_flags(regs->gr[30]),
			  &frame->uc.uc_stack.ss_flags);
	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub