signal32.c

linux-2.4.29操作系统的源码

/*
 * 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 <asm/ptrace.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fs.h> 
#include <linux/mm.h> 
#include <linux/file.h> 
#include <linux/signal.h>
#include <linux/utime.h>
#include <linux/resource.h>
#include <linux/times.h>
#include <linux/utsname.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/sem.h>
#include <linux/msg.h>
#include <linux/shm.h>
#include <linux/slab.h>
#include <linux/uio.h>
#include <linux/nfs_fs.h>
#include <linux/smb_fs.h>
#include <linux/smb_mount.h>
#include <linux/ncp_fs.h>
#include <linux/quota.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/personality.h>
#include <linux/stat.h>
#include <linux/filter.h>
#include <asm/types.h>
#include <asm/ipc.h>
#include <asm/uaccess.h>
#include <linux/elf.h>
#include <asm/ppc32.h>
#include <asm/unistd.h>
#include <asm/ucontext.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
/* 
 * These are the flags in the MSR that the user is allowed to change
 * by modifying the saved value of the MSR on the stack.  SE and BE
 * should not be in this list since gdb may want to change these.  I.e,
 * you should be able to step out of a signal handler to see what
 * instruction executes next after the signal handler completes.
 * Alternately, if you stepped into a signal handler, you should be
 * able to continue 'til the next breakpoint from within the signal
 * handler, even if the handler returns.
 */
#define MSR_USERCHANGE	(MSR_FE0 | MSR_FE1)

struct timespec32 {
	s32    tv_sec;
	s32    tv_nsec;
};

struct sigregs32 {
	/*
	 * the gp_regs array is 32 bit representation of the pt_regs
	 * structure that was stored on the kernle stack during the
	 * system call that was interrupted for the signal.
	 *
	 * Note that the entire pt_regs regs structure will fit in
	 * the gp_regs structure because the ELF_NREG value is 48 for
	 * PPC and the pt_regs structure contains 44 registers
	 */
	elf_gregset_t32	gp_regs;
	double		fp_regs[ELF_NFPREG];
	unsigned int	tramp[2];
	/*
	 * 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];
};


struct rt_sigframe_32 {
	/*
	 * Unused space at start of frame to allow for storing of
	 * stack pointers
	 */
	unsigned long _unused;
	/*
	 * This is a 32 bit pointer in user address space 
	 *     it is a pointer to the siginfo stucture in the rt stack frame 
	 */
	u32 pinfo;
	/*
	 * This is a 32 bit pointer in user address space
	 * it is a pointer to the user context in the rt stack frame
	 */
	u32 puc;
	struct siginfo32  info;
	struct ucontext32 uc;
};





extern asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struct rusage * ru);


/****************************************************************************/
/*  Start of nonRT signal support                                           */
/*                                                                          */
/*     sigset_t is 32 bits for non-rt signals                               */
/*                                                                          */
/*  System Calls                                                            */
/*       sigaction                sys32_sigaction                           */
/*       sigpending               sys32_sigpending                          */
/*       sigprocmask              sys32_sigprocmask                         */
/*       sigreturn                sys32_sigreturn                           */
/*                                                                          */
/*  Note sigsuspend has no special 32 bit routine - uses the 64 bit routine */ 
/*                                                                          */
/*  Other routines                                                          */
/*        setup_frame32                                                     */
/*                                                                          */
/****************************************************************************/


asmlinkage long sys32_sigaction(int sig, struct old_sigaction32 *act, struct old_sigaction32 *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;
	u32 handler, restorer;
	
	if (sig < 0)
		sig = -sig;

	if (act) {
		old_sigset_t32 mask;

		ret = get_user(handler, &act->sa_handler);
		ret |= __get_user(restorer, &act->sa_restorer);
		ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
		ret |= __get_user(mask, &act->sa_mask);
		if (ret)
			return ret;
		new_ka.sa.sa_handler = (__sighandler_t)(long) handler;
		new_ka.sa.sa_restorer = (void (*)(void))(long) restorer;
		siginitset(&new_ka.sa.sa_mask, mask);
	}

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

	if (!ret && oact)
	{
		ret = put_user((long)old_ka.sa.sa_handler, &oact->sa_handler);
		ret |= __put_user((long)old_ka.sa.sa_restorer, &oact->sa_restorer);
		ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
		ret |= __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return ret;
}




extern asmlinkage long sys_sigpending(old_sigset_t *set);

asmlinkage long sys32_sigpending(old_sigset_t32 *set)
{
	old_sigset_t s;
	int ret;
	mm_segment_t old_fs = get_fs();
	
	set_fs (KERNEL_DS);
	ret = sys_sigpending(&s);
	set_fs (old_fs);
	if (put_user (s, set)) return -EFAULT;
	
	return ret;
}




extern asmlinkage long sys_sigprocmask(int how, old_sigset_t *set, old_sigset_t *oset);

/* 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.
 */
asmlinkage long sys32_sigprocmask(u32 how, old_sigset_t32 *set, old_sigset_t32 *oset)
{
	old_sigset_t s;
	int ret;
	mm_segment_t old_fs = get_fs();
	
	if (set && get_user(s, set))
		return -EFAULT;
	set_fs (KERNEL_DS);
	ret = sys_sigprocmask((int)how, set ? &s : NULL, oset ? &s : NULL);
	set_fs (old_fs);
	
	if (ret)
		return ret;
	if (oset && put_user (s, oset))
		return -EFAULT;
	return 0;
}



/*
 * When we have signals to deliver, we set up on the
 * user stack, going down from the original stack pointer:
 *	a sigregs struct
 *	one or more sigcontext structs
 *	a gap of __SIGNAL_FRAMESIZE32 bytes
 *
 * Each of these things must be a multiple of 16 bytes in size.
 *
*/


/*
 * Do a signal return; undo the signal stack.
 */
long sys32_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
		     unsigned long r6, unsigned long r7, unsigned long r8,
		     struct pt_regs *regs)
{
	struct sigcontext32 *sc, sigctx;
	struct sigregs32 *sr;
	elf_gregset_t32 saved_regs;  /* an array of ELF_NGREG unsigned ints (32 bits) */
	sigset_t set;
	int i;

	sc = (struct sigcontext32 *)(regs->gpr[1] + __SIGNAL_FRAMESIZE32);
	if (copy_from_user(&sigctx, sc, sizeof(sigctx)))
		goto badframe;

	/*
	 * Note that PPC32 puts the upper 32 bits of the sigmask in the
	 * unused part of the signal stackframe
	 */
	set.sig[0] = sigctx.oldmask + ((long)(sigctx._unused[3])<< 32);
	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sigmask_lock);
	current->blocked = set;
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	sr = (struct sigregs32*)(u64)sigctx.regs;
	/*
	 * Copy the 32 bit register values off the user stack
	 * into the 32 bit register area
	 */
	if (copy_from_user(saved_regs, &sr->gp_regs,sizeof(sr->gp_regs)))
		goto badframe;

	/*
	 * The saved reg structure in the frame is an elf_grepset_t32,
	 * it is a 32 bit register save of the registers in the
	 * pt_regs structure that was stored on the kernel stack
	 * during the system call when the system call was interrupted
	 * for the signal. Only 32 bits are saved because the
	 * sigcontext contains a pointer to the regs and the sig
	 * context address is passed as a pointer to the signal
	 * handler.  
	 *
	 * The entries in the elf_grepset have the same index as the
	 * elements in the pt_regs structure.
	 */
	for (i = 0; i < 32; i++)
		regs->gpr[i] = (u64)(saved_regs[i]) & 0xFFFFFFFF;

	/*
	 *  restore the non gpr registers 
	 */
	regs->nip = (u64)(saved_regs[PT_NIP]) & 0xFFFFFFFF;
	regs->orig_gpr3 = (u64)(saved_regs[PT_ORIG_R3]) & 0xFFFFFFFF; 
	regs->ctr = (u64)(saved_regs[PT_CTR]) & 0xFFFFFFFF; 
	regs->link = (u64)(saved_regs[PT_LNK]) & 0xFFFFFFFF; 
	regs->xer = (u64)(saved_regs[PT_XER]) & 0xFFFFFFFF; 
	regs->ccr = (u64)(saved_regs[PT_CCR]) & 0xFFFFFFFF;
	/* regs->softe is left unchanged (like the MSR.EE bit) */
	regs->result = (u64)(saved_regs[PT_RESULT]) & 0xFFFFFFFF;

	/* 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);
#ifndef CONFIG_SMP
	if (last_task_used_math == current)
		last_task_used_math = NULL;
#endif
	if (copy_from_user(current->thread.fpr, &sr->fp_regs,
			   sizeof(sr->fp_regs)))
		goto badframe;

	return regs->result;

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

/*
 * Set up a signal frame.
 */
static void
setup_frame32(struct pt_regs *regs, int sig, struct k_sigaction *ka,
	      struct sigregs32 *frame, unsigned int newsp)
{
	int i;

	if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
		goto badframe;
	if (regs->msr & MSR_FP)
		giveup_fpu(current);

	/*
	 * Copy the register contents for the pt_regs structure on the
	 *   kernel stack to the elf_gregset_t32 structure on the user
	 *   stack. This is a copy of 64 bit register values to 32 bit
	 *   register values. The high order 32 bits of the 64 bit
	 *   registers are not needed since a 32 bit application is
	 *   running and the saved registers are the contents of the
	 *   user registers at the time of a system call.
	 * 
	 * The values saved on the user stack will be restored into
	 *  the registers during the signal return processing
	 *
	 * Note the +1 is needed in order to get the lower 32 bits
	 * of 64 bit register
	 */
	for (i = 0; i < sizeof(struct pt_regs32)/sizeof(u32); i++) {
		if (__copy_to_user(&frame->gp_regs[i], (u32*)(&regs->gpr[i])+1, sizeof(u32)))
			goto badframe;
	}

	/*
	 * Now copy the floating point registers onto the user stack 
	 *
	 * Also set up so on the completion of the signal handler, the
	 * sys_sigreturn will get control to reset the stack
	 */
	if (__copy_to_user(&frame->fp_regs, current->thread.fpr,
			   ELF_NFPREG * sizeof(double))
	    /* li r0, __NR_sigreturn */
	    || __put_user(0x38000000U + __NR_sigreturn, &frame->tramp[0])
	    /* sc */
	    || __put_user(0x44000002U, &frame->tramp[1]))
		goto badframe;

	flush_icache_range((unsigned long) &frame->tramp[0],
			   (unsigned long) &frame->tramp[2]);
	current->thread.fpscr = 0;      /* turn off all fp exceptions */

	/*
	 * first parameter to the signal handler is the signal number
	 *  - the value is in gpr3
	 * second parameter to the signal handler is the sigcontext
	 *   - set the value into gpr4
	 */
	regs->gpr[3] = sig;
	regs->gpr[4] = newsp;
	regs->nip = (u64)ka->sa.sa_handler & 0xFFFFFFFF;
	regs->link = (unsigned long) frame->tramp;

	newsp -= __SIGNAL_FRAMESIZE32;
	if (put_user(regs->gpr[1], (u32*)(u64)newsp))
		goto badframe;
	regs->gpr[1] = newsp;

	return;

 badframe:
#if DEBUG_SIG
	printk("badframe in setup_frame32, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}


/*
 *  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