cregit-Linux how code gets into the kernel

Release 4.14 arch/sh/kernel/signal_64.c

Directory: arch/sh/kernel
/*
 * arch/sh/kernel/signal_64.c
 *
 * Copyright (C) 2000, 2001  Paolo Alberelli
 * Copyright (C) 2003 - 2008  Paul Mundt
 * Copyright (C) 2004  Richard Curnow
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tracehook.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/fpu.h>


#define REG_RET 9

#define REG_ARG1 2

#define REG_ARG2 3

#define REG_ARG3 4

#define REG_SP 15

#define REG_PR 18

#define REF_REG_RET regs->regs[REG_RET]

#define REF_REG_SP regs->regs[REG_SP]

#define DEREF_REG_PR regs->regs[REG_PR]


#define DEBUG_SIG 0

static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs);



static inline void

handle_syscall_restart(struct pt_regs *regs, struct sigaction *sa)
{
	/* If we're not from a syscall, bail out */
	if (regs->syscall_nr < 0)
		return;

	/* check for system call restart.. */
	switch (regs->regs[REG_RET]) {
		case -ERESTART_RESTARTBLOCK:
		case -ERESTARTNOHAND:
		no_system_call_restart:
			regs->regs[REG_RET] = -EINTR;
			break;

		case -ERESTARTSYS:
			if (!(sa->sa_flags & SA_RESTART))
				goto no_system_call_restart;
		/* fallthrough */
		case -ERESTARTNOINTR:
			/* Decode syscall # */
			regs->regs[REG_RET] = regs->syscall_nr;
			regs->pc -= 4;
			break;
	}
}


Contributors
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Paul Mundt102100.00%1100.00%


Total102100.00%1100.00%



/*
 * 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)
{
	struct ksignal ksig;

	/*
         * 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 (get_signal(&ksig)) {
		handle_syscall_restart(regs, &ksig.ka.sa);

		/* Whee!  Actually deliver the signal.  */
		handle_signal(&ksig, regs);
		return;
	}

	/* Did we come from a system call? */
	if (regs->syscall_nr >= 0) {
		/* Restart the system call - no handlers present */
		switch (regs->regs[REG_RET]) {
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
			/* Decode Syscall # */
			regs->regs[REG_RET] = regs->syscall_nr;
			regs->pc -= 4;
			break;

		case -ERESTART_RESTARTBLOCK:
			regs->regs[REG_RET] = __NR_restart_syscall;
			regs->pc -= 4;
			break;
		}
	}

	/* No signal to deliver -- put the saved sigmask back */
	restore_saved_sigmask();
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt12290.37%555.56%


Richard Weinberger96.67%111.11%


Al Viro42.96%333.33%


Total135100.00%9100.00%



/*
 * Do a signal return; undo the signal stack.
 */

struct sigframe {
	
struct sigcontext sc;
	
unsigned long extramask[_NSIG_WORDS-1];
	
long long retcode[2];
};


struct rt_sigframe {
	
struct siginfo __user *pinfo;
	
void *puc;
	
struct siginfo info;
	
struct ucontext uc;
	
long long retcode[2];
};

#ifdef CONFIG_SH_FPU


static inline int

restore_sigcontext_fpu(struct pt_regs *regs, struct sigcontext __user *sc)
{
	int err = 0;
	int fpvalid;

	err |= __get_user (fpvalid, &sc->sc_fpvalid);
	conditional_used_math(fpvalid);
	if (! fpvalid)
		return err;

	if (current == last_task_used_math) {
		last_task_used_math = NULL;
		regs->sr |= SR_FD;
	}

	err |= __copy_from_user(&current->thread.xstate->hardfpu, &sc->sc_fpregs[0],
				(sizeof(long long) * 32) + (sizeof(int) * 1));

	return err;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt11097.35%266.67%


Andrea Arcangeli32.65%133.33%


Total113100.00%3100.00%





static inline int

setup_sigcontext_fpu(struct pt_regs *regs, struct sigcontext __user *sc)
{
	int err = 0;
	int fpvalid;

	fpvalid = !!used_math();
	err |= __put_user(fpvalid, &sc->sc_fpvalid);
	if (! fpvalid)
		return err;

	if (current == last_task_used_math) {
		enable_fpu();
		save_fpu(current);
		disable_fpu();
		last_task_used_math = NULL;
		regs->sr |= SR_FD;
	}

	err |= __copy_to_user(&sc->sc_fpregs[0], &current->thread.xstate->hardfpu,
			      (sizeof(long long) * 32) + (sizeof(int) * 1));
	clear_used_math();

	return err;
}

Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt12496.12%480.00%


Andrea Arcangeli53.88%120.00%


Total129100.00%5100.00%



#else


static inline int

restore_sigcontext_fpu(struct pt_regs *regs, struct sigcontext __user *sc)
{
	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt21100.00%2100.00%


Total21100.00%2100.00%





static inline int

setup_sigcontext_fpu(struct pt_regs *regs, struct sigcontext __user *sc)
{
	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt21100.00%2100.00%


Total21100.00%2100.00%



#endif



static int

restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, long long *r2_p)
{
	unsigned int err = 0;
        unsigned long long current_sr, new_sr;

#define SR_MASK 0xffff8cfd


#define COPY(x)		err |= __get_user(regs->x, &sc->sc_##x)

	COPY(regs[0]);	COPY(regs[1]);	COPY(regs[2]);	COPY(regs[3]);
	COPY(regs[4]);	COPY(regs[5]);	COPY(regs[6]);	COPY(regs[7]);
	COPY(regs[8]);	COPY(regs[9]);  COPY(regs[10]);	COPY(regs[11]);
	COPY(regs[12]);	COPY(regs[13]);	COPY(regs[14]);	COPY(regs[15]);
	COPY(regs[16]);	COPY(regs[17]);	COPY(regs[18]);	COPY(regs[19]);
	COPY(regs[20]);	COPY(regs[21]);	COPY(regs[22]);	COPY(regs[23]);
	COPY(regs[24]);	COPY(regs[25]);	COPY(regs[26]);	COPY(regs[27]);
	COPY(regs[28]);	COPY(regs[29]);	COPY(regs[30]);	COPY(regs[31]);
	COPY(regs[32]);	COPY(regs[33]);	COPY(regs[34]);	COPY(regs[35]);
	COPY(regs[36]);	COPY(regs[37]);	COPY(regs[38]);	COPY(regs[39]);
	COPY(regs[40]);	COPY(regs[41]);	COPY(regs[42]);	COPY(regs[43]);
	COPY(regs[44]);	COPY(regs[45]);	COPY(regs[46]);	COPY(regs[47]);
	COPY(regs[48]);	COPY(regs[49]);	COPY(regs[50]);	COPY(regs[51]);
	COPY(regs[52]);	COPY(regs[53]);	COPY(regs[54]);	COPY(regs[55]);
	COPY(regs[56]);	COPY(regs[57]);	COPY(regs[58]);	COPY(regs[59]);
	COPY(regs[60]);	COPY(regs[61]);	COPY(regs[62]);
	COPY(tregs[0]);	COPY(tregs[1]);	COPY(tregs[2]);	COPY(tregs[3]);
	COPY(tregs[4]);	COPY(tregs[5]);	COPY(tregs[6]);	COPY(tregs[7]);

        /* Prevent the signal handler manipulating SR in a way that can
           crash the kernel. i.e. only allow S, Q, M, PR, SZ, FR to be
           modified */
        current_sr = regs->sr;
        err |= __get_user(new_sr, &sc->sc_sr);
        regs->sr &= SR_MASK;
        regs->sr |= (new_sr & ~SR_MASK);

	COPY(pc);


#undef COPY

	/* Must do this last in case it sets regs->sr.fd (i.e. after rest of sr
         * has been restored above.) */
	err |= restore_sigcontext_fpu(regs, sc);

	regs->syscall_nr = -1;		/* disable syscall checks */
	err |= __get_user(*r2_p, &sc->sc_regs[REG_RET]);
	return err;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt695100.00%1100.00%


Total695100.00%1100.00%






asmlinkage int sys_sigreturn(unsigned long r2, unsigned long r3,
				   unsigned long r4, unsigned long r5,
				   unsigned long r6, unsigned long r7,
				   struct pt_regs * regs)
{
	struct sigframe __user *frame = (struct sigframe __user *) (long) REF_REG_SP;
	sigset_t set;
	long long ret;

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	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;

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->sc, &ret))
		goto badframe;
	regs->pc -= 4;

	return (int) ret;

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


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt18297.85%240.00%


Jesper Juhl21.08%120.00%


Andrew Lutomirski10.54%120.00%


Matt Fleming10.54%120.00%


Total186100.00%5100.00%






asmlinkage int sys_rt_sigreturn(unsigned long r2, unsigned long r3,
				unsigned long r4, unsigned long r5,
				unsigned long r6, unsigned long r7,
				struct pt_regs * regs)
{
	struct rt_sigframe __user *frame = (struct rt_sigframe __user *) (long) REF_REG_SP;
	sigset_t set;
	long long ret;

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

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

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ret))
		goto badframe;
	regs->pc -= 4;

	if (restore_altstack(&frame->uc.uc_stack))
		goto badframe;

	return (int) ret;

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


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt17097.14%233.33%


Jesper Juhl21.14%116.67%


Al Viro10.57%116.67%


Matt Fleming10.57%116.67%


Andrew Lutomirski10.57%116.67%


Total175100.00%6100.00%



/*
 * Set up a signal frame.
 */


static int

setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
		 unsigned long mask)
{
	int err = 0;

	/* Do this first, otherwise is this sets sr->fd, that value isn't preserved. */
	err |= setup_sigcontext_fpu(regs, sc);


#define COPY(x)		err |= __put_user(regs->x, &sc->sc_##x)

	COPY(regs[0]);	COPY(regs[1]);	COPY(regs[2]);	COPY(regs[3]);
	COPY(regs[4]);	COPY(regs[5]);	COPY(regs[6]);	COPY(regs[7]);
	COPY(regs[8]);	COPY(regs[9]);	COPY(regs[10]);	COPY(regs[11]);
	COPY(regs[12]);	COPY(regs[13]);	COPY(regs[14]);	COPY(regs[15]);
	COPY(regs[16]);	COPY(regs[17]);	COPY(regs[18]);	COPY(regs[19]);
	COPY(regs[20]);	COPY(regs[21]);	COPY(regs[22]);	COPY(regs[23]);
	COPY(regs[24]);	COPY(regs[25]);	COPY(regs[26]);	COPY(regs[27]);
	COPY(regs[28]);	COPY(regs[29]);	COPY(regs[30]);	COPY(regs[31]);
	COPY(regs[32]);	COPY(regs[33]);	COPY(regs[34]);	COPY(regs[35]);
	COPY(regs[36]);	COPY(regs[37]);	COPY(regs[38]);	COPY(regs[39]);
	COPY(regs[40]);	COPY(regs[41]);	COPY(regs[42]);	COPY(regs[43]);
	COPY(regs[44]);	COPY(regs[45]);	COPY(regs[46]);	COPY(regs[47]);
	COPY(regs[48]);	COPY(regs[49]);	COPY(regs[50]);	COPY(regs[51]);
	COPY(regs[52]);	COPY(regs[53]);	COPY(regs[54]);	COPY(regs[55]);
	COPY(regs[56]);	COPY(regs[57]);	COPY(regs[58]);	COPY(regs[59]);
	COPY(regs[60]);	COPY(regs[61]);	COPY(regs[62]);
	COPY(tregs[0]);	COPY(tregs[1]);	COPY(tregs[2]);	COPY(tregs[3]);
	COPY(tregs[4]);	COPY(tregs[5]);	COPY(tregs[6]);	COPY(tregs[7]);
	COPY(sr);	COPY(pc);


#undef COPY

	err |= __put_user(mask, &sc->oldmask);

	return err;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt639100.00%1100.00%


Total639100.00%1100.00%



/*
 * Determine which stack to use..
 */


static inline void __user *

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

	return (void __user *)((sp - frame_size) & -8ul);
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt6798.53%150.00%


Laurent Meyer11.47%150.00%


Total68100.00%2100.00%



void sa_default_restorer(void);		/* See comments below */
void sa_default_rt_restorer(void);	/* See comments below */




static int setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
	struct sigframe __user *frame;
	int err = 0, sig = ksig->sig;
	int signal;

	frame = get_sigframe(&ksig->ka, regs->regs[REG_SP], sizeof(*frame));

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

	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);

	/* Give up earlier as i386, in case */
	if (err)
		return -EFAULT;

	if (_NSIG_WORDS > 1) {
		err |= __copy_to_user(frame->extramask, &set->sig[1],
				      sizeof(frame->extramask)); }

	/* Give up earlier as i386, in case */
	if (err)
		return -EFAULT;

	/* Set up to return from userspace.  If provided, use a stub
           already in userspace.  */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		/*
                 * On SH5 all edited pointers are subject to NEFF
                 */
		DEREF_REG_PR = neff_sign_extend((unsigned long)
			ksig->ka->sa.sa_restorer | 0x1);
	} else {
		/*
                 * Different approach on SH5.
                 * . Endianness independent asm code gets placed in entry.S .
                 *   This is limited to four ASM instructions corresponding
                 *   to two long longs in size.
                 * . err checking is done on the else branch only
                 * . flush_icache_range() is called upon __put_user() only
                 * . all edited pointers are subject to NEFF
                 * . being code, linker turns ShMedia bit on, always
                 *   dereference index -1.
                 */
		DEREF_REG_PR = neff_sign_extend((unsigned long)
			frame->retcode | 0x01);

		if (__copy_to_user(frame->retcode,
			(void *)((unsigned long)sa_default_restorer & (~1)), 16) != 0)
			return -EFAULT;

		/* Cohere the trampoline with the I-cache. */
		flush_cache_sigtramp(DEREF_REG_PR-1);
	}

	/*
         * Set up registers for signal handler.
         * All edited pointers are subject to NEFF.
         */
	regs->regs[REG_SP] = neff_sign_extend((unsigned long)frame);
	regs->regs[REG_ARG1] = sig; /* Arg for signal handler */

        /* FIXME:
           The glibc profiling support for SH-5 needs to be passed a sigcontext
           so it can retrieve the PC.  At some point during 2003 the glibc
           support was changed to receive the sigcontext through the 2nd
           argument, but there are still versions of libc.so in use that use
           the 3rd argument.  Until libc.so is stabilised, pass the sigcontext
           through both 2nd and 3rd arguments.
        */

	regs->regs[REG_ARG2] = (unsigned long long)(unsigned long)(signed long)&frame->sc;
	regs->regs[REG_ARG3] = (unsigned long long)(unsigned long)(signed long)&frame->sc;

	regs->pc = neff_sign_extend((unsigned long)ksig->ka.sa.sa_handler);

	/* Broken %016Lx */
	pr_debug("SIG deliver (#%d,%s:%d): sp=%p pc=%08Lx%08Lx link=%08Lx%08Lx\n",
		 sig, current->comm, current->pid, frame,
		 regs->pc >> 32, regs->pc & 0xffffffff,
		 DEREF_REG_PR >> 32, DEREF_REG_PR & 0xffffffff);

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt34990.41%466.67%


Richard Weinberger379.59%233.33%


Total386100.00%6100.00%






static int setup_rt_frame(struct ksignal *kig, sigset_t *set,
			  struct pt_regs *regs)
{
	struct rt_sigframe __user *frame;
	int err = 0, sig = ksig->sig;

	frame = get_sigframe(&ksig->ka, regs->regs[REG_SP], sizeof(*frame));

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

	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, &ksig->info);

	/* Give up earlier as i386, in case */
	if (err)
		return -EFAULT;

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __save_altstack(&frame->uc.uc_stack, regs->regs[REG_SP]);
	err |= setup_sigcontext(&frame->uc.uc_mcontext,
			        regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Give up earlier as i386, in case */
	if (err)
		return -EFAULT;

	/* Set up to return from userspace.  If provided, use a stub
           already in userspace.  */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		/*
                 * On SH5 all edited pointers are subject to NEFF
                 */
		DEREF_REG_PR = neff_sign_extend((unsigned long)
			ksig->ka.sa.sa_restorer | 0x1);
	} else {
		/*
                 * Different approach on SH5.
                 * . Endianness independent asm code gets placed in entry.S .
                 *   This is limited to four ASM instructions corresponding
                 *   to two long longs in size.
                 * . err checking is done on the else branch only
                 * . flush_icache_range() is called upon __put_user() only
                 * . all edited pointers are subject to NEFF
                 * . being code, linker turns ShMedia bit on, always
                 *   dereference index -1.
                 */
		DEREF_REG_PR = neff_sign_extend((unsigned long)
			frame->retcode | 0x01);

		if (__copy_to_user(frame->retcode,
			(void *)((unsigned long)sa_default_rt_restorer & (~1)), 16) != 0)
			return -EFAULT;

		/* Cohere the trampoline with the I-cache. */
		flush_icache_range(DEREF_REG_PR-1, DEREF_REG_PR-1+15);
	}

	/*
         * Set up registers for signal handler.
         * All edited pointers are subject to NEFF.
         */
	regs->regs[REG_SP] = neff_sign_extend((unsigned long)frame);
	regs->regs[REG_ARG1] = sig; /* Arg for signal handler */
	regs->regs[REG_ARG2] = (unsigned long long)(unsigned long)(signed long)&frame->info;
	regs->regs[REG_ARG3] = (unsigned long long)(unsigned long)(signed long)&frame->uc.uc_mcontext;
	regs->pc = neff_sign_extend((unsigned long)ksig->ka.sa.sa_handler);

	pr_debug("SIG deliver (#%d,%s:%d): sp=%p pc=%08Lx%08Lx link=%08Lx%08Lx\n",
		 sig, current->comm, current->pid, frame,
		 regs->pc >> 32, regs->pc & 0xffffffff,
		 DEREF_REG_PR >> 32, DEREF_REG_PR & 0xffffffff);

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt42990.89%457.14%


Richard Weinberger418.69%228.57%


Al Viro20.42%114.29%


Total472100.00%7100.00%



/*
 * OK, we're invoking a handler
 */


static void

handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	/* Set up the stack frame */
	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
		ret = setup_rt_frame(ksig, oldset, regs);
	else
		ret = setup_frame(ksig, oldset, regs);

	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt4763.51%350.00%


Al Viro1722.97%233.33%


Richard Weinberger1013.51%116.67%


Total74100.00%6100.00%






asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
{
	if (thread_info_flags & _TIF_SIGPENDING)
		do_signal(regs);

	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
		clear_thread_flag(TIF_NOTIFY_RESUME);
		tracehook_notify_resume(regs);
	}
}

Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt44100.00%3100.00%


Total44100.00%3100.00%




Overall Contributors
PersonTokensPropCommitsCommitProp
Paul Mundt330695.80%1550.00%


Richard Weinberger992.87%26.67%


Al Viro250.72%620.00%


Andrea Arcangeli80.23%13.33%


Jesper Juhl40.12%13.33%


Adrian Bunk30.09%13.33%


Andrew Lutomirski20.06%13.33%


Matt Fleming20.06%13.33%


Linus Torvalds10.03%13.33%


Laurent Meyer10.03%13.33%


Total3451100.00%30100.00%


Directory: arch/sh/kernel



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