sparc: Fix handling of orig_i0 wrt. debugging when restarting syscalls.

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / arch / sparc / kernel / signal_32.c

/*  linux/arch/sparc/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
 *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
 */

#include <linux/sched.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/mm.h>
#include <linux/tty.h>
#include <linux/smp.h>
#include <linux/binfmts.h>      /* do_coredum */
#include <linux/bitops.h>
#include <linux/tracehook.h>

#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>     /* flush_sig_insns */

#include "sigutil.h"

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

extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
                   void *fpqueue, unsigned long *fpqdepth);
extern void fpload(unsigned long *fpregs, unsigned long *fsr);

struct signal_frame {
        struct sparc_stackf     ss;
        __siginfo32_t           info;
        __siginfo_fpu_t __user  *fpu_save;
        unsigned long           insns[2] __attribute__ ((aligned (8)));
        unsigned int            extramask[_NSIG_WORDS - 1];
        unsigned int            extra_size; /* Should be 0 */
        __siginfo_rwin_t __user *rwin_save;
} __attribute__((aligned(8)));

struct rt_signal_frame {
        struct sparc_stackf     ss;
        siginfo_t               info;
        struct pt_regs          regs;
        sigset_t                mask;
        __siginfo_fpu_t __user  *fpu_save;
        unsigned int            insns[2];
        stack_t                 stack;
        unsigned int            extra_size; /* Should be 0 */
        __siginfo_rwin_t __user *rwin_save;
} __attribute__((aligned(8)));

/* Align macros */
#define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
#define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))

static int _sigpause_common(old_sigset_t set)
{
        sigset_t blocked;

        current->saved_sigmask = current->blocked;

        set &= _BLOCKABLE;
        siginitset(&blocked, set);
        set_current_blocked(&blocked);

        current->state = TASK_INTERRUPTIBLE;
        schedule();
        set_thread_flag(TIF_RESTORE_SIGMASK);

        return -ERESTARTNOHAND;
}

asmlinkage int sys_sigsuspend(old_sigset_t set)
{
        return _sigpause_common(set);
}

asmlinkage void do_sigreturn(struct pt_regs *regs)
{
        struct signal_frame __user *sf;
        unsigned long up_psr, pc, npc;
        sigset_t set;
        __siginfo_fpu_t __user *fpu_save;
        __siginfo_rwin_t __user *rwin_save;
        int err;

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

        synchronize_user_stack();

        sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];

        /* 1. Make sure we are not getting garbage from the user */
        if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
                goto segv_and_exit;

        if (((unsigned long) sf) & 3)
                goto segv_and_exit;

        err = __get_user(pc,  &sf->info.si_regs.pc);
        err |= __get_user(npc, &sf->info.si_regs.npc);

        if ((pc | npc) & 3)
                goto segv_and_exit;

        /* 2. Restore the state */
        up_psr = regs->psr;
        err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));

        /* User can only change condition codes and FPU enabling in %psr. */
        regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
                  | (regs->psr & (PSR_ICC | PSR_EF));

        /* Prevent syscall restart.  */
        pt_regs_clear_syscall(regs);

        err |= __get_user(fpu_save, &sf->fpu_save);
        if (fpu_save)
                err |= restore_fpu_state(regs, fpu_save);
        err |= __get_user(rwin_save, &sf->rwin_save);
        if (rwin_save)
                err |= restore_rwin_state(rwin_save);

        /* This is pretty much atomic, no amount locking would prevent
         * the races which exist anyways.
         */
        err |= __get_user(set.sig[0], &sf->info.si_mask);
        err |= __copy_from_user(&set.sig[1], &sf->extramask,
                                (_NSIG_WORDS-1) * sizeof(unsigned int));
                           
        if (err)
                goto segv_and_exit;

        sigdelsetmask(&set, ~_BLOCKABLE);
        set_current_blocked(&set);
        return;

segv_and_exit:
        force_sig(SIGSEGV, current);
}

asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
{
        struct rt_signal_frame __user *sf;
        unsigned int psr, pc, npc;
        __siginfo_fpu_t __user *fpu_save;
        __siginfo_rwin_t __user *rwin_save;
        mm_segment_t old_fs;
        sigset_t set;
        stack_t st;
        int err;

        synchronize_user_stack();
        sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
        if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
            (((unsigned long) sf) & 0x03))
                goto segv;

        err = __get_user(pc, &sf->regs.pc);
        err |= __get_user(npc, &sf->regs.npc);
        err |= ((pc | npc) & 0x03);

        err |= __get_user(regs->y, &sf->regs.y);
        err |= __get_user(psr, &sf->regs.psr);

        err |= __copy_from_user(&regs->u_regs[UREG_G1],
                                &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));

        regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);

        /* Prevent syscall restart.  */
        pt_regs_clear_syscall(regs);

        err |= __get_user(fpu_save, &sf->fpu_save);
        if (!err && fpu_save)
                err |= restore_fpu_state(regs, fpu_save);
        err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
        
        err |= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
        
        if (err)
                goto segv;
                
        regs->pc = pc;
        regs->npc = npc;
        
        /* It is more difficult to avoid calling this function than to
         * call it and ignore errors.
         */
        old_fs = get_fs();
        set_fs(KERNEL_DS);
        do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
        set_fs(old_fs);

        err |= __get_user(rwin_save, &sf->rwin_save);
        if (!err && rwin_save) {
                if (restore_rwin_state(rwin_save))
                        goto segv;
        }

        sigdelsetmask(&set, ~_BLOCKABLE);
        set_current_blocked(&set);
        return;
segv:
        force_sig(SIGSEGV, current);
}

/* Checks if the fp is valid */
static inline int invalid_frame_pointer(void __user *fp, int fplen)
{
        if ((((unsigned long) fp) & 7) ||
            !__access_ok((unsigned long)fp, fplen) ||
            ((sparc_cpu_model == sun4 || sparc_cpu_model == sun4c) &&
             ((unsigned long) fp < 0xe0000000 && (unsigned long) fp >= 0x20000000)))
                return 1;
        
        return 0;
}

static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
{
        unsigned long sp = regs->u_regs[UREG_FP];

        /*
         * If we are on the alternate signal stack and would overflow it, don't.
         * Return an always-bogus address instead so we will die with SIGSEGV.
         */
        if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
                return (void __user *) -1L;

        /* This is the X/Open sanctioned signal stack switching.  */
        if (sa->sa_flags & SA_ONSTACK) {
                if (sas_ss_flags(sp) == 0)
                        sp = current->sas_ss_sp + current->sas_ss_size;
        }

        sp -= framesize;

        /* Always align the stack frame.  This handles two cases.  First,
         * sigaltstack need not be mindful of platform specific stack
         * alignment.  Second, if we took this signal because the stack
         * is not aligned properly, we'd like to take the signal cleanly
         * and report that.
         */
        sp &= ~15UL;

        return (void __user *) sp;
}

static int setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
                       int signo, sigset_t *oldset)
{
        struct signal_frame __user *sf;
        int sigframe_size, err, wsaved;
        void __user *tail;

        /* 1. Make sure everything is clean */
        synchronize_user_stack();

        wsaved = current_thread_info()->w_saved;

        sigframe_size = sizeof(*sf);
        if (used_math())
                sigframe_size += sizeof(__siginfo_fpu_t);
        if (wsaved)
                sigframe_size += sizeof(__siginfo_rwin_t);

        sf = (struct signal_frame __user *)
                get_sigframe(&ka->sa, regs, sigframe_size);

        if (invalid_frame_pointer(sf, sigframe_size))
                goto sigill_and_return;

        tail = sf + 1;

        /* 2. Save the current process state */
        err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
        
        err |= __put_user(0, &sf->extra_size);

        if (used_math()) {
                __siginfo_fpu_t __user *fp = tail;
                tail += sizeof(*fp);
                err |= save_fpu_state(regs, fp);
                err |= __put_user(fp, &sf->fpu_save);
        } else {
                err |= __put_user(0, &sf->fpu_save);
        }
        if (wsaved) {
                __siginfo_rwin_t __user *rwp = tail;
                tail += sizeof(*rwp);
                err |= save_rwin_state(wsaved, rwp);
                err |= __put_user(rwp, &sf->rwin_save);
        } else {
                err |= __put_user(0, &sf->rwin_save);
        }

        err |= __put_user(oldset->sig[0], &sf->info.si_mask);
        err |= __copy_to_user(sf->extramask, &oldset->sig[1],
                              (_NSIG_WORDS - 1) * sizeof(unsigned int));
        if (!wsaved) {
                err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
                                      sizeof(struct reg_window32));
        } else {
                struct reg_window32 *rp;

                rp = &current_thread_info()->reg_window[wsaved - 1];
                err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
        }
        if (err)
                goto sigsegv;
        
        /* 3. signal handler back-trampoline and parameters */
        regs->u_regs[UREG_FP] = (unsigned long) sf;
        regs->u_regs[UREG_I0] = signo;
        regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
        regs->u_regs[UREG_I2] = (unsigned long) &sf->info;

        /* 4. signal handler */
        regs->pc = (unsigned long) ka->sa.sa_handler;
        regs->npc = (regs->pc + 4);

        /* 5. return to kernel instructions */
        if (ka->ka_restorer)
                regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
        else {
                regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

                /* mov __NR_sigreturn, %g1 */
                err |= __put_user(0x821020d8, &sf->insns[0]);

                /* t 0x10 */
                err |= __put_user(0x91d02010, &sf->insns[1]);
                if (err)
                        goto sigsegv;

                /* Flush instruction space. */
                flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
        }
        return 0;

sigill_and_return:
        do_exit(SIGILL);
        return -EINVAL;

sigsegv:
        force_sigsegv(signo, current);
        return -EFAULT;
}

static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
                          int signo, sigset_t *oldset, siginfo_t *info)
{
        struct rt_signal_frame __user *sf;
        int sigframe_size, wsaved;
        void __user *tail;
        unsigned int psr;
        int err;

        synchronize_user_stack();
        wsaved = current_thread_info()->w_saved;
        sigframe_size = sizeof(*sf);
        if (used_math())
                sigframe_size += sizeof(__siginfo_fpu_t);
        if (wsaved)
                sigframe_size += sizeof(__siginfo_rwin_t);
        sf = (struct rt_signal_frame __user *)
                get_sigframe(&ka->sa, regs, sigframe_size);
        if (invalid_frame_pointer(sf, sigframe_size))
                goto sigill;

        tail = sf + 1;
        err  = __put_user(regs->pc, &sf->regs.pc);
        err |= __put_user(regs->npc, &sf->regs.npc);
        err |= __put_user(regs->y, &sf->regs.y);
        psr = regs->psr;
        if (used_math())
                psr |= PSR_EF;
        err |= __put_user(psr, &sf->regs.psr);
        err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
        err |= __put_user(0, &sf->extra_size);

        if (psr & PSR_EF) {
                __siginfo_fpu_t *fp = tail;
                tail += sizeof(*fp);
                err |= save_fpu_state(regs, fp);
                err |= __put_user(fp, &sf->fpu_save);
        } else {
                err |= __put_user(0, &sf->fpu_save);
        }
        if (wsaved) {
                __siginfo_rwin_t *rwp = tail;
                tail += sizeof(*rwp);
                err |= save_rwin_state(wsaved, rwp);
                err |= __put_user(rwp, &sf->rwin_save);
        } else {
                err |= __put_user(0, &sf->rwin_save);
        }
        err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
        
        /* Setup sigaltstack */
        err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
        err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
        err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
        
        if (!wsaved) {
                err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
                                      sizeof(struct reg_window32));
        } else {
                struct reg_window32 *rp;

                rp = &current_thread_info()->reg_window[wsaved - 1];
                err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
        }

        err |= copy_siginfo_to_user(&sf->info, info);

        if (err)
                goto sigsegv;

        regs->u_regs[UREG_FP] = (unsigned long) sf;
        regs->u_regs[UREG_I0] = signo;
        regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
        regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;

        regs->pc = (unsigned long) ka->sa.sa_handler;
        regs->npc = (regs->pc + 4);

        if (ka->ka_restorer)
                regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
        else {
                regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

                /* mov __NR_sigreturn, %g1 */
                err |= __put_user(0x821020d8, &sf->insns[0]);

                /* t 0x10 */
                err |= __put_user(0x91d02010, &sf->insns[1]);
                if (err)
                        goto sigsegv;

                /* Flush instruction space. */
                flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
        }
        return 0;

sigill:
        do_exit(SIGILL);
        return -EINVAL;

sigsegv:
        force_sigsegv(signo, current);
        return -EFAULT;
}

static inline int
handle_signal(unsigned long signr, struct k_sigaction *ka,
              siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
        sigset_t blocked;
        int err;

        if (ka->sa.sa_flags & SA_SIGINFO)
                err = setup_rt_frame(ka, regs, signr, oldset, info);
        else
                err = setup_frame(ka, regs, signr, oldset);

        if (err)
                return err;

        sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
        if (!(ka->sa.sa_flags & SA_NOMASK))
                sigaddset(&blocked, signr);
        set_current_blocked(&blocked);

        tracehook_signal_handler(signr, info, ka, regs, 0);

        return 0;
}

static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
                                   struct sigaction *sa)
{
        switch(regs->u_regs[UREG_I0]) {
        case ERESTART_RESTARTBLOCK:
        case ERESTARTNOHAND:
        no_system_call_restart:
                regs->u_regs[UREG_I0] = EINTR;
                regs->psr |= PSR_C;
                break;
        case ERESTARTSYS:
                if (!(sa->sa_flags & SA_RESTART))
                        goto no_system_call_restart;
                /* fallthrough */
        case ERESTARTNOINTR:
                regs->u_regs[UREG_I0] = orig_i0;
                regs->pc -= 4;
                regs->npc -= 4;
        }
}

/* 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.
 */
static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
{
        struct k_sigaction ka;
        int restart_syscall;
        sigset_t *oldset;
        siginfo_t info;
        int signr;

        /* It's a lot of work and synchronization to add a new ptrace
         * register for GDB to save and restore in order to get
         * orig_i0 correct for syscall restarts when debugging.
         *
         * However, we luckily can use the fact that several registers
         * are volatile across system calls.  One such register is
         * %g2, so use that as a place to save away orig_i0.
         */
        if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
                regs->u_regs[UREG_G2] = orig_i0;

        if (test_thread_flag(TIF_RESTORE_SIGMASK))
                oldset = &current->saved_sigmask;
        else
                oldset = &current->blocked;

        signr = get_signal_to_deliver(&info, &ka, regs, NULL);

        /* If the debugger messes with the program counter, it clears
         * the software "in syscall" bit, directing us to not perform
         * a syscall restart.
         */
        restart_syscall = 0;
        if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
                restart_syscall = 1;
                orig_i0 = regs->u_regs[UREG_G2];
        }


        if (signr > 0) {
                if (restart_syscall)
                        syscall_restart(orig_i0, regs, &ka.sa);
                if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
                        /* a signal was successfully delivered; the saved
                         * sigmask will have been stored in the signal frame,
                         * and will be restored by sigreturn, so we can simply
                         * clear the TIF_RESTORE_SIGMASK flag.
                         */
                        if (test_thread_flag(TIF_RESTORE_SIGMASK))
                                clear_thread_flag(TIF_RESTORE_SIGMASK);
                }
                return;
        }
        if (restart_syscall &&
            (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
             regs->u_regs[UREG_I0] == ERESTARTSYS ||
             regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
                /* replay the system call when we are done */
                regs->u_regs[UREG_I0] = orig_i0;
                regs->pc -= 4;
                regs->npc -= 4;
                pt_regs_clear_syscall(regs);
        }
        if (restart_syscall &&
            regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
                regs->u_regs[UREG_G1] = __NR_restart_syscall;
                regs->pc -= 4;
                regs->npc -= 4;
                pt_regs_clear_syscall(regs);
        }

        /* if there's no signal to deliver, we just put the saved sigmask
         * back
         */
        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
                clear_thread_flag(TIF_RESTORE_SIGMASK);
                set_current_blocked(&current->saved_sigmask);
        }
}

void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
                      unsigned long thread_info_flags)
{
        if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
                do_signal(regs, orig_i0);
        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
                clear_thread_flag(TIF_NOTIFY_RESUME);
                tracehook_notify_resume(regs);
                if (current->replacement_session_keyring)
                        key_replace_session_keyring();
        }
}

asmlinkage int
do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
                unsigned long sp)
{
        int ret = -EFAULT;

        /* First see if old state is wanted. */
        if (ossptr) {
                if (put_user(current->sas_ss_sp + current->sas_ss_size,
                             &ossptr->the_stack) ||
                    __put_user(on_sig_stack(sp), &ossptr->cur_status))
                        goto out;
        }

        /* Now see if we want to update the new state. */
        if (ssptr) {
                char *ss_sp;

                if (get_user(ss_sp, &ssptr->the_stack))
                        goto out;
                /* If the current stack was set with sigaltstack, don't
                   swap stacks while we are on it.  */
                ret = -EPERM;
                if (current->sas_ss_sp && on_sig_stack(sp))
                        goto out;

                /* Since we don't know the extent of the stack, and we don't
                   track onstack-ness, but rather calculate it, we must
                   presume a size.  Ho hum this interface is lossy.  */
                current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
                current->sas_ss_size = SIGSTKSZ;
        }
        ret = 0;
out:
        return ret;
}