UBUNTU: SAUCE: powerpc/tm: Fix illegal TM state in signal handler

[mirror_ubuntu-zesty-kernel.git] / arch / powerpc / kernel / signal_64.c

/*
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Derived from "arch/i386/kernel/signal.c"
 *    Copyright (C) 1991, 1992 Linus Torvalds
 *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 *  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/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/unistd.h>
#include <linux/stddef.h>
#include <linux/elf.h>
#include <linux/ptrace.h>
#include <linux/ratelimit.h>

#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/vdso.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
#include <asm/asm-prototypes.h>

#include "signal.h"


#define GP_REGS_SIZE    min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
#define FP_REGS_SIZE    sizeof(elf_fpregset_t)

#define TRAMP_TRACEBACK 3
#define TRAMP_SIZE      6

/*
 * When we have signals to deliver, we set up on the user stack,
 * going down from the original stack pointer:
 *      1) a rt_sigframe struct which contains the ucontext     
 *      2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
 *         frame for the signal handler.
 */

struct rt_sigframe {
        /* sys_rt_sigreturn requires the ucontext be the first field */
        struct ucontext uc;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        struct ucontext uc_transact;
#endif
        unsigned long _unused[2];
        unsigned int tramp[TRAMP_SIZE];
        struct siginfo __user *pinfo;
        void __user *puc;
        struct siginfo info;
        /* New 64 bit little-endian ABI allows redzone of 512 bytes below sp */
        char abigap[USER_REDZONE_SIZE];
} __attribute__ ((aligned (16)));

static const char fmt32[] = KERN_INFO \
        "%s[%d]: bad frame in %s: %08lx nip %08lx lr %08lx\n";
static const char fmt64[] = KERN_INFO \
        "%s[%d]: bad frame in %s: %016lx nip %016lx lr %016lx\n";

/*
 * This computes a quad word aligned pointer inside the vmx_reserve array
 * element. For historical reasons sigcontext might not be quad word aligned,
 * but the location we write the VMX regs to must be. See the comment in
 * sigcontext for more detail.
 */
#ifdef CONFIG_ALTIVEC
static elf_vrreg_t __user *sigcontext_vmx_regs(struct sigcontext __user *sc)
{
        return (elf_vrreg_t __user *) (((unsigned long)sc->vmx_reserve + 15) & ~0xful);
}
#endif

/*
 * Set up the sigcontext for the signal frame.
 */

static long setup_sigcontext(struct sigcontext __user *sc,
                struct task_struct *tsk, int signr, sigset_t *set,
                unsigned long handler, int ctx_has_vsx_region)
{
        /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
         * process never used altivec yet (MSR_VEC is zero in pt_regs of
         * the context). This is very important because we must ensure we
         * don't lose the VRSAVE content that may have been set prior to
         * the process doing its first vector operation
         * Userland shall check AT_HWCAP to know whether it can rely on the
         * v_regs pointer or not
         */
#ifdef CONFIG_ALTIVEC
        elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
        unsigned long vrsave;
#endif
        struct pt_regs *regs = tsk->thread.regs;
        unsigned long msr = regs->msr;
        long err = 0;

        BUG_ON(tsk != current);

#ifdef CONFIG_ALTIVEC
        err |= __put_user(v_regs, &sc->v_regs);

        /* save altivec registers */
        if (tsk->thread.used_vr) {
                flush_altivec_to_thread(tsk);
                /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
                err |= __copy_to_user(v_regs, &tsk->thread.vr_state,
                                      33 * sizeof(vector128));
                /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
                 * contains valid data.
                 */
                msr |= MSR_VEC;
        }
        /* We always copy to/from vrsave, it's 0 if we don't have or don't
         * use altivec.
         */
        vrsave = 0;
        if (cpu_has_feature(CPU_FTR_ALTIVEC)) {
                vrsave = mfspr(SPRN_VRSAVE);
                tsk->thread.vrsave = vrsave;
        }

        err |= __put_user(vrsave, (u32 __user *)&v_regs[33]);
#else /* CONFIG_ALTIVEC */
        err |= __put_user(0, &sc->v_regs);
#endif /* CONFIG_ALTIVEC */
        flush_fp_to_thread(tsk);
        /* copy fpr regs and fpscr */
        err |= copy_fpr_to_user(&sc->fp_regs, tsk);

        /*
         * Clear the MSR VSX bit to indicate there is no valid state attached
         * to this context, except in the specific case below where we set it.
         */
        msr &= ~MSR_VSX;
#ifdef CONFIG_VSX
        /*
         * Copy VSX low doubleword to local buffer for formatting,
         * then out to userspace.  Update v_regs to point after the
         * VMX data.
         */
        if (tsk->thread.used_vsr && ctx_has_vsx_region) {
                flush_vsx_to_thread(tsk);
                v_regs += ELF_NVRREG;
                err |= copy_vsx_to_user(v_regs, tsk);
                /* set MSR_VSX in the MSR value in the frame to
                 * indicate that sc->vs_reg) contains valid data.
                 */
                msr |= MSR_VSX;
        }
#endif /* CONFIG_VSX */
        err |= __put_user(&sc->gp_regs, &sc->regs);
        WARN_ON(!FULL_REGS(regs));
        err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
        err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
        err |= __put_user(signr, &sc->signal);
        err |= __put_user(handler, &sc->handler);
        if (set != NULL)
                err |=  __put_user(set->sig[0], &sc->oldmask);

        return err;
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
 * As above, but Transactional Memory is in use, so deliver sigcontexts
 * containing checkpointed and transactional register states.
 *
 * To do this, we treclaim (done before entering here) to gather both sets of
 * registers and set up the 'normal' sigcontext registers with rolled-back
 * register values such that a simple signal handler sees a correct
 * checkpointed register state.  If interested, a TM-aware sighandler can
 * examine the transactional registers in the 2nd sigcontext to determine the
 * real origin of the signal.
 */
static long setup_tm_sigcontexts(struct sigcontext __user *sc,
                                 struct sigcontext __user *tm_sc,
                                 struct task_struct *tsk,
                                 int signr, sigset_t *set, unsigned long handler)
{
        /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
         * process never used altivec yet (MSR_VEC is zero in pt_regs of
         * the context). This is very important because we must ensure we
         * don't lose the VRSAVE content that may have been set prior to
         * the process doing its first vector operation
         * Userland shall check AT_HWCAP to know wether it can rely on the
         * v_regs pointer or not.
         */
#ifdef CONFIG_ALTIVEC
        elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
        elf_vrreg_t __user *tm_v_regs = sigcontext_vmx_regs(tm_sc);
#endif
        struct pt_regs *regs = tsk->thread.regs;
        unsigned long msr = tsk->thread.ckpt_regs.msr;
        long err = 0;

        BUG_ON(tsk != current);

        BUG_ON(!MSR_TM_ACTIVE(regs->msr));

        /* Remove TM bits from thread's MSR.  The MSR in the sigcontext
         * just indicates to userland that we were doing a transaction, but we
         * don't want to return in transactional state.  This also ensures
         * that flush_fp_to_thread won't set TIF_RESTORE_TM again.
         */
        regs->msr &= ~MSR_TS_MASK;

#ifdef CONFIG_ALTIVEC
        err |= __put_user(v_regs, &sc->v_regs);
        err |= __put_user(tm_v_regs, &tm_sc->v_regs);

        /* save altivec registers */
        if (tsk->thread.used_vr) {
                /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
                err |= __copy_to_user(v_regs, &tsk->thread.ckvr_state,
                                      33 * sizeof(vector128));
                /* If VEC was enabled there are transactional VRs valid too,
                 * else they're a copy of the checkpointed VRs.
                 */
                if (msr & MSR_VEC)
                        err |= __copy_to_user(tm_v_regs,
                                              &tsk->thread.vr_state,
                                              33 * sizeof(vector128));
                else
                        err |= __copy_to_user(tm_v_regs,
                                              &tsk->thread.ckvr_state,
                                              33 * sizeof(vector128));

                /* set MSR_VEC in the MSR value in the frame to indicate
                 * that sc->v_reg contains valid data.
                 */
                msr |= MSR_VEC;
        }
        /* We always copy to/from vrsave, it's 0 if we don't have or don't
         * use altivec.
         */
        if (cpu_has_feature(CPU_FTR_ALTIVEC))
                tsk->thread.ckvrsave = mfspr(SPRN_VRSAVE);
        err |= __put_user(tsk->thread.ckvrsave, (u32 __user *)&v_regs[33]);
        if (msr & MSR_VEC)
                err |= __put_user(tsk->thread.vrsave,
                                  (u32 __user *)&tm_v_regs[33]);
        else
                err |= __put_user(tsk->thread.ckvrsave,
                                  (u32 __user *)&tm_v_regs[33]);

#else /* CONFIG_ALTIVEC */
        err |= __put_user(0, &sc->v_regs);
        err |= __put_user(0, &tm_sc->v_regs);
#endif /* CONFIG_ALTIVEC */

        /* copy fpr regs and fpscr */
        err |= copy_ckfpr_to_user(&sc->fp_regs, tsk);
        if (msr & MSR_FP)
                err |= copy_fpr_to_user(&tm_sc->fp_regs, tsk);
        else
                err |= copy_ckfpr_to_user(&tm_sc->fp_regs, tsk);

#ifdef CONFIG_VSX
        /*
         * Copy VSX low doubleword to local buffer for formatting,
         * then out to userspace.  Update v_regs to point after the
         * VMX data.
         */
        if (tsk->thread.used_vsr) {
                v_regs += ELF_NVRREG;
                tm_v_regs += ELF_NVRREG;

                err |= copy_ckvsx_to_user(v_regs, tsk);

                if (msr & MSR_VSX)
                        err |= copy_vsx_to_user(tm_v_regs, tsk);
                else
                        err |= copy_ckvsx_to_user(tm_v_regs, tsk);

                /* set MSR_VSX in the MSR value in the frame to
                 * indicate that sc->vs_reg) contains valid data.
                 */
                msr |= MSR_VSX;
        }
#endif /* CONFIG_VSX */

        err |= __put_user(&sc->gp_regs, &sc->regs);
        err |= __put_user(&tm_sc->gp_regs, &tm_sc->regs);
        WARN_ON(!FULL_REGS(regs));
        err |= __copy_to_user(&tm_sc->gp_regs, regs, GP_REGS_SIZE);
        err |= __copy_to_user(&sc->gp_regs,
                              &tsk->thread.ckpt_regs, GP_REGS_SIZE);
        err |= __put_user(msr, &tm_sc->gp_regs[PT_MSR]);
        err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
        err |= __put_user(signr, &sc->signal);
        err |= __put_user(handler, &sc->handler);
        if (set != NULL)
                err |=  __put_user(set->sig[0], &sc->oldmask);

        return err;
}
#endif

/*
 * Restore the sigcontext from the signal frame.
 */

static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig,
                              struct sigcontext __user *sc)
{
#ifdef CONFIG_ALTIVEC
        elf_vrreg_t __user *v_regs;
#endif
        unsigned long err = 0;
        unsigned long save_r13 = 0;
        unsigned long msr;
        struct pt_regs *regs = tsk->thread.regs;
#ifdef CONFIG_VSX
        int i;
#endif

        BUG_ON(tsk != current);

        /* If this is not a signal return, we preserve the TLS in r13 */
        if (!sig)
                save_r13 = regs->gpr[13];

        /* copy the GPRs */
        err |= __copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr));
        err |= __get_user(regs->nip, &sc->gp_regs[PT_NIP]);
        /* get MSR separately, transfer the LE bit if doing signal return */
        err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
        if (sig)
                regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
        err |= __get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3]);
        err |= __get_user(regs->ctr, &sc->gp_regs[PT_CTR]);
        err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]);
        err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]);
        err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]);
        /* skip SOFTE */
        regs->trap = 0;
        err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
        err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
        err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);

        if (!sig)
                regs->gpr[13] = save_r13;
        if (set != NULL)
                err |=  __get_user(set->sig[0], &sc->oldmask);

        /*
         * Force reload of FP/VEC.
         * This has to be done before copying stuff into tsk->thread.fpr/vr
         * for the reasons explained in the previous comment.
         */
        regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX);

#ifdef CONFIG_ALTIVEC
        err |= __get_user(v_regs, &sc->v_regs);
        if (err)
                return err;
        if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
                return -EFAULT;
        /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
        if (v_regs != NULL && (msr & MSR_VEC) != 0) {
                err |= __copy_from_user(&tsk->thread.vr_state, v_regs,
                                        33 * sizeof(vector128));
                tsk->thread.used_vr = true;
        } else if (tsk->thread.used_vr) {
                memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
        }
        /* Always get VRSAVE back */
        if (v_regs != NULL)
                err |= __get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]);
        else
                tsk->thread.vrsave = 0;
        if (cpu_has_feature(CPU_FTR_ALTIVEC))
                mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
#endif /* CONFIG_ALTIVEC */
        /* restore floating point */
        err |= copy_fpr_from_user(tsk, &sc->fp_regs);
#ifdef CONFIG_VSX
        /*
         * Get additional VSX data. Update v_regs to point after the
         * VMX data.  Copy VSX low doubleword from userspace to local
         * buffer for formatting, then into the taskstruct.
         */
        v_regs += ELF_NVRREG;
        if ((msr & MSR_VSX) != 0) {
                err |= copy_vsx_from_user(tsk, v_regs);
                tsk->thread.used_vsr = true;
        } else {
                for (i = 0; i < 32 ; i++)
                        tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
        }
#endif
        return err;
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
 * Restore the two sigcontexts from the frame of a transactional processes.
 */

static long restore_tm_sigcontexts(struct task_struct *tsk,
                                   struct sigcontext __user *sc,
                                   struct sigcontext __user *tm_sc)
{
#ifdef CONFIG_ALTIVEC
        elf_vrreg_t __user *v_regs, *tm_v_regs;
#endif
        unsigned long err = 0;
        unsigned long msr;
        struct pt_regs *regs = tsk->thread.regs;
#ifdef CONFIG_VSX
        int i;
#endif

        BUG_ON(tsk != current);

        /* copy the GPRs */
        err |= __copy_from_user(regs->gpr, tm_sc->gp_regs, sizeof(regs->gpr));
        err |= __copy_from_user(&tsk->thread.ckpt_regs, sc->gp_regs,
                                sizeof(regs->gpr));

        /*
         * TFHAR is restored from the checkpointed 'wound-back' ucontext's NIP.
         * TEXASR was set by the signal delivery reclaim, as was TFIAR.
         * Users doing anything abhorrent like thread-switching w/ signals for
         * TM-Suspended code will have to back TEXASR/TFIAR up themselves.
         * For the case of getting a signal and simply returning from it,
         * we don't need to re-copy them here.
         */
        err |= __get_user(regs->nip, &tm_sc->gp_regs[PT_NIP]);
        err |= __get_user(tsk->thread.tm_tfhar, &sc->gp_regs[PT_NIP]);

        /* get MSR separately, transfer the LE bit if doing signal return */
        err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
        /* Don't allow reserved mode. */
        if (MSR_TM_RESV(msr))
                return -EINVAL;

        /* pull in MSR TS bits from user context */
        regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK);

        /*
         * Ensure that TM is enabled in regs->msr before we leave the signal
         * handler. It could be the case that (a) user disabled the TM bit
         * through the manipulation of the MSR bits in uc_mcontext or (b) the
         * TM bit was disabled because a sufficient number of context switches
         * happened whilst in the signal handler and load_tm overflowed,
         * disabling the TM bit. In either case we can end up with an illegal
         * TM state leading to a TM Bad Thing when we return to userspace.
         */
        regs->msr |= MSR_TM;

        /* pull in MSR LE from user context */
        regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);

        /* The following non-GPR non-FPR non-VR state is also checkpointed: */
        err |= __get_user(regs->ctr, &tm_sc->gp_regs[PT_CTR]);
        err |= __get_user(regs->link, &tm_sc->gp_regs[PT_LNK]);
        err |= __get_user(regs->xer, &tm_sc->gp_regs[PT_XER]);
        err |= __get_user(regs->ccr, &tm_sc->gp_regs[PT_CCR]);
        err |= __get_user(tsk->thread.ckpt_regs.ctr,
                          &sc->gp_regs[PT_CTR]);
        err |= __get_user(tsk->thread.ckpt_regs.link,
                          &sc->gp_regs[PT_LNK]);
        err |= __get_user(tsk->thread.ckpt_regs.xer,
                          &sc->gp_regs[PT_XER]);
        err |= __get_user(tsk->thread.ckpt_regs.ccr,
                          &sc->gp_regs[PT_CCR]);

        /* These regs are not checkpointed; they can go in 'regs'. */
        err |= __get_user(regs->trap, &sc->gp_regs[PT_TRAP]);
        err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
        err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
        err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);

        /*
         * Force reload of FP/VEC.
         * This has to be done before copying stuff into tsk->thread.fpr/vr
         * for the reasons explained in the previous comment.
         */
        regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX);

#ifdef CONFIG_ALTIVEC
        err |= __get_user(v_regs, &sc->v_regs);
        err |= __get_user(tm_v_regs, &tm_sc->v_regs);
        if (err)
                return err;
        if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
                return -EFAULT;
        if (tm_v_regs && !access_ok(VERIFY_READ,
                                    tm_v_regs, 34 * sizeof(vector128)))
                return -EFAULT;
        /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
        if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) {
                err |= __copy_from_user(&tsk->thread.ckvr_state, v_regs,
                                        33 * sizeof(vector128));
                err |= __copy_from_user(&tsk->thread.vr_state, tm_v_regs,
                                        33 * sizeof(vector128));
                current->thread.used_vr = true;
        }
        else if (tsk->thread.used_vr) {
                memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
                memset(&tsk->thread.ckvr_state, 0, 33 * sizeof(vector128));
        }
        /* Always get VRSAVE back */
        if (v_regs != NULL && tm_v_regs != NULL) {
                err |= __get_user(tsk->thread.ckvrsave,
                                  (u32 __user *)&v_regs[33]);
                err |= __get_user(tsk->thread.vrsave,
                                  (u32 __user *)&tm_v_regs[33]);
        }
        else {
                tsk->thread.vrsave = 0;
                tsk->thread.ckvrsave = 0;
        }
        if (cpu_has_feature(CPU_FTR_ALTIVEC))
                mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
#endif /* CONFIG_ALTIVEC */
        /* restore floating point */
        err |= copy_fpr_from_user(tsk, &tm_sc->fp_regs);
        err |= copy_ckfpr_from_user(tsk, &sc->fp_regs);
#ifdef CONFIG_VSX
        /*
         * Get additional VSX data. Update v_regs to point after the
         * VMX data.  Copy VSX low doubleword from userspace to local
         * buffer for formatting, then into the taskstruct.
         */
        if (v_regs && ((msr & MSR_VSX) != 0)) {
                v_regs += ELF_NVRREG;
                tm_v_regs += ELF_NVRREG;
                err |= copy_vsx_from_user(tsk, tm_v_regs);
                err |= copy_ckvsx_from_user(tsk, v_regs);
                tsk->thread.used_vsr = true;
        } else {
                for (i = 0; i < 32 ; i++) {
                        tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
                        tsk->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
                }
        }
#endif
        tm_enable();
        /* Make sure the transaction is marked as failed */
        tsk->thread.tm_texasr |= TEXASR_FS;
        /* This loads the checkpointed FP/VEC state, if used */
        tm_recheckpoint(&tsk->thread, msr);

        msr_check_and_set(msr & (MSR_FP | MSR_VEC));
        if (msr & MSR_FP) {
                load_fp_state(&tsk->thread.fp_state);
                regs->msr |= (MSR_FP | tsk->thread.fpexc_mode);
        }
        if (msr & MSR_VEC) {
                load_vr_state(&tsk->thread.vr_state);
                regs->msr |= MSR_VEC;
        }

        return err;
}
#endif

/*
 * Setup the trampoline code on the stack
 */
static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
{
        int i;
        long err = 0;

        /* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
        err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
        /* li r0, __NR_[rt_]sigreturn| */
        err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
        /* sc */
        err |= __put_user(0x44000002UL, &tramp[2]);

        /* Minimal traceback info */
        for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
                err |= __put_user(0, &tramp[i]);

        if (!err)
                flush_icache_range((unsigned long) &tramp[0],
                           (unsigned long) &tramp[TRAMP_SIZE]);

        return err;
}

/*
 * Userspace code may pass a ucontext which doesn't include VSX added
 * at the end.  We need to check for this case.
 */
#define UCONTEXTSIZEWITHOUTVSX \
                (sizeof(struct ucontext) - 32*sizeof(long))

/*
 * Handle {get,set,swap}_context operations
 */
int sys_swapcontext(struct ucontext __user *old_ctx,
                    struct ucontext __user *new_ctx,
                    long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
{
        unsigned char tmp;
        sigset_t set;
        unsigned long new_msr = 0;
        int ctx_has_vsx_region = 0;

        BUG_ON(regs != current->thread.regs);

        if (new_ctx &&
            get_user(new_msr, &new_ctx->uc_mcontext.gp_regs[PT_MSR]))
                return -EFAULT;
        /*
         * Check that the context is not smaller than the original
         * size (with VMX but without VSX)
         */
        if (ctx_size < UCONTEXTSIZEWITHOUTVSX)
                return -EINVAL;
        /*
         * If the new context state sets the MSR VSX bits but
         * it doesn't provide VSX state.
         */
        if ((ctx_size < sizeof(struct ucontext)) &&
            (new_msr & MSR_VSX))
                return -EINVAL;
        /* Does the context have enough room to store VSX data? */
        if (ctx_size >= sizeof(struct ucontext))
                ctx_has_vsx_region = 1;

        if (old_ctx != NULL) {
                if (!access_ok(VERIFY_WRITE, old_ctx, ctx_size)
                    || setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL, 0,
                                        ctx_has_vsx_region)
                    || __copy_to_user(&old_ctx->uc_sigmask,
                                      &current->blocked, sizeof(sigset_t)))
                        return -EFAULT;
        }
        if (new_ctx == NULL)
                return 0;
        if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
            || __get_user(tmp, (u8 __user *) new_ctx)
            || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
                return -EFAULT;

        /*
         * If we get a fault copying the context into the kernel's
         * image of the user's registers, we can't just return -EFAULT
         * because the user's registers will be corrupted.  For instance
         * the NIP value may have been updated but not some of the
         * other registers.  Given that we have done the access_ok
         * and successfully read the first and last bytes of the region
         * above, this should only happen in an out-of-memory situation
         * or if another thread unmaps the region containing the context.
         * We kill the task with a SIGSEGV in this situation.
         */

        if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
                do_exit(SIGSEGV);
        set_current_blocked(&set);
        if (restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext))
                do_exit(SIGSEGV);

        /* This returns like rt_sigreturn */
        set_thread_flag(TIF_RESTOREALL);
        return 0;
}


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

int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
                     unsigned long r6, unsigned long r7, unsigned long r8,
                     struct pt_regs *regs)
{
        struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
        sigset_t set;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        unsigned long msr;
#endif

        BUG_ON(current->thread.regs != regs);

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

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

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

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        /*
         * If there is a transactional state then throw it away.
         * The purpose of a sigreturn is to destroy all traces of the
         * signal frame, this includes any transactional state created
         * within in. We only check for suspended as we can never be
         * active in the kernel, we are active, there is nothing better to
         * do than go ahead and Bad Thing later.
         * The cause is not important as there will never be a
         * recheckpoint so it's not user visible.
         */
        if (MSR_TM_SUSPENDED(mfmsr()))
                tm_reclaim_current(0);

        if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
                goto badframe;
        if (MSR_TM_ACTIVE(msr)) {
                /* We recheckpoint on return. */
                struct ucontext __user *uc_transact;
                if (__get_user(uc_transact, &uc->uc_link))
                        goto badframe;
                if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
                                           &uc_transact->uc_mcontext))
                        goto badframe;
        }
        else
        /* Fall through, for non-TM restore */
#endif
        if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext))
                goto badframe;

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

        set_thread_flag(TIF_RESTOREALL);
        return 0;

badframe:
        if (show_unhandled_signals)
                printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
                                   current->comm, current->pid, "rt_sigreturn",
                                   (long)uc, regs->nip, regs->link);

        force_sig(SIGSEGV, current);
        return 0;
}

int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
                struct task_struct *tsk)
{
        struct rt_sigframe __user *frame;
        unsigned long newsp = 0;
        long err = 0;
        struct pt_regs *regs = tsk->thread.regs;

        BUG_ON(tsk != current);

        frame = get_sigframe(ksig, get_tm_stackpointer(tsk), sizeof(*frame), 0);
        if (unlikely(frame == NULL))
                goto badframe;

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

        /* Create the ucontext.  */
        err |= __put_user(0, &frame->uc.uc_flags);
        err |= __save_altstack(&frame->uc.uc_stack, regs->gpr[1]);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        if (MSR_TM_ACTIVE(regs->msr)) {
                /* The ucontext_t passed to userland points to the second
                 * ucontext_t (for transactional state) with its uc_link ptr.
                 */
                err |= __put_user(&frame->uc_transact, &frame->uc.uc_link);
                err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
                                            &frame->uc_transact.uc_mcontext,
                                            tsk, ksig->sig, NULL,
                                            (unsigned long)ksig->ka.sa.sa_handler);
        } else
#endif
        {
                err |= __put_user(0, &frame->uc.uc_link);
                err |= setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,
                                        NULL, (unsigned long)ksig->ka.sa.sa_handler,
                                        1);
        }
        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
        if (err)
                goto badframe;

        /* Make sure signal handler doesn't get spurious FP exceptions */
        tsk->thread.fp_state.fpscr = 0;

        /* Set up to return from userspace. */
        if (vdso64_rt_sigtramp && tsk->mm->context.vdso_base) {
                regs->link = tsk->mm->context.vdso_base + vdso64_rt_sigtramp;
        } else {
                err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
                if (err)
                        goto badframe;
                regs->link = (unsigned long) &frame->tramp[0];
        }

        /* Allocate a dummy caller frame for the signal handler. */
        newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
        err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);

        /* Set up "regs" so we "return" to the signal handler. */
        if (is_elf2_task()) {
                regs->nip = (unsigned long) ksig->ka.sa.sa_handler;
                regs->gpr[12] = regs->nip;
        } else {
                /* Handler is *really* a pointer to the function descriptor for
                 * the signal routine.  The first entry in the function
                 * descriptor is the entry address of signal and the second
                 * entry is the TOC value we need to use.
                 */
                func_descr_t __user *funct_desc_ptr =
                        (func_descr_t __user *) ksig->ka.sa.sa_handler;

                err |= get_user(regs->nip, &funct_desc_ptr->entry);
                err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
        }

        /* enter the signal handler in native-endian mode */
        regs->msr &= ~MSR_LE;
        regs->msr |= (MSR_KERNEL & MSR_LE);
        regs->gpr[1] = newsp;
        regs->gpr[3] = ksig->sig;
        regs->result = 0;
        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
                err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
                err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
                regs->gpr[6] = (unsigned long) frame;
        } else {
                regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
        }
        if (err)
                goto badframe;

        return 0;

badframe:
        if (show_unhandled_signals)
                printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
                                   tsk->comm, tsk->pid, "setup_rt_frame",
                                   (long)frame, regs->nip, regs->link);

        return 1;
}