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 *  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/module.h>

#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/vdso.h>

#include "signal.h"

#define DEBUG_SIG 0

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

#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;
      unsigned long _unused[2];
      unsigned int tramp[TRAMP_SIZE];
      struct siginfo __user *pinfo;
      void __user *puc;
      struct siginfo info;
      /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
      char abigap[288];
} __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";

 * Set up the sigcontext for the signal frame.

static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
             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
      elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
      long err = 0;


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

      /* save altivec registers */
      if (current->thread.used_vr) {
            /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
            err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
            /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
             * contains valid data.
            regs->msr |= MSR_VEC;
      /* We always copy to/from vrsave, it's 0 if we don't have or don't
       * use altivec.
      err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
#else /* CONFIG_ALTIVEC */
      err |= __put_user(0, &sc->v_regs);
#endif /* CONFIG_ALTIVEC */
      err |= __put_user(&sc->gp_regs, &sc->regs);
      err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
      err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
      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;

 * Restore the sigcontext from the signal frame.

static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
                        struct sigcontext __user *sc)
      elf_vrreg_t __user *v_regs;
      unsigned long err = 0;
      unsigned long save_r13 = 0;
      elf_greg_t *gregs = (elf_greg_t *)regs;
      unsigned long msr;
      int i;

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

      /* copy everything before MSR */
      err |= __copy_from_user(regs, &sc->gp_regs,
                        PT_MSR*sizeof(unsigned long));

      /* 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);

      /* skip SOFTE */
      for (i = PT_MSR+1; i <= PT_RESULT; i++) {
            if (i == PT_SOFTE)
            err |= __get_user(gregs[i], &sc->gp_regs[i]);

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

       * Do this before updating the thread state in
       * current->thread.fpr/vr.  That way, if we get preempted
       * and another task grabs the FPU/Altivec, it won't be
       * tempted to save the current CPU state into the thread_struct
       * and corrupt what we are writing there.

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

      err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);

      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 != 0 && (msr & MSR_VEC) != 0)
            err |= __copy_from_user(current->thread.vr, v_regs,
                              33 * sizeof(vector128));
      else if (current->thread.used_vr)
            memset(current->thread.vr, 0, 33 * sizeof(vector128));
      /* Always get VRSAVE back */
      if (v_regs != 0)
            err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
            current->thread.vrsave = 0;
#endif /* CONFIG_ALTIVEC */

      return err;

 * 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;

 * 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;

      /* Context size is for future use. Right now, we only make sure
       * we are passed something we understand
      if (ctx_size < sizeof(struct ucontext))
            return -EINVAL;

      if (old_ctx != NULL) {
            if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
                || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0)
                || __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, sizeof(*new_ctx))
          || __get_user(tmp, (u8 __user *) new_ctx)
          || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 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)))
      if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))

      /* This returns like rt_sigreturn */
      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;

      /* Always make any pending restarted system calls return -EINTR */
      current_thread_info()->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;
      if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
            goto badframe;

      /* do_sigaltstack expects a __user pointer and won't modify
       * what's in there anyway
      do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);

      return 0;

      printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
             regs, uc, &uc->uc_mcontext);
      if (show_unhandled_signals && printk_ratelimit())
            printk(regs->msr & MSR_SF ? fmt64 : fmt32,
                  current->comm, current->pid, "rt_sigreturn",
                  (long)uc, regs->nip, regs->link);

      force_sig(SIGSEGV, current);
      return 0;

int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
            sigset_t *set, struct pt_regs *regs)
      /* 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;
      struct rt_sigframe __user *frame;
      unsigned long newsp = 0;
      long err = 0;

      frame = get_sigframe(ka, regs, sizeof(*frame));
      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, info);
      if (err)
            goto badframe;

      /* Create the ucontext.  */
      err |= __put_user(0, &frame->uc.uc_flags);
      err |= __put_user(0, &frame->uc.uc_link);
      err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
      err |= __put_user(sas_ss_flags(regs->gpr[1]),
      err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
      err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
                        (unsigned long)ka->sa.sa_handler);
      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 */
      current->thread.fpscr.val = 0;

      /* Set up to return from userspace. */
      if (vdso64_rt_sigtramp && current->mm->context.vdso_base) {
            regs->link = current->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];
      funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;

      /* 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. */
      err |= get_user(regs->nip, &funct_desc_ptr->entry);
      /* enter the signal handler in big-endian mode */
      regs->msr &= ~MSR_LE;
      regs->gpr[1] = newsp;
      err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
      regs->gpr[3] = signr;
      regs->result = 0;
      if (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 1;

      printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
             regs, frame, newsp);
      if (show_unhandled_signals && printk_ratelimit())
            printk(regs->msr & MSR_SF ? fmt64 : fmt32,
                  current->comm, current->pid, "setup_rt_frame",
                  (long)frame, regs->nip, regs->link);

      force_sigsegv(signr, current);
      return 0;

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