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signal.c

/*
 * Copyright (C) 2003 PathScale, Inc.
 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include "linux/personality.h"
#include "linux/ptrace.h"
#include "asm/unistd.h"
#include "asm/uaccess.h"
#include "asm/ucontext.h"
#include "frame_kern.h"
#include "skas.h"

void copy_sc(struct uml_pt_regs *regs, void *from)
{
      struct sigcontext *sc = from;

#define GETREG(regs, regno, sc, regname)                    \
      (regs)->gp[(regno) / sizeof(unsigned long)] = (sc)->regname

      GETREG(regs, R8, sc, r8);
      GETREG(regs, R9, sc, r9);
      GETREG(regs, R10, sc, r10);
      GETREG(regs, R11, sc, r11);
      GETREG(regs, R12, sc, r12);
      GETREG(regs, R13, sc, r13);
      GETREG(regs, R14, sc, r14);
      GETREG(regs, R15, sc, r15);
      GETREG(regs, RDI, sc, rdi);
      GETREG(regs, RSI, sc, rsi);
      GETREG(regs, RBP, sc, rbp);
      GETREG(regs, RBX, sc, rbx);
      GETREG(regs, RDX, sc, rdx);
      GETREG(regs, RAX, sc, rax);
      GETREG(regs, RCX, sc, rcx);
      GETREG(regs, RSP, sc, rsp);
      GETREG(regs, RIP, sc, rip);
      GETREG(regs, EFLAGS, sc, eflags);
      GETREG(regs, CS, sc, cs);

#undef GETREG
}

static int copy_sc_from_user(struct pt_regs *regs,
                       struct sigcontext __user *from,
                       struct _fpstate __user *fpp)
{
      struct user_i387_struct fp;
      int err = 0;

#define GETREG(regs, regno, sc, regname)                    \
      __get_user((regs)->regs.gp[(regno) / sizeof(unsigned long)],      \
               &(sc)->regname)

      err |= GETREG(regs, R8, from, r8);
      err |= GETREG(regs, R9, from, r9);
      err |= GETREG(regs, R10, from, r10);
      err |= GETREG(regs, R11, from, r11);
      err |= GETREG(regs, R12, from, r12);
      err |= GETREG(regs, R13, from, r13);
      err |= GETREG(regs, R14, from, r14);
      err |= GETREG(regs, R15, from, r15);
      err |= GETREG(regs, RDI, from, rdi);
      err |= GETREG(regs, RSI, from, rsi);
      err |= GETREG(regs, RBP, from, rbp);
      err |= GETREG(regs, RBX, from, rbx);
      err |= GETREG(regs, RDX, from, rdx);
      err |= GETREG(regs, RAX, from, rax);
      err |= GETREG(regs, RCX, from, rcx);
      err |= GETREG(regs, RSP, from, rsp);
      err |= GETREG(regs, RIP, from, rip);
      err |= GETREG(regs, EFLAGS, from, eflags);
      err |= GETREG(regs, CS, from, cs);
      if (err)
            return 1;

#undef GETREG

      err = copy_from_user(&fp, fpp, sizeof(struct user_i387_struct));
      if (err)
            return 1;

      err = restore_fp_registers(userspace_pid[current_thread->cpu],
                           (unsigned long *) &fp);
      if (err < 0) {
            printk(KERN_ERR "copy_sc_from_user - "
                   "restore_fp_registers failed, errno = %d\n",
                   -err);
            return 1;
      }

      return 0;
}

static int copy_sc_to_user(struct sigcontext __user *to,
                     struct _fpstate __user *to_fp, struct pt_regs *regs,
                     unsigned long mask, unsigned long sp)
{
      struct faultinfo * fi = &current->thread.arch.faultinfo;
      struct user_i387_struct fp;
      int err = 0;

      err |= __put_user(0, &to->gs);
      err |= __put_user(0, &to->fs);

#define PUTREG(regs, regno, sc, regname)                    \
      __put_user((regs)->regs.gp[(regno) / sizeof(unsigned long)],      \
               &(sc)->regname)

      err |= PUTREG(regs, RDI, to, rdi);
      err |= PUTREG(regs, RSI, to, rsi);
      err |= PUTREG(regs, RBP, to, rbp);
      /*
       * Must use orignal RSP, which is passed in, rather than what's in
       * the pt_regs, because that's already been updated to point at the
       * signal frame.
       */
      err |= __put_user(sp, &to->rsp);
      err |= PUTREG(regs, RBX, to, rbx);
      err |= PUTREG(regs, RDX, to, rdx);
      err |= PUTREG(regs, RCX, to, rcx);
      err |= PUTREG(regs, RAX, to, rax);
      err |= PUTREG(regs, R8, to, r8);
      err |= PUTREG(regs, R9, to, r9);
      err |= PUTREG(regs, R10, to, r10);
      err |= PUTREG(regs, R11, to, r11);
      err |= PUTREG(regs, R12, to, r12);
      err |= PUTREG(regs, R13, to, r13);
      err |= PUTREG(regs, R14, to, r14);
      err |= PUTREG(regs, R15, to, r15);
      err |= PUTREG(regs, CS, to, cs); /* XXX x86_64 doesn't do this */

      err |= __put_user(fi->cr2, &to->cr2);
      err |= __put_user(fi->error_code, &to->err);
      err |= __put_user(fi->trap_no, &to->trapno);

      err |= PUTREG(regs, RIP, to, rip);
      err |= PUTREG(regs, EFLAGS, to, eflags);
#undef PUTREG

      err |= __put_user(mask, &to->oldmask);
      if (err)
            return 1;

      err = save_fp_registers(userspace_pid[current_thread->cpu],
                        (unsigned long *) &fp);
      if (err < 0) {
            printk(KERN_ERR "copy_sc_from_user - restore_fp_registers "
                   "failed, errno = %d\n", -err);
            return 1;
      }

      if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
            return 1;

      return err;
}

struct rt_sigframe
{
      char __user *pretcode;
      struct ucontext uc;
      struct siginfo info;
      struct _fpstate fpstate;
};

#define round_down(m, n) (((m) / (n)) * (n))

int setup_signal_stack_si(unsigned long stack_top, int sig,
                    struct k_sigaction *ka, struct pt_regs * regs,
                    siginfo_t *info, sigset_t *set)
{
      struct rt_sigframe __user *frame;
      unsigned long save_sp = PT_REGS_RSP(regs);
      int err = 0;
      struct task_struct *me = current;

      frame = (struct rt_sigframe __user *)
            round_down(stack_top - sizeof(struct rt_sigframe), 16);
      /* Subtract 128 for a red zone and 8 for proper alignment */
      frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);

      if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
            goto out;

      if (ka->sa.sa_flags & SA_SIGINFO) {
            err |= copy_siginfo_to_user(&frame->info, info);
            if (err)
                  goto out;
      }

      /*
       * Update SP now because the page fault handler refuses to extend
       * the stack if the faulting address is too far below the current
       * SP, which frame now certainly is.  If there's an error, the original
       * value is restored on the way out.
       * When writing the sigcontext to the stack, we have to write the
       * original value, so that's passed to copy_sc_to_user, which does
       * the right thing with it.
       */
      PT_REGS_RSP(regs) = (unsigned long) frame;

      /* Create the ucontext.  */
      err |= __put_user(0, &frame->uc.uc_flags);
      err |= __put_user(0, &frame->uc.uc_link);
      err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
      err |= __put_user(sas_ss_flags(save_sp),
                    &frame->uc.uc_stack.ss_flags);
      err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
      err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
                         set->sig[0], save_sp);
      err |= __put_user(&frame->fpstate, &frame->uc.uc_mcontext.fpstate);
      if (sizeof(*set) == 16) {
            __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
            __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
      }
      else
            err |= __copy_to_user(&frame->uc.uc_sigmask, set,
                              sizeof(*set));

      /*
       * Set up to return from userspace.  If provided, use a stub
       * already in userspace.
       */
      /* x86-64 should always use SA_RESTORER. */
      if (ka->sa.sa_flags & SA_RESTORER)
            err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
      else
            /* could use a vstub here */
            goto restore_sp;

      if (err)
            goto restore_sp;

      /* Set up registers for signal handler */
      {
            struct exec_domain *ed = current_thread_info()->exec_domain;
            if (unlikely(ed && ed->signal_invmap && sig < 32))
                  sig = ed->signal_invmap[sig];
      }

      PT_REGS_RDI(regs) = sig;
      /* In case the signal handler was declared without prototypes */
      PT_REGS_RAX(regs) = 0;

      /*
       * This also works for non SA_SIGINFO handlers because they expect the
       * next argument after the signal number on the stack.
       */
      PT_REGS_RSI(regs) = (unsigned long) &frame->info;
      PT_REGS_RDX(regs) = (unsigned long) &frame->uc;
      PT_REGS_RIP(regs) = (unsigned long) ka->sa.sa_handler;
 out:
      return err;

restore_sp:
      PT_REGS_RSP(regs) = save_sp;
      return err;
}

long sys_rt_sigreturn(struct pt_regs *regs)
{
      unsigned long sp = PT_REGS_SP(&current->thread.regs);
      struct rt_sigframe __user *frame =
            (struct rt_sigframe __user *)(sp - 8);
      struct ucontext __user *uc = &frame->uc;
      sigset_t set;

      if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
            goto segfault;

      sigdelsetmask(&set, ~_BLOCKABLE);

      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);

      if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext,
                        &frame->fpstate))
            goto segfault;

      /* Avoid ERESTART handling */
      PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
      return PT_REGS_SYSCALL_RET(&current->thread.regs);

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

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