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ia32_signal.c

/*
 *  linux/arch/x86_64/ia32/ia32_signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
 *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
 */

#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/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compat.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/ia32.h>
#include <asm/ptrace.h>
#include <asm/ia32_unistd.h>
#include <asm/user32.h>
#include <asm/sigcontext32.h>
#include <asm/fpu32.h>
#include <asm/proto.h>
#include <asm/vsyscall32.h>

#define DEBUG_SIG 0

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

asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
void signal_fault(struct pt_regs *regs, void __user *frame, char *where);

int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
{
      int err;
      if (!access_ok (VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
            return -EFAULT;

      /* If you change siginfo_t structure, please make sure that
         this code is fixed accordingly.
         It should never copy any pad contained in the structure
         to avoid security leaks, but must copy the generic
         3 ints plus the relevant union member.  */
      err = __put_user(from->si_signo, &to->si_signo);
      err |= __put_user(from->si_errno, &to->si_errno);
      err |= __put_user((short)from->si_code, &to->si_code);

      if (from->si_code < 0) {
            err |= __put_user(from->si_pid, &to->si_pid);
            err |= __put_user(from->si_uid, &to->si_uid);
            err |= __put_user(ptr_to_compat(from->si_ptr), &to->si_ptr);
      } else {
            /* First 32bits of unions are always present:
             * si_pid === si_band === si_tid === si_addr(LS half) */
            err |= __put_user(from->_sifields._pad[0], &to->_sifields._pad[0]);
            switch (from->si_code >> 16) {
            case __SI_FAULT >> 16:
                  break;
            case __SI_CHLD >> 16:
                  err |= __put_user(from->si_utime, &to->si_utime);
                  err |= __put_user(from->si_stime, &to->si_stime);
                  err |= __put_user(from->si_status, &to->si_status);
                  /* FALL THROUGH */
            default:
            case __SI_KILL >> 16:
                  err |= __put_user(from->si_uid, &to->si_uid);
                  break;
            case __SI_POLL >> 16:
                  err |= __put_user(from->si_fd, &to->si_fd); 
                  break;
            case __SI_TIMER >> 16:
                  err |= __put_user(from->si_overrun, &to->si_overrun); 
                  err |= __put_user(ptr_to_compat(from->si_ptr),
                              &to->si_ptr);
                  break;
            case __SI_RT >> 16: /* This is not generated by the kernel as of now.  */
            case __SI_MESGQ >> 16:
                  err |= __put_user(from->si_uid, &to->si_uid);
                  err |= __put_user(from->si_int, &to->si_int);
                  break;
            }
      }
      return err;
}

int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
      int err;
      u32 ptr32;
      if (!access_ok (VERIFY_READ, from, sizeof(compat_siginfo_t)))
            return -EFAULT;

      err = __get_user(to->si_signo, &from->si_signo);
      err |= __get_user(to->si_errno, &from->si_errno);
      err |= __get_user(to->si_code, &from->si_code);

      err |= __get_user(to->si_pid, &from->si_pid);
      err |= __get_user(to->si_uid, &from->si_uid);
      err |= __get_user(ptr32, &from->si_ptr);
      to->si_ptr = compat_ptr(ptr32);

      return err;
}

asmlinkage long
sys32_sigsuspend(int history0, int history1, old_sigset_t mask)
{
      mask &= _BLOCKABLE;
      spin_lock_irq(&current->sighand->siglock);
      current->saved_sigmask = current->blocked;
      siginitset(&current->blocked, mask);
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);

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

asmlinkage long
sys32_sigaltstack(const stack_ia32_t __user *uss_ptr,
              stack_ia32_t __user *uoss_ptr, 
              struct pt_regs *regs)
{
      stack_t uss,uoss; 
      int ret;
      mm_segment_t seg; 
      if (uss_ptr) { 
            u32 ptr;
            memset(&uss,0,sizeof(stack_t));
            if (!access_ok(VERIFY_READ,uss_ptr,sizeof(stack_ia32_t)) ||
                      __get_user(ptr, &uss_ptr->ss_sp) ||
                      __get_user(uss.ss_flags, &uss_ptr->ss_flags) ||
                      __get_user(uss.ss_size, &uss_ptr->ss_size))
                  return -EFAULT;
            uss.ss_sp = compat_ptr(ptr);
      }
      seg = get_fs(); 
      set_fs(KERNEL_DS); 
      ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, regs->rsp);
      set_fs(seg); 
      if (ret >= 0 && uoss_ptr)  {
            if (!access_ok(VERIFY_WRITE,uoss_ptr,sizeof(stack_ia32_t)) ||
                __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
                __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
                __put_user(uoss.ss_size, &uoss_ptr->ss_size))
                  ret = -EFAULT;
      }     
      return ret; 
}

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

struct sigframe
{
      u32 pretcode;
      int sig;
      struct sigcontext_ia32 sc;
      struct _fpstate_ia32 fpstate;
      unsigned int extramask[_COMPAT_NSIG_WORDS-1];
      char retcode[8];
};

struct rt_sigframe
{
      u32 pretcode;
      int sig;
      u32 pinfo;
      u32 puc;
      compat_siginfo_t info;
      struct ucontext_ia32 uc;
      struct _fpstate_ia32 fpstate;
      char retcode[8];
};

static int
ia32_restore_sigcontext(struct pt_regs *regs, struct sigcontext_ia32 __user *sc, unsigned int *peax)
{
      unsigned int err = 0;
      
      /* Always make any pending restarted system calls return -EINTR */
      current_thread_info()->restart_block.fn = do_no_restart_syscall;

#if DEBUG_SIG
      printk("SIG restore_sigcontext: sc=%p err(%x) eip(%x) cs(%x) flg(%x)\n",
            sc, sc->err, sc->eip, sc->cs, sc->eflags);
#endif
#define COPY(x)         { \
      unsigned int reg;             \
      err |= __get_user(reg, &sc->e ##x); \
      regs->r ## x = reg;                 \
}

#define RELOAD_SEG(seg,mask)                                \
      { unsigned int cur;                                   \
        unsigned short pre;                                 \
        err |= __get_user(pre, &sc->seg);                   \
        asm volatile("movl %%" #seg ",%0" : "=r" (cur));          \
        pre |= mask;                                        \
        if (pre != cur) loadsegment(seg,pre); }

      /* Reload fs and gs if they have changed in the signal handler.
         This does not handle long fs/gs base changes in the handler, but 
         does not clobber them at least in the normal case. */ 
      
      {
            unsigned gs, oldgs; 
            err |= __get_user(gs, &sc->gs);
            gs |= 3; 
            asm("movl %%gs,%0" : "=r" (oldgs));
            if (gs != oldgs)
            load_gs_index(gs); 
      } 
      RELOAD_SEG(fs,3);
      RELOAD_SEG(ds,3);
      RELOAD_SEG(es,3);

      COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
      COPY(dx); COPY(cx); COPY(ip);
      /* Don't touch extended registers */ 
      
      err |= __get_user(regs->cs, &sc->cs); 
      regs->cs |= 3;  
      err |= __get_user(regs->ss, &sc->ss); 
      regs->ss |= 3; 

      {
            unsigned int tmpflags;
            err |= __get_user(tmpflags, &sc->eflags);
            regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
            regs->orig_rax = -1;          /* disable syscall checks */
      }

      {
            u32 tmp;
            struct _fpstate_ia32 __user * buf;
            err |= __get_user(tmp, &sc->fpstate);
            buf = compat_ptr(tmp);
            if (buf) {
                  if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
                        goto badframe;
                  err |= restore_i387_ia32(current, buf, 0);
            } else {
                  struct task_struct *me = current;
                  if (used_math()) {
                        clear_fpu(me);
                        clear_used_math();
                  }
            }
      }

      { 
            u32 tmp;
            err |= __get_user(tmp, &sc->eax);
            *peax = tmp;
      }
      return err;

badframe:
      return 1;
}

asmlinkage long sys32_sigreturn(struct pt_regs *regs)
{
      struct sigframe __user *frame = (struct sigframe __user *)(regs->rsp-8);
      sigset_t set;
      unsigned int eax;

      if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
            goto badframe;
      if (__get_user(set.sig[0], &frame->sc.oldmask)
          || (_COMPAT_NSIG_WORDS > 1
            && __copy_from_user((((char *) &set.sig) + 4), &frame->extramask,
                            sizeof(frame->extramask))))
            goto badframe;

      sigdelsetmask(&set, ~_BLOCKABLE);
      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
      
      if (ia32_restore_sigcontext(regs, &frame->sc, &eax))
            goto badframe;
      return eax;

badframe:
      signal_fault(regs, frame, "32bit sigreturn");
      return 0;
}     

asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
{
      struct rt_sigframe __user *frame;
      sigset_t set;
      unsigned int eax;
      struct pt_regs tregs;

      frame = (struct rt_sigframe __user *)(regs->rsp - 4);

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

      sigdelsetmask(&set, ~_BLOCKABLE);
      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
      
      if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
            goto badframe;

      tregs = *regs;
      if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
            goto badframe;

      return eax;

badframe:
      signal_fault(regs,frame,"32bit rt sigreturn");
      return 0;
}     

/*
 * Set up a signal frame.
 */

static int
ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc, struct _fpstate_ia32 __user *fpstate,
             struct pt_regs *regs, unsigned int mask)
{
      int tmp, err = 0;

      tmp = 0;
      __asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
      err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
      __asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp));
      err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
      __asm__("movl %%ds,%0" : "=r"(tmp): "0"(tmp));
      err |= __put_user(tmp, (unsigned int __user *)&sc->ds);
      __asm__("movl %%es,%0" : "=r"(tmp): "0"(tmp));
      err |= __put_user(tmp, (unsigned int __user *)&sc->es);

      err |= __put_user((u32)regs->rdi, &sc->edi);
      err |= __put_user((u32)regs->rsi, &sc->esi);
      err |= __put_user((u32)regs->rbp, &sc->ebp);
      err |= __put_user((u32)regs->rsp, &sc->esp);
      err |= __put_user((u32)regs->rbx, &sc->ebx);
      err |= __put_user((u32)regs->rdx, &sc->edx);
      err |= __put_user((u32)regs->rcx, &sc->ecx);
      err |= __put_user((u32)regs->rax, &sc->eax);
      err |= __put_user((u32)regs->cs, &sc->cs);
      err |= __put_user((u32)regs->ss, &sc->ss);
      err |= __put_user(current->thread.trap_no, &sc->trapno);
      err |= __put_user(current->thread.error_code, &sc->err);
      err |= __put_user((u32)regs->rip, &sc->eip);
      err |= __put_user((u32)regs->eflags, &sc->eflags);
      err |= __put_user((u32)regs->rsp, &sc->esp_at_signal);

      tmp = save_i387_ia32(current, fpstate, regs, 0);
      if (tmp < 0)
            err = -EFAULT;
      else { 
            clear_used_math();
            stts();
            err |= __put_user(ptr_to_compat(tmp ? fpstate : NULL),
                              &sc->fpstate);
      }

      /* non-iBCS2 extensions.. */
      err |= __put_user(mask, &sc->oldmask);
      err |= __put_user(current->thread.cr2, &sc->cr2);

      return err;
}

/*
 * Determine which stack to use..
 */
static void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
      unsigned long rsp;

      /* Default to using normal stack */
      rsp = regs->rsp;

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

      /* This is the legacy signal stack switching. */
      else if ((regs->ss & 0xffff) != __USER_DS &&
            !(ka->sa.sa_flags & SA_RESTORER) &&
             ka->sa.sa_restorer) {
            rsp = (unsigned long) ka->sa.sa_restorer;
      }

      rsp -= frame_size;
      /* Align the stack pointer according to the i386 ABI,
       * i.e. so that on function entry ((sp + 4) & 15) == 0. */
      rsp = ((rsp + 4) & -16ul) - 4;
      return (void __user *) rsp;
}

int ia32_setup_frame(int sig, struct k_sigaction *ka,
                 compat_sigset_t *set, struct pt_regs * regs)
{
      struct sigframe __user *frame;
      int err = 0;

      frame = get_sigframe(ka, regs, sizeof(*frame));

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

      err |= __put_user(sig, &frame->sig);
      if (err)
            goto give_sigsegv;

      err |= ia32_setup_sigcontext(&frame->sc, &frame->fpstate, regs,
                              set->sig[0]);
      if (err)
            goto give_sigsegv;

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

      /* Return stub is in 32bit vsyscall page */
      { 
            void __user *restorer;
            if (current->binfmt->hasvdso)
                  restorer = VSYSCALL32_SIGRETURN;
            else
                  restorer = (void *)&frame->retcode;
            if (ka->sa.sa_flags & SA_RESTORER)
                  restorer = ka->sa.sa_restorer;       
            err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
      }
      /* These are actually not used anymore, but left because some 
         gdb versions depend on them as a marker. */
      { 
            /* copy_to_user optimizes that into a single 8 byte store */
            static const struct { 
                  u16 poplmovl;
                  u32 val;
                  u16 int80;    
                  u16 pad; 
            } __attribute__((packed)) code = { 
                  0xb858,            /* popl %eax ; movl $...,%eax */
                  __NR_ia32_sigreturn,   
                  0x80cd,           /* int $0x80 */
                  0,
            }; 
            err |= __copy_to_user(frame->retcode, &code, 8); 
      }
      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler */
      regs->rsp = (unsigned long) frame;
      regs->rip = (unsigned long) ka->sa.sa_handler;

      /* Make -mregparm=3 work */
      regs->rax = sig;
      regs->rdx = 0;
      regs->rcx = 0;

      asm volatile("movl %0,%%ds" :: "r" (__USER32_DS)); 
      asm volatile("movl %0,%%es" :: "r" (__USER32_DS)); 

      regs->cs = __USER32_CS; 
      regs->ss = __USER32_DS; 

      set_fs(USER_DS);
      regs->eflags &= ~TF_MASK;
      if (test_thread_flag(TIF_SINGLESTEP))
            ptrace_notify(SIGTRAP);

#if DEBUG_SIG
      printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%u\n",
            current->comm, current->pid, frame, regs->rip, frame->pretcode);
#endif

      return 0;

give_sigsegv:
      force_sigsegv(sig, current);
      return -EFAULT;
}

int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                  compat_sigset_t *set, struct pt_regs * regs)
{
      struct rt_sigframe __user *frame;
      int err = 0;

      frame = get_sigframe(ka, regs, sizeof(*frame));

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

      {
            struct exec_domain *ed = current_thread_info()->exec_domain;
            err |= __put_user((ed
                     && ed->signal_invmap
                     && sig < 32
                     ? ed->signal_invmap[sig]
                     : sig),
                    &frame->sig);
      }
      err |= __put_user(ptr_to_compat(&frame->info), &frame->pinfo);
      err |= __put_user(ptr_to_compat(&frame->uc), &frame->puc);
      err |= copy_siginfo_to_user32(&frame->info, info);
      if (err)
            goto give_sigsegv;

      /* 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->rsp),
                    &frame->uc.uc_stack.ss_flags);
      err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
      err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
                          regs, set->sig[0]);
      err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
      if (err)
            goto give_sigsegv;

      
      { 
            void __user *restorer = VSYSCALL32_RTSIGRETURN; 
            if (ka->sa.sa_flags & SA_RESTORER)
                  restorer = ka->sa.sa_restorer;       
            err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
      }

      /* This is movl $,%eax ; int $0x80 */
      /* Not actually used anymore, but left because some gdb versions
         need it. */ 
      { 
            /* __copy_to_user optimizes that into a single 8 byte store */
            static const struct { 
                  u8 movl; 
                  u32 val; 
                  u16 int80; 
                  u16 pad;
                  u8  pad2;                     
            } __attribute__((packed)) code = { 
                  0xb8,
                  __NR_ia32_rt_sigreturn,
                  0x80cd,
                  0,
            }; 
            err |= __copy_to_user(frame->retcode, &code, 8); 
      } 
      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler */
      regs->rsp = (unsigned long) frame;
      regs->rip = (unsigned long) ka->sa.sa_handler;

      /* Make -mregparm=3 work */
      regs->rax = sig;
      regs->rdx = (unsigned long) &frame->info;
      regs->rcx = (unsigned long) &frame->uc;

      /* Make -mregparm=3 work */
      regs->rax = sig;
      regs->rdx = (unsigned long) &frame->info;
      regs->rcx = (unsigned long) &frame->uc;

      asm volatile("movl %0,%%ds" :: "r" (__USER32_DS)); 
      asm volatile("movl %0,%%es" :: "r" (__USER32_DS)); 
      
      regs->cs = __USER32_CS; 
      regs->ss = __USER32_DS; 

      set_fs(USER_DS);
      regs->eflags &= ~TF_MASK;
      if (test_thread_flag(TIF_SINGLESTEP))
            ptrace_notify(SIGTRAP);

#if DEBUG_SIG
      printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%u\n",
            current->comm, current->pid, frame, regs->rip, frame->pretcode);
#endif

      return 0;

give_sigsegv:
      force_sigsegv(sig, current);
      return -EFAULT;
}

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