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* linux/kernel/signal.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#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 <asm/segment.h>
#define _S(nr) (1<<((nr)-1))
#define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs);
asmlinkage int sys_sigprocmask(int how, sigset_t *set, sigset_t *oset)
{
sigset_t new_set, old_set = current->blocked;
int error;
if (set) {
error = verify_area(VERIFY_READ, set, sizeof(sigset_t));
if (error)
return error;
new_set = get_fs_long((unsigned long *) set) & _BLOCKABLE;
switch (how) {
case SIG_BLOCK:
current->blocked |= new_set;
break;
case SIG_UNBLOCK:
current->blocked &= ~new_set;
break;
case SIG_SETMASK:
current->blocked = new_set;
break;
default:
return -EINVAL;
}
}
if (oset) {
error = verify_area(VERIFY_WRITE, oset, sizeof(sigset_t));
if (error)
return error;
put_fs_long(old_set, (unsigned long *) oset);
}
return 0;
}
asmlinkage int sys_sgetmask(void)
{
return current->blocked;
}
asmlinkage int sys_ssetmask(int newmask)
{
int old=current->blocked;
current->blocked = newmask & _BLOCKABLE;
return old;
}
asmlinkage int sys_sigpending(sigset_t *set)
{
int error;
/* fill in "set" with signals pending but blocked. */
error = verify_area(VERIFY_WRITE, set, 4);
if (!error)
put_fs_long(current->blocked & current->signal, (unsigned long *)set);
return error;
}
/*
* atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, unsigned long set)
{
unsigned long mask;
struct pt_regs * regs = (struct pt_regs *) &restart;
mask = current->blocked;
current->blocked = set & _BLOCKABLE;
regs->eax = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(mask,regs))
return -EINTR;
}
}
/*
* POSIX 3.3.1.3:
* "Setting a signal action to SIG_IGN for a signal that is pending
* shall cause the pending signal to be discarded, whether or not
* it is blocked" (but SIGCHLD is unspecified: linux leaves it alone).
*
* "Setting a signal action to SIG_DFL for a signal that is pending
* and whose default action is to ignore the signal (for example,
* SIGCHLD), shall cause the pending signal to be discarded, whether
* or not it is blocked"
*
* Note the silly behaviour of SIGCHLD: SIG_IGN means that the signal
* isn't actually ignored, but does automatic child reaping, while
* SIG_DFL is explicitly said by POSIX to force the signal to be ignored..
*/
static void check_pending(int signum)
{
struct sigaction *p;
p = signum - 1 + current->sigaction;
if (p->sa_handler == SIG_IGN) {
if (signum == SIGCHLD)
return;
current->signal &= ~_S(signum);
return;
}
if (p->sa_handler == SIG_DFL) {
if (signum != SIGCONT && signum != SIGCHLD && signum != SIGWINCH)
return;
current->signal &= ~_S(signum);
return;
}
}
asmlinkage int sys_signal(int signum, unsigned long handler)
{
struct sigaction tmp;
if (signum<1 || signum>32)
return -EINVAL;
if (signum==SIGKILL || signum==SIGSTOP)
return -EINVAL;
if (handler >= TASK_SIZE)
return -EFAULT;
tmp.sa_handler = (void (*)(int)) handler;
tmp.sa_mask = 0;
tmp.sa_flags = SA_ONESHOT | SA_NOMASK;
tmp.sa_restorer = NULL;
handler = (long) current->sigaction[signum-1].sa_handler;
current->sigaction[signum-1] = tmp;
check_pending(signum);
return handler;
}
asmlinkage int sys_sigaction(int signum, const struct sigaction * action,
struct sigaction * oldaction)
{
struct sigaction new_sa, *p;
if (signum<1 || signum>32)
return -EINVAL;
if (signum==SIGKILL || signum==SIGSTOP)
return -EINVAL;
p = signum - 1 + current->sigaction;
if (action) {
int err = verify_area(VERIFY_READ, action, sizeof(*action));
if (err)
return err;
memcpy_fromfs(&new_sa, action, sizeof(struct sigaction));
if (new_sa.sa_flags & SA_NOMASK)
new_sa.sa_mask = 0;
else {
new_sa.sa_mask |= _S(signum);
new_sa.sa_mask &= _BLOCKABLE;
}
if (TASK_SIZE <= (unsigned long) new_sa.sa_handler)
return -EFAULT;
}
if (oldaction) {
int err = verify_area(VERIFY_WRITE, oldaction, sizeof(*oldaction));
if (err)
return err;
memcpy_tofs(oldaction, p, sizeof(struct sigaction));
}
if (action) {
*p = new_sa;
check_pending(signum);
}
return 0;
}
asmlinkage int sys_waitpid(pid_t pid,unsigned long * stat_addr, int options);
/*
* This sets regs->esp even though we don't actually use sigstacks yet..
*/
asmlinkage int sys_sigreturn(unsigned long __unused)
{
#define COPY(x) regs->x = context.x
#define COPY_SEG(x) \
if ((context.x & 0xfffc) && (context.x & 3) != 3) goto badframe; COPY(x);
#define COPY_SEG_STRICT(x) \
if (!(context.x & 0xfffc) || (context.x & 3) != 3) goto badframe; COPY(x);
struct sigcontext_struct context;
struct pt_regs * regs;
regs = (struct pt_regs *) &__unused;
if (verify_area(VERIFY_READ, (void *) regs->esp, sizeof(context)))
goto badframe;
memcpy_fromfs(&context,(void *) regs->esp, sizeof(context));
current->blocked = context.oldmask & _BLOCKABLE;
COPY_SEG(ds);
COPY_SEG(es);
COPY_SEG(fs);
COPY_SEG(gs);
COPY_SEG_STRICT(ss);
COPY_SEG_STRICT(cs);
COPY(eip);
COPY(ecx); COPY(edx);
COPY(ebx);
COPY(esp); COPY(ebp);
COPY(edi); COPY(esi);
regs->eflags &= ~0x40DD5;
regs->eflags |= context.eflags & 0x40DD5;
regs->orig_eax = -1; /* disable syscall checks */
return context.eax;
badframe:
do_exit(SIGSEGV);
}
/*
* Set up a signal frame... Make the stack look the way iBCS2 expects
* it to look.
*/
static void setup_frame(struct sigaction * sa, unsigned long ** fp, unsigned long eip,
struct pt_regs * regs, int signr, unsigned long oldmask)
{
unsigned long * frame;
#define __CODE ((unsigned long)(frame+24))
#define CODE(x) ((unsigned long *) ((x)+__CODE))
frame = *fp;
if (regs->ss != USER_DS)
frame = (unsigned long *) sa->sa_restorer;
frame -= 32;
if (verify_area(VERIFY_WRITE,frame,32*4))
do_exit(SIGSEGV);
/* set up the "normal" stack seen by the signal handler (iBCS2) */
put_fs_long(__CODE,frame);
if (current->exec_domain && current->exec_domain->signal_invmap)
put_fs_long(current->exec_domain->signal_invmap[signr], frame+1);
else
put_fs_long(signr, frame+1);
put_fs_long(regs->gs, frame+2);
put_fs_long(regs->fs, frame+3);
put_fs_long(regs->es, frame+4);
put_fs_long(regs->ds, frame+5);
put_fs_long(regs->edi, frame+6);
put_fs_long(regs->esi, frame+7);
put_fs_long(regs->ebp, frame+8);
put_fs_long((long)*fp, frame+9);
put_fs_long(regs->ebx, frame+10);
put_fs_long(regs->edx, frame+11);
put_fs_long(regs->ecx, frame+12);
put_fs_long(regs->eax, frame+13);
put_fs_long(current->tss.trap_no, frame+14);
put_fs_long(current->tss.error_code, frame+15);
put_fs_long(eip, frame+16);
put_fs_long(regs->cs, frame+17);
put_fs_long(regs->eflags, frame+18);
put_fs_long(regs->esp, frame+19);
put_fs_long(regs->ss, frame+20);
put_fs_long(0,frame+21); /* 387 state pointer - not implemented*/
/* non-iBCS2 extensions.. */
put_fs_long(oldmask, frame+22);
put_fs_long(current->tss.cr2, frame+23);
/* set up the return code... */
put_fs_long(0x0000b858, CODE(0)); /* popl %eax ; movl $,%eax */
put_fs_long(0x80cd0000, CODE(4)); /* int $0x80 */
put_fs_long(__NR_sigreturn, CODE(2));
*fp = frame;
#undef __CODE
#undef CODE
}
/*
* 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.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs)
{
unsigned long mask = ~current->blocked;
unsigned long handler_signal = 0;
unsigned long *frame = NULL;
unsigned long eip = 0;
unsigned long signr;
struct sigaction * sa;
while ((signr = current->signal & mask)) {
__asm__("bsf %2,%1\n\t"
"btrl %1,%0"
:"=m" (current->signal),"=r" (signr)
:"1" (signr));
sa = current->sigaction + signr;
signr++;
if ((current->flags & PF_PTRACED) && signr != SIGKILL) {
current->exit_code = signr;
current->state = TASK_STOPPED;
notify_parent(current);
schedule();
if (!(signr = current->exit_code))
continue;
current->exit_code = 0;
if (signr == SIGSTOP)
continue;
if (_S(signr) & current->blocked) {
current->signal |= _S(signr);
continue;
}
sa = current->sigaction + signr - 1;
}
if (sa->sa_handler == SIG_IGN) {
if (signr != SIGCHLD)
continue;
/* check for SIGCHLD: it's special */
while (sys_waitpid(-1,NULL,WNOHANG) > 0)
/* nothing */;
continue;
}
if (sa->sa_handler == SIG_DFL) {
if (current->pid == 1)
continue;
switch (signr) {
case SIGCONT: case SIGCHLD: case SIGWINCH:
continue;
case SIGSTOP: case SIGTSTP: case SIGTTIN: case SIGTTOU:
if (current->flags & PF_PTRACED)
continue;
current->state = TASK_STOPPED;
current->exit_code = signr;
if (!(current->p_pptr->sigaction[SIGCHLD-1].sa_flags &
SA_NOCLDSTOP))
notify_parent(current);
schedule();
continue;
case SIGQUIT: case SIGILL: case SIGTRAP:
case SIGIOT: case SIGFPE: case SIGSEGV:
if (current->binfmt && current->binfmt->core_dump) {
if (current->binfmt->core_dump(signr, regs))
signr |= 0x80;
}
/* fall through */
default:
current->signal |= _S(signr & 0x7f);
do_exit(signr);
}
}
/*
* OK, we're invoking a handler
*/
if (regs->orig_eax >= 0) {
if (regs->eax == -ERESTARTNOHAND ||
(regs->eax == -ERESTARTSYS && !(sa->sa_flags & SA_RESTART)))
regs->eax = -EINTR;
}
handler_signal |= 1 << (signr-1);
mask &= ~sa->sa_mask;
}
if (regs->orig_eax >= 0 &&
(regs->eax == -ERESTARTNOHAND ||
regs->eax == -ERESTARTSYS ||
regs->eax == -ERESTARTNOINTR)) {
regs->eax = regs->orig_eax;
regs->eip -= 2;
}
if (!handler_signal) /* no handler will be called - return 0 */
return 0;
eip = regs->eip;
frame = (unsigned long *) regs->esp;
signr = 1;
sa = current->sigaction;
for (mask = 1 ; mask ; sa++,signr++,mask += mask) {
if (mask > handler_signal)
break;
if (!(mask & handler_signal))
continue;
setup_frame(sa,&frame,eip,regs,signr,oldmask);
eip = (unsigned long) sa->sa_handler;
if (sa->sa_flags & SA_ONESHOT)
sa->sa_handler = NULL;
/* force a supervisor-mode page-in of the signal handler to reduce races */
__asm__("testb $0,%%fs:%0": :"m" (*(char *) eip));
regs->cs = USER_CS; regs->ss = USER_DS;
regs->ds = USER_DS; regs->es = USER_DS;
regs->gs = USER_DS; regs->fs = USER_DS;
current->blocked |= sa->sa_mask;
oldmask |= sa->sa_mask;
}
regs->esp = (unsigned long) frame;
regs->eip = eip; /* "return" to the first handler */
current->tss.trap_no = current->tss.error_code = 0;
return 1;
}
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