linux/arch/ia64/kernel/signal.c
Steven Rostedt 69be8f1896 [PATCH] convert signal handling of NODEFER to act like other Unix boxes.
It has been reported that the way Linux handles NODEFER for signals is
not consistent with the way other Unix boxes handle it.  I've written a
program to test the behavior of how this flag affects signals and had
several reports from people who ran this on various Unix boxes,
confirming that Linux seems to be unique on the way this is handled.

The way NODEFER affects signals on other Unix boxes is as follows:

1) If NODEFER is set, other signals in sa_mask are still blocked.

2) If NODEFER is set and the signal is in sa_mask, then the signal is
still blocked. (Note: this is the behavior of all tested but Linux _and_
NetBSD 2.0 *).

The way NODEFER affects signals on Linux:

1) If NODEFER is set, other signals are _not_ blocked regardless of
sa_mask (Even NetBSD doesn't do this).

2) If NODEFER is set and the signal is in sa_mask, then the signal being
handled is not blocked.

The patch converts signal handling in all current Linux architectures to
the way most Unix boxes work.

Unix boxes that were tested:  DU4, AIX 5.2, Irix 6.5, NetBSD 2.0, SFU
3.5 on WinXP, AIX 5.3, Mac OSX, and of course Linux 2.6.13-rcX.

* NetBSD was the only other Unix to behave like Linux on point #2. The
main concern was brought up by point #1 which even NetBSD isn't like
Linux.  So with this patch, we leave NetBSD as the lonely one that
behaves differently here with #2.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-29 10:03:11 -07:00

693 lines
22 KiB
C

/*
* Architecture-specific signal handling support.
*
* Copyright (C) 1999-2004 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
*
* Derived from i386 and Alpha versions.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/unistd.h>
#include <linux/wait.h>
#include <asm/ia32.h>
#include <asm/intrinsics.h>
#include <asm/uaccess.h>
#include <asm/rse.h>
#include <asm/sigcontext.h>
#include "sigframe.h"
#define DEBUG_SIG 0
#define STACK_ALIGN 16 /* minimal alignment for stack pointer */
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
#if _NSIG_WORDS > 1
# define PUT_SIGSET(k,u) __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
# define GET_SIGSET(k,u) __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
#else
# define PUT_SIGSET(k,u) __put_user((k)->sig[0], &(u)->sig[0])
# define GET_SIGSET(k,u) __get_user((k)->sig[0], &(u)->sig[0])
#endif
long
ia64_rt_sigsuspend (sigset_t __user *uset, size_t sigsetsize, struct sigscratch *scr)
{
sigset_t oldset, set;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (!access_ok(VERIFY_READ, uset, sigsetsize))
return -EFAULT;
if (GET_SIGSET(&set, uset))
return -EFAULT;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
{
oldset = current->blocked;
current->blocked = set;
recalc_sigpending();
}
spin_unlock_irq(&current->sighand->siglock);
/*
* The return below usually returns to the signal handler. We need to
* pre-set the correct error code here to ensure that the right values
* get saved in sigcontext by ia64_do_signal.
*/
scr->pt.r8 = EINTR;
scr->pt.r10 = -1;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (ia64_do_signal(&oldset, scr, 1))
return -EINTR;
}
}
asmlinkage long
sys_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, long arg2,
long arg3, long arg4, long arg5, long arg6, long arg7,
struct pt_regs regs)
{
return do_sigaltstack(uss, uoss, regs.r12);
}
static long
restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
{
unsigned long ip, flags, nat, um, cfm, rsc;
long err;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/* restore scratch that always needs gets updated during signal delivery: */
err = __get_user(flags, &sc->sc_flags);
err |= __get_user(nat, &sc->sc_nat);
err |= __get_user(ip, &sc->sc_ip); /* instruction pointer */
err |= __get_user(cfm, &sc->sc_cfm);
err |= __get_user(um, &sc->sc_um); /* user mask */
err |= __get_user(rsc, &sc->sc_ar_rsc);
err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
err |= __get_user(scr->pt.pr, &sc->sc_pr); /* predicates */
err |= __get_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
err |= __get_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8); /* r8-r11 */
err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8); /* r12-r13 */
err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8); /* r15 */
scr->pt.cr_ifs = cfm | (1UL << 63);
scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
/* establish new instruction pointer: */
scr->pt.cr_iip = ip & ~0x3UL;
ia64_psr(&scr->pt)->ri = ip & 0x3;
scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
/* Restore most scratch-state only when not in syscall. */
err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
err |= __get_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
err |= __get_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8); /* r2-r3 */
err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8); /* r16-r31 */
}
if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
struct ia64_psr *psr = ia64_psr(&scr->pt);
__copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
psr->mfh = 0; /* drop signal handler's fph contents... */
preempt_disable();
if (psr->dfh)
ia64_drop_fpu(current);
else {
/* We already own the local fph, otherwise psr->dfh wouldn't be 0. */
__ia64_load_fpu(current->thread.fph);
ia64_set_local_fpu_owner(current);
}
preempt_enable();
}
return err;
}
int
copy_siginfo_to_user (siginfo_t __user *to, siginfo_t *from)
{
if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t)))
return -EFAULT;
if (from->si_code < 0) {
if (__copy_to_user(to, from, sizeof(siginfo_t)))
return -EFAULT;
return 0;
} else {
int err;
/*
* If you change siginfo_t structure, please be sure 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);
switch (from->si_code >> 16) {
case __SI_FAULT >> 16:
err |= __put_user(from->si_flags, &to->si_flags);
err |= __put_user(from->si_isr, &to->si_isr);
case __SI_POLL >> 16:
err |= __put_user(from->si_addr, &to->si_addr);
err |= __put_user(from->si_imm, &to->si_imm);
break;
case __SI_TIMER >> 16:
err |= __put_user(from->si_tid, &to->si_tid);
err |= __put_user(from->si_overrun, &to->si_overrun);
err |= __put_user(from->si_ptr, &to->si_ptr);
break;
case __SI_RT >> 16: /* 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_pid, &to->si_pid);
err |= __put_user(from->si_ptr, &to->si_ptr);
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);
default:
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user(from->si_pid, &to->si_pid);
break;
}
return err;
}
}
long
ia64_rt_sigreturn (struct sigscratch *scr)
{
extern char ia64_strace_leave_kernel, ia64_leave_kernel;
struct sigcontext __user *sc;
struct siginfo si;
sigset_t set;
long retval;
sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
/*
* When we return to the previously executing context, r8 and r10 have already
* been setup the way we want them. Indeed, if the signal wasn't delivered while
* in a system call, we must not touch r8 or r10 as otherwise user-level state
* could be corrupted.
*/
retval = (long) &ia64_leave_kernel;
if (test_thread_flag(TIF_SYSCALL_TRACE)
|| test_thread_flag(TIF_SYSCALL_AUDIT))
/*
* strace expects to be notified after sigreturn returns even though the
* context to which we return may not be in the middle of a syscall.
* Thus, the return-value that strace displays for sigreturn is
* meaningless.
*/
retval = (long) &ia64_strace_leave_kernel;
if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
goto give_sigsegv;
if (GET_SIGSET(&set, &sc->sc_mask))
goto give_sigsegv;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
{
current->blocked = set;
recalc_sigpending();
}
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(sc, scr))
goto give_sigsegv;
#if DEBUG_SIG
printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
#endif
/*
* It is more difficult to avoid calling this function than to
* call it and ignore errors.
*/
do_sigaltstack(&sc->sc_stack, NULL, scr->pt.r12);
return retval;
give_sigsegv:
si.si_signo = SIGSEGV;
si.si_errno = 0;
si.si_code = SI_KERNEL;
si.si_pid = current->pid;
si.si_uid = current->uid;
si.si_addr = sc;
force_sig_info(SIGSEGV, &si, current);
return retval;
}
/*
* This does just the minimum required setup of sigcontext.
* Specifically, it only installs data that is either not knowable at
* the user-level or that gets modified before execution in the
* trampoline starts. Everything else is done at the user-level.
*/
static long
setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
{
unsigned long flags = 0, ifs, cfm, nat;
long err;
ifs = scr->pt.cr_ifs;
if (on_sig_stack((unsigned long) sc))
flags |= IA64_SC_FLAG_ONSTACK;
if ((ifs & (1UL << 63)) == 0)
/* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
flags |= IA64_SC_FLAG_IN_SYSCALL;
cfm = ifs & ((1UL << 38) - 1);
ia64_flush_fph(current);
if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
flags |= IA64_SC_FLAG_FPH_VALID;
__copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
}
nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
err = __put_user(flags, &sc->sc_flags);
err |= __put_user(nat, &sc->sc_nat);
err |= PUT_SIGSET(mask, &sc->sc_mask);
err |= __put_user(cfm, &sc->sc_cfm);
err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */
err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */
err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */
err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */
err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */
err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */
err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */
err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
if (flags & IA64_SC_FLAG_IN_SYSCALL) {
/* Clear scratch registers if the signal interrupted a system call. */
err |= __put_user(0, &sc->sc_ar_ccv); /* ar.ccv */
err |= __put_user(0, &sc->sc_br[7]); /* b7 */
err |= __put_user(0, &sc->sc_gr[14]); /* r14 */
err |= __clear_user(&sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
err |= __clear_user(&sc->sc_gr[2], 2*8); /* r2-r3 */
err |= __clear_user(&sc->sc_gr[16], 16*8); /* r16-r31 */
} else {
/* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */
err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */
}
return err;
}
/*
* Check whether the register-backing store is already on the signal stack.
*/
static inline int
rbs_on_sig_stack (unsigned long bsp)
{
return (bsp - current->sas_ss_sp < current->sas_ss_size);
}
static long
force_sigsegv_info (int sig, void __user *addr)
{
unsigned long flags;
struct siginfo si;
if (sig == SIGSEGV) {
/*
* Acquiring siglock around the sa_handler-update is almost
* certainly overkill, but this isn't a
* performance-critical path and I'd rather play it safe
* here than having to debug a nasty race if and when
* something changes in kernel/signal.c that would make it
* no longer safe to modify sa_handler without holding the
* lock.
*/
spin_lock_irqsave(&current->sighand->siglock, flags);
current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
spin_unlock_irqrestore(&current->sighand->siglock, flags);
}
si.si_signo = SIGSEGV;
si.si_errno = 0;
si.si_code = SI_KERNEL;
si.si_pid = current->pid;
si.si_uid = current->uid;
si.si_addr = addr;
force_sig_info(SIGSEGV, &si, current);
return 0;
}
static long
setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
struct sigscratch *scr)
{
extern char __kernel_sigtramp[];
unsigned long tramp_addr, new_rbs = 0;
struct sigframe __user *frame;
long err;
frame = (void __user *) scr->pt.r12;
tramp_addr = (unsigned long) __kernel_sigtramp;
if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags((unsigned long) frame) == 0) {
frame = (void __user *) ((current->sas_ss_sp + current->sas_ss_size)
& ~(STACK_ALIGN - 1));
/*
* We need to check for the register stack being on the signal stack
* separately, because it's switched separately (memory stack is switched
* in the kernel, register stack is switched in the signal trampoline).
*/
if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
new_rbs = (current->sas_ss_sp + sizeof(long) - 1) & ~(sizeof(long) - 1);
}
frame = (void __user *) frame - ((sizeof(*frame) + STACK_ALIGN - 1) & ~(STACK_ALIGN - 1));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return force_sigsegv_info(sig, frame);
err = __put_user(sig, &frame->arg0);
err |= __put_user(&frame->info, &frame->arg1);
err |= __put_user(&frame->sc, &frame->arg2);
err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */
err |= __put_user(ka->sa.sa_handler, &frame->handler);
err |= copy_siginfo_to_user(&frame->info, info);
err |= __put_user(current->sas_ss_sp, &frame->sc.sc_stack.ss_sp);
err |= __put_user(current->sas_ss_size, &frame->sc.sc_stack.ss_size);
err |= __put_user(sas_ss_flags(scr->pt.r12), &frame->sc.sc_stack.ss_flags);
err |= setup_sigcontext(&frame->sc, set, scr);
if (unlikely(err))
return force_sigsegv_info(sig, frame);
scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */
scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */
scr->pt.cr_iip = tramp_addr;
ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */
ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */
/*
* Force the interruption function mask to zero. This has no effect when a
* system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
* ignored), but it has the desirable effect of making it possible to deliver a
* signal with an incomplete register frame (which happens when a mandatory RSE
* load faults). Furthermore, it has no negative effect on the getting the user's
* dirty partition preserved, because that's governed by scr->pt.loadrs.
*/
scr->pt.cr_ifs = (1UL << 63);
/*
* Note: this affects only the NaT bits of the scratch regs (the ones saved in
* pt_regs), which is exactly what we want.
*/
scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
#endif
return 1;
}
static long
handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset,
struct sigscratch *scr)
{
if (IS_IA32_PROCESS(&scr->pt)) {
/* send signal to IA-32 process */
if (!ia32_setup_frame1(sig, ka, info, oldset, &scr->pt))
return 0;
} else
/* send signal to IA-64 process */
if (!setup_frame(sig, ka, info, oldset, scr))
return 0;
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
if (!(ka->sa.sa_flags & SA_NODEFER))
sigaddset(&current->blocked, sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
return 1;
}
/*
* 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.
*/
long
ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
{
struct k_sigaction ka;
siginfo_t info;
long restart = in_syscall;
long errno = scr->pt.r8;
# define ERR_CODE(c) (IS_IA32_PROCESS(&scr->pt) ? -(c) : (c))
/*
* In the ia64_leave_kernel code path, we want the common case to go fast, which
* is why we may in certain cases get here from kernel mode. Just return without
* doing anything if so.
*/
if (!user_mode(&scr->pt))
return 0;
if (!oldset)
oldset = &current->blocked;
/*
* This only loops in the rare cases of handle_signal() failing, in which case we
* need to push through a forced SIGSEGV.
*/
while (1) {
int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL);
/*
* get_signal_to_deliver() may have run a debugger (via notify_parent())
* and the debugger may have modified the state (e.g., to arrange for an
* inferior call), thus it's important to check for restarting _after_
* get_signal_to_deliver().
*/
if (IS_IA32_PROCESS(&scr->pt)) {
if (in_syscall) {
if (errno >= 0)
restart = 0;
else
errno = -errno;
}
} else if ((long) scr->pt.r10 != -1)
/*
* A system calls has to be restarted only if one of the error codes
* ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10
* isn't -1 then r8 doesn't hold an error code and we don't need to
* restart the syscall, so we can clear the "restart" flag here.
*/
restart = 0;
if (signr <= 0)
break;
if (unlikely(restart)) {
switch (errno) {
case ERESTART_RESTARTBLOCK:
case ERESTARTNOHAND:
scr->pt.r8 = ERR_CODE(EINTR);
/* note: scr->pt.r10 is already -1 */
break;
case ERESTARTSYS:
if ((ka.sa.sa_flags & SA_RESTART) == 0) {
scr->pt.r8 = ERR_CODE(EINTR);
/* note: scr->pt.r10 is already -1 */
break;
}
case ERESTARTNOINTR:
if (IS_IA32_PROCESS(&scr->pt)) {
scr->pt.r8 = scr->pt.r1;
scr->pt.cr_iip -= 2;
} else
ia64_decrement_ip(&scr->pt);
restart = 0; /* don't restart twice if handle_signal() fails... */
}
}
/*
* Whee! Actually deliver the signal. If the delivery failed, we need to
* continue to iterate in this loop so we can deliver the SIGSEGV...
*/
if (handle_signal(signr, &ka, &info, oldset, scr))
return 1;
}
/* Did we come from a system call? */
if (restart) {
/* Restart the system call - no handlers present */
if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
|| errno == ERESTART_RESTARTBLOCK)
{
if (IS_IA32_PROCESS(&scr->pt)) {
scr->pt.r8 = scr->pt.r1;
scr->pt.cr_iip -= 2;
if (errno == ERESTART_RESTARTBLOCK)
scr->pt.r8 = 0; /* x86 version of __NR_restart_syscall */
} else {
/*
* Note: the syscall number is in r15 which is saved in
* pt_regs so all we need to do here is adjust ip so that
* the "break" instruction gets re-executed.
*/
ia64_decrement_ip(&scr->pt);
if (errno == ERESTART_RESTARTBLOCK)
scr->pt.r15 = __NR_restart_syscall;
}
}
}
return 0;
}
/* Set a delayed signal that was detected in MCA/INIT/NMI/PMI context where it
* could not be delivered. It is important that the target process is not
* allowed to do any more work in user space. Possible cases for the target
* process:
*
* - It is sleeping and will wake up soon. Store the data in the current task,
* the signal will be sent when the current task returns from the next
* interrupt.
*
* - It is running in user context. Store the data in the current task, the
* signal will be sent when the current task returns from the next interrupt.
*
* - It is running in kernel context on this or another cpu and will return to
* user context. Store the data in the target task, the signal will be sent
* to itself when the target task returns to user space.
*
* - It is running in kernel context on this cpu and will sleep before
* returning to user context. Because this is also the current task, the
* signal will not get delivered and the task could sleep indefinitely.
* Store the data in the idle task for this cpu, the signal will be sent
* after the idle task processes its next interrupt.
*
* To cover all cases, store the data in the target task, the current task and
* the idle task on this cpu. Whatever happens, the signal will be delivered
* to the target task before it can do any useful user space work. Multiple
* deliveries have no unwanted side effects.
*
* Note: This code is executed in MCA/INIT/NMI/PMI context, with interrupts
* disabled. It must not take any locks nor use kernel structures or services
* that require locks.
*/
/* To ensure that we get the right pid, check its start time. To avoid extra
* include files in thread_info.h, convert the task start_time to unsigned long,
* giving us a cycle time of > 580 years.
*/
static inline unsigned long
start_time_ul(const struct task_struct *t)
{
return t->start_time.tv_sec * NSEC_PER_SEC + t->start_time.tv_nsec;
}
void
set_sigdelayed(pid_t pid, int signo, int code, void __user *addr)
{
struct task_struct *t;
unsigned long start_time = 0;
int i;
for (i = 1; i <= 3; ++i) {
switch (i) {
case 1:
t = find_task_by_pid(pid);
if (t)
start_time = start_time_ul(t);
break;
case 2:
t = current;
break;
default:
t = idle_task(smp_processor_id());
break;
}
if (!t)
return;
t->thread_info->sigdelayed.signo = signo;
t->thread_info->sigdelayed.code = code;
t->thread_info->sigdelayed.addr = addr;
t->thread_info->sigdelayed.start_time = start_time;
t->thread_info->sigdelayed.pid = pid;
wmb();
set_tsk_thread_flag(t, TIF_SIGDELAYED);
}
}
/* Called from entry.S when it detects TIF_SIGDELAYED, a delayed signal that
* was detected in MCA/INIT/NMI/PMI context where it could not be delivered.
*/
void
do_sigdelayed(void)
{
struct siginfo siginfo;
pid_t pid;
struct task_struct *t;
clear_thread_flag(TIF_SIGDELAYED);
memset(&siginfo, 0, sizeof(siginfo));
siginfo.si_signo = current_thread_info()->sigdelayed.signo;
siginfo.si_code = current_thread_info()->sigdelayed.code;
siginfo.si_addr = current_thread_info()->sigdelayed.addr;
pid = current_thread_info()->sigdelayed.pid;
t = find_task_by_pid(pid);
if (!t)
return;
if (current_thread_info()->sigdelayed.start_time != start_time_ul(t))
return;
force_sig_info(siginfo.si_signo, &siginfo, t);
}