android_kernel_xiaomi_sm8350/arch/ia64/kernel/signal.c
Matthew Chapman 4ea78729b8 [IA64] ptrace and restore_sigcontext() allow ar.rsc.pl==0
This patch fixes handling of accesses to ar.rsc via ptrace & restore_sigcontext
[With Thanks to Chris Wright for noticing the restore_sigcontext path]

Signed-off-by: Matthew Chapman <matthewc@hp.com>
Acked-by: David Mosberger <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2005-06-21 16:19:20 -07:00

694 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... */
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);
}
}
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;
if (!(ka->sa.sa_flags & SA_NODEFER)) {
spin_lock_irq(&current->sighand->siglock);
{
sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
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);
}