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linux/arch/mn10300/kernel/signal.c
Mark Salter 4c03ee7352 mn10300: signal stack fix 
This fixes a signal stack handling problem in the MN10300 arch.  When new
threads are cloned with CLONE_VM, they don't inherit the alternate signal
stack.  They do share the signal flags, though.  When deciding whether to
use an alternate stack, the arch code needs to check to make sure the task
struct contains a valid alternate stack.  This patch fixes the MN10300
arch by using the sas_ss_flags() test provided by sched.h rather than the
on_sig_stack() test which is insufficient by itself.

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-11 09:34:07 -08:00

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/* MN10300 Signal handling
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#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/tty.h>
#include <linux/personality.h>
#include <linux/suspend.h>
#include <linux/tracehook.h>
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/fpu.h>
#include "sigframe.h"
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
/*
* atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage long sys_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;
}
/*
* set signal action syscall
*/
asmlinkage long sys_sigaction(int sig,
const struct old_sigaction __user *act,
struct old_sigaction __user *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
return -EFAULT;
__get_user(new_ka.sa.sa_flags, &act->sa_flags);
__get_user(mask, &act->sa_mask);
siginitset(&new_ka.sa.sa_mask, mask);
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
return -EFAULT;
__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
}
return ret;
}
/*
* set alternate signal stack syscall
*/
asmlinkage long sys_sigaltstack(const stack_t __user *uss, stack_t *uoss)
{
return do_sigaltstack(uss, uoss, __frame->sp);
}
/*
* do a signal return; undo the signal stack.
*/
static int restore_sigcontext(struct pt_regs *regs,
struct sigcontext __user *sc, long *_d0)
{
unsigned int err = 0;
if (is_using_fpu(current))
fpu_kill_state(current);
#define COPY(x) err |= __get_user(regs->x, &sc->x)
COPY(d1); COPY(d2); COPY(d3);
COPY(a0); COPY(a1); COPY(a2); COPY(a3);
COPY(e0); COPY(e1); COPY(e2); COPY(e3);
COPY(e4); COPY(e5); COPY(e6); COPY(e7);
COPY(lar); COPY(lir);
COPY(mdr); COPY(mdrq);
COPY(mcvf); COPY(mcrl); COPY(mcrh);
COPY(sp); COPY(pc);
#undef COPY
{
unsigned int tmpflags;
#ifndef CONFIG_MN10300_USING_JTAG
#define USER_EPSW (EPSW_FLAG_Z | EPSW_FLAG_N | EPSW_FLAG_C | EPSW_FLAG_V | \
EPSW_T | EPSW_nAR)
#else
#define USER_EPSW (EPSW_FLAG_Z | EPSW_FLAG_N | EPSW_FLAG_C | EPSW_FLAG_V | \
EPSW_nAR)
#endif
err |= __get_user(tmpflags, &sc->epsw);
regs->epsw = (regs->epsw & ~USER_EPSW) |
(tmpflags & USER_EPSW);
regs->orig_d0 = -1; /* disable syscall checks */
}
{
struct fpucontext *buf;
err |= __get_user(buf, &sc->fpucontext);
if (buf) {
if (verify_area(VERIFY_READ, buf, sizeof(*buf)))
goto badframe;
err |= fpu_restore_sigcontext(buf);
}
}
err |= __get_user(*_d0, &sc->d0);
return err;
badframe:
return 1;
}
/*
* standard signal return syscall
*/
asmlinkage long sys_sigreturn(void)
{
struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
sigset_t set;
long d0;
if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask))
goto badframe;
if (_NSIG_WORDS > 1 &&
__copy_from_user(&set.sig[1], &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 (restore_sigcontext(__frame, &frame->sc, &d0))
goto badframe;
return d0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* realtime signal return syscall
*/
asmlinkage long sys_rt_sigreturn(void)
{
struct rt_sigframe __user *frame =
(struct rt_sigframe __user *) __frame->sp;
sigset_t set;
unsigned long d0;
if (verify_area(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 (restore_sigcontext(__frame, &frame->uc.uc_mcontext, &d0))
goto badframe;
if (do_sigaltstack(&frame->uc.uc_stack, NULL, __frame->sp) == -EFAULT)
goto badframe;
return d0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* store the userspace context into a signal frame
*/
static int setup_sigcontext(struct sigcontext __user *sc,
struct fpucontext *fpuctx,
struct pt_regs *regs,
unsigned long mask)
{
int tmp, err = 0;
#define COPY(x) err |= __put_user(regs->x, &sc->x)
COPY(d0); COPY(d1); COPY(d2); COPY(d3);
COPY(a0); COPY(a1); COPY(a2); COPY(a3);
COPY(e0); COPY(e1); COPY(e2); COPY(e3);
COPY(e4); COPY(e5); COPY(e6); COPY(e7);
COPY(lar); COPY(lir);
COPY(mdr); COPY(mdrq);
COPY(mcvf); COPY(mcrl); COPY(mcrh);
COPY(sp); COPY(epsw); COPY(pc);
#undef COPY
tmp = fpu_setup_sigcontext(fpuctx);
if (tmp < 0)
err = 1;
else
err |= __put_user(tmp ? fpuctx : NULL, &sc->fpucontext);
/* non-iBCS2 extensions.. */
err |= __put_user(mask, &sc->oldmask);
return err;
}
/*
* determine which stack to use..
*/
static inline void __user *get_sigframe(struct k_sigaction *ka,
struct pt_regs *regs,
size_t frame_size)
{
unsigned long sp;
/* default to using normal stack */
sp = regs->sp;
/* this is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(sp) == 0)
sp = current->sas_ss_sp + current->sas_ss_size;
}
return (void __user *) ((sp - frame_size) & ~7UL);
}
/*
* set up a normal signal frame
*/
static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
struct pt_regs *regs)
{
struct sigframe __user *frame;
int rsig;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
rsig = sig;
if (sig < 32 &&
current_thread_info()->exec_domain &&
current_thread_info()->exec_domain->signal_invmap)
rsig = current_thread_info()->exec_domain->signal_invmap[sig];
if (__put_user(rsig, &frame->sig) < 0 ||
__put_user(&frame->sc, &frame->psc) < 0)
goto give_sigsegv;
if (setup_sigcontext(&frame->sc, &frame->fpuctx, regs, set->sig[0]))
goto give_sigsegv;
if (_NSIG_WORDS > 1) {
if (__copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask)))
goto give_sigsegv;
}
/* set up to return from userspace. If provided, use a stub already in
* userspace */
if (ka->sa.sa_flags & SA_RESTORER) {
if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
goto give_sigsegv;
} else {
if (__put_user((void (*)(void))frame->retcode,
&frame->pretcode))
goto give_sigsegv;
/* this is mov $,d0; syscall 0 */
if (__put_user(0x2c, (char *)(frame->retcode + 0)) ||
__put_user(__NR_sigreturn, (char *)(frame->retcode + 1)) ||
__put_user(0x00, (char *)(frame->retcode + 2)) ||
__put_user(0xf0, (char *)(frame->retcode + 3)) ||
__put_user(0xe0, (char *)(frame->retcode + 4)))
goto give_sigsegv;
flush_icache_range((unsigned long) frame->retcode,
(unsigned long) frame->retcode + 5);
}
/* set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->pc = (unsigned long) ka->sa.sa_handler;
regs->d0 = sig;
regs->d1 = (unsigned long) &frame->sc;
set_fs(USER_DS);
/* the tracer may want to single-step inside the handler */
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#if DEBUG_SIG
printk(KERN_DEBUG "SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
sig, current->comm, current->pid, frame, regs->pc,
frame->pretcode);
#endif
return 0;
give_sigsegv:
force_sig(SIGSEGV, current);
return -EFAULT;
}
/*
* set up a realtime signal frame
*/
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
int rsig;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
rsig = sig;
if (sig < 32 &&
current_thread_info()->exec_domain &&
current_thread_info()->exec_domain->signal_invmap)
rsig = current_thread_info()->exec_domain->signal_invmap[sig];
if (__put_user(rsig, &frame->sig) ||
__put_user(&frame->info, &frame->pinfo) ||
__put_user(&frame->uc, &frame->puc) ||
copy_siginfo_to_user(&frame->info, info))
goto give_sigsegv;
/* create the ucontext. */
if (__put_user(0, &frame->uc.uc_flags) ||
__put_user(0, &frame->uc.uc_link) ||
__put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp) ||
__put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags) ||
__put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size) ||
setup_sigcontext(&frame->uc.uc_mcontext,
&frame->fpuctx, regs, set->sig[0]) ||
__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
goto give_sigsegv;
/* set up to return from userspace. If provided, use a stub already in
* userspace */
if (ka->sa.sa_flags & SA_RESTORER) {
if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
goto give_sigsegv;
} else {
if (__put_user((void(*)(void))frame->retcode,
&frame->pretcode) ||
/* This is mov $,d0; syscall 0 */
__put_user(0x2c, (char *)(frame->retcode + 0)) ||
__put_user(__NR_rt_sigreturn,
(char *)(frame->retcode + 1)) ||
__put_user(0x00, (char *)(frame->retcode + 2)) ||
__put_user(0xf0, (char *)(frame->retcode + 3)) ||
__put_user(0xe0, (char *)(frame->retcode + 4)))
goto give_sigsegv;
flush_icache_range((u_long) frame->retcode,
(u_long) frame->retcode + 5);
}
/* Set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->pc = (unsigned long) ka->sa.sa_handler;
regs->d0 = sig;
regs->d1 = (long) &frame->info;
set_fs(USER_DS);
/* the tracer may want to single-step inside the handler */
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#if DEBUG_SIG
printk(KERN_DEBUG "SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
sig, current->comm, current->pid, frame, regs->pc,
frame->pretcode);
#endif
return 0;
give_sigsegv:
force_sig(SIGSEGV, current);
return -EFAULT;
}
/*
* handle the actual delivery of a signal to userspace
*/
static int handle_signal(int sig,
siginfo_t *info, struct k_sigaction *ka,
sigset_t *oldset, struct pt_regs *regs)
{
int ret;
/* Are we from a system call? */
if (regs->orig_d0 >= 0) {
/* If so, check system call restarting.. */
switch (regs->d0) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->d0 = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->d0 = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
regs->d0 = regs->orig_d0;
regs->pc -= 2;
}
}
/* Set up the stack frame */
if (ka->sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(sig, ka, info, oldset, regs);
else
ret = setup_frame(sig, ka, oldset, regs);
if (ret == 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 ret;
}
/*
* handle a potential signal
*/
static void do_signal(struct pt_regs *regs)
{
struct k_sigaction ka;
siginfo_t info;
sigset_t *oldset;
int signr;
/* we want the common case to go fast, which is why we may in certain
* cases get here from kernel mode */
if (!user_mode(regs))
return;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = &current->saved_sigmask;
else
oldset = &current->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
/* a signal was successfully delivered; the saved
* sigmask will have been stored in the signal frame,
* and will be restored by sigreturn, so we can simply
* clear the TIF_RESTORE_SIGMASK flag */
if (test_thread_flag(TIF_RESTORE_SIGMASK))
clear_thread_flag(TIF_RESTORE_SIGMASK);
tracehook_signal_handler(signr, &info, &ka, regs,
test_thread_flag(TIF_SINGLESTEP));
}
return;
}
/* did we come from a system call? */
if (regs->orig_d0 >= 0) {
/* restart the system call - no handlers present */
switch (regs->d0) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
regs->d0 = regs->orig_d0;
regs->pc -= 2;
break;
case -ERESTART_RESTARTBLOCK:
regs->d0 = __NR_restart_syscall;
regs->pc -= 2;
break;
}
}
/* if there's no signal to deliver, we just put the saved sigmask
* back */
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
clear_thread_flag(TIF_RESTORE_SIGMASK);
sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
}
}
/*
* notification of userspace execution resumption
* - triggered by current->work.notify_resume
*/
asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags)
{
/* Pending single-step? */
if (thread_info_flags & _TIF_SINGLESTEP) {
#ifndef CONFIG_MN10300_USING_JTAG
regs->epsw |= EPSW_T;
clear_thread_flag(TIF_SINGLESTEP);
#else
BUG(); /* no h/w single-step if using JTAG unit */
#endif
}
/* deal with pending signal delivery */
if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
do_signal(regs);
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(__frame);
if (current->replacement_session_keyring)
key_replace_session_keyring();
}
}
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