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linux-stable-rt/arch/arm/kernel/signal.c

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/*
* linux/arch/arm/kernel/signal.c
*
* Copyright (C) 1995-2002 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include "ptrace.h"
#include "signal.h"
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
/*
* For ARM syscalls, we encode the syscall number into the instruction.
*/
#define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn))
#define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn))
/*
* For Thumb syscalls, we pass the syscall number via r7. We therefore
* need two 16-bit instructions.
*/
#define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
#define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
const unsigned long sigreturn_codes[4] = {
SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN,
SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN
};
static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
/*
* atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
{
sigset_t saveset;
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->ARM_r0 = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&saveset, regs, 0))
return regs->ARM_r0;
}
}
asmlinkage int
sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
{
sigset_t saveset, newset;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&newset, unewset, sizeof(newset)))
return -EFAULT;
sigdelsetmask(&newset, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
current->blocked = newset;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->ARM_r0 = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&saveset, regs, 0))
return regs->ARM_r0;
}
}
asmlinkage int
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 (!access_ok(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 (!access_ok(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;
}
#ifdef CONFIG_IWMMXT
/* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
#define IWMMXT_STORAGE_SIZE (0x98 + 8)
#define IWMMXT_MAGIC0 0x12ef842a
#define IWMMXT_MAGIC1 0x1c07ca71
struct iwmmxt_sigframe {
unsigned long magic0;
unsigned long magic1;
unsigned long storage[0x98/4];
};
static int page_present(struct mm_struct *mm, void __user *uptr, int wr)
{
unsigned long addr = (unsigned long)uptr;
pgd_t *pgd = pgd_offset(mm, addr);
if (pgd_present(*pgd)) {
pmd_t *pmd = pmd_offset(pgd, addr);
if (pmd_present(*pmd)) {
pte_t *pte = pte_offset_map(pmd, addr);
return (pte_present(*pte) && (!wr || pte_write(*pte)));
}
}
return 0;
}
static int copy_locked(void __user *uptr, void *kptr, size_t size, int write,
void (*copyfn)(void *, void __user *))
{
unsigned char v, __user *userptr = uptr;
int err = 0;
do {
struct mm_struct *mm;
if (write) {
__put_user_error(0, userptr, err);
__put_user_error(0, userptr + size - 1, err);
} else {
__get_user_error(v, userptr, err);
__get_user_error(v, userptr + size - 1, err);
}
if (err)
break;
mm = current->mm;
spin_lock(&mm->page_table_lock);
if (page_present(mm, userptr, write) &&
page_present(mm, userptr + size - 1, write)) {
copyfn(kptr, uptr);
} else
err = 1;
spin_unlock(&mm->page_table_lock);
} while (err);
return err;
}
static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
{
int err = 0;
/* the iWMMXt context must be 64 bit aligned */
WARN_ON((unsigned long)frame & 7);
__put_user_error(IWMMXT_MAGIC0, &frame->magic0, err);
__put_user_error(IWMMXT_MAGIC1, &frame->magic1, err);
/*
* iwmmxt_task_copy() doesn't check user permissions.
* Let's do a dummy write on the upper boundary to ensure
* access to user mem is OK all way up.
*/
err |= copy_locked(&frame->storage, current_thread_info(),
sizeof(frame->storage), 1, iwmmxt_task_copy);
return err;
}
static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
{
unsigned long magic0, magic1;
int err = 0;
/* the iWMMXt context is 64 bit aligned */
WARN_ON((unsigned long)frame & 7);
/*
* Validate iWMMXt context signature.
* Also, iwmmxt_task_restore() doesn't check user permissions.
* Let's do a dummy write on the upper boundary to ensure
* access to user mem is OK all way up.
*/
__get_user_error(magic0, &frame->magic0, err);
__get_user_error(magic1, &frame->magic1, err);
if (!err && magic0 == IWMMXT_MAGIC0 && magic1 == IWMMXT_MAGIC1)
err = copy_locked(&frame->storage, current_thread_info(),
sizeof(frame->storage), 0, iwmmxt_task_restore);
return err;
}
#endif
/*
* Auxiliary signal frame. This saves stuff like FP state.
* The layout of this structure is not part of the user ABI.
*/
struct aux_sigframe {
#ifdef CONFIG_IWMMXT
struct iwmmxt_sigframe iwmmxt;
#endif
#ifdef CONFIG_VFP
union vfp_state vfp;
#endif
};
/*
* Do a signal return; undo the signal stack. These are aligned to 64-bit.
*/
struct sigframe {
struct sigcontext sc;
unsigned long extramask[_NSIG_WORDS-1];
unsigned long retcode;
struct aux_sigframe aux __attribute__((aligned(8)));
};
struct rt_sigframe {
struct siginfo __user *pinfo;
void __user *puc;
struct siginfo info;
struct ucontext uc;
unsigned long retcode;
struct aux_sigframe aux __attribute__((aligned(8)));
};
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
struct aux_sigframe __user *aux)
{
int err = 0;
__get_user_error(regs->ARM_r0, &sc->arm_r0, err);
__get_user_error(regs->ARM_r1, &sc->arm_r1, err);
__get_user_error(regs->ARM_r2, &sc->arm_r2, err);
__get_user_error(regs->ARM_r3, &sc->arm_r3, err);
__get_user_error(regs->ARM_r4, &sc->arm_r4, err);
__get_user_error(regs->ARM_r5, &sc->arm_r5, err);
__get_user_error(regs->ARM_r6, &sc->arm_r6, err);
__get_user_error(regs->ARM_r7, &sc->arm_r7, err);
__get_user_error(regs->ARM_r8, &sc->arm_r8, err);
__get_user_error(regs->ARM_r9, &sc->arm_r9, err);
__get_user_error(regs->ARM_r10, &sc->arm_r10, err);
__get_user_error(regs->ARM_fp, &sc->arm_fp, err);
__get_user_error(regs->ARM_ip, &sc->arm_ip, err);
__get_user_error(regs->ARM_sp, &sc->arm_sp, err);
__get_user_error(regs->ARM_lr, &sc->arm_lr, err);
__get_user_error(regs->ARM_pc, &sc->arm_pc, err);
__get_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
err |= !valid_user_regs(regs);
#ifdef CONFIG_IWMMXT
if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
err |= restore_iwmmxt_context(&aux->iwmmxt);
#endif
#ifdef CONFIG_VFP
// if (err == 0)
// err |= vfp_restore_state(&aux->vfp);
#endif
return err;
}
asmlinkage int sys_sigreturn(struct pt_regs *regs)
{
struct sigframe __user *frame;
sigset_t set;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (regs->ARM_sp & 7)
goto badframe;
frame = (struct sigframe __user *)regs->ARM_sp;
if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_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(regs, &frame->sc, &frame->aux))
goto badframe;
/* Send SIGTRAP if we're single-stepping */
if (current->ptrace & PT_SINGLESTEP) {
ptrace_cancel_bpt(current);
send_sig(SIGTRAP, current, 1);
}
return regs->ARM_r0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
sigset_t set;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (regs->ARM_sp & 7)
goto badframe;
frame = (struct rt_sigframe __user *)regs->ARM_sp;
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 (restore_sigcontext(regs, &frame->uc.uc_mcontext, &frame->aux))
goto badframe;
if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
goto badframe;
/* Send SIGTRAP if we're single-stepping */
if (current->ptrace & PT_SINGLESTEP) {
ptrace_cancel_bpt(current);
send_sig(SIGTRAP, current, 1);
}
return regs->ARM_r0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
static int
setup_sigcontext(struct sigcontext __user *sc, struct aux_sigframe __user *aux,
struct pt_regs *regs, unsigned long mask)
{
int err = 0;
__put_user_error(regs->ARM_r0, &sc->arm_r0, err);
__put_user_error(regs->ARM_r1, &sc->arm_r1, err);
__put_user_error(regs->ARM_r2, &sc->arm_r2, err);
__put_user_error(regs->ARM_r3, &sc->arm_r3, err);
__put_user_error(regs->ARM_r4, &sc->arm_r4, err);
__put_user_error(regs->ARM_r5, &sc->arm_r5, err);
__put_user_error(regs->ARM_r6, &sc->arm_r6, err);
__put_user_error(regs->ARM_r7, &sc->arm_r7, err);
__put_user_error(regs->ARM_r8, &sc->arm_r8, err);
__put_user_error(regs->ARM_r9, &sc->arm_r9, err);
__put_user_error(regs->ARM_r10, &sc->arm_r10, err);
__put_user_error(regs->ARM_fp, &sc->arm_fp, err);
__put_user_error(regs->ARM_ip, &sc->arm_ip, err);
__put_user_error(regs->ARM_sp, &sc->arm_sp, err);
__put_user_error(regs->ARM_lr, &sc->arm_lr, err);
__put_user_error(regs->ARM_pc, &sc->arm_pc, err);
__put_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
__put_user_error(current->thread.trap_no, &sc->trap_no, err);
__put_user_error(current->thread.error_code, &sc->error_code, err);
__put_user_error(current->thread.address, &sc->fault_address, err);
__put_user_error(mask, &sc->oldmask, err);
#ifdef CONFIG_IWMMXT
if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
err |= preserve_iwmmxt_context(&aux->iwmmxt);
#endif
#ifdef CONFIG_VFP
// if (err == 0)
// err |= vfp_save_state(&aux->vfp);
#endif
return err;
}
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
{
unsigned long sp = regs->ARM_sp;
void __user *frame;
/*
* This is the X/Open sanctioned signal stack switching.
*/
if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
/*
* ATPCS B01 mandates 8-byte alignment
*/
frame = (void __user *)((sp - framesize) & ~7);
/*
* Check that we can actually write to the signal frame.
*/
if (!access_ok(VERIFY_WRITE, frame, framesize))
frame = NULL;
return frame;
}
static int
setup_return(struct pt_regs *regs, struct k_sigaction *ka,
unsigned long __user *rc, void __user *frame, int usig)
{
unsigned long handler = (unsigned long)ka->sa.sa_handler;
unsigned long retcode;
int thumb = 0;
unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
/*
* Maybe we need to deliver a 32-bit signal to a 26-bit task.
*/
if (ka->sa.sa_flags & SA_THIRTYTWO)
cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
#ifdef CONFIG_ARM_THUMB
if (elf_hwcap & HWCAP_THUMB) {
/*
* The LSB of the handler determines if we're going to
* be using THUMB or ARM mode for this signal handler.
*/
thumb = handler & 1;
if (thumb)
cpsr |= PSR_T_BIT;
else
cpsr &= ~PSR_T_BIT;
}
#endif
if (ka->sa.sa_flags & SA_RESTORER) {
retcode = (unsigned long)ka->sa.sa_restorer;
} else {
unsigned int idx = thumb;
if (ka->sa.sa_flags & SA_SIGINFO)
idx += 2;
if (__put_user(sigreturn_codes[idx], rc))
return 1;
if (cpsr & MODE32_BIT) {
/*
* 32-bit code can use the new high-page
* signal return code support.
*/
retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
} else {
/*
* Ensure that the instruction cache sees
* the return code written onto the stack.
*/
flush_icache_range((unsigned long)rc,
(unsigned long)(rc + 1));
retcode = ((unsigned long)rc) + thumb;
}
}
regs->ARM_r0 = usig;
regs->ARM_sp = (unsigned long)frame;
regs->ARM_lr = retcode;
regs->ARM_pc = handler;
regs->ARM_cpsr = cpsr;
return 0;
}
static int
setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
{
struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
int err = 0;
if (!frame)
return 1;
err |= setup_sigcontext(&frame->sc, &frame->aux, regs, set->sig[0]);
if (_NSIG_WORDS > 1) {
err |= __copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask));
}
if (err == 0)
err = setup_return(regs, ka, &frame->retcode, frame, usig);
return err;
}
static int
setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
stack_t stack;
int err = 0;
if (!frame)
return 1;
__put_user_error(&frame->info, &frame->pinfo, err);
__put_user_error(&frame->uc, &frame->puc, err);
err |= copy_siginfo_to_user(&frame->info, info);
__put_user_error(0, &frame->uc.uc_flags, err);
__put_user_error(NULL, &frame->uc.uc_link, err);
memset(&stack, 0, sizeof(stack));
stack.ss_sp = (void __user *)current->sas_ss_sp;
stack.ss_flags = sas_ss_flags(regs->ARM_sp);
stack.ss_size = current->sas_ss_size;
err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->aux,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err == 0)
err = setup_return(regs, ka, &frame->retcode, frame, usig);
if (err == 0) {
/*
* For realtime signals we must also set the second and third
* arguments for the signal handler.
* -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
*/
regs->ARM_r1 = (unsigned long)&frame->info;
regs->ARM_r2 = (unsigned long)&frame->uc;
}
return err;
}
static inline void restart_syscall(struct pt_regs *regs)
{
regs->ARM_r0 = regs->ARM_ORIG_r0;
regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
}
/*
* OK, we're invoking a handler
*/
static void
handle_signal(unsigned long sig, struct k_sigaction *ka,
siginfo_t *info, sigset_t *oldset,
struct pt_regs * regs, int syscall)
{
struct thread_info *thread = current_thread_info();
struct task_struct *tsk = current;
int usig = sig;
int ret;
/*
* If we were from a system call, check for system call restarting...
*/
if (syscall) {
switch (regs->ARM_r0) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->ARM_r0 = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->ARM_r0 = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
restart_syscall(regs);
}
}
/*
* translate the signal
*/
if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
usig = thread->exec_domain->signal_invmap[usig];
/*
* Set up the stack frame
*/
if (ka->sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(usig, ka, info, oldset, regs);
else
ret = setup_frame(usig, ka, oldset, regs);
/*
* Check that the resulting registers are actually sane.
*/
ret |= !valid_user_regs(regs);
/*
* Block the signal if we were unsuccessful.
*/
if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
spin_lock_irq(&tsk->sighand->siglock);
sigorsets(&tsk->blocked, &tsk->blocked,
&ka->sa.sa_mask);
sigaddset(&tsk->blocked, sig);
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
}
if (ret == 0)
return;
force_sigsegv(sig, tsk);
}
/*
* 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.
*/
static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
{
struct k_sigaction ka;
siginfo_t info;
int signr;
/*
* 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(regs))
return 0;
if (try_to_freeze())
goto no_signal;
if (current->ptrace & PT_SINGLESTEP)
ptrace_cancel_bpt(current);
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
handle_signal(signr, &ka, &info, oldset, regs, syscall);
if (current->ptrace & PT_SINGLESTEP)
ptrace_set_bpt(current);
return 1;
}
no_signal:
/*
* No signal to deliver to the process - restart the syscall.
*/
if (syscall) {
if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
if (thumb_mode(regs)) {
regs->ARM_r7 = __NR_restart_syscall;
regs->ARM_pc -= 2;
} else {
u32 __user *usp;
regs->ARM_sp -= 12;
usp = (u32 __user *)regs->ARM_sp;
put_user(regs->ARM_pc, &usp[0]);
/* swi __NR_restart_syscall */
put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
/* ldr pc, [sp], #12 */
put_user(0xe49df00c, &usp[2]);
flush_icache_range((unsigned long)usp,
(unsigned long)(usp + 3));
regs->ARM_pc = regs->ARM_sp + 4;
}
}
if (regs->ARM_r0 == -ERESTARTNOHAND ||
regs->ARM_r0 == -ERESTARTSYS ||
regs->ARM_r0 == -ERESTARTNOINTR) {
restart_syscall(regs);
}
}
if (current->ptrace & PT_SINGLESTEP)
ptrace_set_bpt(current);
return 0;
}
asmlinkage void
do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
if (thread_flags & _TIF_SIGPENDING)
do_signal(&current->blocked, regs, syscall);
}
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