/*
* linux/arch/cris/kernel/signal.c
*
* Based on arch/i386/kernel/signal.c by
* Copyright (C) 1991, 1992 Linus Torvalds
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson *
*
* Ideas also taken from arch/arm.
*
* Copyright (C) 2000-2007 Axis Communications AB
*
* Authors: Bjorn Wesen (bjornw@axis.com)
*
*/
#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 <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <arch/system.h>
#define DEBUG_SIG 0
/* a syscall in Linux/CRIS is a break 13 instruction which is 2 bytes */
/* manipulate regs so that upon return, it will be re-executed */
/* We rely on that pc points to the instruction after "break 13", so the
* library must never do strange things like putting it in a delay slot.
*/
#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->irp -= 2;
void do_signal(int canrestart, struct pt_regs *regs);
/*
* Do a signal return; undo the signal stack.
*/
struct sigframe {
struct sigcontext sc;
unsigned long extramask[_NSIG_WORDS-1];
unsigned char retcode[8]; /* trampoline code */
};
struct rt_sigframe {
struct siginfo *pinfo;
void *puc;
struct siginfo info;
struct ucontext uc;
unsigned char retcode[8]; /* trampoline code */
};
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
unsigned int err = 0;
unsigned long old_usp;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/* restore the regs from &sc->regs (same as sc, since regs is first)
* (sc is already checked for VERIFY_READ since the sigframe was
* checked in sys_sigreturn previously)
*/
if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
goto badframe;
/* make sure the U-flag is set so user-mode cannot fool us */
regs->dccr |= 1 << 8;
/* restore the old USP as it was before we stacked the sc etc.
* (we cannot just pop the sigcontext since we aligned the sp and
* stuff after pushing it)
*/
err |= __get_user(old_usp, &sc->usp);
wrusp(old_usp);
/* TODO: the other ports use regs->orig_XX to disable syscall checks
* after this completes, but we don't use that mechanism. maybe we can
* use it now ?
*/
return err;
badframe:
return 1;
}
asmlinkage int sys_sigreturn(void)
{
struct pt_regs *regs = current_pt_regs();
struct sigframe __user *frame = (struct sigframe *)rdusp();
sigset_t set;
/*
* Since we stacked the signal on a dword boundary,
* then frame should be dword aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (((long)frame) & 3)
goto badframe;
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;
set_current_blocked(&set);
if (restore_sigcontext(regs, &frame->sc))
goto badframe;
/* TODO: SIGTRAP when single-stepping as in arm ? */
return regs->r10;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int sys_rt_sigreturn(void)
{
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe __user *frame = (struct rt_sigframe *)rdusp();
sigset_t set;
/*
* Since we stacked the signal on a dword boundary,
* then frame should be dword aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (((long)frame) & 3)
goto badframe;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto badframe;
set_current_blocked(&set);
if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
if (restore_altstack(&frame->uc.uc_stack))
goto badframe;
return regs->r10;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
static int setup_sigcontext(struct sigcontext __user *sc,
struct pt_regs *regs, unsigned long mask)
{
int err = 0;
unsigned long usp = rdusp();
/* copy the regs. they are first in sc so we can use sc directly */
err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
/* Set the frametype to CRIS_FRAME_NORMAL for the execution of
the signal handler. The frametype will be restored to its previous
value in restore_sigcontext. */
regs->frametype = CRIS_FRAME_NORMAL;
/* then some other stuff */
err |= __put_user(mask, &sc->oldmask);
err |= __put_user(usp, &sc->usp);
return err;
}
/* Figure out where we want to put the new signal frame
* - usually on the stack. */
static inline void __user *
get_sigframe(struct ksignal *ksig, size_t frame_size)
{
unsigned long sp = sigsp(rdusp(), ksig);
/* make sure the frame is dword-aligned */
sp &= ~3;
return (void __user*)(sp - frame_size);
}
/* grab and setup a signal frame.
*
* basically we stack a lot of state info, and arrange for the
* user-mode program to return to the kernel using either a
* trampoline which performs the syscall sigreturn, or a provided
* user-mode trampoline.
*/
static int setup_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct sigframe __user *frame;
unsigned long return_ip;
int err = 0;
frame = get_sigframe(ksig, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
if (err)
return -EFAULT;
if (_NSIG_WORDS > 1) {
err |= __copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask));
}
if (err)
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
return_ip = (unsigned long)ksig->ka.sa.sa_restorer;
} else {
/* trampoline - the desired return ip is the retcode itself */
return_ip = (unsigned long)&frame->retcode;
/* This is movu.w __NR_sigreturn, r9; break 13; */
err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
}
if (err)
return -EFAULT;
/* Set up registers for signal handler */
regs->irp = (unsigned long) ksig->ka.sa.sa_handler; /* what we enter NOW */
regs->srp = return_ip; /* what we enter LATER */
regs->r10 = ksig->sig; /* first argument is signo */
/* actually move the usp to reflect the stacked frame */
wrusp((unsigned long)frame);
return 0;
}
static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
unsigned long return_ip;
int err = 0;
frame = get_sigframe(ksig, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
err |= __put_user(&frame->info, &frame->pinfo);
err |= __put_user(&frame->uc, &frame->puc);
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
if (err)
return -EFAULT;
/* Clear all the bits of the ucontext we don't use. */
err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
err |= __save_altstack(&frame->uc.uc_stack, rdusp());
if (err)
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
return_ip = (unsigned long)ksig->ka.sa.sa_restorer;
} else {
/* trampoline - the desired return ip is the retcode itself */
return_ip = (unsigned long)&frame->retcode;
/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
err |= __put_user(0x9c5f, (short __user *)(frame->retcode+0));
err |= __put_user(__NR_rt_sigreturn,
(short __user *)(frame->retcode+2));
err |= __put_user(0xe93d, (short __user *)(frame->retcode+4));
}
if (err)
return -EFAULT;
/* TODO what is the current->exec_domain stuff and invmap ? */
/* Set up registers for signal handler */
/* What we enter NOW */
regs->irp = (unsigned long) ksig->ka.sa.sa_handler;
/* What we enter LATER */
regs->srp = return_ip;
/* First argument is signo */
regs->r10 = ksig->sig;
/* Second argument is (siginfo_t *) */
regs->r11 = (unsigned long)&frame->info;
/* Third argument is unused */
regs->r12 = 0;
/* Actually move the usp to reflect the stacked frame */
wrusp((unsigned long)frame);
return 0;
}
/*
* OK, we're invoking a handler
*/
static inline void handle_signal(int canrestart, struct ksignal *ksig,
struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
int ret;
/* Are we from a system call? */
if (canrestart) {
/* If so, check system call restarting.. */
switch (regs->r10) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
/* ERESTARTNOHAND means that the syscall should
* only be restarted if there was no handler for
* the signal, and since we only get here if there
* is a handler, we don't restart */
regs->r10 = -EINTR;
break;
case -ERESTARTSYS:
/* ERESTARTSYS means to restart the syscall if
* there is no handler or the handler was
* registered with SA_RESTART */
if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
regs->r10 = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
/* ERESTARTNOINTR means that the syscall should
* be called again after the signal handler returns. */
RESTART_CRIS_SYS(regs);
}
}
/* Set up the stack frame */
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(ksig, oldset, regs);
else
ret = setup_frame(ksig, oldset, regs);
signal_setup_done(ret, ksig, 0);
}
/*
* 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.
*
* Also note that the regs structure given here as an argument, is the latest
* pushed pt_regs. It may or may not be the same as the first pushed registers
* when the initial usermode->kernelmode transition took place. Therefore
* we can use user_mode(regs) to see if we came directly from kernel or user
* mode below.
*/
void do_signal(int canrestart, struct pt_regs *regs)
{
struct ksignal ksig;
/*
* 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;
if (get_signal(&ksig)) {
/* Whee! Actually deliver the signal. */
handle_signal(canrestart, &ksig, regs);
return;
}
/* Did we come from a system call? */
if (canrestart) {
/* Restart the system call - no handlers present */
if (regs->r10 == -ERESTARTNOHAND ||
regs->r10 == -ERESTARTSYS ||
regs->r10 == -ERESTARTNOINTR) {
RESTART_CRIS_SYS(regs);
}
if (regs->r10 == -ERESTART_RESTARTBLOCK) {
regs->r9 = __NR_restart_syscall;
regs->irp -= 2;
}
}
/* if there's no signal to deliver, we just put the saved sigmask
* back */
restore_saved_sigmask();
}
