/*
* OpenRISC signal.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, 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/tracehook.h>
#include <asm/processor.h>
#include <asm/syscall.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#define DEBUG_SIG 0
struct rt_sigframe {
struct siginfo info;
struct ucontext uc;
unsigned char retcode[16]; /* trampoline code */
};
static int restore_sigcontext(struct pt_regs *regs,
struct sigcontext __user *sc)
{
int err = 0;
/* Always make any pending restarted system calls return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
/*
* Restore the regs from &sc->regs.
* (sc is already checked for VERIFY_READ since the sigframe was
* checked in sys_sigreturn previously)
*/
err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long));
err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long));
/* make sure the SM-bit is cleared so user-mode cannot fool us */
regs->sr &= ~SPR_SR_SM;
regs->orig_gpr11 = -1; /* Avoid syscall restart checks */
/* 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;
}
asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
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->gpr[11];
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
int err = 0;
/* copy the regs */
/* There should be no need to save callee-saved registers here...
* ...but we save them anyway. Revisit this
*/
err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long));
err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long));
return err;
}
static inline unsigned long align_sigframe(unsigned long sp)
{
return sp & ~3UL;
}
/*
* Work out where the signal frame should go. It's either on the user stack
* or the alternate stack.
*/
static inline void __user *get_sigframe(struct ksignal *ksig,
struct pt_regs *regs, size_t frame_size)
{
unsigned long sp = regs->sp;
/* redzone */
sp -= STACK_FRAME_OVERHEAD;
sp = sigsp(sp, ksig);
sp = align_sigframe(sp - frame_size);
return (void __user *)sp;
}
/* 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_rt_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct rt_sigframe *frame;
unsigned long return_ip;
int err = 0;
frame = get_sigframe(ksig, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
/* Create siginfo. */
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(NULL, &frame->uc.uc_link);
err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
/* trampoline - the desired return ip is the retcode itself */
return_ip = (unsigned long)&frame->retcode;
/* This is:
l.ori r11,r0,__NR_sigreturn
l.sys 1
*/
err |= __put_user(0xa960, (short *)(frame->retcode + 0));
err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
if (err)
return -EFAULT;
/* Set up registers for signal handler */
regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */
regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
/* actually move the usp to reflect the stacked frame */
regs->sp = (unsigned long)frame;
return 0;
}
static inline void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
int ret;
ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
}
/*
* 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.
*/
int do_signal(struct pt_regs *regs, int syscall)
{
struct ksignal ksig;
unsigned long continue_addr = 0;
unsigned long restart_addr = 0;
unsigned long retval = 0;
int restart = 0;
if (syscall) {
continue_addr = regs->pc;
restart_addr = continue_addr - 4;
retval = regs->gpr[11];
/*
* Setup syscall restart here so that a debugger will
* see the already changed PC.
*/
switch (retval) {
case -ERESTART_RESTARTBLOCK:
restart = -2;
/* Fall through */
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
restart++;
regs->gpr[11] = regs->orig_gpr11;
regs->pc = restart_addr;
break;
}
}
/*
* Get the signal to deliver. During the call to get_signal the
* debugger may change all our registers so we may need to revert
* the decision to restart the syscall; specifically, if the PC is
* changed, don't restart the syscall.
*/
if (get_signal(&ksig)) {
if (unlikely(restart) && regs->pc == restart_addr) {
if (retval == -ERESTARTNOHAND ||
retval == -ERESTART_RESTARTBLOCK
|| (retval == -ERESTARTSYS
&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
/* No automatic restart */
regs->gpr[11] = -EINTR;
regs->pc = continue_addr;
}
}
handle_signal(&ksig, regs);
} else {
/* no handler */
restore_saved_sigmask();
/*
* Restore pt_regs PC as syscall restart will be handled by
* kernel without return to userspace
*/
if (unlikely(restart) && regs->pc == restart_addr) {
regs->pc = continue_addr;
return restart;
}
}
return 0;
}
asmlinkage int
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
do {
if (likely(thread_flags & _TIF_NEED_RESCHED)) {
schedule();
} else {
if (unlikely(!user_mode(regs)))
return 0;
local_irq_enable();
if (thread_flags & _TIF_SIGPENDING) {
int restart = do_signal(regs, syscall);
if (unlikely(restart)) {
/*
* Restart without handlers.
* Deal with it without leaving
* the kernel space.
*/
return restart;
}
syscall = 0;
} else {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
}
local_irq_disable();
thread_flags = current_thread_info()->flags;
} while (thread_flags & _TIF_WORK_MASK);
return 0;
}