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OpenRISC: Signal handling 

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Jonas Bonn 2011-06-04 21:38:59 +03:00
parent 61e85e3675
commit ac689eb7f9
2 changed files with 434 additions and 0 deletions
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38
arch/openrisc/include/asm/sigcontext.h Normal file
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/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* 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.
*/
#ifndef __ASM_OPENRISC_SIGCONTEXT_H
#define __ASM_OPENRISC_SIGCONTEXT_H
#include <asm/ptrace.h>
/* This struct is saved by setup_frame in signal.c, to keep the current
context while a signal handler is executed. It's restored by sys_sigreturn.
To keep things simple, we use pt_regs here even though normally you just
specify the list of regs to save. Then we can use copy_from_user on the
entire regs instead of a bunch of get_user's as well...
*/
struct sigcontext {
struct pt_regs regs; /* needs to be first */
unsigned long oldmask;
unsigned long usp; /* usp before stacking this gunk on it */
};
#endif /* __ASM_OPENRISC_SIGCONTEXT_H */

396
arch/openrisc/kernel/signal.c Normal file
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/*
* 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/ucontext.h>
#include <asm/uaccess.h>
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
asmlinkage long
_sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs)
{
return do_sigaltstack(uss, uoss, regs->sp);
}
struct rt_sigframe {
struct siginfo *pinfo;
void *puc;
struct siginfo info;
struct ucontext uc;
unsigned char retcode[16]; /* trampoline code */
};
static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
{
unsigned int err = 0;
unsigned long old_usp;
/* Alwys make any pending restarted system call 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 SM-bit is cleared so user-mode cannot fool us */
regs->sr &= ~SPR_SR_SM;
/* 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);
regs->sp = 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 long _sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
sigset_t set;
stack_t st;
/*
* 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;
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))
goto badframe;
if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
goto badframe;
/* It is more difficult to avoid calling this function than to
call it and ignore errors. */
do_sigaltstack(&st, NULL, regs->sp);
return regs->gpr[11];
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
unsigned long mask)
{
int err = 0;
unsigned long usp = regs->sp;
/* copy the regs. they are first in sc so we can use sc directly */
err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
/* then some other stuff */
err |= __put_user(mask, &sc->oldmask);
err |= __put_user(usp, &sc->usp);
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 k_sigaction *ka,
struct pt_regs *regs, size_t frame_size)
{
unsigned long sp = regs->sp;
int onsigstack = on_sig_stack(sp);
/* redzone */
sp -= STACK_FRAME_OVERHEAD;
/* This is the X/Open sanctioned signal stack switching. */
if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) {
if (current->sas_ss_size)
sp = current->sas_ss_sp + current->sas_ss_size;
}
sp = align_sigframe(sp - frame_size);
/*
* If we are on the alternate signal stack and would overflow it, don't.
* Return an always-bogus address instead so we will die with SIGSEGV.
*/
if (onsigstack && !likely(on_sig_stack(sp)))
return (void __user *)-1L;
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 void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe *frame;
unsigned long return_ip;
int err = 0;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
err |= __put_user(&frame->info, &frame->pinfo);
err |= __put_user(&frame->uc, &frame->puc);
if (ka->sa.sa_flags & SA_SIGINFO)
err |= copy_siginfo_to_user(&frame->info, info);
if (err)
goto give_sigsegv;
/* Clear all the bits of the ucontext we don't use. */
err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(NULL, &frame->uc.uc_link);
err |= __put_user((void *)current->sas_ss_sp,
&frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags);
err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
goto give_sigsegv;
/* 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)
goto give_sigsegv;
/* TODO what is the current->exec_domain stuff and invmap ? */
/* Set up registers for signal handler */
regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */
regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
regs->gpr[3] = (unsigned long)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;
give_sigsegv:
if (sig == SIGSEGV)
ka->sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}
static inline void
handle_signal(unsigned long sig,
siginfo_t *info, struct k_sigaction *ka,
sigset_t *oldset, struct pt_regs *regs)
{
setup_rt_frame(sig, ka, info, oldset, regs);
if (ka->sa.sa_flags & SA_ONESHOT)
ka->sa.sa_handler = SIG_DFL;
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);
}
/*
* 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(struct pt_regs *regs)
{
siginfo_t info;
int signr;
struct k_sigaction ka;
/*
* 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;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
/* If we are coming out of a syscall then we need
* to check if the syscall was interrupted and wants to be
* restarted after handling the signal. If so, the original
* syscall number is put back into r11 and the PC rewound to
* point at the l.sys instruction that resulted in the
* original syscall. Syscall results other than the four
* below mean that the syscall executed to completion and no
* restart is necessary.
*/
if (regs->syscallno) {
int restart = 0;
switch (regs->gpr[11]) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
/* Restart if there is no signal handler */
restart = (signr <= 0);
break;
case -ERESTARTSYS:
/* Restart if there no signal handler or
* SA_RESTART flag is set */
restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART));
break;
case -ERESTARTNOINTR:
/* Always restart */
restart = 1;
break;
}
if (restart) {
if (regs->gpr[11] == -ERESTART_RESTARTBLOCK)
regs->gpr[11] = __NR_restart_syscall;
else
regs->gpr[11] = regs->orig_gpr11;
regs->pc -= 4;
} else {
regs->gpr[11] = -EINTR;
}
}
if (signr <= 0) {
/* no signal to deliver so 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);
}
} else { /* signr > 0 */
sigset_t *oldset;
if (current_thread_info()->flags & _TIF_RESTORE_SIGMASK)
oldset = &current->saved_sigmask;
else
oldset = &current->blocked;
/* Whee! Actually deliver the signal. */
handle_signal(signr, &info, &ka, oldset, regs);
/* 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;
}
asmlinkage void do_notify_resume(struct pt_regs *regs)
{
if (current_thread_info()->flags & _TIF_SIGPENDING)
do_signal(regs);
if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
if (current->replacement_session_keyring)
key_replace_session_keyring();
}
}