From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/cris/arch-v32/kernel/signal.c | 540 +++++++++++++++++++++++++++++++++++++ 1 file changed, 540 insertions(+) create mode 100644 arch/cris/arch-v32/kernel/signal.c (limited to 'arch/cris/arch-v32/kernel/signal.c') diff --git a/arch/cris/arch-v32/kernel/signal.c b/arch/cris/arch-v32/kernel/signal.c new file mode 100644 index 000000000..3a36ae6b7 --- /dev/null +++ b/arch/cris/arch-v32/kernel/signal.c @@ -0,0 +1,540 @@ +/* + * Copyright (C) 2003, Axis Communications AB. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +extern unsigned long cris_signal_return_page; + +/* + * A syscall in CRIS is really a "break 13" instruction, which is 2 + * bytes. The registers is manipulated so upon return the instruction + * will be executed again. + * + * This relies on that PC points to the instruction after the break call. + */ +#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2; + +/* Signal frames. */ +struct signal_frame { + struct sigcontext sc; + unsigned long extramask[_NSIG_WORDS - 1]; + unsigned char retcode[8]; /* Trampoline code. */ +}; + +struct rt_signal_frame { + struct siginfo *pinfo; + void *puc; + struct siginfo info; + struct ucontext uc; + unsigned char retcode[8]; /* Trampoline code. */ +}; + +void do_signal(int restart, struct pt_regs *regs); +void keep_debug_flags(unsigned long oldccs, unsigned long oldspc, + struct pt_regs *regs); + +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->restart_block.fn = do_no_restart_syscall; + + /* + * Restore the registers from &sc->regs. sc is already checked + * for VERIFY_READ since the signal_frame was previously + * checked in sys_sigreturn(). + */ + if (__copy_from_user(regs, sc, sizeof(struct pt_regs))) + goto badframe; + + /* Make that the user-mode flag is set. */ + regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT)); + + /* Don't perform syscall restarting */ + regs->exs = -1; + + /* Restore the old USP. */ + err |= __get_user(old_usp, &sc->usp); + wrusp(old_usp); + + return err; + +badframe: + return 1; +} + +asmlinkage int sys_sigreturn(void) +{ + struct pt_regs *regs = current_pt_regs(); + sigset_t set; + struct signal_frame __user *frame; + unsigned long oldspc = regs->spc; + unsigned long oldccs = regs->ccs; + + frame = (struct signal_frame *) rdusp(); + + /* + * Since the signal is stacked on a dword boundary, the frame + * should be dword aligned here as well. It it's not, then the + * user is trying some funny business. + */ + 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; + + keep_debug_flags(oldccs, oldspc, regs); + + return regs->r10; + +badframe: + force_sig(SIGSEGV, current); + return 0; +} + +asmlinkage int sys_rt_sigreturn(void) +{ + struct pt_regs *regs = current_pt_regs(); + sigset_t set; + struct rt_signal_frame __user *frame; + unsigned long oldspc = regs->spc; + unsigned long oldccs = regs->ccs; + + frame = (struct rt_signal_frame *) rdusp(); + + /* + * Since the signal is stacked on a dword boundary, the frame + * should be dword aligned here as well. It it's not, then the + * user is trying some funny business. + */ + 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; + + keep_debug_flags(oldccs, oldspc, regs); + + return regs->r10; + +badframe: + force_sig(SIGSEGV, current); + return 0; +} + +/* Setup a signal frame. */ +static int +setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, + unsigned long mask) +{ + int err; + unsigned long usp; + + err = 0; + usp = rdusp(); + + /* + * Copy the registers. They are located first in sc, so it's + * possible to use sc directly. + */ + err |= __copy_to_user(sc, regs, sizeof(struct pt_regs)); + + err |= __put_user(mask, &sc->oldmask); + err |= __put_user(usp, &sc->usp); + + return err; +} + +/* Figure out where 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 a lot of state-info is stacked, and arranged for the + * user-mode program to return to the kernel using either a trampiline + * 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) +{ + int err; + unsigned long return_ip; + struct signal_frame __user *frame; + + 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 user-space. If provided, use a stub + * already located in user-space. + */ + if (ksig->ka.sa.sa_flags & SA_RESTORER) { + return_ip = (unsigned long)ksig->ka.sa.sa_restorer; + } else { + /* Trampoline - the desired return ip is in the signal return page. */ + return_ip = cris_signal_return_page; + + /* + * This is movu.w __NR_sigreturn, r9; break 13; + * + * WE DO NOT USE IT ANY MORE! It's only left here for historical + * reasons and because gdb uses it as a signature to notice + * signal handler stack frames. + */ + 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. + * + * Where the code enters now. + * Where the code enter later. + * First argument, signo. + */ + regs->erp = (unsigned long) ksig->ka.sa.sa_handler; + regs->srp = return_ip; + regs->r10 = ksig->sig; + + /* 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) +{ + int err; + unsigned long return_ip; + struct rt_signal_frame __user *frame; + + 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 user-space. If provided, use a stub + * already located in user-space. + */ + if (ksig->ka.sa.sa_flags & SA_RESTORER) { + return_ip = (unsigned long) ksig->ka.sa.sa_restorer; + } else { + /* Trampoline - the desired return ip is in the signal return page. */ + return_ip = cris_signal_return_page + 6; + + /* + * This is movu.w __NR_rt_sigreturn, r9; break 13; + * + * WE DO NOT USE IT ANY MORE! It's only left here for historical + * reasons and because gdb uses it as a signature to notice + * signal handler stack frames. + */ + 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; + + /* + * Set up registers for signal handler. + * + * Where the code enters now. + * Where the code enters later. + * First argument is signo. + * Second argument is (siginfo_t *). + * Third argument is unused. + */ + regs->erp = (unsigned long) ksig->ka.sa.sa_handler; + regs->srp = return_ip; + regs->r10 = ksig->sig; + regs->r11 = (unsigned long) &frame->info; + regs->r12 = 0; + + /* Actually move the usp to reflect the stacked frame. */ + wrusp((unsigned long)frame); + + return 0; +} + +/* Invoke a signal handler to, well, handle the signal. */ +static inline void +handle_signal(int canrestart, struct ksignal *ksig, struct pt_regs *regs) +{ + sigset_t *oldset = sigmask_to_save(); + int ret; + + /* Check if this got called from a system call. */ + if (canrestart) { + /* If so, check system call restarting. */ + switch (regs->r10) { + case -ERESTART_RESTARTBLOCK: + case -ERESTARTNOHAND: + /* + * This means that the syscall should + * only be restarted if there was no + * handler for the signal, and since + * this point isn't reached unless + * there is a handler, there's no need + * to restart. + */ + regs->r10 = -EINTR; + break; + + case -ERESTARTSYS: + /* + * This means 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; + } + + /* Fall through. */ + + case -ERESTARTNOINTR: + /* + * This means that the syscall should + * be called again after the signal + * handler returns. + */ + RESTART_CRIS_SYS(regs); + break; + } + } + + /* 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; + + canrestart = canrestart && ((int)regs->exs >= 0); + + /* + * The common case should go fast, which is why this point is + * reached from kernel-mode. If that's the case, just return + * without doing anything. + */ + if (!user_mode(regs)) + return; + + if (get_signal(&ksig)) { + /* Whee! Actually deliver the signal. */ + handle_signal(canrestart, &ksig, regs); + return; + } + + /* Got here 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->erp -= 2; + } + } + + /* if there's no signal to deliver, we just put the saved sigmask + * back */ + restore_saved_sigmask(); +} + +asmlinkage void +ugdb_trap_user(struct thread_info *ti, int sig) +{ + if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) { + /* Zero single-step PC if the reason we stopped wasn't a single + step exception. This is to avoid relying on it when it isn't + reliable. */ + user_regs(ti)->spc = 0; + } + /* FIXME: Filter out false h/w breakpoint hits (i.e. EDA + not within any configured h/w breakpoint range). Synchronize with + what already exists for kernel debugging. */ + if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) { + /* Break 8: subtract 2 from ERP unless in a delay slot. */ + if (!(user_regs(ti)->erp & 0x1)) + user_regs(ti)->erp -= 2; + } + sys_kill(ti->task->pid, sig); +} + +void +keep_debug_flags(unsigned long oldccs, unsigned long oldspc, + struct pt_regs *regs) +{ + if (oldccs & (1 << Q_CCS_BITNR)) { + /* Pending single step due to single-stepping the break 13 + in the signal trampoline: keep the Q flag. */ + regs->ccs |= (1 << Q_CCS_BITNR); + /* S flag should be set - complain if it's not. */ + if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) { + printk("Q flag but no S flag?"); + } + regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT)); + /* Assume the SPC is valid and interesting. */ + regs->spc = oldspc; + + } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) { + /* If a h/w bp was set in the signal handler we need + to keep the S flag. */ + regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT)); + /* Don't keep the old SPC though; if we got here due to + a single-step, the Q flag should have been set. */ + } else if (regs->spc) { + /* If we were single-stepping *before* the signal was taken, + we don't want to restore that state now, because GDB will + have forgotten all about it. */ + regs->spc = 0; + regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT)); + } +} + +/* Set up the trampolines on the signal return page. */ +int __init +cris_init_signal(void) +{ + u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL); + + /* This is movu.w __NR_sigreturn, r9; break 13; */ + data[0] = 0x9c5f; + data[1] = __NR_sigreturn; + data[2] = 0xe93d; + /* This is movu.w __NR_rt_sigreturn, r9; break 13; */ + data[3] = 0x9c5f; + data[4] = __NR_rt_sigreturn; + data[5] = 0xe93d; + + /* Map to userspace with appropriate permissions (no write access...) */ + cris_signal_return_page = (unsigned long) + __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE); + + return 0; +} + +__initcall(cris_init_signal); -- cgit v1.2.3-54-g00ecf