563 lines
14 KiB
C
563 lines
14 KiB
C
/*
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* Copyright (C) 2003, Axis Communications AB.
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*/
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/wait.h>
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#include <linux/ptrace.h>
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#include <linux/unistd.h>
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#include <linux/stddef.h>
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#include <linux/syscalls.h>
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#include <linux/vmalloc.h>
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#include <asm/io.h>
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#include <asm/processor.h>
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#include <asm/ucontext.h>
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#include <asm/uaccess.h>
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#include <arch/ptrace.h>
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#include <arch/hwregs/cpu_vect.h>
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extern unsigned long cris_signal_return_page;
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/*
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* A syscall in CRIS is really a "break 13" instruction, which is 2
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* bytes. The registers is manipulated so upon return the instruction
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* will be executed again.
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*
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* This relies on that PC points to the instruction after the break call.
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*/
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#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;
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/* Signal frames. */
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struct signal_frame {
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struct sigcontext sc;
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unsigned long extramask[_NSIG_WORDS - 1];
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unsigned char retcode[8]; /* Trampoline code. */
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};
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struct rt_signal_frame {
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struct siginfo *pinfo;
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void *puc;
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struct siginfo info;
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struct ucontext uc;
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unsigned char retcode[8]; /* Trampoline code. */
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};
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void do_signal(int restart, struct pt_regs *regs);
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void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
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struct pt_regs *regs);
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static int
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restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
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{
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unsigned int err = 0;
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unsigned long old_usp;
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/* Always make any pending restarted system calls return -EINTR */
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current_thread_info()->restart_block.fn = do_no_restart_syscall;
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/*
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* Restore the registers from &sc->regs. sc is already checked
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* for VERIFY_READ since the signal_frame was previously
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* checked in sys_sigreturn().
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*/
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if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
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goto badframe;
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/* Make that the user-mode flag is set. */
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regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));
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/* Restore the old USP. */
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err |= __get_user(old_usp, &sc->usp);
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wrusp(old_usp);
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return err;
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badframe:
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return 1;
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}
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asmlinkage int sys_sigreturn(void)
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{
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struct pt_regs *regs = current_pt_regs();
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sigset_t set;
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struct signal_frame __user *frame;
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unsigned long oldspc = regs->spc;
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unsigned long oldccs = regs->ccs;
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frame = (struct signal_frame *) rdusp();
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/*
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* Since the signal is stacked on a dword boundary, the frame
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* should be dword aligned here as well. It it's not, then the
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* user is trying some funny business.
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*/
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if (((long)frame) & 3)
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goto badframe;
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__get_user(set.sig[0], &frame->sc.oldmask) ||
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(_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
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frame->extramask,
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sizeof(frame->extramask))))
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goto badframe;
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set_current_blocked(&set);
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if (restore_sigcontext(regs, &frame->sc))
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goto badframe;
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keep_debug_flags(oldccs, oldspc, regs);
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return regs->r10;
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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asmlinkage int sys_rt_sigreturn(void)
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{
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struct pt_regs *regs = current_pt_regs();
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sigset_t set;
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struct rt_signal_frame __user *frame;
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unsigned long oldspc = regs->spc;
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unsigned long oldccs = regs->ccs;
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frame = (struct rt_signal_frame *) rdusp();
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/*
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* Since the signal is stacked on a dword boundary, the frame
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* should be dword aligned here as well. It it's not, then the
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* user is trying some funny business.
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*/
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if (((long)frame) & 3)
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goto badframe;
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
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goto badframe;
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set_current_blocked(&set);
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if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
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goto badframe;
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if (restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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keep_debug_flags(oldccs, oldspc, regs);
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return regs->r10;
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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/* Setup a signal frame. */
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static int
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setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
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unsigned long mask)
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{
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int err;
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unsigned long usp;
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err = 0;
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usp = rdusp();
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/*
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* Copy the registers. They are located first in sc, so it's
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* possible to use sc directly.
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*/
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err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
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err |= __put_user(mask, &sc->oldmask);
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err |= __put_user(usp, &sc->usp);
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return err;
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}
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/* Figure out where to put the new signal frame - usually on the stack. */
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static inline void __user *
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get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
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{
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unsigned long sp;
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sp = rdusp();
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/* This is the X/Open sanctioned signal stack switching. */
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if (ka->sa.sa_flags & SA_ONSTACK) {
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if (!on_sig_stack(sp))
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sp = current->sas_ss_sp + current->sas_ss_size;
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}
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/* Make sure the frame is dword-aligned. */
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sp &= ~3;
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return (void __user *)(sp - frame_size);
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}
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/* Grab and setup a signal frame.
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*
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* Basically a lot of state-info is stacked, and arranged for the
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* user-mode program to return to the kernel using either a trampiline
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* which performs the syscall sigreturn(), or a provided user-mode
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* trampoline.
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*/
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static int
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setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
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struct pt_regs * regs)
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{
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int err;
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unsigned long return_ip;
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struct signal_frame __user *frame;
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err = 0;
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frame = get_sigframe(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
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goto give_sigsegv;
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err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
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if (err)
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goto give_sigsegv;
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if (_NSIG_WORDS > 1) {
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err |= __copy_to_user(frame->extramask, &set->sig[1],
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sizeof(frame->extramask));
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}
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if (err)
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goto give_sigsegv;
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/*
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* Set up to return from user-space. If provided, use a stub
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* already located in user-space.
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*/
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if (ka->sa.sa_flags & SA_RESTORER) {
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return_ip = (unsigned long)ka->sa.sa_restorer;
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} else {
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/* Trampoline - the desired return ip is in the signal return page. */
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return_ip = cris_signal_return_page;
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/*
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* This is movu.w __NR_sigreturn, r9; break 13;
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*
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* WE DO NOT USE IT ANY MORE! It's only left here for historical
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* reasons and because gdb uses it as a signature to notice
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* signal handler stack frames.
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*/
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err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
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err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
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err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
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}
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if (err)
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goto give_sigsegv;
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/*
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* Set up registers for signal handler.
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*
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* Where the code enters now.
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* Where the code enter later.
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* First argument, signo.
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*/
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regs->erp = (unsigned long) ka->sa.sa_handler;
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regs->srp = return_ip;
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regs->r10 = sig;
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/* Actually move the USP to reflect the stacked frame. */
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wrusp((unsigned long)frame);
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return 0;
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give_sigsegv:
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force_sigsegv(sig, current);
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return -EFAULT;
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}
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static int
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setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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sigset_t *set, struct pt_regs * regs)
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{
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int err;
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unsigned long return_ip;
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struct rt_signal_frame __user *frame;
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err = 0;
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frame = get_sigframe(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
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goto give_sigsegv;
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/* TODO: what is the current->exec_domain stuff and invmap ? */
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err |= __put_user(&frame->info, &frame->pinfo);
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err |= __put_user(&frame->uc, &frame->puc);
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err |= copy_siginfo_to_user(&frame->info, info);
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if (err)
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goto give_sigsegv;
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/* Clear all the bits of the ucontext we don't use. */
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err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
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err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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err |= __save_altstack(&frame->uc.uc_stack, rdusp());
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if (err)
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goto give_sigsegv;
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/*
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* Set up to return from user-space. If provided, use a stub
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* already located in user-space.
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*/
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if (ka->sa.sa_flags & SA_RESTORER) {
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return_ip = (unsigned long) ka->sa.sa_restorer;
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} else {
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/* Trampoline - the desired return ip is in the signal return page. */
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return_ip = cris_signal_return_page + 6;
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/*
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* This is movu.w __NR_rt_sigreturn, r9; break 13;
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*
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* WE DO NOT USE IT ANY MORE! It's only left here for historical
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* reasons and because gdb uses it as a signature to notice
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* signal handler stack frames.
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*/
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err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
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err |= __put_user(__NR_rt_sigreturn,
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(short __user*)(frame->retcode+2));
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err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
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}
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if (err)
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goto give_sigsegv;
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/*
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* Set up registers for signal handler.
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*
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* Where the code enters now.
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* Where the code enters later.
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* First argument is signo.
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* Second argument is (siginfo_t *).
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* Third argument is unused.
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*/
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regs->erp = (unsigned long) ka->sa.sa_handler;
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regs->srp = return_ip;
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regs->r10 = sig;
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regs->r11 = (unsigned long) &frame->info;
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regs->r12 = 0;
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/* Actually move the usp to reflect the stacked frame. */
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wrusp((unsigned long)frame);
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return 0;
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give_sigsegv:
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force_sigsegv(sig, current);
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return -EFAULT;
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}
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/* Invoke a signal handler to, well, handle the signal. */
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static inline void
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handle_signal(int canrestart, unsigned long sig,
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siginfo_t *info, struct k_sigaction *ka,
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struct pt_regs * regs)
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{
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sigset_t *oldset = sigmask_to_save();
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int ret;
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/* Check if this got called from a system call. */
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if (canrestart) {
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/* If so, check system call restarting. */
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switch (regs->r10) {
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case -ERESTART_RESTARTBLOCK:
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case -ERESTARTNOHAND:
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/*
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* This means that the syscall should
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* only be restarted if there was no
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* handler for the signal, and since
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* this point isn't reached unless
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* there is a handler, there's no need
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* to restart.
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*/
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regs->r10 = -EINTR;
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break;
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case -ERESTARTSYS:
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/*
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* This means restart the syscall if
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* there is no handler, or the handler
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* was registered with SA_RESTART.
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*/
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if (!(ka->sa.sa_flags & SA_RESTART)) {
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regs->r10 = -EINTR;
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break;
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}
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/* Fall through. */
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case -ERESTARTNOINTR:
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/*
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* This means that the syscall should
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* be called again after the signal
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* handler returns.
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*/
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RESTART_CRIS_SYS(regs);
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break;
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}
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}
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/* Set up the stack frame. */
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if (ka->sa.sa_flags & SA_SIGINFO)
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ret = setup_rt_frame(sig, ka, info, oldset, regs);
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else
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ret = setup_frame(sig, ka, oldset, regs);
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if (ret == 0)
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signal_delivered(sig, info, ka, regs, 0);
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}
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/*
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* Note that 'init' is a special process: it doesn't get signals it doesn't
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* want to handle. Thus you cannot kill init even with a SIGKILL even by
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* mistake.
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*
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* Also note that the regs structure given here as an argument, is the latest
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* pushed pt_regs. It may or may not be the same as the first pushed registers
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* when the initial usermode->kernelmode transition took place. Therefore
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* we can use user_mode(regs) to see if we came directly from kernel or user
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* mode below.
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*/
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void
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do_signal(int canrestart, struct pt_regs *regs)
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{
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int signr;
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siginfo_t info;
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struct k_sigaction ka;
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/*
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* The common case should go fast, which is why this point is
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* reached from kernel-mode. If that's the case, just return
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* without doing anything.
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*/
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if (!user_mode(regs))
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return;
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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if (signr > 0) {
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/* Whee! Actually deliver the signal. */
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handle_signal(canrestart, signr, &info, &ka, regs);
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return;
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}
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/* Got here from a system call? */
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if (canrestart) {
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/* Restart the system call - no handlers present. */
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if (regs->r10 == -ERESTARTNOHAND ||
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regs->r10 == -ERESTARTSYS ||
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regs->r10 == -ERESTARTNOINTR) {
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RESTART_CRIS_SYS(regs);
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}
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if (regs->r10 == -ERESTART_RESTARTBLOCK){
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regs->r9 = __NR_restart_syscall;
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regs->erp -= 2;
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}
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}
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/* if there's no signal to deliver, we just put the saved sigmask
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* back */
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restore_saved_sigmask();
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}
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asmlinkage void
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ugdb_trap_user(struct thread_info *ti, int sig)
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{
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if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
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/* Zero single-step PC if the reason we stopped wasn't a single
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step exception. This is to avoid relying on it when it isn't
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reliable. */
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user_regs(ti)->spc = 0;
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}
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/* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
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not within any configured h/w breakpoint range). Synchronize with
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what already exists for kernel debugging. */
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if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
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/* Break 8: subtract 2 from ERP unless in a delay slot. */
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if (!(user_regs(ti)->erp & 0x1))
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user_regs(ti)->erp -= 2;
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}
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sys_kill(ti->task->pid, sig);
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}
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void
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keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
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struct pt_regs *regs)
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{
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if (oldccs & (1 << Q_CCS_BITNR)) {
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/* Pending single step due to single-stepping the break 13
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in the signal trampoline: keep the Q flag. */
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regs->ccs |= (1 << Q_CCS_BITNR);
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/* S flag should be set - complain if it's not. */
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if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
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printk("Q flag but no S flag?");
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}
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regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
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/* Assume the SPC is valid and interesting. */
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regs->spc = oldspc;
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} else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
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/* If a h/w bp was set in the signal handler we need
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to keep the S flag. */
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regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
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/* Don't keep the old SPC though; if we got here due to
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a single-step, the Q flag should have been set. */
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} else if (regs->spc) {
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/* If we were single-stepping *before* the signal was taken,
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we don't want to restore that state now, because GDB will
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have forgotten all about it. */
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regs->spc = 0;
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|
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);
|