From 262d96b0deb44ed58823447825d6efa5dddb4108 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 9 Oct 2012 10:54:27 +0100 Subject: [PATCH] metag: Signal handling Add signal handling code for metag. Signed-off-by: James Hogan Cc: Al Viro --- arch/metag/include/uapi/asm/sigcontext.h | 31 ++ arch/metag/include/uapi/asm/siginfo.h | 8 + arch/metag/kernel/signal.c | 344 +++++++++++++++++++++++ 3 files changed, 383 insertions(+) create mode 100644 arch/metag/include/uapi/asm/sigcontext.h create mode 100644 arch/metag/include/uapi/asm/siginfo.h create mode 100644 arch/metag/kernel/signal.c diff --git a/arch/metag/include/uapi/asm/sigcontext.h b/arch/metag/include/uapi/asm/sigcontext.h new file mode 100644 index 000000000000..ef79a910c1c4 --- /dev/null +++ b/arch/metag/include/uapi/asm/sigcontext.h @@ -0,0 +1,31 @@ +#ifndef _ASM_METAG_SIGCONTEXT_H +#define _ASM_METAG_SIGCONTEXT_H + +#include + +/* + * In a sigcontext structure we need to store the active state of the + * user process so that it does not get trashed when we call the signal + * handler. That not really the same as a user context that we are + * going to store on syscall etc. + */ +struct sigcontext { + struct user_gp_regs regs; /* needs to be first */ + + /* + * Catch registers describing a memory fault. + * If USER_GP_REGS_STATUS_CATCH_BIT is set in regs.status then catch + * buffers have been saved and will be replayed on sigreturn. + * Clear that bit to discard the catch state instead of replaying it. + */ + struct user_cb_regs cb; + + /* + * Read pipeline state. This will get restored on sigreturn. + */ + struct user_rp_state rp; + + unsigned long oldmask; +}; + +#endif diff --git a/arch/metag/include/uapi/asm/siginfo.h b/arch/metag/include/uapi/asm/siginfo.h new file mode 100644 index 000000000000..b2e0c8b62aef --- /dev/null +++ b/arch/metag/include/uapi/asm/siginfo.h @@ -0,0 +1,8 @@ +#ifndef _METAG_SIGINFO_H +#define _METAG_SIGINFO_H + +#define __ARCH_SI_TRAPNO + +#include + +#endif diff --git a/arch/metag/kernel/signal.c b/arch/metag/kernel/signal.c new file mode 100644 index 000000000000..3be61cf0b147 --- /dev/null +++ b/arch/metag/kernel/signal.c @@ -0,0 +1,344 @@ +/* + * Copyright (C) 1991,1992 Linus Torvalds + * Copyright (C) 2005-2012 Imagination Technologies Ltd. + * + * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#define REG_FLAGS ctx.SaveMask +#define REG_RETVAL ctx.DX[0].U0 +#define REG_SYSCALL ctx.DX[0].U1 +#define REG_SP ctx.AX[0].U0 +#define REG_ARG1 ctx.DX[3].U1 +#define REG_ARG2 ctx.DX[3].U0 +#define REG_ARG3 ctx.DX[2].U1 +#define REG_PC ctx.CurrPC +#define REG_RTP ctx.DX[4].U1 + +struct rt_sigframe { + struct siginfo info; + struct ucontext uc; + unsigned long retcode[2]; +}; + +static int restore_sigcontext(struct pt_regs *regs, + struct sigcontext __user *sc) +{ + int err; + + /* Always make any pending restarted system calls return -EINTR */ + current_thread_info()->restart_block.fn = do_no_restart_syscall; + + err = metag_gp_regs_copyin(regs, 0, sizeof(struct user_gp_regs), NULL, + &sc->regs); + if (!err) + err = metag_cb_regs_copyin(regs, 0, + sizeof(struct user_cb_regs), NULL, + &sc->cb); + if (!err) + err = metag_rp_state_copyin(regs, 0, + sizeof(struct user_rp_state), NULL, + &sc->rp); + + /* This is a user-mode context. */ + regs->REG_FLAGS |= TBICTX_PRIV_BIT; + + return err; +} + +long sys_rt_sigreturn(void) +{ + /* NOTE - Meta stack goes UPWARDS - so we wind the stack back */ + struct pt_regs *regs = current_pt_regs(); + struct rt_sigframe __user *frame; + sigset_t set; + + frame = (__force struct rt_sigframe __user *)(regs->REG_SP - + sizeof(*frame)); + + 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->REG_RETVAL; + +badframe: + force_sig(SIGSEGV, current); + + return 0; +} + +static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, + unsigned long mask) +{ + int err; + + err = metag_gp_regs_copyout(regs, 0, sizeof(struct user_gp_regs), NULL, + &sc->regs); + + if (!err) + err = metag_cb_regs_copyout(regs, 0, + sizeof(struct user_cb_regs), NULL, + &sc->cb); + if (!err) + err = metag_rp_state_copyout(regs, 0, + sizeof(struct user_rp_state), NULL, + &sc->rp); + + /* OK, clear that cbuf flag in the old context, or our stored + * catch buffer will be restored when we go to call the signal + * handler. Also clear out the CBRP RA/RD pipe bit incase + * that is pending as well! + * Note that as we have already stored this context, these + * flags will get restored on sigreturn to their original + * state. + */ + regs->REG_FLAGS &= ~(TBICTX_XCBF_BIT | TBICTX_CBUF_BIT | + TBICTX_CBRP_BIT); + + /* Clear out the LSM_STEP bits in case we are in the middle of + * and MSET/MGET. + */ + regs->ctx.Flags &= ~TXSTATUS_LSM_STEP_BITS; + + err |= __put_user(mask, &sc->oldmask); + + return err; +} + +/* + * Determine which stack to use.. + */ +static void __user *get_sigframe(struct k_sigaction *ka, unsigned long sp, + size_t frame_size) +{ + /* Meta stacks grows upwards */ + if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0)) + sp = current->sas_ss_sp; + + sp = (sp + 7) & ~7; /* 8byte align stack */ + + return (void __user *)sp; +} + +static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, + sigset_t *set, struct pt_regs *regs) +{ + struct rt_sigframe __user *frame; + int err = -EFAULT; + unsigned long code; + + frame = get_sigframe(ka, regs->REG_SP, sizeof(*frame)); + if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) + goto out; + + err = copy_siginfo_to_user(&frame->info, info); + + /* Create the ucontext. */ + err |= __put_user(0, &frame->uc.uc_flags); + err |= __put_user(0, (unsigned long __user *)&frame->uc.uc_link); + err |= __save_altstack(&frame->uc.uc_stack, regs->REG_SP); + 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 out; + + /* Set up to return from userspace. */ + + /* MOV D1Re0 (D1.0), #__NR_rt_sigreturn */ + code = 0x03000004 | (__NR_rt_sigreturn << 3); + err |= __put_user(code, (unsigned long __user *)(&frame->retcode[0])); + + /* SWITCH #__METAG_SW_SYS */ + code = __METAG_SW_ENCODING(SYS); + err |= __put_user(code, (unsigned long __user *)(&frame->retcode[1])); + + if (err) + goto out; + + /* Set up registers for signal handler */ + regs->REG_RTP = (unsigned long) frame->retcode; + regs->REG_SP = (unsigned long) frame + sizeof(*frame); + regs->REG_ARG1 = sig; + regs->REG_ARG2 = (unsigned long) &frame->info; + regs->REG_ARG3 = (unsigned long) &frame->uc; + regs->REG_PC = (unsigned long) ka->sa.sa_handler; + + pr_debug("SIG deliver (%s:%d): sp=%p pc=%08x pr=%08x\n", + current->comm, current->pid, frame, regs->REG_PC, + regs->REG_RTP); + + /* Now pass size of 'new code' into sigtramp so we can do a more + * effective cache flush - directed rather than 'full flush'. + */ + flush_cache_sigtramp(regs->REG_RTP, sizeof(frame->retcode)); +out: + if (err) { + force_sigsegv(sig, current); + return -EFAULT; + } + return 0; +} + +static void handle_signal(unsigned long sig, siginfo_t *info, + struct k_sigaction *ka, struct pt_regs *regs) +{ + sigset_t *oldset = sigmask_to_save(); + + /* Set up the stack frame */ + if (setup_rt_frame(sig, ka, info, oldset, regs)) + return; + + signal_delivered(sig, info, ka, regs, test_thread_flag(TIF_SINGLESTEP)); +} + + /* + * Notes for Meta. + * We have moved from the old 2.4.9 SH way of using syscall_nr (in the stored + * context) to passing in the syscall flag on the stack. + * This is because having syscall_nr in our context does not fit with TBX, and + * corrupted the stack. + */ +static int do_signal(struct pt_regs *regs, int syscall) +{ + unsigned int retval = 0, continue_addr = 0, restart_addr = 0; + struct k_sigaction ka; + siginfo_t info; + int signr; + int restart = 0; + + /* + * By the end of rt_sigreturn the context describes the point that the + * signal was taken (which may happen to be just before a syscall if + * it's already been restarted). This should *never* be mistaken for a + * system call in need of restarting. + */ + if (syscall == __NR_rt_sigreturn) + syscall = -1; + + /* Did we come from a system call? */ + if (syscall >= 0) { + continue_addr = regs->REG_PC; + restart_addr = continue_addr - 4; + retval = regs->REG_RETVAL; + + /* + * Prepare for system call restart. We do this here so that a + * debugger will see the already changed PC. + */ + switch (retval) { + case -ERESTART_RESTARTBLOCK: + restart = -2; + case -ERESTARTNOHAND: + case -ERESTARTSYS: + case -ERESTARTNOINTR: + ++restart; + regs->REG_PC = restart_addr; + break; + } + } + + /* + * Get the signal to deliver. When running under ptrace, at this point + * the debugger may change all our registers ... + */ + signr = get_signal_to_deliver(&info, &ka, regs, NULL); + /* + * Depending on the signal settings we may need to revert the decision + * to restart the system call. But skip this if a debugger has chosen to + * restart at a different PC. + */ + if (regs->REG_PC != restart_addr) + restart = 0; + if (signr > 0) { + if (unlikely(restart)) { + if (retval == -ERESTARTNOHAND + || retval == -ERESTART_RESTARTBLOCK + || (retval == -ERESTARTSYS + && !(ka.sa.sa_flags & SA_RESTART))) { + regs->REG_RETVAL = -EINTR; + regs->REG_PC = continue_addr; + } + } + + /* Whee! Actually deliver the signal. */ + handle_signal(signr, &info, &ka, regs); + return 0; + } + + /* Handlerless -ERESTART_RESTARTBLOCK re-enters via restart_syscall */ + if (unlikely(restart < 0)) + regs->REG_SYSCALL = __NR_restart_syscall; + + /* + * If there's no signal to deliver, we just put the saved sigmask back. + */ + restore_saved_sigmask(); + + return restart; +} + +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 = -1; + } 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; +} -- 2.30.2