// SPDX-License-Identifier: GPL-2.0-or-later /* * 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> */ #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 <linux/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 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 __user *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 (((unsigned long)frame) & 3) goto badframe; if (!access_ok(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); 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 __user *frame; unsigned long return_ip; int err = 0; frame = get_sigframe(ksig, regs, sizeof(*frame)); if (!access_ok(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 __user *)(frame->retcode + 0)); err |= __put_user(__NR_rt_sigreturn, (short __user *)(frame->retcode + 2)); err |= __put_user(0x20000001, (unsigned long __user *)(frame->retcode + 4)); err |= __put_user(0x15000000, (unsigned long __user *)(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; fallthrough; 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|_TIF_NOTIFY_SIGNAL)) { 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 { tracehook_notify_resume(regs); } } local_irq_disable(); thread_flags = current_thread_info()->flags; } while (thread_flags & _TIF_WORK_MASK); return 0; }