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Diffstat (limited to '')
-rw-r--r-- | arch/openrisc/kernel/signal.c | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/signal.c b/arch/openrisc/kernel/signal.c new file mode 100644 index 000000000..80f69740c --- /dev/null +++ b/arch/openrisc/kernel/signal.c @@ -0,0 +1,319 @@ +// 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/resume_user_mode.h> + +#include <asm/processor.h> +#include <asm/syscall.h> +#include <asm/ucontext.h> +#include <linux/uaccess.h> + +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 { + resume_user_mode_work(regs); + } + } + local_irq_disable(); + thread_flags = read_thread_flags(); + } while (thread_flags & _TIF_WORK_MASK); + return 0; +} |