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321 lines
8.4 KiB
321 lines
8.4 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* OpenRISC signal.c |
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* |
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* Linux architectural port borrowing liberally from similar works of |
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* others. All original copyrights apply as per the original source |
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* declaration. |
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* |
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* Modifications for the OpenRISC architecture: |
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* Copyright (C) 2003 Matjaz Breskvar <[email protected]> |
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* Copyright (C) 2010-2011 Jonas Bonn <[email protected]> |
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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/smp.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/tracehook.h> |
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#include <asm/processor.h> |
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#include <asm/syscall.h> |
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#include <asm/ucontext.h> |
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#include <linux/uaccess.h> |
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#define DEBUG_SIG 0 |
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struct rt_sigframe { |
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struct siginfo info; |
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struct ucontext uc; |
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unsigned char retcode[16]; /* trampoline code */ |
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}; |
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static int restore_sigcontext(struct pt_regs *regs, |
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struct sigcontext __user *sc) |
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{ |
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int err = 0; |
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/* Always make any pending restarted system calls return -EINTR */ |
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current->restart_block.fn = do_no_restart_syscall; |
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/* |
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* Restore the regs from &sc->regs. |
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* (sc is already checked since the sigframe was |
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* checked in sys_sigreturn previously) |
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*/ |
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err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)); |
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err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long)); |
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err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long)); |
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/* make sure the SM-bit is cleared so user-mode cannot fool us */ |
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regs->sr &= ~SPR_SR_SM; |
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regs->orig_gpr11 = -1; /* Avoid syscall restart checks */ |
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/* TODO: the other ports use regs->orig_XX to disable syscall checks |
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* after this completes, but we don't use that mechanism. maybe we can |
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* use it now ? |
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*/ |
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return err; |
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} |
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asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) |
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{ |
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struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->sp; |
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sigset_t set; |
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/* |
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* Since we stacked the signal on a dword boundary, |
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* then frame should be dword aligned here. If it's |
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* not, then the user is trying to mess with us. |
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*/ |
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if (((unsigned long)frame) & 3) |
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goto badframe; |
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if (!access_ok(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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return regs->gpr[11]; |
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badframe: |
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force_sig(SIGSEGV); |
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return 0; |
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} |
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/* |
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* Set up a signal frame. |
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*/ |
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static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) |
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{ |
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int err = 0; |
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/* copy the regs */ |
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/* There should be no need to save callee-saved registers here... |
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* ...but we save them anyway. Revisit this |
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*/ |
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err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); |
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err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); |
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err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); |
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return err; |
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} |
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static inline unsigned long align_sigframe(unsigned long sp) |
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{ |
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return sp & ~3UL; |
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} |
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/* |
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* Work out where the signal frame should go. It's either on the user stack |
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* or the alternate stack. |
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*/ |
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static inline void __user *get_sigframe(struct ksignal *ksig, |
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struct pt_regs *regs, size_t frame_size) |
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{ |
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unsigned long sp = regs->sp; |
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/* redzone */ |
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sp -= STACK_FRAME_OVERHEAD; |
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sp = sigsp(sp, ksig); |
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sp = align_sigframe(sp - frame_size); |
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return (void __user *)sp; |
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} |
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/* grab and setup a signal frame. |
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* |
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* basically we stack a lot of state info, and arrange for the |
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* user-mode program to return to the kernel using either a |
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* trampoline which performs the syscall sigreturn, or a provided |
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* user-mode trampoline. |
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*/ |
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static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, |
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struct pt_regs *regs) |
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{ |
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struct rt_sigframe __user *frame; |
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unsigned long return_ip; |
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int err = 0; |
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frame = get_sigframe(ksig, regs, sizeof(*frame)); |
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if (!access_ok(frame, sizeof(*frame))) |
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return -EFAULT; |
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/* Create siginfo. */ |
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if (ksig->ka.sa.sa_flags & SA_SIGINFO) |
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err |= copy_siginfo_to_user(&frame->info, &ksig->info); |
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/* Create the ucontext. */ |
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err |= __put_user(0, &frame->uc.uc_flags); |
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err |= __put_user(NULL, &frame->uc.uc_link); |
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err |= __save_altstack(&frame->uc.uc_stack, regs->sp); |
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err |= setup_sigcontext(regs, &frame->uc.uc_mcontext); |
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); |
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if (err) |
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return -EFAULT; |
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/* trampoline - the desired return ip is the retcode itself */ |
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return_ip = (unsigned long)&frame->retcode; |
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/* This is: |
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l.ori r11,r0,__NR_sigreturn |
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l.sys 1 |
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*/ |
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err |= __put_user(0xa960, (short __user *)(frame->retcode + 0)); |
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err |= __put_user(__NR_rt_sigreturn, (short __user *)(frame->retcode + 2)); |
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err |= __put_user(0x20000001, (unsigned long __user *)(frame->retcode + 4)); |
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err |= __put_user(0x15000000, (unsigned long __user *)(frame->retcode + 8)); |
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if (err) |
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return -EFAULT; |
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/* Set up registers for signal handler */ |
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regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */ |
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regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ |
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regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */ |
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regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ |
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regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ |
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/* actually move the usp to reflect the stacked frame */ |
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regs->sp = (unsigned long)frame; |
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return 0; |
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} |
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static inline void |
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handle_signal(struct ksignal *ksig, struct pt_regs *regs) |
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{ |
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int ret; |
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ret = setup_rt_frame(ksig, sigmask_to_save(), regs); |
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signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); |
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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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int do_signal(struct pt_regs *regs, int syscall) |
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{ |
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struct ksignal ksig; |
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unsigned long continue_addr = 0; |
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unsigned long restart_addr = 0; |
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unsigned long retval = 0; |
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int restart = 0; |
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if (syscall) { |
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continue_addr = regs->pc; |
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restart_addr = continue_addr - 4; |
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retval = regs->gpr[11]; |
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/* |
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* Setup syscall restart here so that a debugger will |
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* see the already changed PC. |
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*/ |
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switch (retval) { |
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case -ERESTART_RESTARTBLOCK: |
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restart = -2; |
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fallthrough; |
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case -ERESTARTNOHAND: |
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case -ERESTARTSYS: |
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case -ERESTARTNOINTR: |
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restart++; |
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regs->gpr[11] = regs->orig_gpr11; |
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regs->pc = restart_addr; |
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break; |
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} |
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} |
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/* |
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* Get the signal to deliver. During the call to get_signal the |
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* debugger may change all our registers so we may need to revert |
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* the decision to restart the syscall; specifically, if the PC is |
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* changed, don't restart the syscall. |
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*/ |
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if (get_signal(&ksig)) { |
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if (unlikely(restart) && regs->pc == restart_addr) { |
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if (retval == -ERESTARTNOHAND || |
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retval == -ERESTART_RESTARTBLOCK |
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|| (retval == -ERESTARTSYS |
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&& !(ksig.ka.sa.sa_flags & SA_RESTART))) { |
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/* No automatic restart */ |
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regs->gpr[11] = -EINTR; |
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regs->pc = continue_addr; |
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} |
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} |
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handle_signal(&ksig, regs); |
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} else { |
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/* no handler */ |
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restore_saved_sigmask(); |
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/* |
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* Restore pt_regs PC as syscall restart will be handled by |
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* kernel without return to userspace |
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*/ |
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if (unlikely(restart) && regs->pc == restart_addr) { |
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regs->pc = continue_addr; |
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return restart; |
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} |
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} |
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return 0; |
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} |
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asmlinkage int |
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do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) |
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{ |
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do { |
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if (likely(thread_flags & _TIF_NEED_RESCHED)) { |
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schedule(); |
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} else { |
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if (unlikely(!user_mode(regs))) |
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return 0; |
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local_irq_enable(); |
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if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) { |
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int restart = do_signal(regs, syscall); |
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if (unlikely(restart)) { |
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/* |
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* Restart without handlers. |
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* Deal with it without leaving |
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* the kernel space. |
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*/ |
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return restart; |
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} |
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syscall = 0; |
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} else { |
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tracehook_notify_resume(regs); |
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} |
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} |
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local_irq_disable(); |
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thread_flags = current_thread_info()->flags; |
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} while (thread_flags & _TIF_WORK_MASK); |
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return 0; |
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}
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