347 lines
8.6 KiB
C
347 lines
8.6 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
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* Chen Liqin <liqin.chen@sunplusct.com>
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* Lennox Wu <lennox.wu@sunplusct.com>
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* Copyright (C) 2012 Regents of the University of California
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*/
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#include <linux/compat.h>
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#include <linux/signal.h>
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#include <linux/uaccess.h>
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#include <linux/syscalls.h>
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#include <linux/resume_user_mode.h>
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#include <linux/linkage.h>
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#include <asm/ucontext.h>
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#include <asm/vdso.h>
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#include <asm/signal.h>
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#include <asm/signal32.h>
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#include <asm/switch_to.h>
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#include <asm/csr.h>
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#include <asm/cacheflush.h>
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extern u32 __user_rt_sigreturn[2];
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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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#ifndef CONFIG_MMU
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u32 sigreturn_code[2];
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#endif
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};
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#ifdef CONFIG_FPU
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static long restore_fp_state(struct pt_regs *regs,
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union __riscv_fp_state __user *sc_fpregs)
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{
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long err;
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struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
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size_t i;
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err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state));
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if (unlikely(err))
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return err;
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fstate_restore(current, regs);
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/* We support no other extension state at this time. */
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for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
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u32 value;
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err = __get_user(value, &sc_fpregs->q.reserved[i]);
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if (unlikely(err))
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break;
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if (value != 0)
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return -EINVAL;
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}
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return err;
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}
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static long save_fp_state(struct pt_regs *regs,
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union __riscv_fp_state __user *sc_fpregs)
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{
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long err;
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struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
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size_t i;
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fstate_save(current, regs);
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err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state));
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if (unlikely(err))
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return err;
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/* We support no other extension state at this time. */
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for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
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err = __put_user(0, &sc_fpregs->q.reserved[i]);
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if (unlikely(err))
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break;
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}
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return err;
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}
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#else
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#define save_fp_state(task, regs) (0)
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#define restore_fp_state(task, regs) (0)
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#endif
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static long restore_sigcontext(struct pt_regs *regs,
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struct sigcontext __user *sc)
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{
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long err;
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/* sc_regs is structured the same as the start of pt_regs */
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err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
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/* Restore the floating-point state. */
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if (has_fpu())
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err |= restore_fp_state(regs, &sc->sc_fpregs);
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return err;
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}
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SYSCALL_DEFINE0(rt_sigreturn)
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{
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struct pt_regs *regs = current_pt_regs();
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struct rt_sigframe __user *frame;
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struct task_struct *task;
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sigset_t set;
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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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frame = (struct rt_sigframe __user *)regs->sp;
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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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regs->cause = -1UL;
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return regs->a0;
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badframe:
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task = current;
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if (show_unhandled_signals) {
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pr_info_ratelimited(
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"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
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task->comm, task_pid_nr(task), __func__,
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frame, (void *)regs->epc, (void *)regs->sp);
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}
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force_sig(SIGSEGV);
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return 0;
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}
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static long setup_sigcontext(struct rt_sigframe __user *frame,
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struct pt_regs *regs)
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{
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struct sigcontext __user *sc = &frame->uc.uc_mcontext;
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long err;
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/* sc_regs is structured the same as the start of pt_regs */
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err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
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/* Save the floating-point state. */
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if (has_fpu())
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err |= save_fp_state(regs, &sc->sc_fpregs);
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return err;
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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 framesize)
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{
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unsigned long sp;
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/* Default to using normal stack */
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sp = regs->sp;
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/*
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* If we are on the alternate signal stack and would overflow it, don't.
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* Return an always-bogus address instead so we will die with SIGSEGV.
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*/
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if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
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return (void __user __force *)(-1UL);
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/* This is the X/Open sanctioned signal stack switching. */
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sp = sigsp(sp, ksig) - framesize;
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/* Align the stack frame. */
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sp &= ~0xfUL;
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return (void __user *)sp;
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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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long err = 0;
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unsigned long __maybe_unused addr;
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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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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(frame, regs);
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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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/* Set up to return from userspace. */
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#ifdef CONFIG_MMU
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regs->ra = (unsigned long)VDSO_SYMBOL(
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current->mm->context.vdso, rt_sigreturn);
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#else
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/*
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* For the nommu case we don't have a VDSO. Instead we push two
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* instructions to call the rt_sigreturn syscall onto the user stack.
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*/
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if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
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sizeof(frame->sigreturn_code)))
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return -EFAULT;
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addr = (unsigned long)&frame->sigreturn_code;
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/* Make sure the two instructions are pushed to icache. */
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flush_icache_range(addr, addr + sizeof(frame->sigreturn_code));
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regs->ra = addr;
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#endif /* CONFIG_MMU */
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/*
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* Set up registers for signal handler.
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* Registers that we don't modify keep the value they had from
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* user-space at the time we took the signal.
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* We always pass siginfo and mcontext, regardless of SA_SIGINFO,
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* since some things rely on this (e.g. glibc's debug/segfault.c).
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*/
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regs->epc = (unsigned long)ksig->ka.sa.sa_handler;
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regs->sp = (unsigned long)frame;
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regs->a0 = ksig->sig; /* a0: signal number */
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regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
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regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */
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#if DEBUG_SIG
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pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
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current->comm, task_pid_nr(current), ksig->sig,
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(void *)regs->epc, (void *)regs->ra, frame);
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#endif
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return 0;
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}
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static void handle_signal(struct ksignal *ksig, 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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/* Are we from a system call? */
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if (regs->cause == EXC_SYSCALL) {
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/* Avoid additional syscall restarting via ret_from_exception */
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regs->cause = -1UL;
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/* If so, check system call restarting.. */
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switch (regs->a0) {
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case -ERESTART_RESTARTBLOCK:
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case -ERESTARTNOHAND:
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regs->a0 = -EINTR;
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break;
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case -ERESTARTSYS:
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if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
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regs->a0 = -EINTR;
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break;
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}
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fallthrough;
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case -ERESTARTNOINTR:
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regs->a0 = regs->orig_a0;
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regs->epc -= 0x4;
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break;
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}
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}
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rseq_signal_deliver(ksig, regs);
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/* Set up the stack frame */
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if (is_compat_task())
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ret = compat_setup_rt_frame(ksig, oldset, regs);
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else
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ret = setup_rt_frame(ksig, oldset, regs);
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signal_setup_done(ret, ksig, 0);
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}
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static void do_signal(struct pt_regs *regs)
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{
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struct ksignal ksig;
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if (get_signal(&ksig)) {
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/* Actually deliver the signal */
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handle_signal(&ksig, regs);
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return;
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}
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/* Did we come from a system call? */
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if (regs->cause == EXC_SYSCALL) {
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/* Avoid additional syscall restarting via ret_from_exception */
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regs->cause = -1UL;
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/* Restart the system call - no handlers present */
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switch (regs->a0) {
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case -ERESTARTNOHAND:
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case -ERESTARTSYS:
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case -ERESTARTNOINTR:
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regs->a0 = regs->orig_a0;
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regs->epc -= 0x4;
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break;
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case -ERESTART_RESTARTBLOCK:
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regs->a0 = regs->orig_a0;
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regs->a7 = __NR_restart_syscall;
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regs->epc -= 0x4;
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break;
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}
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}
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/*
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* If there is no signal to deliver, we just put the saved
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* sigmask back.
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*/
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restore_saved_sigmask();
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}
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/*
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* Handle any pending work on the resume-to-userspace path, as indicated by
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* _TIF_WORK_MASK. Entered from assembly with IRQs off.
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*/
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asmlinkage __visible void do_work_pending(struct pt_regs *regs,
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unsigned long thread_info_flags)
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{
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do {
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if (thread_info_flags & _TIF_NEED_RESCHED) {
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schedule();
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} else {
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local_irq_enable();
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if (thread_info_flags & _TIF_UPROBE)
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uprobe_notify_resume(regs);
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/* Handle pending signal delivery */
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if (thread_info_flags & (_TIF_SIGPENDING |
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_TIF_NOTIFY_SIGNAL))
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do_signal(regs);
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if (thread_info_flags & _TIF_NOTIFY_RESUME)
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resume_user_mode_work(regs);
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}
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local_irq_disable();
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thread_info_flags = read_thread_flags();
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} while (thread_info_flags & _TIF_WORK_MASK);
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}
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