Message-ID: <CAK8P3a1cCU-42EdtRUQMcGM36yppgZG8LsPGimd9X=+4PRmE4w@mail.gmail.com>
Date:   Fri, 17 Sep 2021 10:26:53 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Huacai Chen <chenhuacai@...ngson.cn>
Cc:     Arnd Bergmann <arnd@...db.de>, Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Airlie <airlied@...ux.ie>,
        Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Yanteng Si <siyanteng@...ngson.cn>,
        Huacai Chen <chenhuacai@...il.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH V3 14/22] LoongArch: Add signal handling support

On Fri, Sep 17, 2021 at 5:57 AM Huacai Chen <chenhuacai@...ngson.cn> wrote:
>
> This patch adds signal handling support for LoongArch.
>
> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> ---
>  arch/loongarch/include/asm/abi.h             |  27 ++
>  arch/loongarch/include/uapi/asm/sigcontext.h |  40 ++
>  arch/loongarch/include/uapi/asm/ucontext.h   |  35 ++
>  arch/loongarch/kernel/signal-common.h        |  38 ++
>  arch/loongarch/kernel/signal.c               | 467 +++++++++++++++++++

Please add Eric Biederman and Al Viro as reviewers to Cc. I have no
further comments
below, but a full quote for them as reference.

       Arnd

> diff --git a/arch/loongarch/include/asm/abi.h b/arch/loongarch/include/asm/abi.h
> new file mode 100644
> index 000000000000..ced8534db4df
> --- /dev/null
> +++ b/arch/loongarch/include/asm/abi.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
> + */
> +#ifndef _ASM_ABI_H
> +#define _ASM_ABI_H
> +
> +#include <linux/signal_types.h>
> +
> +#include <asm/signal.h>
> +#include <asm/siginfo.h>
> +#include <asm/vdso.h>
> +
> +struct loongarch_abi {
> +       const unsigned long     restart;
> +       const int               audit_arch;
> +
> +       unsigned int off_sc_fpregs;
> +       unsigned int off_sc_fcc;
> +       unsigned int off_sc_fcsr;
> +       unsigned int off_sc_vcsr;
> +       unsigned int off_sc_flags;
> +
> +       struct loongarch_vdso_info *vdso;
> +};
> +
> +#endif /* _ASM_ABI_H */
> diff --git a/arch/loongarch/include/uapi/asm/sigcontext.h b/arch/loongarch/include/uapi/asm/sigcontext.h
> new file mode 100644
> index 000000000000..da0e5bac2d80
> --- /dev/null
> +++ b/arch/loongarch/include/uapi/asm/sigcontext.h
> @@ -0,0 +1,40 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/*
> + * Author: Hanlu Li <lihanlu@...ngson.cn>
> + *         Huacai Chen <chenhuacai@...ngson.cn>
> + *
> + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
> + */
> +#ifndef _UAPI_ASM_SIGCONTEXT_H
> +#define _UAPI_ASM_SIGCONTEXT_H
> +
> +#include <linux/types.h>
> +#include <asm/processor.h>
> +
> +/* scalar FP context was used */
> +#define USED_FP                        (1 << 0)
> +
> +/* extended context was used, see struct extcontext for details */
> +#define USED_EXTCONTEXT                (1 << 1)
> +
> +#include <linux/posix_types.h>
> +/*
> + * Keep this struct definition in sync with the sigcontext fragment
> + * in arch/loongarch/kernel/asm-offsets.c
> + *
> + */
> +struct sigcontext {
> +       __u64   sc_pc;
> +       __u64   sc_regs[32];
> +       __u32   sc_flags;
> +
> +       __u32   sc_fcsr;
> +       __u32   sc_vcsr;
> +       __u64   sc_fcc;
> +       __u64   sc_scr[4];
> +
> +       union fpureg sc_fpregs[32] FPU_ALIGN;
> +       __u8    sc_reserved[4096] __attribute__((__aligned__(16)));
> +};
> +
> +#endif /* _UAPI_ASM_SIGCONTEXT_H */
> diff --git a/arch/loongarch/include/uapi/asm/ucontext.h b/arch/loongarch/include/uapi/asm/ucontext.h
> new file mode 100644
> index 000000000000..12577e22b1c7
> --- /dev/null
> +++ b/arch/loongarch/include/uapi/asm/ucontext.h
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +#ifndef __LOONGARCH_UAPI_ASM_UCONTEXT_H
> +#define __LOONGARCH_UAPI_ASM_UCONTEXT_H
> +
> +/**
> + * struct ucontext - user context structure
> + * @uc_flags:
> + * @uc_link:
> + * @uc_stack:
> + * @uc_mcontext:       holds basic processor state
> + * @uc_sigmask:
> + * @uc_extcontext:     holds extended processor state
> + */
> +struct ucontext {
> +       unsigned long           uc_flags;
> +       struct ucontext         *uc_link;
> +       stack_t                 uc_stack;
> +       sigset_t                uc_sigmask;
> +       /* There's some padding here to allow sigset_t to be expanded in the
> +        * future.  Though this is unlikely, other architectures put uc_sigmask
> +        * at the end of this structure and explicitly state it can be
> +        * expanded, so we didn't want to box ourselves in here. */
> +       __u8              __unused[1024 / 8 - sizeof(sigset_t)];
> +       /* We can't put uc_sigmask at the end of this structure because we need
> +        * to be able to expand sigcontext in the future.  For example, the
> +        * vector ISA extension will almost certainly add ISA state.  We want
> +        * to ensure all user-visible ISA state can be saved and restored via a
> +        * ucontext, so we're putting this at the end in order to allow for
> +        * infinite extensibility.  Since we know this will be extended and we
> +        * assume sigset_t won't be extended an extreme amount, we're
> +        * prioritizing this. */
> +       struct sigcontext       uc_mcontext;
> +};
> +
> +#endif /* __LOONGARCH_UAPI_ASM_UCONTEXT_H */
> diff --git a/arch/loongarch/kernel/signal-common.h b/arch/loongarch/kernel/signal-common.h
> new file mode 100644
> index 000000000000..1693fbdedeaa
> --- /dev/null
> +++ b/arch/loongarch/kernel/signal-common.h
> @@ -0,0 +1,38 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Author: Hanlu Li <lihanlu@...ngson.cn>
> + *         Huacai Chen <chenhuacai@...ngson.cn>
> + *
> + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef __SIGNAL_COMMON_H
> +#define __SIGNAL_COMMON_H
> +
> +/* #define DEBUG_SIG */
> +
> +#ifdef DEBUG_SIG
> +#  define DEBUGP(fmt, args...) printk("%s: " fmt, __func__, ##args)
> +#else
> +#  define DEBUGP(fmt, args...)
> +#endif
> +
> +/*
> + * Determine which stack to use..
> + */
> +extern void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
> +                                size_t frame_size);
> +/* Check and clear pending FPU exceptions in saved CSR */
> +extern int fpcsr_pending(unsigned int __user *fpcsr);
> +
> +/* Make sure we will not lose FPU ownership */
> +#define lock_fpu_owner()       ({ preempt_disable(); pagefault_disable(); })
> +#define unlock_fpu_owner()     ({ pagefault_enable(); preempt_enable(); })
> +
> +/* Assembly functions to move context to/from the FPU */
> +extern asmlinkage int
> +_save_fp_context(void __user *fpregs, void __user *fcc, void __user *csr);
> +extern asmlinkage int
> +_restore_fp_context(void __user *fpregs, void __user *fcc, void __user *csr);
> +
> +#endif /* __SIGNAL_COMMON_H */
> diff --git a/arch/loongarch/kernel/signal.c b/arch/loongarch/kernel/signal.c
> new file mode 100644
> index 000000000000..78319d2575c6
> --- /dev/null
> +++ b/arch/loongarch/kernel/signal.c
> @@ -0,0 +1,467 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Author: Hanlu Li <lihanlu@...ngson.cn>
> + *         Huacai Chen <chenhuacai@...ngson.cn>
> + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
> + *
> + * Derived from MIPS:
> + * Copyright (C) 1991, 1992  Linus Torvalds
> + * Copyright (C) 1994 - 2000  Ralf Baechle
> + * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
> + * Copyright (C) 2014, Imagination Technologies Ltd.
> + */
> +#include <linux/audit.h>
> +#include <linux/cache.h>
> +#include <linux/context_tracking.h>
> +#include <linux/irqflags.h>
> +#include <linux/sched.h>
> +#include <linux/mm.h>
> +#include <linux/personality.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/uprobes.h>
> +#include <linux/compiler.h>
> +#include <linux/syscalls.h>
> +#include <linux/uaccess.h>
> +#include <linux/tracehook.h>
> +
> +#include <asm/abi.h>
> +#include <asm/asm.h>
> +#include <asm/cacheflush.h>
> +#include <asm/fpu.h>
> +#include <asm/ucontext.h>
> +#include <asm/cpu-features.h>
> +
> +#include "signal-common.h"
> +
> +static int (*save_fp_context)(void __user *sc);
> +static int (*restore_fp_context)(void __user *sc);
> +
> +struct rt_sigframe {
> +       struct siginfo rs_info;
> +       struct ucontext rs_uctx;
> +};
> +
> +/*
> + * Thread saved context copy to/from a signal context presumed to be on the
> + * user stack, and therefore accessed with appropriate macros from uaccess.h.
> + */
> +static int copy_fp_to_sigcontext(void __user *sc)
> +{
> +       struct loongarch_abi *abi = current->thread.abi;
> +       uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
> +       uint64_t __user *fcc = sc + abi->off_sc_fcc;
> +       uint32_t __user *csr = sc + abi->off_sc_fcsr;
> +       int i;
> +       int err = 0;
> +       int inc = 1;
> +
> +       for (i = 0; i < NUM_FPU_REGS; i += inc) {
> +               err |=
> +                   __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
> +                              &fpregs[4*i]);
> +       }
> +       err |= __put_user(current->thread.fpu.fcsr, csr);
> +       err |= __put_user(current->thread.fpu.fcc, fcc);
> +
> +       return err;
> +}
> +
> +static int copy_fp_from_sigcontext(void __user *sc)
> +{
> +       struct loongarch_abi *abi = current->thread.abi;
> +       uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
> +       uint64_t __user *fcc = sc + abi->off_sc_fcc;
> +       uint32_t __user *csr = sc + abi->off_sc_fcsr;
> +       int i;
> +       int err = 0;
> +       int inc = 1;
> +       u64 fpr_val;
> +
> +       for (i = 0; i < NUM_FPU_REGS; i += inc) {
> +               err |= __get_user(fpr_val, &fpregs[4*i]);
> +               set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
> +       }
> +       err |= __get_user(current->thread.fpu.fcsr, csr);
> +       err |= __get_user(current->thread.fpu.fcc, fcc);
> +
> +       return err;
> +}
> +
> +/*
> + * Wrappers for the assembly _{save,restore}_fp_context functions.
> + */
> +static int save_hw_fp_context(void __user *sc)
> +{
> +       struct loongarch_abi *abi = current->thread.abi;
> +       uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
> +       uint64_t __user *fcc = sc + abi->off_sc_fcc;
> +       uint32_t __user *fcsr = sc + abi->off_sc_fcsr;
> +
> +       return _save_fp_context(fpregs, fcc, fcsr);
> +}
> +
> +static int restore_hw_fp_context(void __user *sc)
> +{
> +       struct loongarch_abi *abi = current->thread.abi;
> +       uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
> +       uint64_t __user *fcc = sc + abi->off_sc_fcc;
> +       uint32_t __user *csr = sc + abi->off_sc_fcsr;
> +
> +       return _restore_fp_context(fpregs, fcc, csr);
> +}
> +
> +/*
> + * Helper routines
> + */
> +static int protected_save_fp_context(void __user *sc)
> +{
> +       int err = 0;
> +       unsigned int used;
> +       struct loongarch_abi *abi = current->thread.abi;
> +       uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
> +       uint32_t __user *fcc = sc + abi->off_sc_fcsr;
> +       uint32_t __user *fcsr = sc + abi->off_sc_fcsr;
> +       uint32_t __user *vcsr = sc + abi->off_sc_vcsr;
> +       uint32_t __user *flags = sc + abi->off_sc_flags;
> +
> +       used = used_math() ? USED_FP : 0;
> +       if (!used)
> +               goto fp_done;
> +
> +       while (1) {
> +               lock_fpu_owner();
> +               if (is_fpu_owner())
> +                       err = save_fp_context(sc);
> +               else
> +                       err |= copy_fp_to_sigcontext(sc);
> +               unlock_fpu_owner();
> +               if (likely(!err))
> +                       break;
> +               /* touch the sigcontext and try again */
> +               err = __put_user(0, &fpregs[0]) |
> +                       __put_user(0, &fpregs[32*4 - 1]) |
> +                       __put_user(0, fcc) |
> +                       __put_user(0, fcsr) |
> +                       __put_user(0, vcsr);
> +               if (err)
> +                       return err;     /* really bad sigcontext */
> +       }
> +
> +fp_done:
> +       return __put_user(used, flags);
> +}
> +
> +static int protected_restore_fp_context(void __user *sc)
> +{
> +       unsigned int used;
> +       int err = 0, sig = 0, tmp __maybe_unused;
> +       struct loongarch_abi *abi = current->thread.abi;
> +       uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
> +       uint32_t __user *fcsr = sc + abi->off_sc_fcsr;
> +       uint32_t __user *fcc = sc + abi->off_sc_fcsr;
> +       uint32_t __user *vcsr = sc + abi->off_sc_vcsr;
> +       uint32_t __user *flags = sc + abi->off_sc_flags;
> +
> +       err = __get_user(used, flags);
> +       conditional_used_math(used & USED_FP);
> +
> +       /*
> +        * The signal handler may have used FPU; give it up if the program
> +        * doesn't want it following sigreturn.
> +        */
> +       if (err || !(used & USED_FP))
> +               lose_fpu(0);
> +
> +       if (err)
> +               return err;
> +
> +       if (!(used & USED_FP))
> +               goto fp_done;
> +
> +       err = sig = fpcsr_pending(fcsr);
> +       if (err < 0)
> +               return err;
> +
> +       while (1) {
> +               lock_fpu_owner();
> +               if (is_fpu_owner())
> +                       err = restore_fp_context(sc);
> +               else
> +                       err |= copy_fp_from_sigcontext(sc);
> +               unlock_fpu_owner();
> +               if (likely(!err))
> +                       break;
> +               /* touch the sigcontext and try again */
> +               err = __get_user(tmp, &fpregs[0]) |
> +                       __get_user(tmp, &fpregs[32*4 - 1]) |
> +                       __get_user(tmp, fcc) |
> +                       __get_user(tmp, fcsr) |
> +                       __get_user(tmp, vcsr);
> +               if (err)
> +                       break;  /* really bad sigcontext */
> +       }
> +
> +fp_done:
> +       return err ?: sig;
> +}
> +
> +static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
> +{
> +       int err = 0;
> +       int i;
> +
> +       err |= __put_user(regs->csr_epc, &sc->sc_pc);
> +
> +       err |= __put_user(0, &sc->sc_regs[0]);
> +       for (i = 1; i < 32; i++)
> +               err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
> +
> +       /*
> +        * Save FPU state to signal context. Signal handler
> +        * will "inherit" current FPU state.
> +        */
> +       err |= protected_save_fp_context(sc);
> +
> +       return err;
> +}
> +
> +int fpcsr_pending(unsigned int __user *fpcsr)
> +{
> +       int err, sig = 0;
> +       unsigned int csr, enabled;
> +
> +       err = __get_user(csr, fpcsr);
> +       enabled = ((csr & FPU_CSR_ALL_E) << 24);
> +       /*
> +        * If the signal handler set some FPU exceptions, clear it and
> +        * send SIGFPE.
> +        */
> +       if (csr & enabled) {
> +               csr &= ~enabled;
> +               err |= __put_user(csr, fpcsr);
> +               sig = SIGFPE;
> +       }
> +       return err ?: sig;
> +}
> +
> +static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
> +{
> +       int err = 0;
> +       int i;
> +
> +       /* Always make any pending restarted system calls return -EINTR */
> +       current->restart_block.fn = do_no_restart_syscall;
> +
> +       err |= __get_user(regs->csr_epc, &sc->sc_pc);
> +
> +       for (i = 1; i < 32; i++)
> +               err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
> +
> +       return err ?: protected_restore_fp_context(sc);
> +}
> +
> +void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
> +                         size_t frame_size)
> +{
> +       unsigned long sp;
> +
> +       /* Default to using normal stack */
> +       sp = regs->regs[3];
> +       sp -= 32;   /* Reserve 32-bytes. */
> +
> +       sp = sigsp(sp, ksig);
> +
> +       return (void __user *)((sp - frame_size) & ALMASK);
> +}
> +
> +/*
> + * Atomically swap in the new signal mask, and wait for a signal.
> + */
> +
> +asmlinkage long sys_rt_sigreturn(void)
> +{
> +       struct rt_sigframe __user *frame;
> +       struct pt_regs *regs;
> +       sigset_t set;
> +       int sig;
> +
> +       regs = current_pt_regs();
> +       frame = (struct rt_sigframe __user *)regs->regs[3];
> +       if (!access_ok(frame, sizeof(*frame)))
> +               goto badframe;
> +       if (__copy_from_user(&set, &frame->rs_uctx.uc_sigmask, sizeof(set)))
> +               goto badframe;
> +
> +       set_current_blocked(&set);
> +
> +       sig = restore_sigcontext(regs, &frame->rs_uctx.uc_mcontext);
> +       if (sig < 0)
> +               goto badframe;
> +       else if (sig)
> +               force_sig(sig);
> +
> +       if (restore_altstack(&frame->rs_uctx.uc_stack))
> +               goto badframe;
> +
> +       return regs->regs[4];
> +
> +badframe:
> +       force_sig(SIGSEGV);
> +       return 0;
> +}
> +
> +static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
> +                         struct pt_regs *regs, sigset_t *set)
> +{
> +       struct rt_sigframe __user *frame;
> +       int err = 0;
> +
> +       frame = get_sigframe(ksig, regs, sizeof(*frame));
> +       if (!access_ok(frame, sizeof(*frame)))
> +               return -EFAULT;
> +
> +       /* Create siginfo.  */
> +       err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
> +
> +       /* Create the ucontext.  */
> +       err |= __put_user(0, &frame->rs_uctx.uc_flags);
> +       err |= __put_user(NULL, &frame->rs_uctx.uc_link);
> +       err |= __save_altstack(&frame->rs_uctx.uc_stack, regs->regs[3]);
> +       err |= setup_sigcontext(regs, &frame->rs_uctx.uc_mcontext);
> +       err |= __copy_to_user(&frame->rs_uctx.uc_sigmask, set, sizeof(*set));
> +
> +       if (err)
> +               return -EFAULT;
> +
> +       /*
> +        * Arguments to signal handler:
> +        *
> +        *   a0 = signal number
> +        *   a1 = 0 (should be cause)
> +        *   a2 = pointer to ucontext
> +        *
> +        * $25 and c0_epc point to the signal handler, $29 points to
> +        * the struct rt_sigframe.
> +        */
> +       regs->regs[4] = ksig->sig;
> +       regs->regs[5] = (unsigned long) &frame->rs_info;
> +       regs->regs[6] = (unsigned long) &frame->rs_uctx;
> +       regs->regs[3] = (unsigned long) frame;
> +       regs->regs[1] = (unsigned long) sig_return;
> +       regs->csr_epc = (unsigned long) ksig->ka.sa.sa_handler;
> +
> +       DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
> +              current->comm, current->pid,
> +              frame, regs->csr_epc, regs->regs[1]);
> +
> +       return 0;
> +}
> +
> +struct loongarch_abi loongarch_abi = {
> +       .restart        = __NR_restart_syscall,
> +#ifdef CONFIG_32BIT
> +       .audit_arch     = AUDIT_ARCH_LOONGARCH32,
> +#else
> +       .audit_arch     = AUDIT_ARCH_LOONGARCH64,
> +#endif
> +
> +       .off_sc_fpregs  = offsetof(struct sigcontext, sc_fpregs),
> +       .off_sc_fcc     = offsetof(struct sigcontext, sc_fcc),
> +       .off_sc_fcsr    = offsetof(struct sigcontext, sc_fcsr),
> +       .off_sc_vcsr    = offsetof(struct sigcontext, sc_vcsr),
> +       .off_sc_flags   = offsetof(struct sigcontext, sc_flags),
> +
> +       .vdso           = &vdso_info,
> +};
> +
> +static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
> +{
> +       int ret;
> +       sigset_t *oldset = sigmask_to_save();
> +       struct loongarch_abi *abi = current->thread.abi;
> +       void *vdso = current->mm->context.vdso;
> +
> +       /* Are we from a system call? */
> +       if (regs->regs[0]) {
> +               switch (regs->regs[4]) {
> +               case -ERESTART_RESTARTBLOCK:
> +               case -ERESTARTNOHAND:
> +                       regs->regs[4] = -EINTR;
> +                       break;
> +               case -ERESTARTSYS:
> +                       if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
> +                               regs->regs[4] = -EINTR;
> +                               break;
> +                       }
> +                       fallthrough;
> +               case -ERESTARTNOINTR:
> +                       regs->regs[4] = regs->orig_a0;
> +                       regs->csr_epc -= 4;
> +               }
> +
> +               regs->regs[0] = 0;      /* Don't deal with this again.  */
> +       }
> +
> +       rseq_signal_deliver(ksig, regs);
> +
> +       ret = setup_rt_frame(vdso + abi->vdso->offset_sigreturn, ksig, regs, oldset);
> +
> +       signal_setup_done(ret, ksig, 0);
> +}
> +
> +void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
> +{
> +       struct ksignal ksig;
> +
> +       if (has_signal && get_signal(&ksig)) {
> +               /* Whee!  Actually deliver the signal.  */
> +               handle_signal(&ksig, regs);
> +               return;
> +       }
> +
> +       /* Are we from a system call? */
> +       if (regs->regs[0]) {
> +               switch (regs->regs[4]) {
> +               case -ERESTARTNOHAND:
> +               case -ERESTARTSYS:
> +               case -ERESTARTNOINTR:
> +                       regs->regs[4] = regs->orig_a0;
> +                       regs->csr_epc -= 4;
> +                       break;
> +
> +               case -ERESTART_RESTARTBLOCK:
> +                       regs->regs[4] = regs->orig_a0;
> +                       regs->regs[11] = current->thread.abi->restart;
> +                       regs->csr_epc -= 4;
> +                       break;
> +               }
> +               regs->regs[0] = 0;      /* Don't deal with this again.  */
> +       }
> +
> +       /*
> +        * If there's no signal to deliver, we just put the saved sigmask
> +        * back
> +        */
> +       restore_saved_sigmask();
> +}
> +
> +static int signal_setup(void)
> +{
> +       if (cpu_has_fpu) {
> +               save_fp_context = save_hw_fp_context;
> +               restore_fp_context = restore_hw_fp_context;
> +       } else {
> +               save_fp_context = copy_fp_to_sigcontext;
> +               restore_fp_context = copy_fp_from_sigcontext;
> +       }
> +
> +       return 0;
> +}
> +
> +arch_initcall(signal_setup);
> --
> 2.27.0
>

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