// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2003 Broadcom Corporation
 */
#include <linux/cache.h>
#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/compat.h>
#include <linux/bitops.h>

#include <asm/abi.h>
#include <asm/asm.h>
#include <asm/cacheflush.h>
#include <asm/compat-signal.h>
#include <asm/sim.h>
#include <linux/uaccess.h>
#include <asm/ucontext.h>
#include <asm/fpu.h>
#include <asm/cpu-features.h>
#include <asm/syscalls.h>

#include "signal-common.h"

/*
 * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
 */
#define __NR_N32_restart_syscall        6214

struct ucontextn32 {
        u32                 uc_flags;
        s32                 uc_link;
        compat_stack_t      uc_stack;
        struct sigcontext   uc_mcontext;
        compat_sigset_t     uc_sigmask;   /* mask last for extensibility */
};

struct rt_sigframe_n32 {
        u32 rs_ass[4];                  /* argument save space for o32 */
        u32 rs_pad[2];                  /* Was: signal trampoline */
        struct compat_siginfo rs_info;
        struct ucontextn32 rs_uc;
};

asmlinkage void sysn32_rt_sigreturn(void)
{
        struct rt_sigframe_n32 __user *frame;
        struct pt_regs *regs;
        sigset_t set;
        int sig;

        regs = current_pt_regs();
        frame = (struct rt_sigframe_n32 __user *)regs->regs[29];
        if (!access_ok(frame, sizeof(*frame)))
                goto badframe;
        if (__copy_conv_sigset_from_user(&set, &frame->rs_uc.uc_sigmask))
                goto badframe;

        set_current_blocked(&set);

        sig = restore_sigcontext(regs, &frame->rs_uc.uc_mcontext);
        if (sig < 0)
                goto badframe;
        else if (sig)
                force_sig(sig);

        if (compat_restore_altstack(&frame->rs_uc.uc_stack))
                goto badframe;

        /*
         * Don't let your children do this ...
         */
        __asm__ __volatile__(
                "move\t$29, %0\n\t"
                "j\tsyscall_exit"
                : /* no outputs */
                : "r" (regs));
        /* Unreached */

badframe:
        force_sig(SIGSEGV);
}

static int setup_rt_frame_n32(void *sig_return, struct ksignal *ksig,
                              struct pt_regs *regs, sigset_t *set)
{
        struct rt_sigframe_n32 __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_user32(&frame->rs_info, &ksig->info);

        /* Create the ucontext.  */
        err |= __put_user(0, &frame->rs_uc.uc_flags);
        err |= __put_user(0, &frame->rs_uc.uc_link);
        err |= __compat_save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
        err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
        err |= __copy_conv_sigset_to_user(&frame->rs_uc.uc_sigmask, 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_uc;
        regs->regs[29] = (unsigned long) frame;
        regs->regs[31] = (unsigned long) sig_return;
        regs->cp0_epc = regs->regs[25] = (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->cp0_epc, regs->regs[31]);

        return 0;
}

struct mips_abi mips_abi_n32 = {
        .setup_rt_frame = setup_rt_frame_n32,
        .restart        = __NR_N32_restart_syscall,

        .off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
        .off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
        .off_sc_used_math = offsetof(struct sigcontext, sc_used_math),

        .vdso           = &vdso_image_n32,
};