/*      $NetBSD: linux_machdep.c,v 1.44 2021/09/07 11:43:04 riastradh Exp $ */

/*-
* Copyright (c) 1995, 2000, 2001 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Frank van der Linden and Emmanuel Dreyfus.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: linux_machdep.c,v 1.44 2021/09/07 11:43:04 riastradh Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/reboot.h>
#include <sys/conf.h>
#include <sys/exec.h>
#include <sys/file.h>
#include <sys/callout.h>
#include <sys/mbuf.h>
#include <sys/msgbuf.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/device.h>
#include <sys/syscallargs.h>
#include <sys/filedesc.h>
#include <sys/exec_elf.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>
#include <miscfs/specfs/specdev.h>

#include <compat/linux/common/linux_types.h>
#include <compat/linux/common/linux_signal.h>
#include <compat/linux/common/linux_util.h>
#include <compat/linux/common/linux_ioctl.h>
#include <compat/linux/common/linux_hdio.h>
#include <compat/linux/common/linux_exec.h>
#include <compat/linux/common/linux_machdep.h>

#include <compat/linux/linux_syscallargs.h>

#include <sys/cpu.h>
#include <machine/psl.h>
#include <machine/reg.h>
#include <machine/regnum.h>
#include <machine/vmparam.h>
#include <machine/locore.h>

#include <mips/cache.h>

union linux_ksigframe {
       struct linux_sigframe sf;
#if !defined(__mips_o32)
       struct linux_sigframe32 sf32;
#endif
};

/*
* To see whether wscons is configured (for virtual console ioctl calls).
*/
#if defined(_KERNEL_OPT)
#include "wsdisplay.h"
#endif
#if (NWSDISPLAY > 0)
#include <dev/wscons/wsconsio.h>
#include <dev/wscons/wsdisplay_usl_io.h>
#endif

/*
* Set set up registers on exec.
*/
void
linux_setregs(struct lwp *l, struct exec_package *pack, vaddr_t stack)
{
       setregs(l, pack, stack);
       return;
}

#if !defined(__mips_o32)
static void
linux_setup_sigcontext32(struct linux_sigcontext32 *sc,
    const struct trapframe *tf)
{
       for (u_int i = 0; i < 32; i++) {
               sc->lsc_regs[i] = tf->tf_regs[i];
       }
       sc->lsc_mdhi = tf->tf_regs[_R_MULHI];
       sc->lsc_mdlo = tf->tf_regs[_R_MULLO];
       sc->lsc_pc = tf->tf_regs[_R_PC];
}
#endif

static void
linux_setup_sigcontext(struct linux_sigcontext *sc,
    const struct trapframe *tf)
{
       for (u_int i = 0; i < 32; i++) {
               sc->lsc_regs[i] = tf->tf_regs[i];
       }
       sc->lsc_mdhi = tf->tf_regs[_R_MULHI];
       sc->lsc_mdlo = tf->tf_regs[_R_MULLO];
       sc->lsc_pc = tf->tf_regs[_R_PC];
}

/*
* Send an interrupt to process.
*
* Adapted from sys/arch/mips/mips/mips_machdep.c
*
* XXX Does not work well yet with RT signals
*
*/

void
linux_sendsig(const ksiginfo_t *ksi, const sigset_t *mask)
{
       const int sig = ksi->ksi_signo;
       struct lwp * const l = curlwp;
       struct proc * const p = l->l_proc;
       struct trapframe * const tf = l->l_md.md_utf;
#ifdef __mips_o32
       const int abi = _MIPS_BSD_API_O32;
#else
       const int abi = p->p_md.md_abi;
#endif
       union linux_ksigframe ksf, *sf;
       bool onstack;
       int error;
       sig_t catcher = SIGACTION(p, sig).sa_handler;

#ifdef DEBUG_LINUX
       printf("linux_sendsig()\n");
#endif /* DEBUG_LINUX */

       /*
        * Do we need to jump onto the signal stack?
        */
       onstack = (l->l_sigstk.ss_flags & (SS_DISABLE | SS_ONSTACK)) == 0
           && (SIGACTION(p, sig).sa_flags & SA_ONSTACK) != 0;

       /*
        * Signal stack is broken (see at the end of linux_sigreturn), so we do
        * not use it yet. XXX fix this.
        */
       onstack = false;

       /*
        * Allocate space for the signal handler context.
        */
       sf = (void *)(onstack
           ? (uintptr_t) l->l_sigstk.ss_sp + l->l_sigstk.ss_size
           : (uintptr_t) tf->tf_regs[_R_SP]);

       /*
        * Build stack frame for signal trampoline.
        */
       memset(&ksf, 0, sizeof ksf);

       /*
        * This is the signal trampoline used by Linux, we don't use it,
        * but we set it up in case an application expects it to be there
        */
       ksf.sf.lsf_code[0] = 0x24020000; /* li  v0, __NR_sigreturn      */
       ksf.sf.lsf_code[1] = 0x0000000c; /* syscall                     */

       switch (abi) {
       default:
               native_to_linux_sigset(&ksf.sf.lsf_mask, mask);
               linux_setup_sigcontext(&ksf.sf.lsf_sc, tf);
               break;
#if !defined(__mips_o32)
       case _MIPS_BSD_API_O32:
               native_to_linux_sigset(&ksf.sf32.lsf_mask, mask);
               linux_setup_sigcontext32(&ksf.sf32.lsf_sc, tf);
               break;
#endif
       }
       sendsig_reset(l, sig);

       /*
        * Save signal stack.  XXX broken
        */
       /* kregs.sc_onstack = l->l_sigstk.ss_flags & SS_ONSTACK; */

       /*
        * Install the sigframe onto the stack
        */
       sf -= sizeof(*sf);
       mutex_exit(p->p_lock);
       error = copyout(&ksf, sf, sizeof(ksf));
       mutex_enter(p->p_lock);

       if (error != 0) {
               /*
                * Process has trashed its stack; give it an illegal
                * instruction to halt it in its tracks.
                */
#ifdef DEBUG_LINUX
               printf("linux_sendsig: stack trashed\n");
#endif /* DEBUG_LINUX */
               sigexit(l, SIGILL);
               /* NOTREACHED */
       }

       /* Set up the registers to return to sigcode. */
       tf->tf_regs[_R_A0] = native_to_linux_signo[sig];
       tf->tf_regs[_R_A1] = 0;
       tf->tf_regs[_R_A2] = (intptr_t)&sf->sf.lsf_sc;

#ifdef DEBUG_LINUX
       printf("sigcontext is at %p\n", &sf->sf.lsf_sc);
#endif /* DEBUG_LINUX */

       tf->tf_regs[_R_SP] = (intptr_t)sf;
       /* Signal trampoline code is at base of user stack. */
       tf->tf_regs[_R_RA] = (intptr_t)p->p_sigctx.ps_sigcode;
       tf->tf_regs[_R_T9] = (intptr_t)catcher;
       tf->tf_regs[_R_PC] = (intptr_t)catcher;

       /* Remember that we're now on the signal stack. */
       if (onstack)
               l->l_sigstk.ss_flags |= SS_ONSTACK;

       return;
}

static void
linux_putaway_sigcontext(struct trapframe *tf,
   const struct linux_sigcontext *sc)
{
       for (u_int i = 0; i < 32; i++) {
               tf->tf_regs[i] = sc->lsc_regs[i];
       }
       tf->tf_regs[_R_MULLO] = sc->lsc_mdlo;
       tf->tf_regs[_R_MULHI] = sc->lsc_mdhi;
       tf->tf_regs[_R_PC] = sc->lsc_pc;
}

#ifndef __mips_o32
static void
linux_putaway_sigcontext32(struct trapframe *tf,
   const struct linux_sigcontext32 *sc)
{
       for (u_int i = 0; i < 32; i++) {
               tf->tf_regs[i] = sc->lsc_regs[i];
       }
       tf->tf_regs[_R_MULLO] = sc->lsc_mdlo;
       tf->tf_regs[_R_MULHI] = sc->lsc_mdhi;
       tf->tf_regs[_R_PC] = sc->lsc_pc;
}
#endif

/*
* System call to cleanup state after a signal
* has been taken.  Reset signal mask and
* stack state from context left by sendsig (above).
*/
int
linux_sys_sigreturn(struct lwp *l, const struct linux_sys_sigreturn_args *uap, register_t *retval)
{
       /* {
               syscallarg(struct linux_sigframe *) sf;
       } */
       struct proc *p = l->l_proc;
       union linux_ksigframe ksf, *sf;
#ifdef __mips_o32
       const int abi = _MIPS_BSD_API_O32;
#else
       const int abi = p->p_md.md_abi;
#endif
       linux_sigset_t *lmask;
       sigset_t mask;
       int error;

#ifdef DEBUG_LINUX
       printf("linux_sys_sigreturn()\n");
#endif /* DEBUG_LINUX */

       /*
        * The trampoline code hands us the context.
        * It is unsafe to keep track of it ourselves, in the event that a
        * program jumps out of a signal handler.
        */
       sf = (void *)SCARG(uap, sf);

       if ((error = copyin(sf, &ksf, sizeof(ksf))) != 0)
               return (error);

       /* Restore the register context. */
       switch (abi) {
       default:
               lmask = &ksf.sf.lsf_mask;
               linux_putaway_sigcontext(l->l_md.md_utf, &ksf.sf.lsf_sc);
               break;
#if !defined(__mips_o32)
       case _MIPS_BSD_API_O32:
               lmask = &ksf.sf32.lsf_mask;
               linux_putaway_sigcontext32(l->l_md.md_utf, &ksf.sf32.lsf_sc);
               break;
#endif
       }

       mutex_enter(p->p_lock);

       /* Restore signal stack. */
       l->l_sigstk.ss_flags &= ~SS_ONSTACK;

       /* Restore signal mask. */
       linux_to_native_sigset(&mask, lmask);
       (void)sigprocmask1(l, SIG_SETMASK, &mask, 0);

       mutex_exit(p->p_lock);

       return (EJUSTRETURN);
}


int
linux_sys_rt_sigreturn(struct lwp *l, const struct linux_sys_rt_sigreturn_args *v, register_t *retval)
{
       return (ENOSYS);
}


/*
* major device numbers remapping
*/
dev_t
linux_fakedev(dev_t dev, int raw)
{
       /* XXX write me */
       return dev;
}

/*
* We come here in a last attempt to satisfy a Linux ioctl() call
*/
int
linux_machdepioctl(struct lwp *l, const struct linux_sys_ioctl_args *uap, register_t *retval)
{
       return 0;
}

/*
* See above. If a root process tries to set access to an I/O port,
* just let it have the whole range.
*/
int
linux_sys_ioperm(struct lwp *l, const struct linux_sys_ioperm_args *uap, register_t *retval)
{
       /*
        * This syscall is not implemented in Linux/Mips: we should not be here
        */
#ifdef DEBUG_LINUX
       printf("linux_sys_ioperm: should not be here.\n");
#endif /* DEBUG_LINUX */
       return 0;
}

/*
* wrapper linux_sys_new_uname() -> linux_sys_uname()
*/
int
linux_sys_new_uname(struct lwp *l, const struct linux_sys_new_uname_args *uap, register_t *retval)
{
/*
* Use this if you want to try Linux emulation with a glibc-2.2
* or higher. Note that signals will not work
*/
#if 0
       struct linux_sys_uname_args /* {
               syscallarg(struct linux_utsname *) up;
       } */ *uap = v;
       struct linux_utsname luts;

       memset(&luts, 0, sizeof(luts));
       strlcpy(luts.l_sysname, linux_sysname, sizeof(luts.l_sysname));
       strlcpy(luts.l_nodename, hostname, sizeof(luts.l_nodename));
       strlcpy(luts.l_release, "2.4.0", sizeof(luts.l_release));
       strlcpy(luts.l_version, linux_version, sizeof(luts.l_version));
       strlcpy(luts.l_machine, machine, sizeof(luts.l_machine));
       strlcpy(luts.l_domainname, domainname, sizeof(luts.l_domainname));

       return copyout(&luts, SCARG(uap, up), sizeof(luts));
#else
       return linux_sys_uname(l, (const void *)uap, retval);
#endif
}

/*
* In Linux, cacheflush is currently implemented
* as a whole cache flush (arguments are ignored)
* we emulate this broken beahior.
*/
int
linux_sys_cacheflush(struct lwp *l, const struct linux_sys_cacheflush_args *uap, register_t *retval)
{
       mips_icache_sync_all();
       mips_dcache_wbinv_all();
       return 0;
}

/*
* This system call is depecated in Linux, but
* some binaries and some libraries use it.
*/
int
linux_sys_sysmips(struct lwp *l, const struct linux_sys_sysmips_args *uap, register_t *retval)
{
       /* {
               syscallarg(long) cmd;
               syscallarg(long) arg1;
               syscallarg(long) arg2;
               syscallarg(long) arg3;
       } */
       int error;

       switch (SCARG(uap, cmd)) {
       case LINUX_SETNAME: {
               char nodename [LINUX___NEW_UTS_LEN + 1];
               int name[2];
               size_t len;

               if ((error = copyinstr((char *)SCARG(uap, arg1), nodename,
                   LINUX___NEW_UTS_LEN, &len)) != 0)
                       return error;

               name[0] = CTL_KERN;
               name[1] = KERN_HOSTNAME;
               return (old_sysctl(&name[0], 2, 0, 0, nodename, len, NULL));

               break;
       }
       case LINUX_MIPS_ATOMIC_SET: {
               void *addr;
               int s;
               u_int8_t value = 0;

               addr = (void *)SCARG(uap, arg1);

               s = splhigh();
               /*
                * No error testing here. This is bad, but Linux does
                * it like this. The source aknowledge "This is broken"
                * in a comment...
                */
               (void) copyin(addr, &value, 1);
               *retval = value;
               value = (u_int8_t) SCARG(uap, arg2);
               error = copyout(&value, addr, 1);
               splx(s);

               return 0;
               break;
       }
       case LINUX_MIPS_FIXADE:         /* XXX not implemented */
               break;
       case LINUX_FLUSH_CACHE:
               mips_icache_sync_all();
               mips_dcache_wbinv_all();
               break;
       case LINUX_MIPS_RDNVRAM:
               return EIO;
               break;
       default:
               return EINVAL;
               break;
       }
#ifdef DEBUG_LINUX
       printf("linux_sys_sysmips(): unimplemented command %d\n",
           SCARG(uap,cmd));
#endif /* DEBUG_LINUX */
       return 0;
}

int
linux_usertrap(struct lwp *l, vaddr_t trapaddr, void *arg)
{
       return 0;
}

int
linux_sys_set_thread_area(struct lwp *l, const struct linux_sys_set_thread_area_args *uap, register_t *retval)
{
       /* {
               syscallarg(void *) tls;
       } */

       return lwp_setprivate(l, SCARG(uap, tls));
}