/* $NetBSD: cpu_i386.c,v 1.8 2018/11/27 14:09:54 maxv Exp $ */

/*-
 * Copyright (c) 2011 Reinoud Zandijk <reinoud@netbsd.org>
 * Copyright (c) 2007 Jared D. McNeill <jmcneill@invisible.ca>
 * All rights reserved.
 *
 * 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: cpu_i386.c,v 1.8 2018/11/27 14:09:54 maxv Exp $");

#include <sys/types.h>
#include <sys/systm.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/exec.h>
#include <sys/buf.h>
#include <sys/boot_flag.h>
#include <sys/ucontext.h>
#include <sys/utsname.h>
#include <machine/pcb.h>
#include <machine/psl.h>

#include <uvm/uvm_extern.h>
#include <uvm/uvm_page.h>

#include <dev/mm.h>
#include <machine/machdep.h>
#include <machine/thunk.h>
#include <machine/mcontext.h>

#include "opt_exec.h"

#if 0
static void dump_regs(register_t *reg);

static void
dump_regs(register_t *reg)
{
        int i;

        /* register dump before call */
        const char *name[] = {"GS", "FS", "ES", "DS", "EDI", "ESI", "EBP", "ESP",
                "EBX", "EDX", "ECX", "EAX", "TRAPNO", "ERR", "EIP", "CS", "EFL",
                "UESP", "SS"};

        for (i =0; i < 19; i++)
                printf("reg[%02d] (%6s) = %"PRIx32"\n", i, name[i], (uint32_t) reg[i]);
}
#endif


/* from sys/arch/i386/include/frame.h : KEEP IN SYNC */

/*
 * New-style signal frame
 */
struct sigframe_siginfo {
        int             sf_ra;          /* return address for handler */
        int             sf_signum;      /* "signum" argument for handler */
        siginfo_t       *sf_sip;        /* "sip" argument for handler */
        ucontext_t      *sf_ucp;        /* "ucp" argument for handler */
        siginfo_t       sf_si;          /* actual saved siginfo */
        ucontext_t      sf_uc;          /* actual saved ucontext */
};


/*
 * mcontext extensions to handle signal delivery.
 */

void
sendsig_siginfo(const ksiginfo_t *ksi, const sigset_t *mask)
{
        struct lwp *l = curlwp;
        struct proc *p = l->l_proc;
        struct pcb *pcb = lwp_getpcb(l);
        struct sigacts *ps = p->p_sigacts;
        struct sigframe_siginfo *fp, frame;
        int sig = ksi->ksi_signo;
        sig_t catcher = SIGACTION(p, sig).sa_handler;
        ucontext_t *ucp;
        register_t *reg;
        int onstack, error;

        KASSERT(mutex_owned(p->p_lock));

        ucp = &pcb->pcb_userret_ucp;
        reg = (register_t *) &ucp->uc_mcontext.__gregs;
#if 0
        thunk_printf("%s: ", __func__);
        thunk_printf("flags %d, ", (int) ksi->ksi_flags);
        thunk_printf("to lwp %d, signo %d, code %d, errno %d\n",
                (int) ksi->ksi_lid,
                ksi->ksi_signo,
                ksi->ksi_code,
                ksi->ksi_errno);
#endif

        /* 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;

        fp = (void *) reg[17];  /* ESP */
        if (onstack)
                fp = (void *)
                        ((char *) l->l_sigstk.ss_sp + l->l_sigstk.ss_size);

        fp--;

        /* set up stack frame */
        memset(&frame, 0, sizeof(frame));
        frame.sf_ra = (int)ps->sa_sigdesc[sig].sd_tramp;
        frame.sf_signum = sig;
        frame.sf_sip = &fp->sf_si;
        frame.sf_ucp = &fp->sf_uc;
        frame.sf_si._info = ksi->ksi_info;

        /* copy our userret context into sf_uc */
        memcpy(&frame.sf_uc, ucp, sizeof(ucontext_t));
        frame.sf_uc.uc_sigmask = *mask;
        frame.sf_uc.uc_link = l->l_ctxlink; /* XXX ??? */
        frame.sf_uc.uc_flags |= (l->l_sigstk.ss_flags & SS_ONSTACK)
            ? _UC_SETSTACK : _UC_CLRSTACK;
        memset(&frame.sf_uc.uc_stack, 0, sizeof(frame.sf_uc.uc_stack));

        sendsig_reset(l, sig);

        /* copyout our frame to the stackframe */
        mutex_exit(p->p_lock);
        error = copyout(&frame, fp, sizeof(frame));
        mutex_enter(p->p_lock);

        if (error != 0) {
                /*
                 * Process has trashed its stack; give it an illegal
                 * instruction to halt it in its tracks.
                 */
                sigexit(l, SIGILL);
                /* NOTREACHED */
        }

        /* set catcher and the new stack pointer */
        reg[17] = (register_t) fp;      /* ESP */
        reg[14] = (register_t) catcher; /* EIP */

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

void
setregs(struct lwp *l, struct exec_package *pack, vaddr_t stack)
{
        struct pcb *pcb = lwp_getpcb(l);
        ucontext_t *ucp;
        uint *reg, i;

#ifdef DEBUG_EXEC
        printf("setregs called: lwp %p, exec package %p, stack %p\n",
                l, pack, (void *) stack);
        printf("current stat of pcb %p\n", pcb);
        printf("\tpcb->pcb_ucp.uc_stack.ss_sp   = %p\n",
                pcb->pcb_ucp.uc_stack.ss_sp);
        printf("\tpcb->pcb_ucp.uc_stack.ss_size = %d\n",
                (int) pcb->pcb_ucp.uc_stack.ss_size);
#endif

        /* set up the user context */
        ucp = &pcb->pcb_userret_ucp;
        reg = (int *) &ucp->uc_mcontext.__gregs;
        for (i = 4; i < 11; i++)
                reg[i] = 0;

        /* use given stack */
        ucp->uc_stack.ss_sp = (void *) (stack-4);       /* to prevent clearing */
        ucp->uc_stack.ss_size = 0; //pack->ep_ssize;
        thunk_makecontext(ucp, (void *) pack->ep_entry,
                0, NULL, NULL, NULL, NULL);

        /* patch up */
        reg[ 8] = l->l_proc->p_psstrp;  /* _REG_EBX */
        reg[17] = (stack);              /* _REG_UESP */

        //dump_regs(reg);

#ifdef DEBUG_EXEC
        printf("updated pcb %p\n", pcb);
        printf("\tpcb->pcb_ucp.uc_stack.ss_sp   = %p\n",
                pcb->pcb_ucp.uc_stack.ss_sp);
        printf("\tpcb->pcb_ucp.uc_stack.ss_size = %d\n",
                (int) pcb->pcb_ucp.uc_stack.ss_size);
        printf("\tpack->ep_entry                = %p\n",
                (void *) pack->ep_entry);
#endif
}

void
md_syscall_get_syscallnumber(ucontext_t *ucp, uint32_t *code)
{
        uint *reg = (int *) &ucp->uc_mcontext.__gregs;
        *code = reg[11];                        /* EAX */
}

int
md_syscall_getargs(lwp_t *l, ucontext_t *ucp, int nargs, int argsize,
        register_t *args)
{
        uint *reg = (int *) &ucp->uc_mcontext.__gregs;
        register_t *sp = (register_t *) reg[17];/* ESP */
        int ret;

        //dump_regs(reg);
        ret = copyin(sp + 1, args, argsize);

        return ret;
}

void
md_syscall_set_returnargs(lwp_t *l, ucontext_t *ucp,
        int error, register_t *rval)
{
        register_t *reg = (register_t *) &ucp->uc_mcontext.__gregs;

        reg[16] &= ~PSL_C;              /* EFL */
        if (error > 0) {
                rval[0] = error;
                reg[16] |= PSL_C;       /* EFL */
        }

        /* set return parameters */
        reg[11] = rval[0];              /* EAX */
        if (error == 0)
                reg[ 9] = rval[1];      /* EDX */

        //dump_regs(reg);
}

register_t
md_get_pc(ucontext_t *ucp)
{
        KASSERT(ucp);
        register_t *reg = (register_t *) &ucp->uc_mcontext.__gregs;

        return reg[14];                 /* EIP */
}

register_t
md_get_sp(ucontext_t *ucp)
{
        KASSERT(ucp);
        register_t *reg = (register_t *) &ucp->uc_mcontext.__gregs;

        return reg[17];                 /* ESP */
}

int
md_syscall_check_opcode(ucontext_t *ucp)
{
        uint32_t opcode;

        md_syscall_get_opcode(ucp, &opcode);

        switch (opcode) {
        case 0xff0f:    /* UD1      */
        case 0xff0b:    /* UD2      */
        case 0x80cd:    /* int $80  */
        case 0x340f:    /* sysenter */
        case 0x050f:    /* syscall */
                return 1;
        default:
                return 0;
        }
}

void
md_syscall_get_opcode(ucontext_t *ucp, uint32_t *opcode)
{
        KASSERT(ucp);
        register_t *reg = (register_t *) &ucp->uc_mcontext.__gregs;
//      uint8_t  *p8  = (uint8_t *) (reg[14]);
        uint16_t *p16 = (uint16_t*) (reg[14]);  /* EIP */

        switch (*p16) {
        case 0xff0f:    /* UD1      */
        case 0xff0b:    /* UD2      */
        case 0x80cd:    /* int $80  */
        case 0x340f:    /* sysenter */
        case 0x050f:    /* syscall */
                *opcode = *p16;
                break;
        default:
                *opcode = 0;
        }
}

void
md_syscall_inc_pc(ucontext_t *ucp, uint32_t opcode)
{
        KASSERT(ucp);
        uint *reg = (int *) &ucp->uc_mcontext.__gregs;

        /* advance program counter */
        switch (opcode) {
        case 0xff0f:    /* UD1      */
        case 0xff0b:    /* UD2      */
        case 0x80cd:    /* int $80  */
        case 0x340f:    /* sysenter */
        case 0x050f:    /* syscall */
                reg[14] += 2;   /* EIP */
                break;
        default:
                panic("%s, unknown illegal instruction: opcode = %x\n",
                        __func__, (uint32_t) opcode);
        }
}

void
md_syscall_dec_pc(ucontext_t *ucp, uint32_t opcode)
{
        KASSERT(ucp);
        uint *reg = (int *) &ucp->uc_mcontext.__gregs;

        switch (opcode) {
        case 0xff0f:    /* UD1      */
        case 0xff0b:    /* UD2      */
        case 0x80cd:    /* int $80  */
        case 0x340f:    /* sysenter */
        case 0x050f:    /* syscall */
                reg[14] -= 2;   /* EIP */
                break;
        default:
                panic("%s, unknown illegal instruction: opcode = %x\n",
                        __func__, (uint32_t) opcode);
        }
}