/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2018, Joyent, Inc.
 */

#include <sys/stack.h>
#include <sys/regset.h>
#include <sys/frame.h>
#include <sys/sysmacros.h>
#include <sys/trap.h>
#include <sys/machelf.h>

#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <string.h>

#include "Pcontrol.h"
#include "Pstack.h"

static uchar_t int_syscall_instr[] = { 0xCD, T_SYSCALLINT };

const char *
Ppltdest(struct ps_prochandle *P, uintptr_t pltaddr)
{
        map_info_t *mp = Paddr2mptr(P, pltaddr);

        uintptr_t r_addr;
        file_info_t *fp;
        Elf32_Rel r;
        size_t i;

        if (mp == NULL || (fp = mp->map_file) == NULL ||
            fp->file_plt_base == 0 ||
            pltaddr - fp->file_plt_base >= fp->file_plt_size) {
                errno = EINVAL;
                return (NULL);
        }

        i = (pltaddr - fp->file_plt_base) / M_PLT_ENTSIZE - M_PLT_XNumber;

        r_addr = fp->file_jmp_rel + i * sizeof (r);

        if (Pread(P, &r, sizeof (r), r_addr) == sizeof (r) &&
            (i = ELF32_R_SYM(r.r_info)) < fp->file_dynsym.sym_symn) {

                Elf_Data *data = fp->file_dynsym.sym_data_pri;
                Elf32_Sym *symp = &(((Elf32_Sym *)data->d_buf)[i]);

                return (fp->file_dynsym.sym_strs + symp->st_name);
        }

        return (NULL);
}

int
Pissyscall(struct ps_prochandle *P, uintptr_t addr)
{
        uchar_t instr[16];

        if (Pread(P, instr, sizeof (int_syscall_instr), addr) !=
            sizeof (int_syscall_instr))
                return (0);

        if (memcmp(instr, int_syscall_instr, sizeof (int_syscall_instr)) == 0)
                return (1);

        return (0);
}

int
Pissyscall_prev(struct ps_prochandle *P, uintptr_t addr, uintptr_t *dst)
{
        int ret;

        if (ret = Pissyscall(P, addr - sizeof (int_syscall_instr))) {
                if (dst)
                        *dst = addr - sizeof (int_syscall_instr);
                return (ret);
        }

        return (0);
}

/* ARGSUSED */
int
Pissyscall_text(struct ps_prochandle *P, const void *buf, size_t buflen)
{
        if (buflen < sizeof (int_syscall_instr))
                return (0);

        if (memcmp(buf, int_syscall_instr, sizeof (int_syscall_instr)) == 0)
                return (1);

        return (0);
}

#define TR_ARG_MAX 6    /* Max args to print, same as SPARC */

static boolean_t
argcount_ctf(struct ps_prochandle *P, long pc, uint_t *countp)
{
        GElf_Sym sym;
        ctf_file_t *ctfp;
        ctf_funcinfo_t finfo;
        prsyminfo_t si = { 0 };

        if (Pxlookup_by_addr(P, pc, NULL, 0, &sym, &si) != 0)
                return (B_FALSE);

        if ((ctfp = Paddr_to_ctf(P, pc)) == NULL)
                return (B_FALSE);

        if (ctf_func_info(ctfp, si.prs_id, &finfo) == CTF_ERR)
                return (B_FALSE);

        *countp = finfo.ctc_argc;

        return (B_TRUE);
}

/*
 * Given a return address, determine the likely number of arguments
 * that were pushed on the stack prior to its execution.  We do this by
 * expecting that a typical call sequence consists of pushing arguments on
 * the stack, executing a call instruction, and then performing an add
 * on %esp to restore it to the value prior to pushing the arguments for
 * the call.  We attempt to detect such an add, and divide the addend
 * by the size of a word to determine the number of pushed arguments.
 *
 * If we do not find such an add, this does not necessarily imply that the
 * function took no arguments. It is not possible to reliably detect such a
 * void function because hand-coded assembler does not always perform an add
 * to %esp immediately after the "call" instruction (eg. _sys_call()).
 * Because of this, we default to returning MIN(sz, TR_ARG_MAX) instead of 0
 * in the absence of an add to %esp.
 */
static ulong_t
argcount(struct ps_prochandle *P, long pc, ssize_t sz)
{
        uchar_t instr[6];
        ulong_t count, max;

        max = MIN(sz / sizeof (long), TR_ARG_MAX);

        /*
         * Read the instruction at the return location.
         */
        if (Pread(P, instr, sizeof (instr), pc) != sizeof (instr) ||
            instr[1] != 0xc4)
                return (max);

        switch (instr[0]) {
        case 0x81:      /* count is a longword */
                count = instr[2]+(instr[3]<<8)+(instr[4]<<16)+(instr[5]<<24);
                break;
        case 0x83:      /* count is a byte */
                count = instr[2];
                break;
        default:
                return (max);
        }

        count /= sizeof (long);
        return (MIN(count, max));
}

static void
ucontext_n_to_prgregs(const ucontext_t *src, prgregset_t dst)
{
        (void) memcpy(dst, src->uc_mcontext.gregs, sizeof (gregset_t));
}

int
Pstack_iter(struct ps_prochandle *P, const prgregset_t regs,
    proc_stack_f *func, void *arg)
{
        prgreg_t *prevfp = NULL;
        uint_t pfpsize = 0;
        int nfp = 0;
        struct {
                long    fp;
                long    pc;
                long    args[32];
        } frame;
        uint_t argc;
        ssize_t sz;
        prgregset_t gregs;
        prgreg_t fp, pfp;
        prgreg_t pc, ctf_pc;
        int rv;

        /*
         * Type definition for a structure corresponding to an IA32
         * signal frame.  Refer to the comments in Pstack.c for more info
         */
        typedef struct {
                long fp;
                long pc;
                int signo;
                ucontext_t *ucp;
                siginfo_t *sip;
        } sf_t;

        uclist_t ucl;
        ucontext_t uc;
        uintptr_t uc_addr;

        init_uclist(&ucl, P);
        (void) memcpy(gregs, regs, sizeof (gregs));

        fp = regs[R_FP];
        ctf_pc = pc = regs[R_PC];

        while (fp != 0 || pc != 0) {
                if (stack_loop(fp, &prevfp, &nfp, &pfpsize))
                        break;

                if (fp != 0 &&
                    (sz = Pread(P, &frame, sizeof (frame), (uintptr_t)fp)
                    >= (ssize_t)(2* sizeof (long)))) {
                        /*
                         * One more trick for signal frames: the kernel sets
                         * the return pc of the signal frame to 0xffffffff on
                         * Intel IA32, so argcount won't work.
                         */
                        if (frame.pc != -1L) {
                                sz -= 2* sizeof (long);
                                if (argcount_ctf(P, ctf_pc, &argc)) {
                                        argc = MIN(argc, 32);
                                } else {
                                        argc = argcount(P, (long)frame.pc, sz);
                                }
                        } else
                                argc = 3; /* sighandler(signo, sip, ucp) */
                } else {
                        (void) memset(&frame, 0, sizeof (frame));
                        argc = 0;
                }

                ctf_pc = frame.pc;
                gregs[R_FP] = fp;
                gregs[R_PC] = pc;

                if ((rv = func(arg, gregs, argc, frame.args)) != 0)
                        break;

                /*
                 * In order to allow iteration over java frames (which can have
                 * their own frame pointers), we allow the iterator to change
                 * the contents of gregs.  If we detect a change, then we assume
                 * that the new values point to the next frame.
                 */
                if (gregs[R_FP] != fp || gregs[R_PC] != pc) {
                        fp = gregs[R_FP];
                        pc = gregs[R_PC];
                        continue;
                }

                pfp = fp;
                fp = frame.fp;
                pc = frame.pc;

                if (find_uclink(&ucl, pfp + sizeof (sf_t)))
                        uc_addr = pfp + sizeof (sf_t);
                else
                        uc_addr = (uintptr_t)NULL;

                if (uc_addr != (uintptr_t)NULL &&
                    Pread(P, &uc, sizeof (uc), uc_addr) == sizeof (uc)) {

                        ucontext_n_to_prgregs(&uc, gregs);
                        fp = gregs[R_FP];
                        pc = gregs[R_PC];
                }
        }

        if (prevfp)
                free(prevfp);

        free_uclist(&ucl);
        return (rv);
}

uintptr_t
Psyscall_setup(struct ps_prochandle *P, int nargs, int sysindex, uintptr_t sp)
{
        sp -= sizeof (int) * (nargs+2); /* space for arg list + CALL parms */

        P->status.pr_lwp.pr_reg[EAX] = sysindex;
        P->status.pr_lwp.pr_reg[R_SP] = sp;
        P->status.pr_lwp.pr_reg[R_PC] = P->sysaddr;

        return (sp);
}

int
Psyscall_copyinargs(struct ps_prochandle *P, int nargs, argdes_t *argp,
    uintptr_t ap)
{
        int32_t arglist[MAXARGS+2];
        int i;
        argdes_t *adp;

        for (i = 0, adp = argp; i < nargs; i++, adp++)
                arglist[1 + i] = (int32_t)adp->arg_value;

        arglist[0] = P->status.pr_lwp.pr_reg[R_PC];
        if (Pwrite(P, &arglist[0], sizeof (int) * (nargs+1),
            (uintptr_t)ap) != sizeof (int) * (nargs+1))
                return (-1);

        return (0);
}

int
Psyscall_copyoutargs(struct ps_prochandle *P, int nargs, argdes_t *argp,
    uintptr_t ap)
{
        uint32_t arglist[MAXARGS + 2];
        int i;
        argdes_t *adp;

        if (Pread(P, &arglist[0], sizeof (int) * (nargs+1), (uintptr_t)ap)
            != sizeof (int) * (nargs+1))
                return (-1);

        for (i = 0, adp = argp; i < nargs; i++, adp++)
                adp->arg_value = arglist[i];

        return (0);
}