/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

#include "misc.h"
#include <ucontext.h>
#include <sys/frame.h>
#include <sys/stack.h>
#include <stdio.h>

#if defined(__sparc) || defined(__sparcv9)
extern void flush_windows(void);
#define UMEM_FRAMESIZE  MINFRAME

#elif defined(__i386) || defined(__amd64)
/*
 * On x86, MINFRAME is defined to be 0, but we want to be sure we can
 * dereference the entire frame structure.
 */
#define UMEM_FRAMESIZE  (sizeof (struct frame))

#else
#error needs update for new architecture
#endif

/*
 * Get a pc-only stacktrace.  Used for kmem_alloc() buffer ownership tracking.
 * Returns MIN(current stack depth, pcstack_limit).
 */
/*ARGSUSED*/
int
getpcstack(uintptr_t *pcstack, int pcstack_limit, int check_signal)
{
        struct frame *fp;
        struct frame *nextfp, *minfp;
        int depth = 0;
        uintptr_t base = 0;
        size_t size = 0;
#ifndef UMEM_STANDALONE
        int on_altstack = 0;
        uintptr_t sigbase = 0;
        size_t sigsize = 0;

        stack_t st;

        if (stack_getbounds(&st) != 0) {
                if (thr_stksegment(&st) != 0 ||
                    (uintptr_t)st.ss_sp < st.ss_size) {
                        return (0);             /* unable to get stack bounds */
                }
                /*
                 * thr_stksegment(3C) has a slightly different interface than
                 * stack_getbounds(3C) -- correct it
                 */
                st.ss_sp = (void *)(((uintptr_t)st.ss_sp) - st.ss_size);
                st.ss_flags = 0;                /* can't be on-stack */
        }
        on_altstack = (st.ss_flags & SS_ONSTACK);

        if (st.ss_size != 0) {
                base = (uintptr_t)st.ss_sp;
                size = st.ss_size;
        } else {
                /*
                 * If size == 0, then ss_sp is the *top* of the stack.
                 *
                 * Since we only allow increasing frame pointers, and we
                 * know our caller set its up correctly, we can treat ss_sp
                 * as an upper bound safely.
                 */
                base = 0;
                size = (uintptr_t)st.ss_sp;
        }

        if (check_signal != 0) {
                void (*sigfunc)() = NULL;
                int sigfuncsize = 0;
                extern void thr_sighndlrinfo(void (**)(), int *);

                thr_sighndlrinfo(&sigfunc, &sigfuncsize);
                sigbase = (uintptr_t)sigfunc;
                sigsize = sigfuncsize;
        }
#else /* UMEM_STANDALONE */
        base = (uintptr_t)umem_min_stack;
        size = umem_max_stack - umem_min_stack;
#endif

        /*
         * shorten size so that fr_savfp and fr_savpc will be within the stack
         * bounds.
         */
        if (size >= UMEM_FRAMESIZE - 1)
                size -= (UMEM_FRAMESIZE - 1);
        else
                size = 0;

#if defined(__sparc) || defined(__sparcv9)
        flush_windows();
#endif

        /* LINTED alignment */
        fp = (struct frame *)((caddr_t)getfp() + STACK_BIAS);

        minfp = fp;

        if (((uintptr_t)fp - base) >= size)
                return (0);     /* the frame pointer isn't in our stack */

        while (depth < pcstack_limit) {
                uintptr_t tmp;

                /* LINTED alignment */
                nextfp = (struct frame *)((caddr_t)fp->fr_savfp + STACK_BIAS);
                tmp = (uintptr_t)nextfp;

                /*
                 * Check nextfp for validity.  It must be properly aligned,
                 * increasing compared to the last %fp (or the top of the
                 * stack we just switched to), and it must be inside
                 * [base, base + size).
                 */
                if (tmp != SA(tmp))
                        break;
                else if (nextfp <= minfp || (tmp - base) >= size) {
#ifndef UMEM_STANDALONE
                        if (tmp == (uintptr_t)NULL || !on_altstack)
                                break;
                        /*
                         * If we're on an alternate signal stack, try jumping
                         * to the main thread stack.
                         *
                         * If the main thread stack has an unlimited size, we
                         * punt, since we don't know where the frame pointer's
                         * been.
                         *
                         * (thr_stksegment() returns the *top of stack*
                         * in ss_sp, not the bottom)
                         */
                        if (thr_stksegment(&st) == 0) {
                                if (st.ss_size >= (uintptr_t)st.ss_sp ||
                                    st.ss_size < UMEM_FRAMESIZE - 1)
                                        break;

                                on_altstack = 0;
                                base = (uintptr_t)st.ss_sp - st.ss_size;
                                size = st.ss_size - (UMEM_FRAMESIZE - 1);
                                minfp = (struct frame *)base;
                                continue;               /* try again */
                        }
#endif
                        break;
                }

#ifndef UMEM_STANDALONE
                if (check_signal && (fp->fr_savpc - sigbase) <= sigsize)
                        umem_panic("called from signal handler");
#endif
                pcstack[depth++] = fp->fr_savpc;
                fp = nextfp;
                minfp = fp;
        }
        return (depth);
}