/*-
 * Copyright (c) 2004 Doug Rabson
 * 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 AUTHOR 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 AUTHOR 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.
 *
 *      $FreeBSD: src/lib/libc/gen/tls.c,v 1.7 2005/03/01 23:42:00 davidxu Exp $
 */

/*
 * Define stubs for TLS internals so that programs and libraries can
 * link. These functions will be replaced by functional versions at
 * runtime from ld-elf.so.1.
 */

#include <sys/param.h>
#include <sys/tls.h>
#include <sys/mman.h>

#include <machine/tls.h>

#include <stdlib.h>
#include <string.h>
#include <elf.h>
#include <assert.h>
#include <errno.h>
#include <unistd.h>

#include "libc_private.h"

struct tls_tcb *__libc_allocate_tls(void);
void __libc_free_tls(struct tls_tcb *tcb);
void __libc_call_init(void);

#if !defined(RTLD_STATIC_TLS_VARIANT_II)
#error "Unsupported TLS layout"
#endif

#ifndef PIC

static size_t tls_static_space;
static size_t tls_init_size;
static void *tls_init;
static struct tls_tcb *initial_tcb;
#endif

void *__libc_tls_get_addr(void *ti);
void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *);

void *
__libc_tls_get_addr(void *ti __unused)
{
        return (NULL);
}

void *
__libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused)
{
        return (NULL);
}

#ifndef PIC

/*
 * Free Static TLS, weakly bound to _rtld_free_tls()
 */
void
__libc_free_tls(struct tls_tcb *tcb)
{
        size_t data_size;

        data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
                    ~RTLD_STATIC_TLS_ALIGN_MASK;

        if (tcb == initial_tcb) {
                /* initial_tcb was allocated with mmap(), cannot call free() */
        } else {
                free((char *)tcb - data_size);
        }
}

/*
 * Allocate Static TLS, weakly bound to _rtld_allocate_tls()
 *
 * NOTE!  There is a chicken-and-egg problem here because no TLS exists
 * on the first call into this function. 
 */
struct tls_tcb *
__libc_allocate_tls(void)
{
        size_t data_size;
        struct tls_tcb *tcb;
        Elf_Addr *dtv;

        data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
                    ~RTLD_STATIC_TLS_ALIGN_MASK;

        /*
         * Allocate space.  malloc() may require a working TLS segment
         * so we use sbrk() for main's TLS.  Oops, but in order to be
         * compatible with older kernels we cannot use sbrk() because it
         * will generate an errno (which needs the TLS), so use mmap().
         */
        if (initial_tcb == NULL) {
                size_t bytes;

                bytes = data_size + sizeof(*tcb) + 3 * sizeof(*dtv);
                bytes = (bytes + PAGE_MASK) & ~(size_t)PAGE_MASK;
                tcb = mmap((void *)1, bytes,
                           PROT_READ | PROT_WRITE,
                           MAP_PRIVATE | MAP_ANON,
                           -1, 0);
        } else {
                tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv));
        }

        tcb = (struct tls_tcb *)((char *)tcb + data_size);
        dtv = (Elf_Addr *)(tcb + 1);

        memset(tcb, 0, sizeof(*tcb));
#ifdef RTLD_TCB_HAS_SELF_POINTER
        tcb->tcb_self = tcb;
#endif
        tcb->tcb_dtv = dtv;

        /*
         * Dummy-up the module array.  A static binary has only one.  This
         * allows us to support the generic __tls_get_addr compiler ABI
         * function.  However, if there is no RTLD linked in, nothing in
         * the program should ever call __tls_get_addr (and our version
         * of it doesn't do anything).
         */
        dtv[0] = 1;
        dtv[1] = 1;
        dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space);

        memcpy((char *)tcb - tls_static_space,
                tls_init, tls_init_size);
        memset((char *)tcb - tls_static_space + tls_init_size,
                0, tls_static_space - tls_init_size);

        /*
         * Activate the initial TCB
         */
        if (initial_tcb == NULL) {
                initial_tcb = tcb;
                tls_set_tcb(tcb);
        }
        return (tcb);
}

#else

struct tls_tcb *
__libc_allocate_tls(void)
{
        return (NULL);
}

void
__libc_free_tls(struct tls_tcb *tcb __unused)
{
}

#endif /* PIC */

void
__libc_call_init(void)
{
}

extern char **environ;

struct tls_tcb *
_libc_init_tls(void)
{
        struct tls_tcb *tcb;

#ifndef PIC
        /*
         * If this is a static binary there is no RTLD and so we have not
         * yet calculated the static space requirement.  Do so now.
         */
        Elf_Addr *sp;
        Elf_Auxinfo *aux, *auxp;
        Elf_Phdr *phdr;
        size_t phent, phnum;
        int i;

        sp = (Elf_Addr *) environ;
        while (*sp++ != 0)
                ;
        aux = (Elf_Auxinfo *) sp;
        phdr = NULL;
        phent = phnum = 0;
        for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
                switch (auxp->a_type) {
                case AT_PHDR:
                        phdr = auxp->a_un.a_ptr;
                        break;

                case AT_PHENT:
                        phent = auxp->a_un.a_val;
                        break;

                case AT_PHNUM:
                        phnum = auxp->a_un.a_val;
                        break;
                }
        }
        if (phdr == NULL || phent != sizeof(Elf_Phdr) || phnum == 0)
                return(NULL);

        for (i = 0; (unsigned)i < phnum; i++) {
                if (phdr[i].p_type == PT_TLS) {
                        tls_static_space = roundup2(phdr[i].p_memsz,
                            phdr[i].p_align);
                        tls_init_size = phdr[i].p_filesz;
                        tls_init = (void*) phdr[i].p_vaddr;
                }
        }
#endif

        /*
         * Allocate the initial TLS segment.  The TLS has not been set up
         * yet for either the static or dynamic linked case (RTLD no longer
         * sets up an initial TLS segment for us).
         */
        tcb = _libc_allocate_tls();
        tls_set_tcb(tcb);
        return(tcb);
}

/*
 * Allocate a standard TLS.  This function is called by libc and by 
 * thread libraries to create a new TCB with libc-related fields properly
 * initialized (whereas _rtld_allocate_tls() is unable to completely set
 * up the TCB).
 *
 * Note that this is different from __libc_allocate_tls which is the
 * weakly bound symbol that handles the case where _rtld_allocate_tls
 * does not exist.
 */
struct tls_tcb *
_libc_allocate_tls(void)
{
        struct tls_tcb *tcb;

        tcb = _rtld_allocate_tls();
        return(tcb);
}

__weak_reference(__libc_allocate_tls, _rtld_allocate_tls);
__weak_reference(__libc_free_tls, _rtld_free_tls);
__weak_reference(__libc_call_init, _rtld_call_init);
__weak_reference(__libc_tls_get_addr, __tls_get_addr);
__weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb);
__weak_reference(_libc_init_tls, _init_tls);