/*

 * Mesa 3-D graphics library

 *

 * Copyright (C) 2010 LunarG Inc.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included

 * in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 *

 * Authors:

 *    Chia-I Wu <olv@lunarg.com>

 */

#include "entry.h"

#include "entry_common.h"

#include <assert.h>

#include <stdint.h>

#include <sys/mman.h>

#include <unistd.h>

#include <string.h>

#include "u_macros.h"

#include "glapi.h"

#include "glvnd/GLdispatchABI.h"

#define ENTRY_STUB_ALIGN 64

#if !defined(GLDISPATCH_PAGE_SIZE)

#define GLDISPATCH_PAGE_SIZE 4096

#endif

__asm__(".section wtext,\"ax\",@progbits\n");

__asm__(".balign " U_STRINGIFY(GLDISPATCH_PAGE_SIZE) "\n"

       ".globl public_entry_start\n"

       ".hidden public_entry_start\n"

        "public_entry_start:");

#define STUB_ASM_ENTRY(func)        \

    ".globl " func "\n"              \

    ".type " func ", @function\n"    \

    ".balign " U_STRINGIFY(ENTRY_STUB_ALIGN) "\n" \

    func ":\n"

#define STUB_ASM_CODE(slot)         \

    "push %ebx\n" \

    "call 1f\n" \

    "1:\n" \

    "popl %ebx\n" \

    "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ebx\n" \

    "movl _glapi_Current@GOT(%ebx), %eax\n" \

    "mov (%eax), %eax\n" \

    "testl %eax, %eax\n" \

    "jne 1f\n" \

    "call _glapi_get_current@PLT\n" \

    "1:\n" \

    "pop %ebx\n" \

    "jmp *(4 * " slot ")(%eax)\n"

#define MAPI_TMP_STUB_ASM_GCC

#include "mapi_tmp.h"

__asm__(".balign " U_STRINGIFY(GLDISPATCH_PAGE_SIZE) "\n"

       ".globl public_entry_end\n"

       ".hidden public_entry_end\n"

        "public_entry_end:");

__asm__(".text\n");

const int entry_type = __GLDISPATCH_STUB_X86;

const int entry_stub_size = ENTRY_STUB_ALIGN;

// Note that the generated stubs are simpler than the assembly stubs above.

// For the generated stubs, we can patch in the addresses of _glapi_Current and

// _glapi_get_current, so we don't need to go through the GOT and PLT lookups.

static const unsigned char ENTRY_TEMPLATE[] =

{

    0xa1, 0x40, 0x30, 0x20, 0x10,       // <ENTRY>:    mov    _glapi_Current, %eax

    0x85, 0xc0,                         // <ENTRY+5>:  test   %eax, %eax

    0x74, 0x06,                         // <ENTRY+7>:  je     <ENTRY+15>

    0xff, 0xa0, 0x40, 0x30, 0x20, 0x10, // <ENTRY+9>:  jmp    *slot(%eax)

    0xe8, 0x40, 0x30, 0x20, 0x10,       // <ENTRY+15>: call   _glapi_get_current

    0xff, 0xa0, 0x40, 0x30, 0x20, 0x10, // <ENTRY+20>: jmp    *slot(%eax)

};

// These are the offsets in ENTRY_TEMPLATE of the values that we have to patch.

static const int TEMPLATE_OFFSET_CURRENT_TABLE = 1;

static const int TEMPLATE_OFFSET_CURRENT_TABLE_GET = 16;

static const int TEMPLATE_OFFSET_CURRENT_TABLE_GET_RELATIVE = 20;

static const int TEMPLATE_OFFSET_SLOT1 = 11;

static const int TEMPLATE_OFFSET_SLOT2 = 22;

void entry_generate_default_code(char *entry, int slot)

{

    char *writeEntry = u_execmem_get_writable(entry);

    uintptr_t getTableOffset;

    memcpy(writeEntry, ENTRY_TEMPLATE, sizeof(ENTRY_TEMPLATE));

    *((uint32_t *) (writeEntry + TEMPLATE_OFFSET_SLOT1)) = slot * sizeof(mapi_func);

    *((uint32_t *) (writeEntry + TEMPLATE_OFFSET_SLOT2)) = slot * sizeof(mapi_func);

    *((uintptr_t *) (writeEntry + TEMPLATE_OFFSET_CURRENT_TABLE)) = (uintptr_t) _glapi_Current;

    // Calculate the offset to patch for the CALL instruction to

    // _glapi_get_current.

    getTableOffset = (uintptr_t) _glapi_get_current;

    getTableOffset -= (((uintptr_t) entry) + TEMPLATE_OFFSET_CURRENT_TABLE_GET_RELATIVE);

    *((uintptr_t *) (writeEntry + TEMPLATE_OFFSET_CURRENT_TABLE_GET)) = getTableOffset;

}