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/*
* Copyright (c) 2015, NVIDIA CORPORATION.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and/or associated documentation files (the
* "Materials"), to deal in the Materials without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Materials, and to
* permit persons to whom the Materials are furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* unaltered in all copies or substantial portions of the Materials.
* Any additions, deletions, or changes to the original source files
* must be clearly indicated in accompanying documentation.
*
* If only executable code is distributed, then the accompanying
* documentation must state that "this software is based in part on the
* work of the Khronos Group."
*
* THE MATERIALS ARE 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
* MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
*/
#include "entry.h"
#include "entry_common.h"
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <assert.h>
#include "glapi/glapi.h"
#include "u_macros.h"
#include "u_current.h"
#include "utils_misc.h"
#include "glvnd/GLdispatchABI.h"
/*
* See: https://sourceware.org/binutils/docs/as/ARM-Directives.html
*/
__asm__(".syntax unified\n\t");
/*
* u_execmem_alloc() allocates 64 bytes per stub.
*/
#define ARMV7_ENTRY_SIZE 64
/*
* This runs in Thumb mode.
*
* libglvnd on armv7 is built with -march=armv7-a, which uses the AAPCS ABI
* that has ARM/Thumb interworking enabled by default.
*
* See: https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html
*/
#define STUB_ASM_ENTRY(func) \
".balign " U_STRINGIFY(ARMV7_ENTRY_SIZE) "\n\t" \
".thumb_func\n\t" \
".global " func "\n\t" \
".type " func ", %function\n\t" \
func ":\n\t"
/*
* Looks up the current dispatch table, finds the stub address at the given slot
* then jumps to it.
*
* First tries to find a dispatch table in _glapi_Current[GLAPI_CURRENT_DISPATCH],
* if not found then it jumps to the 'lookup_dispatch' and calls
* _glapi_get_current() then jumps back to the 'found_dispatch' label.
*
* The 'found_dispatch' section computes the correct offset in the dispatch
* table then does a branch without link to the function address.
*
* This routine preserves the r0-r3 volatile registers as they store the
* parameters of the entry point that is being looked up.
*/
#define STUB_ASM_CODE(slot) \
"push {r0-r3}\n\t" \
"ldr r0, 1f\n\t" \
"ldr r0, [r0]\n\t" \
"cmp r0, #0\n\t" \
"it eq\n\t" \
"beq 10f\n\t" \
"11:\n\t" /* found_dispatch */ \
"ldr r1, 3f\n\t" \
"mov r2, #4\n\t" /* sizeof(void *) */ \
"mul r1, r1, r2\n\t" \
"ldr ip, [r0, +r1]\n\t" \
"pop {r0-r3}\n\t" \
"bx ip\n\t" \
"10:\n\t" /* lookup_dispatch */ \
"push {lr}\n\t" \
"ldr r0, 2f\n\t" \
"blx r0\n\t" \
"pop {lr}\n\t" \
"b 11b\n\t" \
"1:\n\t" \
".word _glapi_Current\n\t" \
"2:\n\t" \
".word _glapi_get_current\n\t" \
"3:\n\t" \
".word " slot "\n\t"
/*
* Bytecode for STUB_ASM_CODE()
*/
static unsigned char BYTECODE_TEMPLATE[] =
{
0xb4, 0x0f,
0xf8, 0xdf, 0x00, 0x28,
0x68, 0x00,
0x28, 0x00,
0xbf, 0x08,
0xe0, 0x08,
0x49, 0x09,
0xf0, 0x4f, 0x02, 0x04,
0xfb, 0x01, 0xf1, 0x02,
0xf8, 0x50, 0xc0, 0x01,
0xbc, 0x0f,
0x47, 0x60,
0xb5, 0x00,
0x48, 0x03,
0x47, 0x80,
0xf8, 0x5d, 0xeb, 0x04,
0xe7, 0xf0,
// Offsets that need to be patched
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
};
#define ARMV7_BYTECODE_SIZE sizeof(BYTECODE_TEMPLATE)
__asm__(".section wtext,\"ax\"\n"
".balign 4096\n"
".globl public_entry_start\n"
"public_entry_start:\n");
#define MAPI_TMP_STUB_ASM_GCC
#include "mapi_tmp.h"
__asm__(".balign 4096\n"
".globl public_entry_end\n"
"public_entry_end:\n"
".text\n\t");
/*
* If built with -marm, let the assembler know that we are done with Thumb
*/
#if !defined(__thumb__)
__asm__(".arm\n\t");
#endif
const int entry_type = __GLDISPATCH_STUB_ARMV7_THUMB;
const int entry_stub_size = ARMV7_ENTRY_SIZE;
static const int TEMPLATE_OFFSET_CURRENT_TABLE = ARMV7_BYTECODE_SIZE - 3*4;
static const int TEMPLATE_OFFSET_CURRENT_TABLE_GET = ARMV7_BYTECODE_SIZE - 2*4;
static const int TEMPLATE_OFFSET_SLOT = ARMV7_BYTECODE_SIZE - 4;
static const int TEMPLATE_OFFSETS_SIZE = 3*4;
void
entry_init_public(void)
{
STATIC_ASSERT(ARMV7_BYTECODE_SIZE <= ARMV7_ENTRY_SIZE);
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
glvnd_byte_swap16((uint16_t *)BYTECODE_TEMPLATE,
entry_stub_size - TEMPLATE_OFFSETS_SIZE);
#endif
}
void entry_generate_default_code(char *entry, int slot)
{
char *writeEntry;
// Make sure the base address has the Thumb mode bit
assert((uintptr_t)entry & (uintptr_t)0x1);
// Get the pointer to the writable mapping.
writeEntry = (char *) u_execmem_get_writable(entry - 1);
memcpy(writeEntry, BYTECODE_TEMPLATE, ARMV7_BYTECODE_SIZE);
*((uint32_t *)(writeEntry + TEMPLATE_OFFSET_SLOT)) = slot;
*((uint32_t *)(writeEntry + TEMPLATE_OFFSET_CURRENT_TABLE)) =
(uint32_t)_glapi_Current;
*((uint32_t *)(writeEntry + TEMPLATE_OFFSET_CURRENT_TABLE_GET)) =
(uint32_t)_glapi_get_current;
// See http://community.arm.com/groups/processors/blog/2010/02/17/caches-and-self-modifying-code
__builtin___clear_cache(writeEntry, writeEntry + ARMV7_BYTECODE_SIZE);
}
// Note: The rest of these functions could also be used for ARMv7 TLS stubs,
// once those are implemented.
mapi_func
entry_get_public(int index)
{
// Add 1 to the base address to force Thumb mode when jumping to the stub
return (mapi_func)(public_entry_start + (index * entry_stub_size) + 1);
}
void entry_get_patch_addresses(mapi_func entry, void **writePtr, const void **execPtr)
{
// Get the actual beginning of the stub allocation
void *entryBase = (void *) (((uintptr_t) entry) - 1);
*execPtr = (const void *) entryBase;
*writePtr = u_execmem_get_writable(entryBase);
}
#if !defined(STATIC_DISPATCH_ONLY)
mapi_func entry_generate(int slot)
{
void *code = u_execmem_alloc(entry_stub_size);
if (!code) {
return NULL;
}
// Add 1 to the base address to force Thumb mode when jumping to the stub
code = (void *)((char *)code + 1);
entry_generate_default_code(code, slot);
return (mapi_func) code;
}
#endif // !defined(STATIC_DISPATCH_ONLY)
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