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/*
* Copyright (c) 2008 Mans Rullgard <mans@mansr.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#ifdef __ELF__
# define ELF
#else
# define ELF #
#endif
#if HAVE_AS_FUNC
# define FUNC
#else
# define FUNC #
#endif
#ifndef __has_feature
# define __has_feature(x) 0
#endif
/* Support macros for
* - Armv8.3-A Pointer Authentication and
* - Armv8.5-A Branch Target Identification
* features which require emitting a .note.gnu.property section with the
* appropriate architecture-dependent feature bits set.
*
* |AARCH64_SIGN_LINK_REGISTER| and |AARCH64_VALIDATE_LINK_REGISTER| expand to
* PACIxSP and AUTIxSP, respectively. |AARCH64_SIGN_LINK_REGISTER| should be
* used immediately before saving the LR register (x30) to the stack.
* |AARCH64_VALIDATE_LINK_REGISTER| should be used immediately after restoring
* it. Note |AARCH64_SIGN_LINK_REGISTER|'s modifications to LR must be undone
* with |AARCH64_VALIDATE_LINK_REGISTER| before RET. The SP register must also
* have the same value at the two points. For example:
*
* .global f
* f:
* AARCH64_SIGN_LINK_REGISTER
* stp x29, x30, [sp, #-96]!
* mov x29, sp
* ...
* ldp x29, x30, [sp], #96
* AARCH64_VALIDATE_LINK_REGISTER
* ret
*
* |AARCH64_VALID_CALL_TARGET| expands to BTI 'c'. Either it, or
* |AARCH64_SIGN_LINK_REGISTER|, must be used at every point that may be an
* indirect call target. In particular, all symbols exported from a file must
* begin with one of these macros. For example, a leaf function that does not
* save LR can instead use |AARCH64_VALID_CALL_TARGET|:
*
* .globl return_zero
* return_zero:
* AARCH64_VALID_CALL_TARGET
* mov x0, #0
* ret
*
* A non-leaf function which does not immediately save LR may need both macros
* because |AARCH64_SIGN_LINK_REGISTER| appears late. For example, the function
* may jump to an alternate implementation before setting up the stack:
*
* .globl with_early_jump
* with_early_jump:
* AARCH64_VALID_CALL_TARGET
* cmp x0, #128
* b.lt .Lwith_early_jump_128
* AARCH64_SIGN_LINK_REGISTER
* stp x29, x30, [sp, #-96]!
* mov x29, sp
* ...
* ldp x29, x30, [sp], #96
* AARCH64_VALIDATE_LINK_REGISTER
* ret
*
* .Lwith_early_jump_128:
* ...
* ret
*
* These annotations are only required with indirect calls. Private symbols that
* are only the target of direct calls do not require annotations. Also note
* that |AARCH64_VALID_CALL_TARGET| is only valid for indirect calls (BLR), not
* indirect jumps (BR). Indirect jumps in assembly are supported through
* |AARCH64_VALID_JUMP_TARGET|. Landing Pads which shall serve for jumps and
* calls can be created using |AARCH64_VALID_JUMP_CALL_TARGET|.
*
* Although not necessary, it is safe to use these macros in 32-bit ARM
* assembly. This may be used to simplify dual 32-bit and 64-bit files.
*
* References:
* - "ELF for the Arm® 64-bit Architecture"
* https: *github.com/ARM-software/abi-aa/blob/master/aaelf64/aaelf64.rst
* - "Providing protection for complex software"
* https://developer.arm.com/architectures/learn-the-architecture/providing-protection-for-complex-software
*/
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
# define GNU_PROPERTY_AARCH64_BTI (1 << 0) // Has BTI
# define AARCH64_VALID_CALL_TARGET hint #34 // BTI 'c'
# define AARCH64_VALID_JUMP_TARGET hint #38 // BTI 'j'
#else
# define GNU_PROPERTY_AARCH64_BTI 0 // No BTI
# define AARCH64_VALID_CALL_TARGET
# define AARCH64_VALID_JUMP_TARGET
#endif
#if defined(__ARM_FEATURE_PAC_DEFAULT)
# if ((__ARM_FEATURE_PAC_DEFAULT & (1 << 0)) != 0) // authentication using key A
# define AARCH64_SIGN_LINK_REGISTER paciasp
# define AARCH64_VALIDATE_LINK_REGISTER autiasp
# elif ((__ARM_FEATURE_PAC_DEFAULT & (1 << 1)) != 0) // authentication using key B
# define AARCH64_SIGN_LINK_REGISTER pacibsp
# define AARCH64_VALIDATE_LINK_REGISTER autibsp
# else
# error Pointer authentication defines no valid key!
# endif
# if ((__ARM_FEATURE_PAC_DEFAULT & (1 << 2)) != 0)
# error Authentication of leaf functions is enabled but not supported in FFmpeg!
# endif
# define GNU_PROPERTY_AARCH64_PAC (1 << 1)
#else
# define GNU_PROPERTY_AARCH64_PAC 0
# define AARCH64_SIGN_LINK_REGISTER
# define AARCH64_VALIDATE_LINK_REGISTER
#endif
#if (GNU_PROPERTY_AARCH64_BTI != 0 || GNU_PROPERTY_AARCH64_PAC != 0) && defined(__ELF__)
.pushsection .note.gnu.property, "a"
.balign 8
.long 4
.long 0x10
.long 0x5
.asciz "GNU"
.long 0xc0000000 /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */
.long 4
.long (GNU_PROPERTY_AARCH64_BTI | GNU_PROPERTY_AARCH64_PAC)
.long 0
.popsection
#endif
.macro function name, export=0, align=2
.macro endfunc
ELF .size \name, . - \name
FUNC .endfunc
.purgem endfunc
.endm
.text
.align \align
.if \export
.global EXTERN_ASM\name
ELF .type EXTERN_ASM\name, %function
FUNC .func EXTERN_ASM\name
EXTERN_ASM\name:
AARCH64_VALID_CALL_TARGET
.else
ELF .type \name, %function
FUNC .func \name
\name:
.endif
.endm
.macro const name, align=2, relocate=0
.macro endconst
ELF .size \name, . - \name
.purgem endconst
.endm
#if HAVE_SECTION_DATA_REL_RO
.if \relocate
.section .data.rel.ro
.else
.section .rodata
.endif
#elif defined(_WIN32)
.section .rdata
#elif !defined(__MACH__)
.section .rodata
#else
.const_data
#endif
.align \align
\name:
.endm
.macro movrel rd, val, offset=0
#if CONFIG_PIC && defined(__APPLE__)
.if \offset < 0
adrp \rd, \val@PAGE
add \rd, \rd, \val@PAGEOFF
sub \rd, \rd, -(\offset)
.else
adrp \rd, \val+(\offset)@PAGE
add \rd, \rd, \val+(\offset)@PAGEOFF
.endif
#elif CONFIG_PIC && defined(_WIN32)
.if \offset < 0
adrp \rd, \val
add \rd, \rd, :lo12:\val
sub \rd, \rd, -(\offset)
.else
adrp \rd, \val+(\offset)
add \rd, \rd, :lo12:\val+(\offset)
.endif
#elif CONFIG_PIC
# if __has_feature(hwaddress_sanitizer)
adrp \rd, :pg_hi21_nc:\val+(\offset)
# else
adrp \rd, \val+(\offset)
# endif
add \rd, \rd, :lo12:\val+(\offset)
#else
ldr \rd, =\val+\offset
#endif
.endm
#define GLUE(a, b) a ## b
#define JOIN(a, b) GLUE(a, b)
#define X(s) JOIN(EXTERN_ASM, s)
#define x18 do_not_use_x18
#define w18 do_not_use_w18
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