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llvm-project/libunwind/src/assembly.h
gejin 21b25a1fb3 [libunwind] Support stack unwind in CET environment 
Control-flow Enforcement Technology (CET), published by Intel,
introduces shadow stack feature aiming to ensure a return from
a function is directed to where the function was called.
In a CET enabled system, each function call will push return
address into normal stack and shadow stack, when the function
returns, the address stored in shadow stack will be popped and
compared with the return address, program will fail if the 2
addresses don't match.
In exception handling, the control flow may skip some stack frames
and we must adjust shadow stack to avoid violating CET restriction.
In order to achieve this, we count the number of stack frames skipped
and adjust shadow stack by this number before jumping to landing pad.

Reviewed By: hjl.tools, compnerd, MaskRay
Differential Revision: https://reviews.llvm.org/D105968

Signed-off-by: gejin <ge.jin@intel.com>
2021-08-26 16:20:38 +08:00

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/* ===-- assembly.h - libUnwind assembler support macros -------------------===
*
* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
* See https://llvm.org/LICENSE.txt for license information.
* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
*
* ===----------------------------------------------------------------------===
*
* This file defines macros for use in libUnwind assembler source.
* This file is not part of the interface of this library.
*
* ===----------------------------------------------------------------------===
*/
#ifndef UNWIND_ASSEMBLY_H
#define UNWIND_ASSEMBLY_H
#if (defined(__i386__) || defined(__x86_64__)) && defined(__linux__)
#include <cet.h>
#define _LIBUNWIND_CET_ENDBR _CET_ENDBR
#else
#define _LIBUNWIND_CET_ENDBR
#endif
#if defined(__powerpc64__)
#define SEPARATOR ;
#define PPC64_OFFS_SRR0 0
#define PPC64_OFFS_CR 272
#define PPC64_OFFS_XER 280
#define PPC64_OFFS_LR 288
#define PPC64_OFFS_CTR 296
#define PPC64_OFFS_VRSAVE 304
#define PPC64_OFFS_FP 312
#define PPC64_OFFS_V 824
#elif defined(__APPLE__) && defined(__aarch64__)
#define SEPARATOR %%
#elif defined(__riscv)
# define RISCV_ISIZE (__riscv_xlen / 8)
# define RISCV_FOFFSET (RISCV_ISIZE * 32)
# if defined(__riscv_flen)
# define RISCV_FSIZE (__riscv_flen / 8)
# endif
# if __riscv_xlen == 64
# define ILOAD ld
# define ISTORE sd
# elif __riscv_xlen == 32
# define ILOAD lw
# define ISTORE sw
# else
# error "Unsupported __riscv_xlen"
# endif
# if defined(__riscv_flen)
# if __riscv_flen == 64
# define FLOAD fld
# define FSTORE fsd
# elif __riscv_flen == 32
# define FLOAD flw
# define FSTORE fsw
# else
# error "Unsupported __riscv_flen"
# endif
# endif
# define SEPARATOR ;
#else
#define SEPARATOR ;
#endif
#if defined(__powerpc64__) && (!defined(_CALL_ELF) || _CALL_ELF == 1)
#define PPC64_OPD1 .section .opd,"aw",@progbits SEPARATOR
#define PPC64_OPD2 SEPARATOR \
.p2align 3 SEPARATOR \
.quad .Lfunc_begin0 SEPARATOR \
.quad .TOC.@tocbase SEPARATOR \
.quad 0 SEPARATOR \
.text SEPARATOR \
.Lfunc_begin0:
#else
#define PPC64_OPD1
#define PPC64_OPD2
#endif
#if defined(__ARM_FEATURE_BTI_DEFAULT)
.pushsection ".note.gnu.property", "a" SEPARATOR \
.balign 8 SEPARATOR \
.long 4 SEPARATOR \
.long 0x10 SEPARATOR \
.long 0x5 SEPARATOR \
.asciz "GNU" SEPARATOR \
.long 0xc0000000 SEPARATOR /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */ \
.long 4 SEPARATOR \
.long 3 SEPARATOR /* GNU_PROPERTY_AARCH64_FEATURE_1_BTI AND */ \
/* GNU_PROPERTY_AARCH64_FEATURE_1_PAC */ \
.long 0 SEPARATOR \
.popsection SEPARATOR
#define AARCH64_BTI bti c
#else
#define AARCH64_BTI
#endif
#define GLUE2(a, b) a ## b
#define GLUE(a, b) GLUE2(a, b)
#define SYMBOL_NAME(name) GLUE(__USER_LABEL_PREFIX__, name)
#if defined(__APPLE__)
#define SYMBOL_IS_FUNC(name)
#define HIDDEN_SYMBOL(name) .private_extern name
#if defined(_LIBUNWIND_HIDE_SYMBOLS)
#define EXPORT_SYMBOL(name) HIDDEN_SYMBOL(name)
#else
#define EXPORT_SYMBOL(name)
#endif
#define WEAK_ALIAS(name, aliasname) \
.globl SYMBOL_NAME(aliasname) SEPARATOR \
EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
SYMBOL_NAME(aliasname) = SYMBOL_NAME(name)
#define NO_EXEC_STACK_DIRECTIVE
#elif defined(__ELF__)
#if defined(__arm__)
#define SYMBOL_IS_FUNC(name) .type name,%function
#else
#define SYMBOL_IS_FUNC(name) .type name,@function
#endif
#define HIDDEN_SYMBOL(name) .hidden name
#if defined(_LIBUNWIND_HIDE_SYMBOLS)
#define EXPORT_SYMBOL(name) HIDDEN_SYMBOL(name)
#else
#define EXPORT_SYMBOL(name)
#endif
#define WEAK_SYMBOL(name) .weak name
#if defined(__hexagon__)
#define WEAK_ALIAS(name, aliasname) \
EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
WEAK_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
.equiv SYMBOL_NAME(aliasname), SYMBOL_NAME(name)
#else
#define WEAK_ALIAS(name, aliasname) \
EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
WEAK_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
SYMBOL_NAME(aliasname) = SYMBOL_NAME(name)
#endif
#if defined(__GNU__) || defined(__FreeBSD__) || defined(__Fuchsia__) || \
defined(__linux__)
#define NO_EXEC_STACK_DIRECTIVE .section .note.GNU-stack,"",%progbits
#else
#define NO_EXEC_STACK_DIRECTIVE
#endif
#elif defined(_WIN32)
#define SYMBOL_IS_FUNC(name) \
.def name SEPARATOR \
.scl 2 SEPARATOR \
.type 32 SEPARATOR \
.endef
#define EXPORT_SYMBOL2(name) \
.section .drectve,"yn" SEPARATOR \
.ascii "-export:", #name, "\0" SEPARATOR \
.text
#if defined(_LIBUNWIND_HIDE_SYMBOLS)
#define EXPORT_SYMBOL(name)
#else
#define EXPORT_SYMBOL(name) EXPORT_SYMBOL2(name)
#endif
#define HIDDEN_SYMBOL(name)
#if defined(__MINGW32__)
#define WEAK_ALIAS(name, aliasname) \
.globl SYMBOL_NAME(aliasname) SEPARATOR \
EXPORT_SYMBOL(aliasname) SEPARATOR \
SYMBOL_NAME(aliasname) = SYMBOL_NAME(name)
#else
#define WEAK_ALIAS3(name, aliasname) \
.section .drectve,"yn" SEPARATOR \
.ascii "-alternatename:", #aliasname, "=", #name, "\0" SEPARATOR \
.text
#define WEAK_ALIAS2(name, aliasname) \
WEAK_ALIAS3(name, aliasname)
#define WEAK_ALIAS(name, aliasname) \
EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
WEAK_ALIAS2(SYMBOL_NAME(name), SYMBOL_NAME(aliasname))
#endif
#define NO_EXEC_STACK_DIRECTIVE
#elif defined(__sparc__)
#else
#error Unsupported target
#endif
#define DEFINE_LIBUNWIND_FUNCTION(name) \
.globl SYMBOL_NAME(name) SEPARATOR \
HIDDEN_SYMBOL(SYMBOL_NAME(name)) SEPARATOR \
SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR \
PPC64_OPD1 \
SYMBOL_NAME(name): \
PPC64_OPD2 \
AARCH64_BTI
#if defined(__arm__)
#if !defined(__ARM_ARCH)
#define __ARM_ARCH 4
#endif
#if defined(__ARM_ARCH_4T__) || __ARM_ARCH >= 5
#define ARM_HAS_BX
#endif
#ifdef ARM_HAS_BX
#define JMP(r) bx r
#else
#define JMP(r) mov pc, r
#endif
#endif /* __arm__ */
#if defined(__ppc__) || defined(__powerpc64__)
#define PPC_LEFT_SHIFT(index) << (index)
#endif
#endif /* UNWIND_ASSEMBLY_H */
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