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c++ source #1
Output
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Intel asm syntax
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Filters
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Debug intrinsics
Compiler
6502-c++ 11.1.0
ARM GCC 10.2.0
ARM GCC 10.3.0
ARM GCC 10.4.0
ARM GCC 10.5.0
ARM GCC 11.1.0
ARM GCC 11.2.0
ARM GCC 11.3.0
ARM GCC 11.4.0
ARM GCC 12.1.0
ARM GCC 12.2.0
ARM GCC 12.3.0
ARM GCC 12.4.0
ARM GCC 13.1.0
ARM GCC 13.2.0
ARM GCC 13.2.0 (unknown-eabi)
ARM GCC 13.3.0
ARM GCC 13.3.0 (unknown-eabi)
ARM GCC 14.1.0
ARM GCC 14.1.0 (unknown-eabi)
ARM GCC 14.2.0
ARM GCC 14.2.0 (unknown-eabi)
ARM GCC 4.5.4
ARM GCC 4.6.4
ARM GCC 5.4
ARM GCC 6.3.0
ARM GCC 6.4.0
ARM GCC 7.3.0
ARM GCC 7.5.0
ARM GCC 8.2.0
ARM GCC 8.5.0
ARM GCC 9.3.0
ARM GCC 9.4.0
ARM GCC 9.5.0
ARM GCC trunk
ARM gcc 10.2.1 (none)
ARM gcc 10.3.1 (2021.07 none)
ARM gcc 10.3.1 (2021.10 none)
ARM gcc 11.2.1 (none)
ARM gcc 5.4.1 (none)
ARM gcc 7.2.1 (none)
ARM gcc 8.2 (WinCE)
ARM gcc 8.3.1 (none)
ARM gcc 9.2.1 (none)
ARM msvc v19.0 (WINE)
ARM msvc v19.10 (WINE)
ARM msvc v19.14 (WINE)
ARM64 Morello gcc 10.1 Alpha 2
ARM64 gcc 10.2
ARM64 gcc 10.3
ARM64 gcc 10.4
ARM64 gcc 10.5.0
ARM64 gcc 11.1
ARM64 gcc 11.2
ARM64 gcc 11.3
ARM64 gcc 11.4.0
ARM64 gcc 12.1
ARM64 gcc 12.2.0
ARM64 gcc 12.3.0
ARM64 gcc 12.4.0
ARM64 gcc 13.1.0
ARM64 gcc 13.2.0
ARM64 gcc 13.3.0
ARM64 gcc 14.1.0
ARM64 gcc 14.2.0
ARM64 gcc 4.9.4
ARM64 gcc 5.4
ARM64 gcc 5.5.0
ARM64 gcc 6.3
ARM64 gcc 6.4
ARM64 gcc 7.3
ARM64 gcc 7.5
ARM64 gcc 8.2
ARM64 gcc 8.5
ARM64 gcc 9.3
ARM64 gcc 9.4
ARM64 gcc 9.5
ARM64 gcc trunk
ARM64 msvc v19.14 (WINE)
AVR gcc 10.3.0
AVR gcc 11.1.0
AVR gcc 12.1.0
AVR gcc 12.2.0
AVR gcc 12.3.0
AVR gcc 12.4.0
AVR gcc 13.1.0
AVR gcc 13.2.0
AVR gcc 13.3.0
AVR gcc 14.1.0
AVR gcc 14.2.0
AVR gcc 4.5.4
AVR gcc 4.6.4
AVR gcc 5.4.0
AVR gcc 9.2.0
AVR gcc 9.3.0
Arduino Mega (1.8.9)
Arduino Uno (1.8.9)
BPF clang (trunk)
BPF clang 13.0.0
BPF clang 14.0.0
BPF clang 15.0.0
BPF clang 16.0.0
BPF clang 17.0.1
BPF clang 18.1.0
BPF clang 19.1.0
BPF gcc 13.1.0
BPF gcc 13.2.0
BPF gcc 13.3.0
BPF gcc trunk
EDG (experimental reflection)
EDG 6.5
EDG 6.5 (GNU mode gcc 13)
EDG 6.6
EDG 6.6 (GNU mode gcc 13)
FRC 2019
FRC 2020
FRC 2023
KVX ACB 4.1.0 (GCC 7.5.0)
KVX ACB 4.1.0-cd1 (GCC 7.5.0)
KVX ACB 4.10.0 (GCC 10.3.1)
KVX ACB 4.11.1 (GCC 10.3.1)
KVX ACB 4.12.0 (GCC 11.3.0)
KVX ACB 4.2.0 (GCC 7.5.0)
KVX ACB 4.3.0 (GCC 7.5.0)
KVX ACB 4.4.0 (GCC 7.5.0)
KVX ACB 4.6.0 (GCC 9.4.1)
KVX ACB 4.8.0 (GCC 9.4.1)
KVX ACB 4.9.0 (GCC 9.4.1)
KVX ACB 5.0.0 (GCC 12.2.1)
LoongArch64 clang (trunk)
LoongArch64 clang 17.0.1
LoongArch64 clang 18.1.0
LoongArch64 clang 19.1.0
M68K gcc 13.1.0
M68K gcc 13.2.0
M68K gcc 13.3.0
M68K gcc 14.1.0
M68K gcc 14.2.0
M68k clang (trunk)
MRISC32 gcc (trunk)
MSP430 gcc 4.5.3
MSP430 gcc 5.3.0
MSP430 gcc 6.2.1
MinGW clang 14.0.3
MinGW clang 14.0.6
MinGW clang 15.0.7
MinGW clang 16.0.0
MinGW clang 16.0.2
MinGW gcc 11.3.0
MinGW gcc 12.1.0
MinGW gcc 12.2.0
MinGW gcc 13.1.0
RISC-V (32-bits) gcc (trunk)
RISC-V (32-bits) gcc 10.2.0
RISC-V (32-bits) gcc 10.3.0
RISC-V (32-bits) gcc 11.2.0
RISC-V (32-bits) gcc 11.3.0
RISC-V (32-bits) gcc 11.4.0
RISC-V (32-bits) gcc 12.1.0
RISC-V (32-bits) gcc 12.2.0
RISC-V (32-bits) gcc 12.3.0
RISC-V (32-bits) gcc 12.4.0
RISC-V (32-bits) gcc 13.1.0
RISC-V (32-bits) gcc 13.2.0
RISC-V (32-bits) gcc 13.3.0
RISC-V (32-bits) gcc 14.1.0
RISC-V (32-bits) gcc 14.2.0
RISC-V (32-bits) gcc 8.2.0
RISC-V (32-bits) gcc 8.5.0
RISC-V (32-bits) gcc 9.4.0
RISC-V (64-bits) gcc (trunk)
RISC-V (64-bits) gcc 10.2.0
RISC-V (64-bits) gcc 10.3.0
RISC-V (64-bits) gcc 11.2.0
RISC-V (64-bits) gcc 11.3.0
RISC-V (64-bits) gcc 11.4.0
RISC-V (64-bits) gcc 12.1.0
RISC-V (64-bits) gcc 12.2.0
RISC-V (64-bits) gcc 12.3.0
RISC-V (64-bits) gcc 12.4.0
RISC-V (64-bits) gcc 13.1.0
RISC-V (64-bits) gcc 13.2.0
RISC-V (64-bits) gcc 13.3.0
RISC-V (64-bits) gcc 14.1.0
RISC-V (64-bits) gcc 14.2.0
RISC-V (64-bits) gcc 8.2.0
RISC-V (64-bits) gcc 8.5.0
RISC-V (64-bits) gcc 9.4.0
RISC-V rv32gc clang (trunk)
RISC-V rv32gc clang 10.0.0
RISC-V rv32gc clang 10.0.1
RISC-V rv32gc clang 11.0.0
RISC-V rv32gc clang 11.0.1
RISC-V rv32gc clang 12.0.0
RISC-V rv32gc clang 12.0.1
RISC-V rv32gc clang 13.0.0
RISC-V rv32gc clang 13.0.1
RISC-V rv32gc clang 14.0.0
RISC-V rv32gc clang 15.0.0
RISC-V rv32gc clang 16.0.0
RISC-V rv32gc clang 17.0.1
RISC-V rv32gc clang 18.1.0
RISC-V rv32gc clang 19.1.0
RISC-V rv32gc clang 9.0.0
RISC-V rv32gc clang 9.0.1
RISC-V rv64gc clang (trunk)
RISC-V rv64gc clang 10.0.0
RISC-V rv64gc clang 10.0.1
RISC-V rv64gc clang 11.0.0
RISC-V rv64gc clang 11.0.1
RISC-V rv64gc clang 12.0.0
RISC-V rv64gc clang 12.0.1
RISC-V rv64gc clang 13.0.0
RISC-V rv64gc clang 13.0.1
RISC-V rv64gc clang 14.0.0
RISC-V rv64gc clang 15.0.0
RISC-V rv64gc clang 16.0.0
RISC-V rv64gc clang 17.0.1
RISC-V rv64gc clang 18.1.0
RISC-V rv64gc clang 19.1.0
RISC-V rv64gc clang 9.0.0
RISC-V rv64gc clang 9.0.1
Raspbian Buster
Raspbian Stretch
SPARC LEON gcc 12.2.0
SPARC LEON gcc 12.3.0
SPARC LEON gcc 12.4.0
SPARC LEON gcc 13.1.0
SPARC LEON gcc 13.2.0
SPARC LEON gcc 13.3.0
SPARC LEON gcc 14.1.0
SPARC LEON gcc 14.2.0
SPARC gcc 12.2.0
SPARC gcc 12.3.0
SPARC gcc 12.4.0
SPARC gcc 13.1.0
SPARC gcc 13.2.0
SPARC gcc 13.3.0
SPARC gcc 14.1.0
SPARC gcc 14.2.0
SPARC64 gcc 12.2.0
SPARC64 gcc 12.3.0
SPARC64 gcc 12.4.0
SPARC64 gcc 13.1.0
SPARC64 gcc 13.2.0
SPARC64 gcc 13.3.0
SPARC64 gcc 14.1.0
SPARC64 gcc 14.2.0
TI C6x gcc 12.2.0
TI C6x gcc 12.3.0
TI C6x gcc 12.4.0
TI C6x gcc 13.1.0
TI C6x gcc 13.2.0
TI C6x gcc 13.3.0
TI C6x gcc 14.1.0
TI C6x gcc 14.2.0
TI CL430 21.6.1
VAX gcc NetBSDELF 10.4.0
VAX gcc NetBSDELF 10.5.0 (Nov 15 03:50:22 2023)
WebAssembly clang (trunk)
Xtensa ESP32 gcc 11.2.0 (2022r1)
Xtensa ESP32 gcc 12.2.0 (20230208)
Xtensa ESP32 gcc 8.2.0 (2019r2)
Xtensa ESP32 gcc 8.2.0 (2020r1)
Xtensa ESP32 gcc 8.2.0 (2020r2)
Xtensa ESP32 gcc 8.4.0 (2020r3)
Xtensa ESP32 gcc 8.4.0 (2021r1)
Xtensa ESP32 gcc 8.4.0 (2021r2)
Xtensa ESP32-S2 gcc 11.2.0 (2022r1)
Xtensa ESP32-S2 gcc 12.2.0 (20230208)
Xtensa ESP32-S2 gcc 8.2.0 (2019r2)
Xtensa ESP32-S2 gcc 8.2.0 (2020r1)
Xtensa ESP32-S2 gcc 8.2.0 (2020r2)
Xtensa ESP32-S2 gcc 8.4.0 (2020r3)
Xtensa ESP32-S2 gcc 8.4.0 (2021r1)
Xtensa ESP32-S2 gcc 8.4.0 (2021r2)
Xtensa ESP32-S3 gcc 11.2.0 (2022r1)
Xtensa ESP32-S3 gcc 12.2.0 (20230208)
Xtensa ESP32-S3 gcc 8.4.0 (2020r3)
Xtensa ESP32-S3 gcc 8.4.0 (2021r1)
Xtensa ESP32-S3 gcc 8.4.0 (2021r2)
arm64 msvc v19.20 VS16.0
arm64 msvc v19.21 VS16.1
arm64 msvc v19.22 VS16.2
arm64 msvc v19.23 VS16.3
arm64 msvc v19.24 VS16.4
arm64 msvc v19.25 VS16.5
arm64 msvc v19.27 VS16.7
arm64 msvc v19.28 VS16.8
arm64 msvc v19.28 VS16.9
arm64 msvc v19.29 VS16.10
arm64 msvc v19.29 VS16.11
arm64 msvc v19.30 VS17.0
arm64 msvc v19.31 VS17.1
arm64 msvc v19.32 VS17.2
arm64 msvc v19.33 VS17.3
arm64 msvc v19.34 VS17.4
arm64 msvc v19.35 VS17.5
arm64 msvc v19.36 VS17.6
arm64 msvc v19.37 VS17.7
arm64 msvc v19.38 VS17.8
arm64 msvc v19.39 VS17.9
arm64 msvc v19.40 VS17.10
arm64 msvc v19.latest
armv7-a clang (trunk)
armv7-a clang 10.0.0
armv7-a clang 10.0.1
armv7-a clang 11.0.0
armv7-a clang 11.0.1
armv7-a clang 12.0.0
armv7-a clang 12.0.1
armv7-a clang 13.0.0
armv7-a clang 13.0.1
armv7-a clang 14.0.0
armv7-a clang 15.0.0
armv7-a clang 16.0.0
armv7-a clang 17.0.1
armv7-a clang 18.1.0
armv7-a clang 19.1.0
armv7-a clang 9.0.0
armv7-a clang 9.0.1
armv8-a clang (all architectural features, trunk)
armv8-a clang (trunk)
armv8-a clang 10.0.0
armv8-a clang 10.0.1
armv8-a clang 11.0.0
armv8-a clang 11.0.1
armv8-a clang 12.0.0
armv8-a clang 13.0.0
armv8-a clang 14.0.0
armv8-a clang 15.0.0
armv8-a clang 16.0.0
armv8-a clang 17.0.1
armv8-a clang 18.1.0
armv8-a clang 19.1.0
armv8-a clang 9.0.0
armv8-a clang 9.0.1
ellcc 0.1.33
ellcc 0.1.34
ellcc 2017-07-16
hexagon-clang 16.0.5
llvm-mos atari2600-3e
llvm-mos atari2600-4k
llvm-mos atari2600-common
llvm-mos atari5200-supercart
llvm-mos atari8-cart-megacart
llvm-mos atari8-cart-std
llvm-mos atari8-cart-xegs
llvm-mos atari8-common
llvm-mos atari8-dos
llvm-mos c128
llvm-mos c64
llvm-mos commodore
llvm-mos cpm65
llvm-mos cx16
llvm-mos dodo
llvm-mos eater
llvm-mos mega65
llvm-mos nes
llvm-mos nes-action53
llvm-mos nes-cnrom
llvm-mos nes-gtrom
llvm-mos nes-mmc1
llvm-mos nes-mmc3
llvm-mos nes-nrom
llvm-mos nes-unrom
llvm-mos nes-unrom-512
llvm-mos osi-c1p
llvm-mos pce
llvm-mos pce-cd
llvm-mos pce-common
llvm-mos pet
llvm-mos rp6502
llvm-mos rpc8e
llvm-mos supervision
llvm-mos vic20
loongarch64 gcc 12.2.0
loongarch64 gcc 12.3.0
loongarch64 gcc 12.4.0
loongarch64 gcc 13.1.0
loongarch64 gcc 13.2.0
loongarch64 gcc 13.3.0
loongarch64 gcc 14.1.0
loongarch64 gcc 14.2.0
mips clang 13.0.0
mips clang 14.0.0
mips clang 15.0.0
mips clang 16.0.0
mips clang 17.0.1
mips clang 18.1.0
mips clang 19.1.0
mips gcc 11.2.0
mips gcc 12.1.0
mips gcc 12.2.0
mips gcc 12.3.0
mips gcc 12.4.0
mips gcc 13.1.0
mips gcc 13.2.0
mips gcc 13.3.0
mips gcc 14.1.0
mips gcc 14.2.0
mips gcc 4.9.4
mips gcc 5.4
mips gcc 5.5.0
mips gcc 9.3.0 (codescape)
mips gcc 9.5.0
mips64 (el) gcc 12.1.0
mips64 (el) gcc 12.2.0
mips64 (el) gcc 12.3.0
mips64 (el) gcc 12.4.0
mips64 (el) gcc 13.1.0
mips64 (el) gcc 13.2.0
mips64 (el) gcc 13.3.0
mips64 (el) gcc 14.1.0
mips64 (el) gcc 14.2.0
mips64 (el) gcc 4.9.4
mips64 (el) gcc 5.4.0
mips64 (el) gcc 5.5.0
mips64 (el) gcc 9.5.0
mips64 clang 13.0.0
mips64 clang 14.0.0
mips64 clang 15.0.0
mips64 clang 16.0.0
mips64 clang 17.0.1
mips64 clang 18.1.0
mips64 clang 19.1.0
mips64 gcc 11.2.0
mips64 gcc 12.1.0
mips64 gcc 12.2.0
mips64 gcc 12.3.0
mips64 gcc 12.4.0
mips64 gcc 13.1.0
mips64 gcc 13.2.0
mips64 gcc 13.3.0
mips64 gcc 14.1.0
mips64 gcc 14.2.0
mips64 gcc 4.9.4
mips64 gcc 5.4.0
mips64 gcc 5.5.0
mips64 gcc 9.5.0
mips64el clang 13.0.0
mips64el clang 14.0.0
mips64el clang 15.0.0
mips64el clang 16.0.0
mips64el clang 17.0.1
mips64el clang 18.1.0
mips64el clang 19.1.0
mipsel clang 13.0.0
mipsel clang 14.0.0
mipsel clang 15.0.0
mipsel clang 16.0.0
mipsel clang 17.0.1
mipsel clang 18.1.0
mipsel clang 19.1.0
mipsel gcc 12.1.0
mipsel gcc 12.2.0
mipsel gcc 12.3.0
mipsel gcc 12.4.0
mipsel gcc 13.1.0
mipsel gcc 13.2.0
mipsel gcc 13.3.0
mipsel gcc 14.1.0
mipsel gcc 14.2.0
mipsel gcc 4.9.4
mipsel gcc 5.4.0
mipsel gcc 5.5.0
mipsel gcc 9.5.0
nanoMIPS gcc 6.3.0 (mtk)
power gcc 11.2.0
power gcc 12.1.0
power gcc 12.2.0
power gcc 12.3.0
power gcc 12.4.0
power gcc 13.1.0
power gcc 13.2.0
power gcc 13.3.0
power gcc 14.1.0
power gcc 14.2.0
power gcc 4.8.5
power64 AT12.0 (gcc8)
power64 AT13.0 (gcc9)
power64 gcc 11.2.0
power64 gcc 12.1.0
power64 gcc 12.2.0
power64 gcc 12.3.0
power64 gcc 12.4.0
power64 gcc 13.1.0
power64 gcc 13.2.0
power64 gcc 13.3.0
power64 gcc 14.1.0
power64 gcc 14.2.0
power64 gcc trunk
power64le AT12.0 (gcc8)
power64le AT13.0 (gcc9)
power64le clang (trunk)
power64le gcc 11.2.0
power64le gcc 12.1.0
power64le gcc 12.2.0
power64le gcc 12.3.0
power64le gcc 12.4.0
power64le gcc 13.1.0
power64le gcc 13.2.0
power64le gcc 13.3.0
power64le gcc 14.1.0
power64le gcc 14.2.0
power64le gcc 6.3.0
power64le gcc trunk
powerpc64 clang (trunk)
s390x gcc 11.2.0
s390x gcc 12.1.0
s390x gcc 12.2.0
s390x gcc 12.3.0
s390x gcc 12.4.0
s390x gcc 13.1.0
s390x gcc 13.2.0
s390x gcc 13.3.0
s390x gcc 14.1.0
s390x gcc 14.2.0
sh gcc 12.2.0
sh gcc 12.3.0
sh gcc 12.4.0
sh gcc 13.1.0
sh gcc 13.2.0
sh gcc 13.3.0
sh gcc 14.1.0
sh gcc 14.2.0
sh gcc 4.9.4
sh gcc 9.5.0
vast (trunk)
x64 msvc v19.0 (WINE)
x64 msvc v19.10 (WINE)
x64 msvc v19.14 (WINE)
x64 msvc v19.20 VS16.0
x64 msvc v19.21 VS16.1
x64 msvc v19.22 VS16.2
x64 msvc v19.23 VS16.3
x64 msvc v19.24 VS16.4
x64 msvc v19.25 VS16.5
x64 msvc v19.27 VS16.7
x64 msvc v19.28 VS16.8
x64 msvc v19.28 VS16.9
x64 msvc v19.29 VS16.10
x64 msvc v19.29 VS16.11
x64 msvc v19.30 VS17.0
x64 msvc v19.31 VS17.1
x64 msvc v19.32 VS17.2
x64 msvc v19.33 VS17.3
x64 msvc v19.34 VS17.4
x64 msvc v19.35 VS17.5
x64 msvc v19.36 VS17.6
x64 msvc v19.37 VS17.7
x64 msvc v19.38 VS17.8
x64 msvc v19.39 VS17.9
x64 msvc v19.40 VS17.10
x64 msvc v19.latest
x86 djgpp 4.9.4
x86 djgpp 5.5.0
x86 djgpp 6.4.0
x86 djgpp 7.2.0
x86 msvc v19.0 (WINE)
x86 msvc v19.10 (WINE)
x86 msvc v19.14 (WINE)
x86 msvc v19.20 VS16.0
x86 msvc v19.21 VS16.1
x86 msvc v19.22 VS16.2
x86 msvc v19.23 VS16.3
x86 msvc v19.24 VS16.4
x86 msvc v19.25 VS16.5
x86 msvc v19.27 VS16.7
x86 msvc v19.28 VS16.8
x86 msvc v19.28 VS16.9
x86 msvc v19.29 VS16.10
x86 msvc v19.29 VS16.11
x86 msvc v19.30 VS17.0
x86 msvc v19.31 VS17.1
x86 msvc v19.32 VS17.2
x86 msvc v19.33 VS17.3
x86 msvc v19.34 VS17.4
x86 msvc v19.35 VS17.5
x86 msvc v19.36 VS17.6
x86 msvc v19.37 VS17.7
x86 msvc v19.38 VS17.8
x86 msvc v19.39 VS17.9
x86 msvc v19.40 VS17.10
x86 msvc v19.latest
x86 nvc++ 22.11
x86 nvc++ 22.7
x86 nvc++ 22.9
x86 nvc++ 23.1
x86 nvc++ 23.11
x86 nvc++ 23.3
x86 nvc++ 23.5
x86 nvc++ 23.7
x86 nvc++ 23.9
x86 nvc++ 24.1
x86 nvc++ 24.3
x86 nvc++ 24.5
x86 nvc++ 24.7
x86-64 Zapcc 190308
x86-64 clang (EricWF contracts)
x86-64 clang (amd-staging)
x86-64 clang (assertions trunk)
x86-64 clang (clangir)
x86-64 clang (dascandy contracts)
x86-64 clang (experimental -Wlifetime)
x86-64 clang (experimental P1061)
x86-64 clang (experimental P1144)
x86-64 clang (experimental P1221)
x86-64 clang (experimental P2996)
x86-64 clang (experimental P3068)
x86-64 clang (experimental P3309)
x86-64 clang (experimental P3367)
x86-64 clang (experimental P3372)
x86-64 clang (experimental metaprogramming - P2632)
x86-64 clang (old concepts branch)
x86-64 clang (p1974)
x86-64 clang (pattern matching - P2688)
x86-64 clang (reflection)
x86-64 clang (resugar)
x86-64 clang (thephd.dev)
x86-64 clang (trunk)
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Source code
#include <string.h> #include <stdio.h> #include <stdint.h> #include "absl/base/attributes.h" #include "absl/base/optimization.h" // Offset from __rseq_abi to the cached slabs address. #define TCMALLOC_RSEQ_SLABS_OFFSET -4 #define TCMALLOC_PERCPU_RSEQ_SIGNATURE 0xd428bc00 // The bit denotes that tcmalloc_rseq.slabs contains valid slabs offset. #define TCMALLOC_CACHED_SLABS_BIT 63 #define TCMALLOC_CACHED_SLABS_MASK (1ul << TCMALLOC_CACHED_SLABS_BIT) struct kernel_rseq { unsigned cpu_id_start; unsigned cpu_id; unsigned long long rseq_cs; unsigned flags; unsigned padding[2]; // This is a prototype extension to the rseq() syscall. Since a process may // run on only a few cores at a time, we can use a dense set of "v(irtual) // cpus." This can reduce cache requirements, as we only need N caches for // the cores we actually run on simultaneously, rather than a cache for every // physical core. union { struct { short numa_node_id; short vcpu_id; }; int vcpu_flat; }; } __attribute__((aligned(4 * sizeof(unsigned long long)))); extern "C" ABSL_CONST_INIT thread_local volatile kernel_rseq __rseq_abi; // The trampoline uses a non-local branch to restart critical sections. // The trampoline is located in the .text.unlikely section, and the maximum // distance of B and BL branches in ARM64 is limited to 128MB. If the linker // detects the distance being too large, it injects a thunk which may clobber // the x16 or x17 register according to the ARMv8 ABI standard. // The actual clobbering is hard to trigger in a test, so instead of waiting // for clobbering to happen in production binaries, we proactively always // clobber x16 and x17 to shake out bugs earlier. // RSEQ critical section asm blocks should use TCMALLOC_RSEQ_CLOBBER // in the clobber list to account for this. #define TCMALLOC_RSEQ_TRAMPLINE_SMASH \ "mov x16, #-2097\n" \ "mov x17, #-2099\n" #define TCMALLOC_RSEQ_CLOBBER "x16", "x17" #define TCMALLOC_RSEQ_RELOC_TYPE "R_AARCH64_NONE" #define TCMALLOC_RSEQ_JUMP "b" #define TCMALLOC_RSEQ_SET_CS(name) \ TCMALLOC_RSEQ_TRAMPLINE_SMASH \ "adrp %[scratch], __rseq_cs_" #name \ "_%=\n" \ "add %[scratch], %[scratch], :lo12:__rseq_cs_" #name \ "_%=\n" \ "str %[scratch], %[rseq_cs_addr]\n" #if !defined(__clang_major__) || __clang_major__ >= 9 #define TCMALLOC_RSEQ_RELOC ".reloc 0, " TCMALLOC_RSEQ_RELOC_TYPE ", 1f\n" #else #define TCMALLOC_RSEQ_RELOC #endif // Common rseq asm prologue. // It uses labels 1-4 and assumes the critical section ends with label 5. // The prologue assumes there is [scratch] input with a scratch register. #define TCMALLOC_RSEQ_PROLOGUE(name) \ /* __rseq_cs only needs to be writeable to allow for relocations.*/ \ ".pushsection __rseq_cs, \"aw?\"\n" \ ".balign 32\n" \ ".local __rseq_cs_" #name \ "_%=\n" \ ".type __rseq_cs_" #name \ "_%=,@object\n" \ ".size __rseq_cs_" #name \ "_%=,32\n" \ "__rseq_cs_" #name \ "_%=:\n" \ ".long 0x0\n" \ ".long 0x0\n" \ ".quad 4f\n" \ ".quad 5f - 4f\n" \ ".quad 2f\n" \ ".popsection\n" TCMALLOC_RSEQ_RELOC \ ".pushsection __rseq_cs_ptr_array, \"aw?\"\n" \ "1:\n" \ ".balign 8\n" \ ".quad __rseq_cs_" #name \ "_%=\n" /* Force this section to be retained. \ It is for debugging, but is otherwise not referenced. */ \ ".popsection\n" \ ".pushsection .text.unlikely, \"ax?\"\n" /* This is part of the upstream \ rseq ABI. The 4 bytes prior to \ the abort IP must match \ TCMALLOC_PERCPU_RSEQ_SIGNATURE \ (as configured by our rseq \ syscall's signature parameter). \ This signature is used to \ annotate valid abort IPs (since \ rseq_cs could live in a \ user-writable segment). */ \ ".long %c[rseq_sig]\n" \ ".local " #name \ "_trampoline_%=\n" \ ".type " #name \ "_trampoline_%=,@function\n" \ "" #name \ "_trampoline_%=:\n" \ "2:\n" TCMALLOC_RSEQ_JUMP \ " 3f\n" \ ".size " #name "_trampoline_%=, . - " #name \ "_trampoline_%=\n" \ ".popsection\n" /* Prepare */ \ "3:\n" TCMALLOC_RSEQ_SET_CS(name) /* Start */ \ "4:\n" #define TCMALLOC_RSEQ_INPUTS \ [rseq_cs_addr] "m"(__rseq_abi.rseq_cs), \ [rseq_slabs_addr] "m"(*reinterpret_cast<volatile char*>( \ reinterpret_cast<uintptr_t>(&__rseq_abi) + \ TCMALLOC_RSEQ_SLABS_OFFSET)), \ [rseq_sig] "n"( \ TCMALLOC_PERCPU_RSEQ_SIGNATURE), /* Also pass common consts, there \ is no cost to passing unused \ consts. */ \ [cached_slabs_bit] "n"(TCMALLOC_CACHED_SLABS_BIT), \ [cached_slabs_mask_neg] "n"(~TCMALLOC_CACHED_SLABS_MASK) static inline ABSL_ATTRIBUTE_ALWAYS_INLINE bool TcmallocSlab_Internal_Push( size_t size_class, void* item) { uintptr_t region_start, scratch, end_ptr, end; bool overflow; asm volatile( TCMALLOC_RSEQ_PROLOGUE(TcmallocSlab_Internal_Push) // region_start = tcmalloc_slabs; "ldr %[region_start], %[rseq_slabs_addr]\n" // if (region_start & TCMALLOC_CACHED_SLABS_MASK) goto overflow_label; // region_start &= ~TCMALLOC_CACHED_SLABS_MASK; "subs %[region_start], %[region_start], %[cached_slabs_mask]\n" "b.ls 5f\n" // end_ptr = &(slab_headers[0]->end) "add %[end_ptr], %[region_start], #2\n" // scratch = slab_headers[size_class]->current (current index) "ldrh %w[scratch], [%[region_start], %[size_class_lsl2]]\n" // end = slab_headers[size_class]->end (end index) "ldrh %w[end], [%[end_ptr], %[size_class_lsl2]]\n" // if (ABSL_PREDICT_FALSE(end <= scratch)) { goto overflow_label; } "cmp %[end], %[scratch]\n" "b.ls 5f\n" // Important! code below this must not affect any flags (i.e.: ccls) // If so, the above code needs to explicitly set a ccls return value. "str %[item], [%[region_start], %[scratch], LSL #3]\n" "add %w[scratch], %w[scratch], #1\n" "strh %w[scratch], [%[region_start], %[size_class_lsl2]]\n" // Commit "5:\n" : [end_ptr] "=&r"(end_ptr), [scratch] "=&r"(scratch), [end] "=&r"(end), [overflow] "=@ccls"(overflow), [region_start] "=&r"(region_start) : TCMALLOC_RSEQ_INPUTS, [cached_slabs_mask] "r"(TCMALLOC_CACHED_SLABS_MASK), [size_class_lsl2] "r"(size_class << 2), [item] "r"(item) : TCMALLOC_RSEQ_CLOBBER, "cc", "memory" ); if (ABSL_PREDICT_FALSE(overflow)) { goto overflow_label; } return true; overflow_label: return false; } int main(int argc, char** argv) { TcmallocSlab_Internal_Push(123, nullptr); return 0; }
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