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Subject[PATCH v3 0/7] Optimize jump label implementation for ARM64
From: Jiang Liu <>

This patchset tries to optimize arch specfic jump label implementation
for ARM64 by dynamic kernel text patching.

To enable this feature, your toolchain must support "asm goto" extension
and "%c" constraint extesion. Current GCC for AARCH64 doesn't support
"%c", so you need a GCC patch similiar to this:

It has been tested on ARM Fast mode and a real hardware platform.

Any comments are welcomed!

1) fix a bug in comparing signed and unsigned values
2) detect big endian by checking __AARCH64EB__

V1->V2: address review comments of V1
1) refine comments
2) add a new interface to always synchronize with stop_machine()
when patching code
3) handle endian issue when patching code

Jiang Liu (7):
arm64: introduce basic aarch64 instruction decoding helpers
arm64: introduce interfaces to hotpatch kernel and module code
arm64: move encode_insn_immediate() from module.c to insn.c
arm64: introduce aarch64_insn_gen_{nop|branch_imm}() helper functions
arm64, jump label: detect %c support for ARM64
arm64, jump label: optimize jump label implementation
jump_label: use defined macros instead of hard-coding for better
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/insn.h | 79 ++++++++++
arch/arm64/include/asm/jump_label.h | 52 +++++++
arch/arm64/kernel/Makefile | 3 +-
arch/arm64/kernel/insn.c | 285 ++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/jump_label.c | 60 ++++++++
arch/arm64/kernel/module.c | 151 ++++---------------
include/linux/jump_label.h | 15 +-
scripts/ | 2 +-
9 files changed, 522 insertions(+), 126 deletions(-)
create mode 100644 arch/arm64/include/asm/insn.h
create mode 100644 arch/arm64/include/asm/jump_label.h
create mode 100644 arch/arm64/kernel/insn.c
create mode 100644 arch/arm64/kernel/jump_label.c

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