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SubjectRe: [RFC PATCH 0/5] livepatch: add support on arm64
On 2015/05/28 14:51, Li Bin wrote:
> This patchset propose a method for gcc -mfentry feature(profile
> before prologue) implementation for arm64, and propose the livepatch
> implementation for arm64 based on this feature.
> The gcc implementation about this feature will be post to the gcc
> community soon.
>
> With this -mfentry feature, the entry of each function like:
>
> foo:
> mov x9, x30
> bl __fentry__
> mov x30, x9
> [prologue]
> ...
>
> The x9 is a callee corruptible register, and the __fentry__ function
> is responsible to protect all registers, so it can be used to protect
> the x30. And the added two instructions which is register mov operation
> have ralatively small impact on performance.

Hm, this implementation looks good to me :)
This also enables us to KPROBES_ON_FTRACE too.

Thanks,

>
> This patchset has been tested on arm64 platform.
>
> Li Bin (4):
> livepatch: ftrace: arm64: Add support for DYNAMIC_FTRACE_WITH_REGS
> livepatch: ftrace: add ftrace_function_stub_ip function
> livepatch: ftrace: arm64: Add support for -mfentry on arm64
> livepatch: arm64: add support for livepatch on arm64
>
> Xie XiuQi (1):
> livepatch: arm64: support relocation in a module
>
> arch/arm64/Kconfig | 5 +
> arch/arm64/include/asm/ftrace.h | 9 +
> arch/arm64/include/asm/livepatch.h | 45 +++++
> arch/arm64/kernel/Makefile | 1 +
> arch/arm64/kernel/arm64ksyms.c | 4 +
> arch/arm64/kernel/entry-ftrace.S | 154 +++++++++++++++-
> arch/arm64/kernel/ftrace.c | 28 +++-
> arch/arm64/kernel/livepatch.c | 41 ++++
> arch/arm64/kernel/module.c | 355 ++++++++++++++++++------------------
> include/linux/ftrace.h | 1 +
> kernel/livepatch/core.c | 17 ++-
> kernel/trace/ftrace.c | 32 ++++
> scripts/recordmcount.pl | 2 +-
> 13 files changed, 508 insertions(+), 186 deletions(-)
> create mode 100644 arch/arm64/include/asm/livepatch.h
> create mode 100644 arch/arm64/kernel/livepatch.c
>
> --
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--
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@hitachi.com


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