Re: [RFC PATCH v3 1/1] arch: arm64: Implement unaligned atomic emulation

From: André Almeida

Date: Wed Sep 30 2026 - 06:42:10 EST


Hi Will, thanks for the quickly reply,

Em 30/09/2026 04:48, Will Deacon escreveu:
On Tue, Sep 29, 2026 at 11:01:38PM -0300, André Almeida wrote:
Implement support for emulating unaligned atomic operations on arm64.
User applications that wish to enable support for this should use the
pctrl() flag `PR_ARM64_UNALIGN_ATOMIC_EMULATE`.

Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
---
arch/arm64/Kconfig | 6 +
arch/arm64/include/asm/exception.h | 1 +
arch/arm64/include/asm/processor.h | 5 +
arch/arm64/include/asm/rwonce.h | 14 +-
arch/arm64/include/asm/thread_info.h | 1 +
arch/arm64/kernel/Makefile | 3 +-
arch/arm64/kernel/process.c | 15 +
arch/arm64/kernel/unaligned_atomic.c | 521 +++++++++++++++++++++++++++
arch/arm64/mm/fault.c | 10 +
include/uapi/linux/prctl.h | 5 +
kernel/sys.c | 7 +-
11 files changed, 579 insertions(+), 9 deletions(-)
create mode 100644 arch/arm64/kernel/unaligned_atomic.c

No.

I already explained to you why this doesn't work:

https://lore.kernel.org/r/aV1YnOetDHhKe4hz@willie-the-truck

Indeed, last time you raised some points, and then Ryan replied them. Is there any specific point that doesn't work? I couldn't find a reply for Ryan's answers:

https://lore.kernel.org/all/CABnRqDf5EQUoXu=pJ6mj4-JfwAzEfcAE2cYrNzJANFycx7cMUA@xxxxxxxxxxxxxx/


Will