linux-kernel - [PATCH 0/3] locking/atomic/x86: Improve arch_cmpxchg64() and friends for x86

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Date: Mon,  8 Apr 2024 11:13:55 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 0/3] locking/atomic/x86: Improve arch_cmpxchg64() and friends for x86_32

Following patch series improves arch_cmpxchg64() family
of functions and rewrites arch_cmpxchg64() family in a
similar way as was recently done for arch_cmpxchg128() family.

The improvements builds on recent improvement of emulated
cmpxchg8b_emu() library function and introduce
arch_try_cmpxchg64() also for !CONFIG_X86_CMPXCHG64 targets.

While the patch series enables impressive assembly code
reductions for somehow obsolete !CONFIG_X86_CMPXCHG64 targets,
the true reason for the changes will be evident from the
follow-up patch series, where this series enables unification
of several atomic functions between x86_64 and x86_32 targets.

OTOH, by adopting the same approach and similar structure of
arch_cmpxchg64() macros to arch_cmpxchg128() macros, these
patches lower future maintenace burden and technical debt
of the source code.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Peter Zijlstra <peterz@...radead.org>

Uros Bizjak (3):
  locking/atomic/x86: Correct the definition of __arch_try_cmpxchg128()
  locking/atomic/x86: Modernize x86_32 arch_{,try_}_cmpxchg64{,_local}()
  locking/atomic/x86: Introduce arch_try_cmpxchg64() for
    !CONFIG_X86_CMPXCHG64

 arch/x86/include/asm/cmpxchg_32.h | 207 ++++++++++++++++++------------
 arch/x86/include/asm/cmpxchg_64.h |   2 +-
 2 files changed, 129 insertions(+), 80 deletions(-)

-- 
2.44.0