linux-kernel - [PATCH v2 3/3] x86/percpu: Introduce raw_cpu_read

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Date: Thu,  4 Apr 2024 11:42:03 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH v2 3/3] x86/percpu: Introduce raw_cpu_read_long() to reduce ifdeffery

Introduce raw_cpu_read_long() macro to slightly reduce ifdeffery
in arch/x86/include/asm/percpu.h.

No functional changes intended.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
---
v2: Merge the patch with the rest of percpu series.
---
 arch/x86/include/asm/percpu.h | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index d6ff0db32209..3bedee1801e2 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -59,12 +59,6 @@
 #define __force_percpu_prefix	"%%"__stringify(__percpu_seg)":"
 #define __my_cpu_offset		this_cpu_read(this_cpu_off)
 
-#ifdef CONFIG_X86_64
-#define __raw_my_cpu_offset	raw_cpu_read_8(this_cpu_off);
-#else
-#define __raw_my_cpu_offset	raw_cpu_read_4(this_cpu_off);
-#endif
-
 /*
  * Compared to the generic __my_cpu_offset version, the following
  * saves one instruction and avoids clobbering a temp register.
@@ -76,7 +70,7 @@
 #ifndef BUILD_VDSO32_64
 #define arch_raw_cpu_ptr(_ptr)					\
 ({								\
-	unsigned long tcp_ptr__ = __raw_my_cpu_offset;		\
+	unsigned long tcp_ptr__ = raw_cpu_read_long(this_cpu_off); \
 	tcp_ptr__ += (__force unsigned long)(_ptr);		\
 	(typeof(*(_ptr)) __kernel __force *)tcp_ptr__;		\
 })
@@ -563,9 +557,13 @@ do {									\
 #define this_cpu_xchg_8(pcp, nval)		this_percpu_xchg_op(pcp, nval)
 #define this_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(8, volatile, pcp, oval, nval)
 #define this_cpu_try_cmpxchg_8(pcp, ovalp, nval)	percpu_try_cmpxchg_op(8, volatile, pcp, ovalp, nval)
+
+#define raw_cpu_read_long(pcp)		raw_cpu_read_8(pcp)
 #else
 /* There is no generic 64 bit read stable operation for 32 bit targets. */
-#define this_cpu_read_stable_8(pcp)    ({ BUILD_BUG(); (typeof(pcp))0; })
+#define this_cpu_read_stable_8(pcp)	({ BUILD_BUG(); (typeof(pcp))0; })
+
+#define raw_cpu_read_long(pcp)		raw_cpu_read_4(pcp)
 #endif
 
 #define x86_this_cpu_constant_test_bit(_nr, _var)			\
-- 
2.44.0