linux-kernel - [PATCH 2/2] prefetch: Add ARCH_HAS_PREFETCH definition when the architecture is not defined

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Date: Wed, 29 May 2024 11:20:59 +0800
From: Youling Tang <youling.tang@...ux.dev>
To: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>,
	Youling Tang <tangyouling@...inos.cn>
Subject: [PATCH 2/2] prefetch: Add ARCH_HAS_PREFETCH definition when the architecture is not defined

From: Youling Tang <tangyouling@...inos.cn>

After commit ab483570a13b ("x86 & generic: change to __builtin_prefetch()"), the
__builtin_prefetch implementation will be used by default, so add its definition
to return to a state similar to before commit[1].

Currently prefetch_range() will be empty implemented under the x86_64 architecture,
there was a concrete implementation before "x86 & generic: change to
__builtin_prefetch()", so fix it.

No similar changes have been made to ARCH_HAS_PREFETCHW at this time.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/linux/prefetch.h?id=8e4f2fd31bf737abb392e694898a1496157623b5

Fixes: ab483570a13b ("x86 & generic: change to __builtin_prefetch()")
Signed-off-by: Youling Tang <tangyouling@...inos.cn>
---
 include/linux/prefetch.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/prefetch.h b/include/linux/prefetch.h
index b068e2e60939..162b7105e37c 100644
--- a/include/linux/prefetch.h
+++ b/include/linux/prefetch.h
@@ -36,6 +36,7 @@ struct page;
 */
 
 #ifndef ARCH_HAS_PREFETCH
+#define ARCH_HAS_PREFETCH
 #define prefetch(x) __builtin_prefetch(x)
 #endif
 
-- 
2.34.1