linux-kernel - [PATCH 1/8] x86/fpu: Introduce the x86_task

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Message-ID: <20250409211127.3544993-2-mingo@kernel.org>
Date: Wed,  9 Apr 2025 23:11:20 +0200
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Andy Lutomirski <luto@...capital.net>,
	Dave Hansen <dave@...1.net>,
	Brian Gerst <brgerst@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	"H . Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Chang S . Bae" <chang.seok.bae@...el.com>,
	Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 1/8] x86/fpu: Introduce the x86_task_fpu() helper method

The per-task FPU context/save area is allocated right
next to task_struct, currently in a variable-size
array via task_struct::thread.fpu[], but we plan to
fully hide it from the C type scope.

Introduce the x86_task_fpu() accessor that gets to the
FPU context pointer explicitly from the task pointer.

Right now this is a simple (task)->thread.fpu wrapper.

Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/processor.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 5d2f7e5aff26..2f631e0adea3 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -523,6 +523,8 @@ struct thread_struct {
 	 */
 };
 
+#define x86_task_fpu(task) (&(task)->thread.fpu)
+
 extern void fpu_thread_struct_whitelist(unsigned long *offset, unsigned long *size);
 
 static inline void arch_thread_struct_whitelist(unsigned long *offset,
-- 
2.45.2