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Sender: Ingo Molnar <mingo.kernel.org@gmail.com>
Date: Thu, 6 Jun 2024 10:46:23 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.kernel.org,
	Andy Lutomirski <luto@amacapital.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave@sr71.net>, Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Uros Bizjak <ubizjak@gmail.com>
Subject: [PATCH 4/3] x86/fpu: Push 'fpu' pointer calculation into the
 fpu__drop() call
Message-ID: <ZmF3Xx7kFzSuHm4P@gmail.com>
References: <20240605083557.2051480-1-mingo@kernel.org>
 <20240605083557.2051480-4-mingo@kernel.org>
 <20240605141733.GC25006@redhat.com>
 <CAHk-=wi4773Ls82kqVbPmM1deghS2NXkHNCCzWPc270kcByXPA@mail.gmail.com>
 <20240605162610.GF25006@redhat.com>
 <CAHk-=wg2zJgy69j8n6C9T4YARkxcJ09SFkpMiqrCqhChf0s3NQ@mail.gmail.com>
 <ZmFziN0i10sILaIo@gmail.com>
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In-Reply-To: <ZmFziN0i10sILaIo@gmail.com>

This encapsulates the fpu__drop() functionality better, and it
will also enable other changes that want to check a task for
PF_KTHREAD before calling x86_task_fpu().

Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/fpu/sched.h | 2 +-
 arch/x86/kernel/fpu/core.c       | 4 +++-
 arch/x86/kernel/process.c        | 3 +--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/fpu/sched.h b/arch/x86/include/asm/fpu/sched.h
index 1feaa68b7567..5fd12634bcc4 100644
--- a/arch/x86/include/asm/fpu/sched.h
+++ b/arch/x86/include/asm/fpu/sched.h
@@ -10,7 +10,7 @@
 #include <asm/trace/fpu.h>
 
 extern void save_fpregs_to_fpstate(struct fpu *fpu);
-extern void fpu__drop(struct fpu *fpu);
+extern void fpu__drop(struct task_struct *tsk);
 extern int  fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal,
 		      unsigned long shstk_addr);
 extern void fpu_flush_thread(void);
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index d9ff8ca5b32d..3223eb3dd09d 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -679,8 +679,10 @@ int fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal,
  * a state-restore is coming: either an explicit one,
  * or a reschedule.
  */
-void fpu__drop(struct fpu *fpu)
+void fpu__drop(struct task_struct *tsk)
 {
+	struct fpu *fpu = x86_task_fpu(tsk);
+
 	preempt_disable();
 
 	if (fpu == x86_task_fpu(current)) {
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 4184c085627e..0a24997c8cc6 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -114,7 +114,6 @@ void arch_release_task_struct(struct task_struct *tsk)
 void exit_thread(struct task_struct *tsk)
 {
 	struct thread_struct *t = &tsk->thread;
-	struct fpu *fpu = x86_task_fpu(tsk);
 
 	if (test_thread_flag(TIF_IO_BITMAP))
 		io_bitmap_exit(tsk);
@@ -122,7 +121,7 @@ void exit_thread(struct task_struct *tsk)
 	free_vm86(t);
 
 	shstk_free(tsk);
-	fpu__drop(fpu);
+	fpu__drop(tsk);
 }
 
 static int set_new_tls(struct task_struct *p, unsigned long tls)