[PATCH 4/3] x86/fpu: Push 'fpu' pointer calculation into the fpu__drop() call

From: Ingo Molnar
Date: Thu Jun 06 2024 - 04:46:35 EST


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@xxxxxxxxxx>
---
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)