Revert "LinuxKPI: Add explicit software context to FPU sections"

kmalloc() support within FPU sections will be redone in other way.

This reverts commit 5a3bd28167.

Sponsored by:	Serenity Cyber Security, LLC
Requested by:	jhb

sys/compat/linuxkpi/common/include/linux/compat.h

@@ -33,11 +33,6 @@
 #include <sys/proc.h>
 #include <sys/malloc.h>
 
-#if defined(__aarch64__) || defined(__arm__) || defined(__amd64__) ||	\
-    defined(__i386__) || defined(__powerpc64__)
-#define	LKPI_HAVE_FPU_CTX
-#endif
-
 struct domainset;
 struct thread;
 struct task_struct;
@@ -45,7 +40,6 @@ struct task_struct;
 extern int linux_alloc_current(struct thread *, int flags);
 extern void linux_free_current(struct task_struct *);
 extern struct domainset *linux_get_vm_domain_set(int node);
-extern int linux_set_fpu_ctx(struct task_struct *);
 
 static inline void
 linux_set_current(struct thread *td)

sys/compat/linuxkpi/common/include/linux/sched.h

@@ -64,7 +64,6 @@
 #define	TASK_COMM_LEN		(MAXCOMLEN + 1)
 
 struct seq_file;
-struct fpu_kern_ctx;
 
 struct work_struct;
 struct task_struct {
@@ -90,7 +89,6 @@ struct task_struct {
 	struct task_struct *group_leader;
 	unsigned rcu_section[TS_RCU_TYPE_MAX];
 	unsigned int fpu_ctx_level;
-	struct fpu_kern_ctx *fpu_ctx;
 };
 
 #define	current	({ \

sys/compat/linuxkpi/common/src/linux_current.c

@@ -43,10 +43,6 @@
 #include <sys/sysctl.h>
 #include <vm/uma.h>
 
-#ifdef LKPI_HAVE_FPU_CTX
-#include <machine/fpu.h>
-#endif
-
 #ifdef DEV_APIC
 extern u_int first_msi_irq, num_msi_irqs;
 #endif
@@ -157,16 +153,6 @@ linux_alloc_current(struct thread *td, int flags)
 	return (0);
 }
 
-int
-linux_set_fpu_ctx(struct task_struct *task)
-{
-#ifdef LKPI_HAVE_FPU_CTX
-	if (task->fpu_ctx == NULL && curthread->td_critnest == 0)
-		task->fpu_ctx = fpu_kern_alloc_ctx(FPU_KERN_NOWAIT);
-#endif
-	return (task->fpu_ctx != NULL ? 0 : ENOMEM);
-}
-
 struct mm_struct *
 linux_get_task_mm(struct task_struct *task)
 {
@@ -190,10 +176,6 @@ void
 linux_free_current(struct task_struct *ts)
 {
 	mmput(ts->mm);
-#ifdef LKPI_HAVE_FPU_CTX
-	if (ts->fpu_ctx != NULL)
-		fpu_kern_free_ctx(ts->fpu_ctx);
-#endif
 	uma_zfree(linux_current_zone, ts);
 }
 

sys/compat/linuxkpi/common/src/linux_fpu.c

@@ -30,12 +30,11 @@
 #include <sys/proc.h>
 #include <sys/kernel.h>
 
-#include <linux/compat.h>
 #include <linux/sched.h>
 
 #include <asm/fpu/api.h>
 
-#ifdef LKPI_HAVE_FPU_CTX
+#if defined(__aarch64__) || defined(__amd64__) || defined(__i386__)
 
 #include <machine/fpu.h>
 
@@ -48,20 +47,15 @@
 void
 lkpi_kernel_fpu_begin(void)
 {
-	int err;
-
-	if ((current->fpu_ctx_level)++ == 0) {
-		err = linux_set_fpu_ctx(current);
-		fpu_kern_enter(curthread, current->fpu_ctx,
-		    err == 0 ? FPU_KERN_KTHR : FPU_KERN_NOCTX);
-	}
+	if ((current->fpu_ctx_level)++ == 0)
+		fpu_kern_enter(curthread, NULL, FPU_KERN_NOCTX);
 }
 
 void
 lkpi_kernel_fpu_end(void)
 {
 	if (--(current->fpu_ctx_level) == 0)
-		fpu_kern_leave(curthread, current->fpu_ctx);
+		fpu_kern_leave(curthread, NULL);
 }
 
 #else