Revert "x86/fpu: Correct pkru/xstate inconsistency"

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I590ZC
CVE: NA

--------------------------------

This reverts commit 039ea496.

Since the enabling of Intel AMX involves the complete rewriting of the
PKRU handling, then this workaround is no longer needed.
Signed-off-by: NLin Wang <lin.x.wang@intel.com>

arch/x86/include/asm/fpu/internal.h

@@ -531,11 +531,9 @@ static inline void __fpregs_load_activate(void)
  * The FPU context is only stored/restored for a user task and
  * PF_KTHREAD is used to distinguish between kernel and user threads.
  */
-static inline void switch_fpu_prepare(struct task_struct *prev, int cpu)
+static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu)
 {
-	struct fpu *old_fpu = &prev->thread.fpu;
-
-	if (static_cpu_has(X86_FEATURE_FPU) && !(prev->flags & PF_KTHREAD)) {
+	if (static_cpu_has(X86_FEATURE_FPU) && !(current->flags & PF_KTHREAD)) {
 		if (!copy_fpregs_to_fpstate(old_fpu))
 			old_fpu->last_cpu = -1;
 		else
@@ -554,11 +552,10 @@ static inline void switch_fpu_prepare(struct task_struct *prev, int cpu)
  * Load PKRU from the FPU context if available. Delay loading of the
  * complete FPU state until the return to userland.
  */
-static inline void switch_fpu_finish(struct task_struct *next)
+static inline void switch_fpu_finish(struct fpu *new_fpu)
 {
 	u32 pkru_val = init_pkru_value;
 	struct pkru_state *pk;
-	struct fpu *next_fpu = &next->thread.fpu;
 
 	if (!static_cpu_has(X86_FEATURE_FPU))
 		return;
@@ -572,7 +569,7 @@ static inline void switch_fpu_finish(struct task_struct *next)
 	 * PKRU state is switched eagerly because it needs to be valid before we
 	 * return to userland e.g. for a copy_to_user() operation.
 	 */
-	if (!(next->flags & PF_KTHREAD)) {
+	if (!(current->flags & PF_KTHREAD)) {
 		/*
 		 * If the PKRU bit in xsave.header.xfeatures is not set,
 		 * then the PKRU component was in init state, which means
@@ -581,7 +578,7 @@ static inline void switch_fpu_finish(struct task_struct *next)
 		 * in memory is not valid. This means pkru_val has to be
 		 * set to 0 and not to init_pkru_value.
 		 */
-		pk = get_xsave_addr(&next_fpu->state.xsave, XFEATURE_PKRU);
+		pk = get_xsave_addr(&new_fpu->state.xsave, XFEATURE_PKRU);
 		pkru_val = pk ? pk->pkru : 0;
 	}
 	__write_pkru(pkru_val);

arch/x86/kernel/process_32.c

@@ -159,12 +159,14 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 {
 	struct thread_struct *prev = &prev_p->thread,
 			     *next = &next_p->thread;
+	struct fpu *prev_fpu = &prev->fpu;
+	struct fpu *next_fpu = &next->fpu;
 	int cpu = smp_processor_id();
 
 	/* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
 
 	if (!test_thread_flag(TIF_NEED_FPU_LOAD))
-		switch_fpu_prepare(prev_p, cpu);
+		switch_fpu_prepare(prev_fpu, cpu);
 
 	/*
 	 * Save away %gs. No need to save %fs, as it was saved on the
@@ -211,7 +213,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
 	this_cpu_write(current_task, next_p);
 
-	switch_fpu_finish(next_p);
+	switch_fpu_finish(next_fpu);
 
 	/* Load the Intel cache allocation PQR MSR. */
 	resctrl_sched_in();

arch/x86/kernel/process_64.c

@@ -535,13 +535,15 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 {
 	struct thread_struct *prev = &prev_p->thread;
 	struct thread_struct *next = &next_p->thread;
+	struct fpu *prev_fpu = &prev->fpu;
+	struct fpu *next_fpu = &next->fpu;
 	int cpu = smp_processor_id();
 
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) &&
 		     this_cpu_read(irq_count) != -1);
 
 	if (!test_thread_flag(TIF_NEED_FPU_LOAD))
-		switch_fpu_prepare(prev_p, cpu);
+		switch_fpu_prepare(prev_fpu, cpu);
 
 	/* We must save %fs and %gs before load_TLS() because
 	 * %fs and %gs may be cleared by load_TLS().
@@ -593,7 +595,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	this_cpu_write(current_task, next_p);
 	this_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p));
 
-	switch_fpu_finish(next_p);
+	switch_fpu_finish(next_fpu);
 
 	/* Reload sp0. */
 	update_task_stack(next_p);