Commit 419abc4d authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390/fpu: convert FPU CIF flag to regular TIF flag 



The FPU state, as represented by the CIF_FPU flag reflects the FPU state of
a task, not the CPU it is running on. Therefore convert the flag to a
regular TIF flag.

This removes the magic in switch_to() where a save_fpu_regs() call for the
currently (previous) running task sets the per-cpu CIF_FPU flag, which is
required to restore FPU register contents of the next task, when it returns
to user space.

Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 918c7cad

arch/s390/include/asm/entry-common.h

+1 −1
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ static __always_inline void arch_exit_to_user_mode_work(struct pt_regs *regs, 


static __always_inline void arch_exit_to_user_mode(void)

{

	if (test_cpu_flag(CIF_FPU))

	if (test_thread_flag(TIF_FPU))

		__load_fpu_regs();



	if (IS_ENABLED(CONFIG_DEBUG_ENTRY))

arch/s390/include/asm/fpu.h

+1 −1
Original line number Diff line number Diff line
@@ -148,7 +148,7 @@ static inline void kernel_fpu_begin(struct kernel_fpu *state, u32 flags) 
{

	preempt_disable();

	state->mask = S390_lowcore.fpu_flags;

	if (!test_cpu_flag(CIF_FPU)) {

	if (!test_thread_flag(TIF_FPU)) {

		/* Save user space FPU state and register contents */

		save_fpu_regs();

	} else if (state->mask & flags) {

arch/s390/include/asm/processor.h

+0 −2
Original line number Diff line number Diff line
@@ -15,13 +15,11 @@ 
#include <linux/bits.h>



#define CIF_NOHZ_DELAY		2	/* delay HZ disable for a tick */

#define CIF_FPU			3	/* restore FPU registers */

#define CIF_ENABLED_WAIT	5	/* in enabled wait state */

#define CIF_MCCK_GUEST		6	/* machine check happening in guest */

#define CIF_DEDICATED_CPU	7	/* this CPU is dedicated */



#define _CIF_NOHZ_DELAY		BIT(CIF_NOHZ_DELAY)

#define _CIF_FPU		BIT(CIF_FPU)

#define _CIF_ENABLED_WAIT	BIT(CIF_ENABLED_WAIT)

#define _CIF_MCCK_GUEST		BIT(CIF_MCCK_GUEST)

#define _CIF_DEDICATED_CPU	BIT(CIF_DEDICATED_CPU)

arch/s390/include/asm/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ void arch_setup_new_exec(void); 
#define TIF_PATCH_PENDING	5	/* pending live patching update */

#define TIF_PGSTE		6	/* New mm's will use 4K page tables */

#define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */

#define TIF_FPU			8	/* restore FPU registers on exit to usermode */

#define TIF_ISOLATE_BP_GUEST	9	/* Run KVM guests with isolated BP */

#define TIF_PER_TRAP		10	/* Need to handle PER trap on exit to usermode */
@@ -92,6 +93,7 @@ void arch_setup_new_exec(void); 
#define _TIF_UPROBE		BIT(TIF_UPROBE)

#define _TIF_GUARDED_STORAGE	BIT(TIF_GUARDED_STORAGE)

#define _TIF_PATCH_PENDING	BIT(TIF_PATCH_PENDING)

#define _TIF_FPU		BIT(TIF_FPU)

#define _TIF_ISOLATE_BP_GUEST	BIT(TIF_ISOLATE_BP_GUEST)

#define _TIF_PER_TRAP		BIT(TIF_PER_TRAP)

arch/s390/kernel/entry.S

+1 −1
Original line number Diff line number Diff line
@@ -220,7 +220,7 @@ SYM_FUNC_START(__sie64a) 
	oi	__SIE_PROG0C+3(%r14),1		# we are going into SIE now

	tm	__SIE_PROG20+3(%r14),3		# last exit...

	jnz	.Lsie_skip

	TSTMSK	__LC_CPU_FLAGS,_CIF_FPU

	TSTMSK	__SF_SIE_FLAGS(%r15),_TIF_FPU

	jo	.Lsie_skip			# exit if fp/vx regs changed

	lg	%r14,__SF_SIE_CONTROL_PHYS(%r15)	# get sie block phys addr

	BPEXIT	__SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST