s390/kernel: remove save_fpu_regs() parameter and use __LC_CURRENT instead

All calls to save_fpu_regs() specify the fpu structure of the current task
pointer as parameter.  The task pointer of the current task can also be
retrieved from the CPU lowcore directly.  Remove the parameter definition,
load the __LC_CURRENT task pointer from the CPU lowcore, and rebase the FPU
structure onto the task structure.  Apply the same approach for the
load_fpu_regs() function.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/fpu-internal.h

@@ -28,7 +28,7 @@ struct fpu {
 	};
 };
 
-void save_fpu_regs(struct fpu *fpu);
+void save_fpu_regs(void);
 
 #define is_vx_fpu(fpu) (!!((fpu)->flags & FPU_USE_VX))
 #define is_vx_task(tsk) (!!((tsk)->thread.fpu.flags & FPU_USE_VX))

arch/s390/include/asm/switch_to.h

@@ -30,7 +30,7 @@ static inline void restore_access_regs(unsigned int *acrs)
 
 #define switch_to(prev,next,last) do {					\
 	if (prev->mm) {							\
-		save_fpu_regs(&prev->thread.fpu);			\
+		save_fpu_regs();					\
 		save_access_regs(&prev->thread.acrs[0]);		\
 		save_ri_cb(prev->thread.ri_cb);				\
 	}								\

arch/s390/kernel/asm-offsets.c

@@ -28,16 +28,14 @@ int main(void)
 	DEFINE(__TASK_pid, offsetof(struct task_struct, pid));
 	BLANK();
 	DEFINE(__THREAD_ksp, offsetof(struct thread_struct, ksp));
-	DEFINE(__THREAD_fpu, offsetof(struct task_struct, thread.fpu));
+	DEFINE(__THREAD_FPU_fpc, offsetof(struct thread_struct, fpu.fpc));
+	DEFINE(__THREAD_FPU_flags, offsetof(struct thread_struct, fpu.flags));
+	DEFINE(__THREAD_FPU_regs, offsetof(struct thread_struct, fpu.regs));
 	DEFINE(__THREAD_per_cause, offsetof(struct thread_struct, per_event.cause));
 	DEFINE(__THREAD_per_address, offsetof(struct thread_struct, per_event.address));
 	DEFINE(__THREAD_per_paid, offsetof(struct thread_struct, per_event.paid));
 	DEFINE(__THREAD_trap_tdb, offsetof(struct thread_struct, trap_tdb));
 	BLANK();
-	DEFINE(__FPU_fpc, offsetof(struct fpu, fpc));
-	DEFINE(__FPU_flags, offsetof(struct fpu, flags));
-	DEFINE(__FPU_regs, offsetof(struct fpu, regs));
-	BLANK();
 	DEFINE(__TI_task, offsetof(struct thread_info, task));
 	DEFINE(__TI_flags, offsetof(struct thread_info, flags));
 	DEFINE(__TI_sysc_table, offsetof(struct thread_info, sys_call_table));

arch/s390/kernel/compat_signal.c

@@ -154,7 +154,7 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 static void store_sigregs(void)
 {
 	save_access_regs(current->thread.acrs);
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 }
 
 /* Load registers after signal return */
@@ -286,7 +286,7 @@ COMPAT_SYSCALL_DEFINE0(sigreturn)
 	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE32))
 		goto badframe;
 	set_current_blocked(&set);
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	if (restore_sigregs32(regs, &frame->sregs))
 		goto badframe;
 	if (restore_sigregs_ext32(regs, &frame->sregs_ext))
@@ -309,7 +309,7 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 	set_current_blocked(&set);
 	if (compat_restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	if (restore_sigregs32(regs, &frame->uc.uc_mcontext))
 		goto badframe;
 	if (restore_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))

arch/s390/kernel/entry.S

@@ -183,7 +183,6 @@ ENTRY(sie64a)
 	xc	__SF_EMPTY+16(16,%r15),__SF_EMPTY+16(%r15) # host id & reason
 	tm	__LC_CPU_FLAGS+7,_CIF_FPU	# load guest fp/vx registers ?
 	jno	.Lsie_load_guest_gprs
-	lg	%r12,__LC_THREAD_INFO		# load fp/vx regs save area
 	brasl	%r14,load_fpu_regs		# load guest fp/vx regs
 .Lsie_load_guest_gprs:
 	lmg	%r0,%r13,0(%r3)			# load guest gprs 0-13
@@ -752,14 +751,16 @@ ENTRY(psw_idle)
  * of the register contents at system call or io return.
  */
 ENTRY(save_fpu_regs)
+	lg	%r2,__LC_CURRENT
+	aghi	%r2,__TASK_thread
 	tm	__LC_CPU_FLAGS+7,_CIF_FPU
 	bor	%r14
-	stfpc	__FPU_fpc(%r2)
+	stfpc	__THREAD_FPU_fpc(%r2)
 .Lsave_fpu_regs_fpc_end:
-	lg	%r3,__FPU_regs(%r2)
+	lg	%r3,__THREAD_FPU_regs(%r2)
 	ltgr	%r3,%r3
 	jz	.Lsave_fpu_regs_done	  # no save area -> set CIF_FPU
-	tm	__FPU_flags+3(%r2),FPU_USE_VX
+	tm	__THREAD_FPU_flags+3(%r2),FPU_USE_VX
 	jz	.Lsave_fpu_regs_fp	  # no -> store FP regs
 .Lsave_fpu_regs_vx_low:
 	VSTM	%v0,%v15,0,%r3		  # vstm 0,15,0(3)
@@ -794,20 +795,19 @@ ENTRY(save_fpu_regs)
  * FP/VX state, the vector-enablement control, CR0.46, is either set or cleared.
  *
  * There are special calling conventions to fit into sysc and io return work:
- *	%r12:	__LC_THREAD_INFO
  *	%r15:	<kernel stack>
  * The function requires:
  *	%r4 and __SF_EMPTY+32(%r15)
  */
 load_fpu_regs:
+	lg	%r4,__LC_CURRENT
+	aghi	%r4,__TASK_thread
 	tm	__LC_CPU_FLAGS+7,_CIF_FPU
 	bnor	%r14
-	lg	%r4,__TI_task(%r12)
-	la	%r4,__THREAD_fpu(%r4)
-	lfpc	__FPU_fpc(%r4)
+	lfpc	__THREAD_FPU_fpc(%r4)
 	stctg	%c0,%c0,__SF_EMPTY+32(%r15)	# store CR0
-	tm	__FPU_flags+3(%r4),FPU_USE_VX	# VX-enabled task ?
-	lg	%r4,__FPU_regs(%r4)		# %r4 <- reg save area
+	tm	__THREAD_FPU_flags+3(%r4),FPU_USE_VX	# VX-enabled task ?
+	lg	%r4,__THREAD_FPU_regs(%r4)	# %r4 <- reg save area
 	jz	.Lload_fpu_regs_fp_ctl		# -> no VX, load FP regs
 .Lload_fpu_regs_vx_ctl:
 	tm	__SF_EMPTY+32+5(%r15),2		# test VX control
@@ -1190,13 +1190,14 @@ cleanup_critical:
 	jhe	2f
 	clg	%r9,BASED(.Lcleanup_save_fpu_fpc_end)
 	jhe	1f
+	lg	%r2,__LC_CURRENT
 0:	# Store floating-point controls
-	stfpc	__FPU_fpc(%r2)
+	stfpc	__THREAD_FPU_fpc(%r2)
 1:	# Load register save area and check if VX is active
-	lg	%r3,__FPU_regs(%r2)
+	lg	%r3,__THREAD_FPU_regs(%r2)
 	ltgr	%r3,%r3
 	jz	5f			  # no save area -> set CIF_FPU
-	tm	__FPU_flags+3(%r2),FPU_USE_VX
+	tm	__THREAD_FPU_flags+3(%r2),FPU_USE_VX
 	jz	4f			  # no VX -> store FP regs
 2:	# Store vector registers (V0-V15)
 	VSTM	%v0,%v15,0,%r3		  # vstm 0,15,0(3)
@@ -1250,11 +1251,10 @@ cleanup_critical:
 	jhe	5f
 	clg	%r9,BASED(.Lcleanup_load_fpu_regs_vx_ctl)
 	jhe	6f
-	lg	%r4,__TI_task(%r12)
-	la	%r4,__THREAD_fpu(%r4)
-	lfpc	__FPU_fpc(%r4)
-	tm	__FPU_flags+3(%r4),FPU_USE_VX	# VX-enabled task ?
-	lg	%r4,__FPU_regs(%r4)		# %r4 <- reg save area
+	lg	%r4,__LC_CURRENT
+	lfpc	__THREAD_FPU_fpc(%r4)
+	tm	__THREAD_FPU_flags+3(%r4),FPU_USE_VX	# VX-enabled task ?
+	lg	%r4,__THREAD_FPU_regs(%r4)	# %r4 <- reg save area
 	jz	3f				# -> no VX, load FP regs
 6:	# Set VX-enablement control
 	stctg	%c0,%c0,__SF_EMPTY+32(%r15)	# store CR0

arch/s390/kernel/process.c

@@ -104,7 +104,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 	 * The CIF_FPU flag is set in any case to lazy clear or restore a saved
 	 * state when switching to a different task or returning to user space.
 	 */
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	dst->thread.fpu.fpc = current->thread.fpu.fpc;
 	if (is_vx_task(current))
 		convert_vx_to_fp(dst->thread.fpu.fprs,
@@ -196,7 +196,7 @@ asmlinkage void execve_tail(void)
  */
 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 {
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	fpregs->fpc = current->thread.fpu.fpc;
 	fpregs->pad = 0;
 	if (is_vx_task(current))

arch/s390/kernel/ptrace.c

@@ -943,7 +943,7 @@ static int s390_fpregs_get(struct task_struct *target,
 	_s390_fp_regs fp_regs;
 
 	if (target == current)
-		save_fpu_regs(&target->thread.fpu);
+		save_fpu_regs();
 
 	fp_regs.fpc = target->thread.fpu.fpc;
 	fpregs_store(&fp_regs, &target->thread.fpu);
@@ -961,7 +961,7 @@ static int s390_fpregs_set(struct task_struct *target,
 	freg_t fprs[__NUM_FPRS];
 
 	if (target == current)
-		save_fpu_regs(&target->thread.fpu);
+		save_fpu_regs();
 
 	/* If setting FPC, must validate it first. */
 	if (count > 0 && pos < offsetof(s390_fp_regs, fprs)) {
@@ -1049,7 +1049,7 @@ static int s390_vxrs_low_get(struct task_struct *target,
 		return -ENODEV;
 	if (is_vx_task(target)) {
 		if (target == current)
-			save_fpu_regs(&target->thread.fpu);
+			save_fpu_regs();
 		for (i = 0; i < __NUM_VXRS_LOW; i++)
 			vxrs[i] = *((__u64 *)(target->thread.fpu.vxrs + i) + 1);
 	} else
@@ -1072,7 +1072,7 @@ static int s390_vxrs_low_set(struct task_struct *target,
 		if (rc)
 			return rc;
 	} else if (target == current)
-		save_fpu_regs(&target->thread.fpu);
+		save_fpu_regs();
 
 	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf, vxrs, 0, -1);
 	if (rc == 0)
@@ -1093,7 +1093,7 @@ static int s390_vxrs_high_get(struct task_struct *target,
 		return -ENODEV;
 	if (is_vx_task(target)) {
 		if (target == current)
-			save_fpu_regs(&target->thread.fpu);
+			save_fpu_regs();
 		memcpy(vxrs, target->thread.fpu.vxrs + __NUM_VXRS_LOW,
 		       sizeof(vxrs));
 	} else
@@ -1115,7 +1115,7 @@ static int s390_vxrs_high_set(struct task_struct *target,
 		if (rc)
 			return rc;
 	} else if (target == current)
-		save_fpu_regs(&target->thread.fpu);
+		save_fpu_regs();
 
 	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 				target->thread.fpu.vxrs + __NUM_VXRS_LOW, 0, -1);

arch/s390/kernel/signal.c

@@ -105,7 +105,7 @@ struct rt_sigframe
 static void store_sigregs(void)
 {
 	save_access_regs(current->thread.acrs);
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 }
 
 /* Load registers after signal return */
@@ -222,7 +222,7 @@ SYSCALL_DEFINE0(sigreturn)
 	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 		goto badframe;
 	set_current_blocked(&set);
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	if (restore_sigregs(regs, &frame->sregs))
 		goto badframe;
 	if (restore_sigregs_ext(regs, &frame->sregs_ext))
@@ -246,7 +246,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	set_current_blocked(&set);
 	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 		goto badframe;
 	if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))

arch/s390/kernel/traps.c

@@ -236,7 +236,7 @@ int alloc_vector_registers(struct task_struct *tsk)
 		return -ENOMEM;
 	preempt_disable();
 	if (tsk == current)
-		save_fpu_regs(&tsk->thread.fpu);
+		save_fpu_regs();
 	/* Copy the 16 floating point registers */
 	convert_fp_to_vx(vxrs, tsk->thread.fpu.fprs);
 	fprs = tsk->thread.fpu.fprs;
@@ -257,7 +257,7 @@ void vector_exception(struct pt_regs *regs)
 	}
 
 	/* get vector interrupt code from fpc */
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	vic = (current->thread.fpu.fpc & 0xf00) >> 8;
 	switch (vic) {
 	case 1: /* invalid vector operation */
@@ -295,7 +295,7 @@ void data_exception(struct pt_regs *regs)
 
 	location = get_trap_ip(regs);
 
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	/* Check for vector register enablement */
 	if (MACHINE_HAS_VX && !is_vx_task(current) &&
 	    (current->thread.fpu.fpc & FPC_DXC_MASK) == 0xfe00) {

arch/s390/kvm/kvm-s390.c

@@ -1224,7 +1224,7 @@ static inline void load_fpu_from(struct fpu *from)
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	/* Save host register state */
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	save_fpu_to(&vcpu->arch.host_fpregs);
 
 	if (test_kvm_facility(vcpu->kvm, 129)) {
@@ -1256,7 +1256,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	atomic_clear_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags);
 	gmap_disable(vcpu->arch.gmap);
 
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 
 	if (test_kvm_facility(vcpu->kvm, 129))
 		/*
@@ -1671,7 +1671,7 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
 		return -EINVAL;
 	memcpy(vcpu->arch.guest_fpregs.fprs, &fpu->fprs, sizeof(fpu->fprs));
 	vcpu->arch.guest_fpregs.fpc = fpu->fpc;
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	load_fpu_from(&vcpu->arch.guest_fpregs);
 	return 0;
 }
@@ -2241,7 +2241,7 @@ int kvm_s390_vcpu_store_status(struct kvm_vcpu *vcpu, unsigned long addr)
 	 * copying in vcpu load/put. Lets update our copies before we save
 	 * it into the save area
 	 */
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 	if (test_kvm_facility(vcpu->kvm, 129)) {
 		/*
 		 * If the vector extension is available, the vector registers
@@ -2288,7 +2288,7 @@ int kvm_s390_vcpu_store_adtl_status(struct kvm_vcpu *vcpu, unsigned long addr)
 	 *
 	 * Let's update our copies before we save it into the save area.
 	 */
-	save_fpu_regs(&current->thread.fpu);
+	save_fpu_regs();
 
 	return kvm_s390_store_adtl_status_unloaded(vcpu, addr);
 }