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>

7 files changed, 38 insertions, 40 deletions

diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 6bc42c08be09..48c9af7a7683 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/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));
diff --git a/arch/s390/kernel/compat_signal.c b/arch/s390/kernel/compat_signal.c
index 0b46fd4aa31e..eb4664238613 100644
--- a/arch/s390/kernel/compat_signal.c
+++ b/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))
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 21c1219122af..5a966dea937f 100644
--- a/arch/s390/kernel/entry.S
+++ b/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
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 9cf0063f920e..f2dac9f0799d 100644
--- a/arch/s390/kernel/process.c
+++ b/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))
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 8c525880a3ff..8b1c8e33f184 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/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);
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 2f4c7e2638c9..9549af102d75 100644
--- a/arch/s390/kernel/signal.c
+++ b/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))
diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 76f76932ccb9..9861613fb35a 100644
--- a/arch/s390/kernel/traps.c
+++ b/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) {