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>

10 files changed, 45 insertions, 47 deletions

diff --git a/arch/s390/include/asm/fpu-internal.h b/arch/s390/include/asm/fpu-internal.h
index 237f8fcbe46b..55dc2c0fb40a 100644
--- a/arch/s390/include/asm/fpu-internal.h
+++ b/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))
diff --git a/arch/s390/include/asm/switch_to.h b/arch/s390/include/asm/switch_to.h
index 0a4a3150b7d7..dcadfde32265 100644
--- a/arch/s390/include/asm/switch_to.h
+++ b/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);                         \
         }                                                               \
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) {
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c0cceaf4a92e..1903f0212bd0 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/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);
 }