s390/kernel: dynamically allocate FP register save area

Make the floating-point save area dynamically allocated and uses a flag
to distinguish whether a task uses floating-point or vector registers.

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

diff --git a/arch/s390/include/asm/fpu-internal.h b/arch/s390/include/asm/fpu-internal.h
index 04b4cfc..cc44c75 100644 (file)
--- a/arch/s390/include/asm/fpu-internal.h
+++ b/arch/s390/include/asm/fpu-internal.h
@@ -8,6 +8,10 @@
 #ifndef _ASM_S390_FPU_INTERNAL_H
 #define _ASM_S390_FPU_INTERNAL_H
 
+#define FPU_USE_VX             1       /* Vector extension is active */
+
+#ifndef __ASSEMBLY__
+
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <asm/linkage.h>
@@ -16,13 +20,16 @@
 
 struct fpu {
        __u32 fpc;                      /* Floating-point control */
-       __u32 pad;
-       freg_t fprs[__NUM_FPRS];        /* Floating-point register save area */
-       __vector128 *vxrs;              /* Vector register save area */
+       __u32 flags;
+       union {
+               void *regs;
+               freg_t *fprs;           /* Floating-point register save area */
+               __vector128 *vxrs;      /* Vector register save area */
+       };
 };
 
-#define is_vx_fpu(fpu) (!!(fpu)->vxrs)
-#define is_vx_task(tsk) (!!(tsk)->thread.fpu.vxrs)
+#define is_vx_fpu(fpu) (!!((fpu)->flags & FPU_USE_VX))
+#define is_vx_task(tsk) (!!((tsk)->thread.fpu.flags & FPU_USE_VX))
 
 static inline int test_fp_ctl(u32 fpc)
 {
@@ -188,4 +195,6 @@ static inline void restore_fpu_regs(struct fpu *fpu)
                restore_fp_regs(fpu->fprs);
 }
 
+#endif
+
 #endif /* _ASM_S390_FPU_INTERNAL_H */

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 61795bc..56949c9 100644 (file)
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -81,8 +81,26 @@ void release_thread(struct task_struct *dead_task)
 
 void arch_release_task_struct(struct task_struct *tsk)
 {
-       if (is_vx_task(tsk))
-               kfree(tsk->thread.fpu.vxrs);
+       /* Free either the floating-point or the vector register save area */
+       kfree(tsk->thread.fpu.regs);
+}
+
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
+{
+       *dst = *src;
+
+       /* Set up a new floating-point register save area */
+       dst->thread.fpu.fprs = kzalloc(sizeof(freg_t) * __NUM_FPRS,
+                                      GFP_KERNEL|__GFP_REPEAT);
+       if (!dst->thread.fpu.fprs)
+               return -ENOMEM;
+
+       /* Save the fpu registers to new thread structure. */
+       save_fp_ctl(&dst->thread.fpu.fpc);
+       save_fp_regs(dst->thread.fpu.fprs);
+       dst->thread.fpu.flags = 0;     /* Always start with VX disabled */
+
+       return 0;
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
@@ -142,11 +160,6 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
        p->thread.ri_signum = 0;
        frame->childregs.psw.mask &= ~PSW_MASK_RI;
 
-       /* Save the fpu registers to new thread structure. */
-       save_fp_ctl(&p->thread.fpu.fpc);
-       save_fp_regs(p->thread.fpu.fprs);
-       p->thread.fpu.pad = 0;
-       p->thread.fpu.vxrs = NULL;
        /* Set a new TLS ?  */
        if (clone_flags & CLONE_SETTLS) {
                unsigned long tls = frame->childregs.gprs[6];

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 97598d1..7b09224 100644 (file)
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -227,6 +227,7 @@ DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 int alloc_vector_registers(struct task_struct *tsk)
 {
        __vector128 *vxrs;
+       freg_t *fprs;
 
        /* Allocate vector register save area. */
        vxrs = kzalloc(sizeof(__vector128) * __NUM_VXRS,
@@ -238,7 +239,10 @@ int alloc_vector_registers(struct task_struct *tsk)
                save_fp_regs(tsk->thread.fpu.fprs);
        /* Copy the 16 floating point registers */
        convert_fp_to_vx(vxrs, tsk->thread.fpu.fprs);
+       fprs = tsk->thread.fpu.fprs;
        tsk->thread.fpu.vxrs = vxrs;
+       tsk->thread.fpu.flags |= FPU_USE_VX;
+       kfree(fprs);
        if (tsk == current) {
                __ctl_set_bit(0, 17);
                restore_vx_regs(vxrs);