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s390/kernel: dynamically allocate FP register save area
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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>
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Hendrik Brueckner authored and Martin Schwidefsky committed Jul 22, 2015
1 parent 904818e commit 155e839
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Showing 3 changed files with 38 additions and 12 deletions.
19 changes: 14 additions & 5 deletions arch/s390/include/asm/fpu-internal.h
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand All @@ -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)
{
Expand Down Expand Up @@ -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 */
27 changes: 20 additions & 7 deletions arch/s390/kernel/process.c
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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];
Expand Down
4 changes: 4 additions & 0 deletions arch/s390/kernel/traps.c
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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);
Expand Down

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