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MIPS: Simplify ptrace_getfpregs FPU IR retrieval

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All architecturally defined bits in the FPU implementation register
are read only & unchanging. It contains some implementation-defined
bits but the architecture manual states "This bits are explicitly not
intended to be used for mode control functions" which seems to provide
justification for viewing the register as a whole as unchanging. This
being the case we can simply re-use the value we read at boot rather
than having to re-read it later, and avoid the complexity which that
read entails.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6147/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2013-11-19 17:30:36 +00:00 • committed by Ralf Baechle
parent 3351047f01
commit dab75dd956
1 changed files with 1 additions and 24 deletions
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25
arch/mips/kernel/ptrace.c
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@ -114,7 +114,6 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data)
int ptrace_getfpregs(struct task_struct *child, __u32 __user *data) int ptrace_getfpregs(struct task_struct *child, __u32 __user *data)
{ {
int i; int i;
unsigned int tmp;
if (!access_ok(VERIFY_WRITE, data, 33 * 8)) if (!access_ok(VERIFY_WRITE, data, 33 * 8))
return -EIO; return -EIO;
@ -130,29 +129,7 @@ int ptrace_getfpregs(struct task_struct *child, __u32 __user *data)
} }
__put_user(child->thread.fpu.fcr31, data + 64); __put_user(child->thread.fpu.fcr31, data + 64);
__put_user(current_cpu_data.fpu_id, data + 65);
preempt_disable();
if (cpu_has_fpu) {
unsigned int flags;
if (cpu_has_mipsmt) {
unsigned int vpflags = dvpe();
flags = read_c0_status();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
write_c0_status(flags);
evpe(vpflags);
} else {
flags = read_c0_status();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
write_c0_status(flags);
}
} else {
tmp = 0;
}
preempt_enable();
__put_user(tmp, data + 65);
return 0; return 0;
} }