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MIPS: Simplify PTRACE_PEEKUSR for FPC_EIR 

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>
Reviewed-by: Qais Yousef <qais.yousef@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6144/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2013-11-19 17:30:35 +00:00 committed by Ralf Baechle
parent d7b12056bc
commit 3351047f01
2 changed files with 6 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
arch/mips/kernel/ptrace.c
View File

@ -501,44 +501,10 @@ long arch_ptrace(struct task_struct *child, long request,
case FPC_CSR:
tmp = child->thread.fpu.fcr31;
break;
case FPC_EIR: { /* implementation / version register */
unsigned int flags;
#ifdef CONFIG_MIPS_MT_SMTC
unsigned long irqflags;
unsigned int mtflags;
#endif /* CONFIG_MIPS_MT_SMTC */
preempt_disable();
if (!cpu_has_fpu) {
preempt_enable();
break;
}
#ifdef CONFIG_MIPS_MT_SMTC
/* Read-modify-write of Status must be atomic */
local_irq_save(irqflags);
mtflags = dmt();
#endif /* CONFIG_MIPS_MT_SMTC */
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);
}
#ifdef CONFIG_MIPS_MT_SMTC
emt(mtflags);
local_irq_restore(irqflags);
#endif /* CONFIG_MIPS_MT_SMTC */
preempt_enable();
case FPC_EIR:
/* implementation / version register */
tmp = current_cpu_data.fpu_id;
break;
}
case DSP_BASE ... DSP_BASE + 5: {
dspreg_t *dregs;

42
arch/mips/kernel/ptrace32.c
View File

@ -127,46 +127,10 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
case FPC_CSR:
tmp = child->thread.fpu.fcr31;
break;
case FPC_EIR: { /* implementation / version register */
unsigned int flags;
#ifdef CONFIG_MIPS_MT_SMTC
unsigned int irqflags;
unsigned int mtflags;
#endif /* CONFIG_MIPS_MT_SMTC */
preempt_disable();
if (!cpu_has_fpu) {
preempt_enable();
tmp = 0;
break;
}
#ifdef CONFIG_MIPS_MT_SMTC
/* Read-modify-write of Status must be atomic */
local_irq_save(irqflags);
mtflags = dmt();
#endif /* CONFIG_MIPS_MT_SMTC */
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);
}
#ifdef CONFIG_MIPS_MT_SMTC
emt(mtflags);
local_irq_restore(irqflags);
#endif /* CONFIG_MIPS_MT_SMTC */
preempt_enable();
case FPC_EIR:
/* implementation / version register */
tmp = current_cpu_data.fpu_id;
break;
}
case DSP_BASE ... DSP_BASE + 5: {
dspreg_t *dregs;