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x86/fpu: Rename init_fpu() to fpu__unlazy_stopped() and add debugging check 

This function name is a misnomer now that we've split out all the
other users from it. Rename it accordingly: it's used to save
the FPU state of (ptrace-)stopped child tasks.

Add debugging check to double check this intended usage: that this
function is only called for non-current, stopped child tasks.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2015-04-03 12:21:03 +02:00
parent bda283796b
commit 67e97fc2ec
1 changed files with 17 additions and 14 deletions
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31
arch/x86/kernel/i387.c
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@ -283,27 +283,30 @@ EXPORT_SYMBOL_GPL(fpstate_alloc_init);
* value at reset if we support XMM instructions and then * value at reset if we support XMM instructions and then
* remember the current task has used the FPU. * remember the current task has used the FPU.
*/ */
static int init_fpu(struct task_struct *tsk) static int fpu__unlazy_stopped(struct task_struct *child)
{ {
int ret; int ret;
if (tsk_used_math(tsk)) { if (WARN_ON_ONCE(child == current))
if (cpu_has_fpu && tsk == current) return -EINVAL;
fpu__save(tsk);
task_disable_lazy_fpu_restore(tsk); if (tsk_used_math(child)) {
if (cpu_has_fpu && child == current)
fpu__save(child);
task_disable_lazy_fpu_restore(child);
return 0; return 0;
} }
/* /*
* Memory allocation at the first usage of the FPU and other state. * Memory allocation at the first usage of the FPU and other state.
*/ */
ret = fpu_alloc(&tsk->thread.fpu); ret = fpu_alloc(&child->thread.fpu);
if (ret) if (ret)
return ret; return ret;
fpu_finit(&tsk->thread.fpu); fpu_finit(&child->thread.fpu);
set_stopped_child_used_math(tsk); set_stopped_child_used_math(child);
return 0; return 0;
} }
@ -331,7 +334,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr) if (!cpu_has_fxsr)
return -ENODEV; return -ENODEV;
ret = init_fpu(target); ret = fpu__unlazy_stopped(target);
if (ret) if (ret)
return ret; return ret;
@ -350,7 +353,7 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr) if (!cpu_has_fxsr)
return -ENODEV; return -ENODEV;
ret = init_fpu(target); ret = fpu__unlazy_stopped(target);
if (ret) if (ret)
return ret; return ret;
@ -384,7 +387,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_xsave) if (!cpu_has_xsave)
return -ENODEV; return -ENODEV;
ret = init_fpu(target); ret = fpu__unlazy_stopped(target);
if (ret) if (ret)
return ret; return ret;
@ -414,7 +417,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_xsave) if (!cpu_has_xsave)
return -ENODEV; return -ENODEV;
ret = init_fpu(target); ret = fpu__unlazy_stopped(target);
if (ret) if (ret)
return ret; return ret;
@ -577,7 +580,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env; struct user_i387_ia32_struct env;
int ret; int ret;
ret = init_fpu(target); ret = fpu__unlazy_stopped(target);
if (ret) if (ret)
return ret; return ret;
@ -608,7 +611,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env; struct user_i387_ia32_struct env;
int ret; int ret;
ret = init_fpu(target); ret = fpu__unlazy_stopped(target);
if (ret) if (ret)
return ret; return ret;