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Commit 67e97fc2 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent bda28379

arch/x86/kernel/i387.c

+17 −14
Original line number Diff line number Diff line
@@ -283,27 +283,30 @@ EXPORT_SYMBOL_GPL(fpstate_alloc_init); 
 * value at reset if we support XMM instructions and then

 * 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;



	if (tsk_used_math(tsk)) {

		if (cpu_has_fpu && tsk == current)

			fpu__save(tsk);

		task_disable_lazy_fpu_restore(tsk);

	if (WARN_ON_ONCE(child == current))

		return -EINVAL;



	if (tsk_used_math(child)) {

		if (cpu_has_fpu && child == current)

			fpu__save(child);

		task_disable_lazy_fpu_restore(child);

		return 0;

	}



	/*

	 * 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)

		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;

}
@@ -331,7 +334,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset, 
	if (!cpu_has_fxsr)

		return -ENODEV;



	ret = init_fpu(target);

	ret = fpu__unlazy_stopped(target);

	if (ret)

		return ret;
@@ -350,7 +353,7 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset, 
	if (!cpu_has_fxsr)

		return -ENODEV;



	ret = init_fpu(target);

	ret = fpu__unlazy_stopped(target);

	if (ret)

		return ret;
@@ -384,7 +387,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset, 
	if (!cpu_has_xsave)

		return -ENODEV;



	ret = init_fpu(target);

	ret = fpu__unlazy_stopped(target);

	if (ret)

		return ret;
@@ -414,7 +417,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, 
	if (!cpu_has_xsave)

		return -ENODEV;



	ret = init_fpu(target);

	ret = fpu__unlazy_stopped(target);

	if (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;

	int ret;



	ret = init_fpu(target);

	ret = fpu__unlazy_stopped(target);

	if (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;

	int ret;



	ret = init_fpu(target);

	ret = fpu__unlazy_stopped(target);

	if (ret)

		return ret;