Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e7f180dc authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
Browse files

x86/fpu: Change xstateregs_get()/set() to use ->xsave.i387 rather than ->fxsave 



This is a cosmetic change: xstateregs_get() and xstateregs_set()
abuse ->fxsave to access xsave->i387.sw_reserved.

This practice is correct, ->fxsave and xsave->i387 share the same memory,
but IMHO this looks confusing.

And we can make this code more readable if we add a
"struct xsave_struct *" local variable as well.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1425967585-4725-1-git-send-email-bp@alien8.de
Link: http://lkml.kernel.org/r/20150302183237.GB23085@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ae486033

arch/x86/kernel/i387.c

+9 −16
Original line number Diff line number Diff line
@@ -339,6 +339,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset, 
		unsigned int pos, unsigned int count,

		void *kbuf, void __user *ubuf)

{

	struct xsave_struct *xsave = &target->thread.fpu.state->xsave;

	int ret;



	if (!cpu_has_xsave)
@@ -353,14 +354,12 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset, 
	 * memory layout in the thread struct, so that we can copy the entire

	 * xstateregs to the user using one user_regset_copyout().

	 */

	memcpy(&target->thread.fpu.state->fxsave.sw_reserved,

	memcpy(&xsave->i387.sw_reserved,

		xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));



	/*

	 * Copy the xstate memory layout.

	 */

	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,

				  &target->thread.fpu.state->xsave, 0, -1);

	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);

	return ret;

}
@@ -368,8 +367,8 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, 
		  unsigned int pos, unsigned int count,

		  const void *kbuf, const void __user *ubuf)

{

	struct xsave_struct *xsave = &target->thread.fpu.state->xsave;

	int ret;

	struct xsave_hdr_struct *xsave_hdr;



	if (!cpu_has_xsave)

		return -ENODEV;
@@ -378,22 +377,16 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, 
	if (ret)

		return ret;



	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,

				 &target->thread.fpu.state->xsave, 0, -1);



	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);

	/*

	 * mxcsr reserved bits must be masked to zero for security reasons.

	 */

	target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;



	xsave_hdr = &target->thread.fpu.state->xsave.xsave_hdr;



	xsave_hdr->xstate_bv &= pcntxt_mask;

	xsave->i387.mxcsr &= mxcsr_feature_mask;

	xsave->xsave_hdr.xstate_bv &= pcntxt_mask;

	/*

	 * These bits must be zero.

	 */

	memset(xsave_hdr->reserved, 0, 48);



	memset(&xsave->xsave_hdr.reserved, 0, 48);

	return ret;

}