Commit 1d23c451 authored Mar 10, 2015 by Oleg Nesterov Committed by Ingo Molnar Mar 10, 2015

x86/fpu: Factor out memset(xstate, 0) in fpu_finit() paths



fx_finit() has two users but only fpu_finit() needs to clear
xstate, alloc_bootmem_align() in setup_init_fpu_buf() returns
zero-filled memory.

And note that both memset()'s look confusing. Yes, offsetof() is
0 for ->fxsave or ->fsave, but it would be cleaner to turn
them into a single memset() which zeroes fpu->state.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Rik 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/1425967585-4725-2-git-send-email-bp@alien8.de
Link: http://lkml.kernel.org/r/20150302183257.GC23085@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent e7f180dc

arch/x86/include/asm/fpu-internal.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -135,7 +135,6 @@ static __always_inline __pure bool use_fxsr(void)

		static inline void fx_finit(struct i387_fxsave_struct *fx)
		{
		memset(fx, 0, xstate_size);
		fx->cwd = 0x37f;
		fx->mxcsr = MXCSR_DEFAULT;
		}

arch/x86/kernel/i387.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -224,11 +224,12 @@ void fpu_finit(struct fpu *fpu)
		return;
		}

		memset(fpu->state, 0, xstate_size);

		if (cpu_has_fxsr) {
		fx_finit(&fpu->state->fxsave);
		} else {
		struct i387_fsave_struct *fp = &fpu->state->fsave;
		memset(fp, 0, xstate_size);
		fp->cwd = 0xffff037fu;
		fp->swd = 0xffff0000u;
		fp->twd = 0xffffffffu;