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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>
This commit is contained in:
Oleg Nesterov 2015-03-10 07:06:25 +01:00 committed by Ingo Molnar
parent e7f180dcd8
commit 1d23c4518b
2 changed files with 2 additions and 2 deletions
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1
arch/x86/include/asm/fpu-internal.h
View File

@ -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;
}

3
arch/x86/kernel/i387.c
View File

@ -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;