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Date: Sat, 23 Sep 2017 15:00:06 +0200 From: Ingo Molnar <mingo@...nel.org> To: linux-kernel@...r.kernel.org Cc: Andrew Morton <akpm@...ux-foundation.org>, Eric Biggers <ebiggers3@...il.com>, Andy Lutomirski <luto@...capital.net>, Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, Fenghua Yu <fenghua.yu@...el.com>, "H . Peter Anvin" <hpa@...or.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Oleg Nesterov <oleg@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Rik van Riel <riel@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Yu-cheng Yu <yu-cheng.yu@...el.com> Subject: [PATCH 23/33] x86/fpu: Turn WARN_ON() in context switch into WARN_ON_FPU() From: Andi Kleen <ak@...ux.intel.com> copy_xregs_to_kernel checks if the alternatives have been already patched. This WARN_ON() is always executed in every context switch. All the other checks in fpu internal.h are WARN_ON_FPU(), but this one is plain WARN_ON(). I assume it was forgotten to switch it. So switch it to WARN_ON_FPU() too to avoid some unnecessary code in the context switch, and a potentially expensive cache line miss for the global variable. Signed-off-by: Andi Kleen <ak@...ux.intel.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Thomas Gleixner <tglx@...utronix.de> Link: http://lkml.kernel.org/r/20170329062605.4970-1-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@...nel.org> --- arch/x86/include/asm/fpu/internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 629e7abcd6c9..2dca7c65319c 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -350,7 +350,7 @@ static inline void copy_xregs_to_kernel(struct xregs_state *xstate) u32 hmask = mask >> 32; int err; - WARN_ON(!alternatives_patched); + WARN_ON_FPU(!alternatives_patched); XSTATE_XSAVE(xstate, lmask, hmask, err); -- 2.11.0
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