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Date: Tue, 28 Mar 2017 23:26:05 -0700 From: Andi Kleen <andi@...stfloor.org> To: x86@...nel.org Cc: peterz@...radead.org, linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com> Subject: [PATCH] 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. (or could be removed since if it hasn't triggered by now it probably never will) Signed-off-by: Andi Kleen <ak@...ux.intel.com> --- 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 d4a684997497..ec0c542a91ab 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -340,7 +340,7 @@ 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); -- 2.9.3
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