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Message-ID: <57311DC6.5000503@linux.intel.com>
Date: Mon, 9 May 2016 16:31:18 -0700
From: Dave Hansen <dave.hansen@...ux.intel.com>
To: Yu-cheng Yu <yu-cheng.yu@...el.com>, linux-kernel@...r.kernel.org,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...e.de>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH v5 11/13] x86/xsaves: Add WARN_ON_FPU() when a disabled
xstate component offset is requested for a compacted format
On 05/09/2016 01:46 PM, Yu-cheng Yu wrote:
> Add a warning in case a disabled (not existing) xstate component offset
> is requested.
...
> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> index 350814c..2e6dbfe 100644
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -756,6 +756,7 @@ void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
> {
> int feature_nr = fls64(xstate_feature_mask) - 1;
>
> + WARN_ON_FPU(using_compacted_format() && !xfeature_enabled(feature_nr));
> return (void *)xsave + xstate_comp_offsets[feature_nr];
> }
Why the using_compacted_format()? Shouldn't this be an error, regardless.
Also, what is xstate_comp_offsets[feature_nr] in this case? Isn't it
-1? Should we be returning NULL along with WARN()ing?
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