linux-kernel - Re: [PATCH v7 23/27] x86/cet/shstk: ELF header parsing of Shadow Stack

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Date:   Fri, 7 Jun 2019 09:54:28 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc:     x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...capital.net>,
        Balbir Singh <bsingharora@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
        Dave Martin <Dave.Martin@....com>
Subject: Re: [PATCH v7 23/27] x86/cet/shstk: ELF header parsing of Shadow
 Stack

On Thu, Jun 06, 2019 at 01:06:42PM -0700, Yu-cheng Yu wrote:

> +#ifdef CONFIG_ARCH_USE_GNU_PROPERTY
> +int arch_setup_property(void *ehdr, void *phdr, struct file *f, bool inter)
> +{
> +	int r;
> +	uint32_t property;

Flip those two lines around.

> +
> +	r = get_gnu_property(ehdr, phdr, f, GNU_PROPERTY_X86_FEATURE_1_AND,
> +			     &property);
> +
> +	memset(&current->thread.cet, 0, sizeof(struct cet_status));

It seems to me that memset would be better placed before
get_gnu_property().

> +	if (r)
> +		return r;
> +
> +	if (cpu_feature_enabled(X86_FEATURE_SHSTK)) {

	if (r || !cpu_feature_enabled())
		return r;

> +		if (property & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
> +			r = cet_setup_shstk();
> +		if (r < 0)
> +			return r;
> +	}
> +	return r;

and loose the indent.

> +}
> +#endif
> -- 
> 2.17.1
>