linux-kernel - Re: [PATCH v7u1 03/31] x86, realmode: set real

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Date:	Fri, 4 Jan 2013 12:58:15 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Borislav Petkov <bp@...en8.de>, Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kiszka <jan.kiszka@....de>,
	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7u1 03/31] x86, realmode: set real_mode permissions early

On Fri, Jan 4, 2013 at 12:15 PM, Borislav Petkov <bp@...en8.de> wrote:
>  /*
> - * set_real_mode_permissions() gets called very early, to guarantee the
> - * availability of low memory.  This is before the proper kernel page
> - * tables are set up, so we cannot set page permissions in that
> - * function.  Thus, we use an arch_initcall instead.
> + * This function gets called very early to guarantee the availability
> + * of low memory. This is even before the proper kernel page tables are
> + * set up, so we cannot set page permissions in that function. However,
> + * trampoline code will be executed by APs so we need it to be marked
> + * executable at pre-SMP time, thus run it as a early_initcall().
>   */

more than that, that set_real_mode_permissions reference is wrong,
actually it is set_real_mode.

 /*
- * set_real_mode_permissions() gets called very early, to guarantee the
- * availability of low memory.  This is before the proper kernel page
+ * set_real_mode() gets called very early, to guarantee the
+ * availability of low memory. This is before the proper kernel page
  * tables are set up, so we cannot set page permissions in that
- * function.  Thus, we use an arch_initcall instead.
+ * function. Also trampoline code will be executed by APs so we
+ * need to mark it executable at do_pre_smp_initcalls() at least,
+ * thus run it as a early_initcall().
  */
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