linux-kernel - Re: -tip tree resume fail, bisect to 5bd5a45(x86: Add NX protection for kernel data)

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Date:	Tue, 30 Nov 2010 12:27:18 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	mat <castet.matthieu@...e.fr>, Andi Kleen <andi@...stfloor.org>,
	Siarhei Liakh <sliakh.lkml@...il.com>,
	Xuxian Jiang <jiang@...ncsu.edu>, Ingo Molnar <mingo@...e.hu>,
	Arjan van de Ven <arjan@...radead.org>,
	lkml <linux-kernel@...r.kernel.org>, tglx <tglx@...utronix.de>
Subject: Re: -tip tree resume fail, bisect to 5bd5a45(x86: Add NX
 protection for kernel data)

On Tue, 2010-11-30 at 13:00 +0800, Lin Ming wrote:
> echo 0 > /sys/devices/system/cpu/cpu1/online;
> echo 1 > /sys/devices/system/cpu/cpu1/online;
> 
> then machine just reboots...
> 

That should work on current -tip (and my test machine confirms with a
-tip of yesterday) due to:

---
commit 691513f70d3957939a318da970987b876c720861
Author: Lin Ming <ming.m.lin@...el.com>
Date:   Mon Nov 22 14:03:28 2010 +0100

    x86: Resume trampoline must be executable
    
    commit 5bd5a452(x86: Add NX protection for kernel data) marked the
    trampoline area NX - which unsurprisingly breaks resume and cpu
    hotplug.
    
    Revert the portion of that commit, which touches the trampoline.
    
    Originally-from: Lin Ming <ming.m.lin@...el.com>
    LKML-Reference: <1290410581.2405.24.camel@...ggr.sh.intel.com>
    Cc: Matthieu Castet <castet.matthieu@...e.fr>
    Cc: Siarhei Liakh <sliakh.lkml@...il.com>
    Cc: Xuxian Jiang <jiang@...ncsu.edu>
    Cc: Ingo Molnar <mingo@...e.hu>
    Cc: Arjan van de Ven <arjan@...radead.org>
    Cc: Andi Kleen <andi@...stfloor.org>
    Tested-by: Peter Zijlstra <peterz@...radead.org>
    Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index ce59c05..71a5929 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -788,7 +788,6 @@ void mark_rodata_ro(void)
 	unsigned long rodata_start =
 		((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
 	unsigned long end = (unsigned long) &__end_rodata_hpage_align;
-	unsigned long kernel_end = (((unsigned long)&__init_end + HPAGE_SIZE) & HPAGE_MASK);
 	unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
 	unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
 	unsigned long data_start = (unsigned long) &_sdata;
@@ -803,7 +802,7 @@ void mark_rodata_ro(void)
 	 * The rodata section (but not the kernel text!) should also be
 	 * not-executable.
 	 */
-	set_memory_nx(rodata_start, (kernel_end - rodata_start) >> PAGE_SHIFT);
+	set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
 
 	rodata_test();
 

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