linux-kernel - [PATCH 3/5] x86, pageattr: make set_memory

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Date:	Fri, 13 Nov 2009 15:28:15 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, tglx@...utronix.de, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Huang Ying <ying.huang@...el.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Tejun Heo <tj@...nel.org>,
	Tim Starling <tstarling@...imedia.org>,
	Hannes Eder <hannes@...neseder.net>
Subject: [PATCH 3/5] x86, pageattr: make set_memory_(x|nx) aware of NX support

Make set_memory_x/set_memory_nx directly aware of if NX is supported
in the system or not, rather than requiring that every caller assesses
that support independently.

Signed-off-by: H. Peter Anvin <hpa@...or.com>
Cc: Huang Ying <ying.huang@...el.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Cc: Suresh Siddha <suresh.b.siddha@...el.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Tim Starling <tstarling@...imedia.org>
Cc: Hannes Eder <hannes@...neseder.net>
---
 arch/x86/kernel/machine_kexec_32.c |    6 ++----
 arch/x86/mm/pageattr.c             |    6 ++++++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index c1c429d..03657e7 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -157,8 +157,7 @@ int machine_kexec_prepare(struct kimage *image)
 {
 	int error;
 
-	if (nx_enabled)
-		set_pages_x(image->control_code_page, 1);
+	set_pages_x(image->control_code_page, 1);
 	error = machine_kexec_alloc_page_tables(image);
 	if (error)
 		return error;
@@ -172,8 +171,7 @@ int machine_kexec_prepare(struct kimage *image)
  */
 void machine_kexec_cleanup(struct kimage *image)
 {
-	if (nx_enabled)
-		set_pages_nx(image->control_code_page, 1);
+	set_pages_nx(image->control_code_page, 1);
 	machine_kexec_free_page_tables(image);
 }
 
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index dd38bfb..442b8ac 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1069,12 +1069,18 @@ EXPORT_SYMBOL(set_memory_array_wb);
 
 int set_memory_x(unsigned long addr, int numpages)
 {
+	if (!(__supported_pte_mask & _PAGE_NX))
+		return 0;
+
 	return change_page_attr_clear(&addr, numpages, __pgprot(_PAGE_NX), 0);
 }
 EXPORT_SYMBOL(set_memory_x);
 
 int set_memory_nx(unsigned long addr, int numpages)
 {
+	if (!(__supported_pte_mask & _PAGE_NX))
+		return 0;
+
 	return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_NX), 0);
 }
 EXPORT_SYMBOL(set_memory_nx);
-- 
1.6.2.5

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