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Subject[PATCH 3/5] x86, pageattr: make set_memory_(x|nx) aware of NX support
Date
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@zytor.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tim Starling <tstarling@wikimedia.org>
Cc: Hannes Eder <hannes@hanneseder.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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