x86: unify noexec handling

This patch unifies noexec handling on 32-bit and 64-bit.

[ Impact: cleanup ]

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
[ mingo@elte.hu: build fix ]
LKML-Reference: <1240303167.771.69.camel@penberg-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 63 insertions, 4 deletions

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index fd3da1dda1c9..fedde5359a04 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -22,6 +22,69 @@ int direct_gbpages
 #endif
 ;
 
+int nx_enabled;
+
+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
+static int disable_nx __cpuinitdata;
+
+/*
+ * noexec = on|off
+ *
+ * Control non-executable mappings for processes.
+ *
+ * on      Enable
+ * off     Disable
+ */
+static int __init noexec_setup(char *str)
+{
+        if (!str)
+                return -EINVAL;
+        if (!strncmp(str, "on", 2)) {
+                __supported_pte_mask |= _PAGE_NX;
+                disable_nx = 0;
+        } else if (!strncmp(str, "off", 3)) {
+                disable_nx = 1;
+                __supported_pte_mask &= ~_PAGE_NX;
+        }
+        return 0;
+}
+early_param("noexec", noexec_setup);
+#endif
+
+#ifdef CONFIG_X86_PAE
+static void __init set_nx(void)
+{
+        unsigned int v[4], l, h;
+
+        if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
+                cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
+
+                if ((v[3] & (1 << 20)) && !disable_nx) {
+                        rdmsr(MSR_EFER, l, h);
+                        l |= EFER_NX;
+                        wrmsr(MSR_EFER, l, h);
+                        nx_enabled = 1;
+                        __supported_pte_mask |= _PAGE_NX;
+                }
+        }
+}
+#else
+static inline void set_nx(void)
+{
+}
+#endif
+
+#ifdef CONFIG_X86_64
+void __cpuinit check_efer(void)
+{
+        unsigned long efer;
+
+        rdmsrl(MSR_EFER, efer);
+        if (!(efer & EFER_NX) || disable_nx)
+                __supported_pte_mask &= ~_PAGE_NX;
+}
+#endif
+
 static void __init find_early_table_space(unsigned long end, int use_pse,
                                           int use_gbpages)
 {
@@ -158,12 +221,9 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
         use_gbpages = direct_gbpages;
 #endif
 
-#ifdef CONFIG_X86_32
-#ifdef CONFIG_X86_PAE
         set_nx();
         if (nx_enabled)
                 printk(KERN_INFO "NX (Execute Disable) protection: active\n");
-#endif
 
         /* Enable PSE if available */
         if (cpu_has_pse)
@@ -174,7 +234,6 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
                 set_in_cr4(X86_CR4_PGE);
                 __supported_pte_mask |= _PAGE_GLOBAL;
         }
-#endif
 
         if (use_gbpages)
                 page_size_mask |= 1 << PG_LEVEL_1G;