9 files changed, 54 insertions, 7 deletions

diff --git a/arch/x86_64/Kconfig.debug b/arch/x86_64/Kconfig.debug
index e2c6e64a..fcb06a5 100644
--- a/arch/x86_64/Kconfig.debug
+++ b/arch/x86_64/Kconfig.debug
@@ -9,6 +9,16 @@ config INIT_DEBUG
 	  Fill __init and __initdata at the end of boot. This helps debugging
 	  illegal uses of __init and __initdata after initialization.
 
+config DEBUG_RODATA
+       bool "Write protect kernel read-only data structures"
+       depends on DEBUG_KERNEL
+       help
+	 Mark the kernel read-only data as write-protected in the pagetables,
+	 in order to catch accidental (and incorrect) writes to such const data.
+	 This option may have a slight performance impact because a portion
+	 of the kernel code won't be covered by a 2MB TLB anymore.
+	 If in doubt, say "N".
+
 config IOMMU_DEBUG
        depends on GART_IOMMU && DEBUG_KERNEL
        bool "Enable IOMMU debugging"
diff --git a/arch/x86_64/boot/.gitignore b/arch/x86_64/boot/.gitignore
new file mode 100644
index 0000000..495f20c
--- /dev/null
+++ b/arch/x86_64/boot/.gitignore
@@ -0,0 +1,3 @@
+bootsect
+bzImage
+setup
diff --git a/arch/x86_64/boot/tools/.gitignore b/arch/x86_64/boot/tools/.gitignore
new file mode 100644
index 0000000..378eac2
--- /dev/null
+++ b/arch/x86_64/boot/tools/.gitignore
@@ -0,0 +1 @@
+build
diff --git a/arch/x86_64/ia32/ia32entry.S b/arch/x86_64/ia32/ia32entry.S
index e0eb0c7..df0773c 100644
--- a/arch/x86_64/ia32/ia32entry.S
+++ b/arch/x86_64/ia32/ia32entry.S
@@ -341,7 +341,7 @@ ENTRY(ia32_ptregs_common)
 	jmp  ia32_sysret	/* misbalances the return cache */
 	CFI_ENDPROC
 
-	.data
+	.section .rodata,"a"
 	.align 8
 	.globl ia32_sys_call_table
 ia32_sys_call_table:
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 7519fc5..3060ed9 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -157,7 +157,7 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
 DECLARE_PER_CPU(int, cpu_state);
 
 #include <asm/nmi.h>
-/* We don't actually take CPU down, just spin without interrupts. */
+/* We halt the CPU with physical CPU hotplug */
 static inline void play_dead(void)
 {
 	idle_task_exit();
@@ -166,8 +166,9 @@ static inline void play_dead(void)
 	/* Ack it */
 	__get_cpu_var(cpu_state) = CPU_DEAD;
 
+	local_irq_disable();
 	while (1)
-		safe_halt();
+		halt();
 }
 #else
 static inline void play_dead(void)
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 750e01d..64c4534 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -42,6 +42,7 @@
 #include <linux/edd.h>
 #include <linux/mmzone.h>
 #include <linux/kexec.h>
+#include <linux/cpufreq.h>
 
 #include <asm/mtrr.h>
 #include <asm/uaccess.h>
@@ -1256,8 +1257,11 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_printf(m, "stepping\t: unknown\n");
 	
 	if (cpu_has(c,X86_FEATURE_TSC)) {
+		unsigned int freq = cpufreq_quick_get((unsigned)(c-cpu_data));
+		if (!freq)
+			freq = cpu_khz;
 		seq_printf(m, "cpu MHz\t\t: %u.%03u\n",
-			     cpu_khz / 1000, (cpu_khz % 1000));
+			     freq / 1000, (freq % 1000));
 	}
 
 	/* Cache size */
diff --git a/arch/x86_64/kernel/syscall.c b/arch/x86_64/kernel/syscall.c
index e263685..7c176b3 100644
--- a/arch/x86_64/kernel/syscall.c
+++ b/arch/x86_64/kernel/syscall.c
@@ -19,7 +19,7 @@ typedef void (*sys_call_ptr_t)(void);
 
 extern void sys_ni_syscall(void);
 
-sys_call_ptr_t sys_call_table[__NR_syscall_max+1] __cacheline_aligned = { 
+const sys_call_ptr_t sys_call_table[__NR_syscall_max+1] = {
 	/* Smells like a like a compiler bug -- it doesn't work when the & below is removed. */ 
 	[0 ... __NR_syscall_max] = &sys_ni_syscall,
 #include <asm-x86_64/unistd.h>
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index c016dfe..1faae5f 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -498,6 +498,29 @@ void free_initmem(void)
 	printk ("Freeing unused kernel memory: %luk freed\n", (__init_end - __init_begin) >> 10);
 }
 
+#ifdef CONFIG_DEBUG_RODATA
+
+extern char __start_rodata, __end_rodata;
+void mark_rodata_ro(void)
+{
+	unsigned long addr = (unsigned long)&__start_rodata;
+
+	for (; addr < (unsigned long)&__end_rodata; addr += PAGE_SIZE)
+		change_page_attr_addr(addr, 1, PAGE_KERNEL_RO);
+
+	printk ("Write protecting the kernel read-only data: %luk\n",
+			(&__end_rodata - &__start_rodata) >> 10);
+
+	/*
+	 * change_page_attr_addr() requires a global_flush_tlb() call after it.
+	 * We do this after the printk so that if something went wrong in the
+	 * change, the printk gets out at least to give a better debug hint
+	 * of who is the culprit.
+	 */
+	global_flush_tlb();
+}
+#endif
+
 #ifdef CONFIG_BLK_DEV_INITRD
 void free_initrd_mem(unsigned long start, unsigned long end)
 {
diff --git a/arch/x86_64/mm/pageattr.c b/arch/x86_64/mm/pageattr.c
index b90e8fe..35f1f1a 100644
--- a/arch/x86_64/mm/pageattr.c
+++ b/arch/x86_64/mm/pageattr.c
@@ -128,6 +128,7 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
 	pte_t *kpte; 
 	struct page *kpte_page;
 	unsigned kpte_flags;
+	pgprot_t ref_prot2;
 	kpte = lookup_address(address);
 	if (!kpte) return 0;
 	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
@@ -140,10 +141,14 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
  			 * split_large_page will take the reference for this change_page_attr
  			 * on the split page.
  			 */
-			struct page *split = split_large_page(address, prot, ref_prot); 
+
+			struct page *split;
+			ref_prot2 = __pgprot(pgprot_val(pte_pgprot(*lookup_address(address))) & ~(1<<_PAGE_BIT_PSE));
+
+			split = split_large_page(address, prot, ref_prot2);
 			if (!split)
 				return -ENOMEM;
-			set_pte(kpte,mk_pte(split, ref_prot));
+			set_pte(kpte,mk_pte(split, ref_prot2));
 			kpte_page = split;
 		}	
 		get_page(kpte_page);