Use map_vm_area() instead of vmap() in text_poke() for avoiding page allocation
and delayed unmapping.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
---
 arch/x86/include/asm/alternative.h |    1 +
 arch/x86/kernel/alternative.c      |   25 ++++++++++++++++++++-----
 init/main.c                        |    3 +++
 3 files changed, 24 insertions(+), 5 deletions(-)

Index: linux-2.6/arch/x86/include/asm/alternative.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/alternative.h
+++ linux-2.6/arch/x86/include/asm/alternative.h
@@ -177,6 +177,7 @@ extern void add_nops(void *insns, unsign
  * The _early version expects the memory to already be RW.
  */
 
+extern void text_poke_init(void);
 extern void *text_poke(void *addr, const void *opcode, size_t len);
 extern void *text_poke_early(void *addr, const void *opcode, size_t len);
 
Index: linux-2.6/arch/x86/kernel/alternative.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/alternative.c
+++ linux-2.6/arch/x86/kernel/alternative.c
@@ -485,6 +485,16 @@ void *text_poke_early(void *addr, const 
 	return addr;
 }
 
+static struct vm_struct *text_poke_area[2];
+static DEFINE_SPINLOCK(text_poke_lock);
+
+void __init text_poke_init(void)
+{
+	text_poke_area[0] = get_vm_area(PAGE_SIZE, VM_ALLOC);
+	text_poke_area[1] = get_vm_area(2 * PAGE_SIZE, VM_ALLOC);
+	BUG_ON(!text_poke_area[0] || !text_poke_area[1]);
+}
+
 /**
  * text_poke - Update instructions on a live kernel
  * @addr: address to modify
@@ -501,8 +511,9 @@ void *__kprobes text_poke(void *addr, co
 	unsigned long flags;
 	char *vaddr;
 	int nr_pages = 2;
-	struct page *pages[2];
-	int i;
+	struct page *pages[2], **pgp = pages;
+	int i, ret;
+	struct vm_struct *vma;
 
 	if (!core_kernel_text((unsigned long)addr)) {
 		pages[0] = vmalloc_to_page(addr);
@@ -515,12 +526,16 @@ void *__kprobes text_poke(void *addr, co
 	BUG_ON(!pages[0]);
 	if (!pages[1])
 		nr_pages = 1;
-	vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
-	BUG_ON(!vaddr);
+	spin_lock(&text_poke_lock);
+	vma = text_poke_area[nr_pages-1];
+	ret = map_vm_area(vma, PAGE_KERNEL, &pgp);
+	BUG_ON(ret);
+	vaddr = vma->addr;
 	local_irq_save(flags);
 	memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
 	local_irq_restore(flags);
-	vunmap(vaddr);
+	unmap_kernel_range((unsigned long)vma->addr, (unsigned long)vma->size);
+	spin_unlock(&text_poke_lock);
 	sync_core();
 	/* Could also do a CLFLUSH here to speed up CPU recovery; but
 	   that causes hangs on some VIA CPUs. */
@@ -528,3 +543,4 @@ void *__kprobes text_poke(void *addr, co
 		BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]);
 	return addr;
 }
+EXPORT_SYMBOL_GPL(text_poke);
Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c
+++ linux-2.6/init/main.c
@@ -676,6 +676,9 @@ asmlinkage void __init start_kernel(void
 	taskstats_init_early();
 	delayacct_init();
 
+#ifdef CONFIG_X86
+	text_poke_init();
+#endif
 	check_bugs();
 
 	acpi_early_init(); /* before LAPIC and SMP init */