Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  extable, core_kernel_data(): Make sure all archs define _sdata
  core_kernel_data(): Fix architectures that do not define _sdata

arch/alpha/kernel/vmlinux.lds.S

@@ -46,6 +46,7 @@ SECTIONS
 	__init_end = .;
 	/* Freed after init ends here */
 
+	_sdata = .;	/* Start of rw data section */
 	_data = .;
 	RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
 

arch/m32r/kernel/vmlinux.lds.S

@@ -44,6 +44,7 @@ SECTIONS
   EXCEPTION_TABLE(16)
   NOTES
 
+  _sdata = .;			/* Start of data section */
   RODATA
   RW_DATA_SECTION(32, PAGE_SIZE, THREAD_SIZE)
   _edata = .;			/* End of data section */

arch/m68k/kernel/vmlinux-std.lds

@@ -25,6 +25,8 @@ SECTIONS
 
   EXCEPTION_TABLE(16)
 
+  _sdata = .;			/* Start of data section */
+
   RODATA
 
   RW_DATA_SECTION(16, PAGE_SIZE, THREAD_SIZE)

arch/m68k/kernel/vmlinux-sun3.lds

@@ -25,6 +25,7 @@ SECTIONS
   _etext = .;			/* End of text section */
 
   EXCEPTION_TABLE(16) :data
+  _sdata = .;			/* Start of rw data section */
   RW_DATA_SECTION(16, PAGE_SIZE, THREAD_SIZE) :data
   /* End of data goes *here* so that freeing init code works properly. */
   _edata = .;

arch/mips/kernel/vmlinux.lds.S

@@ -65,6 +65,7 @@ SECTIONS
 	NOTES :text :note
 	.dummy : { *(.dummy) } :text
 
+	_sdata = .;			/* Start of data section */
 	RODATA
 
 	/* writeable */

arch/parisc/kernel/vmlinux.lds.S

@@ -69,6 +69,9 @@ SECTIONS
 	/* End of text section */
 	_etext = .;
 
+	/* Start of data section */
+	_sdata = .;
+
 	RODATA
 
 	/* writeable */

kernel/extable.c

@@ -72,6 +72,16 @@ int core_kernel_text(unsigned long addr)
 	return 0;
 }
 
+/**
+ * core_kernel_data - tell if addr points to kernel data
+ * @addr: address to test
+ *
+ * Returns true if @addr passed in is from the core kernel data
+ * section.
+ *
+ * Note: On some archs it may return true for core RODATA, and false
+ *  for others. But will always be true for core RW data.
+ */
 int core_kernel_data(unsigned long addr)
 {
 	if (addr >= (unsigned long)_sdata &&