Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[firefly-linux-kernel-4.4.55.git] / arch / x86 / include / asm / processor.h

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 2db56c57a2812952345ef97fff5f4222e5a45602..e08ea043e085c7a35882cf382dc218d17a97b00c 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -403,7 +403,17 @@ extern unsigned long kernel_eflags;
 extern asmlinkage void ignore_sysret(void);
 #else  /* X86_64 */
 #ifdef CONFIG_CC_STACKPROTECTOR
-DECLARE_PER_CPU(unsigned long, stack_canary);
+/*
+ * Make sure stack canary segment base is cached-aligned:
+ *   "For Intel Atom processors, avoid non zero segment base address
+ *    that is not aligned to cache line boundary at all cost."
+ * (Optim Ref Manual Assembly/Compiler Coding Rule 15.)
+ */
+struct stack_canary {
+       char __pad[20];         /* canary at %gs:20 */
+       unsigned long canary;
+};
+DECLARE_PER_CPU_ALIGNED(struct stack_canary, stack_canary);
 #endif
 #endif /* X86_64 */