x86: cleanup stack protector
Impact: cleanup
Make the following cleanups.
* remove duplicate comment from boot_init_stack_canary() which fits
better in the other place - cpu_idle().
* move stack_canary offset check from __switch_to() to
boot_init_stack_canary().
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
index 5976cd8..4a8c9d3 100644
--- a/arch/x86/include/asm/pda.h
+++ b/arch/x86/include/asm/pda.h
@@ -40,6 +40,4 @@
#endif
-#define refresh_stack_canary() write_pda(stack_canary, current->stack_canary)
-
#endif /* _ASM_X86_PDA_H */
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index c7f0d10..2383e5b 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -16,13 +16,12 @@
u64 tsc;
/*
- * If we're the non-boot CPU, nothing set the PDA stack
- * canary up for us - and if we are the boot CPU we have
- * a 0 stack canary. This is a good place for updating
- * it, as we wont ever return from this function (so the
- * invalid canaries already on the stack wont ever
- * trigger).
- *
+ * Build time only check to make sure the stack_canary is at
+ * offset 40 in the pda; this is a gcc ABI requirement
+ */
+ BUILD_BUG_ON(offsetof(struct x8664_pda, stack_canary) != 40);
+
+ /*
* We both use the random pool and the current TSC as a source
* of randomness. The TSC only matters for very early init,
* there it already has some randomness on most systems. Later
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index aa89eab..088bc9a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -638,13 +638,6 @@
percpu_write(kernel_stack,
(unsigned long)task_stack_page(next_p) +
THREAD_SIZE - KERNEL_STACK_OFFSET);
-#ifdef CONFIG_CC_STACKPROTECTOR
- /*
- * Build time only check to make sure the stack_canary is at
- * offset 40 in the pda; this is a gcc ABI requirement
- */
- BUILD_BUG_ON(offsetof(struct x8664_pda, stack_canary) != 40);
-#endif
/*
* Now maybe reload the debug registers and handle I/O bitmaps