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

Pull x86 fixes from Thomas Gleixner:
 "A small set of changes:

   - a fixup for kexec related to 5-level paging mode. That covers most
     of the cases except kexec from a 5-level kernel to a 4-level
     kernel. The latter needs more work and is going to come in 4.17

   - two trivial fixes for build warnings triggered by LTO and gcc-8"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/power: Fix swsusp_arch_resume prototype
  x86/dumpstack: Avoid uninitlized variable
  x86/kexec: Make kexec (mostly) work in 5-level paging mode

4 files changed, 11 insertions, 3 deletions

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index afbecff161d1..a2d8a3908670 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -109,7 +109,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	struct stack_info stack_info = {0};
 	unsigned long visit_mask = 0;
 	int graph_idx = 0;
-	bool partial;
+	bool partial = false;
 
 	printk("%sCall Trace:\n", log_lvl);
 
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 307d3bac5f04..11eda21eb697 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -68,6 +68,9 @@ relocate_kernel:
 	movq	%cr4, %rax
 	movq	%rax, CR4(%r11)
 
+	/* Save CR4. Required to enable the right paging mode later. */
+	movq	%rax, %r13
+
 	/* zero out flags, and disable interrupts */
 	pushq $0
 	popfq
@@ -126,8 +129,13 @@ identity_mapped:
 	/*
 	 * Set cr4 to a known state:
 	 *  - physical address extension enabled
+	 *  - 5-level paging, if it was enabled before
 	 */
 	movl	$X86_CR4_PAE, %eax
+	testq	$X86_CR4_LA57, %r13
+	jz	1f
+	orl	$X86_CR4_LA57, %eax
+1:
 	movq	%rax, %cr4
 
 	jmp 1f
diff --git a/arch/x86/power/hibernate_32.c b/arch/x86/power/hibernate_32.c
index c35fdb585c68..afc4ed7b1578 100644
--- a/arch/x86/power/hibernate_32.c
+++ b/arch/x86/power/hibernate_32.c
@@ -145,7 +145,7 @@ static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
 #endif
 }
 
-int swsusp_arch_resume(void)
+asmlinkage int swsusp_arch_resume(void)
 {
 	int error;
 
diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
index f910c514438f..0ef5e5204968 100644
--- a/arch/x86/power/hibernate_64.c
+++ b/arch/x86/power/hibernate_64.c
@@ -174,7 +174,7 @@ out:
 	return 0;
 }
 
-int swsusp_arch_resume(void)
+asmlinkage int swsusp_arch_resume(void)
 {
 	int error;